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Are novel aryl phosphates competitors for bisphenol A bis(diphenyl phosphate) in halogen-free flame-retarded polycarbonate/acrylonitrile-butadiene-styrene blend?
Abstract
The reactivity of the flame retardant and its decomposition temperature control the condensed-
phase action in bisphenol A polycarbonate/acrylonitrile–butadiene–styrene/polytetrafluoroethylene
(PC/ABSPTFE) blends. Thus, to increase charring in the condensed
phase of PC/ABSPTFE + aryl phosphate, two halogen-free flame retardants were synthesized:
3,3,5-trimethylcyclohexylbisphenol bis(diphenyl phosphate) (TMC-BDP) and bisphenol A
bis(diethyl phosphate) (BEP). Their performance is compared to bisphenol A bis(diphenyl
phosphate) (BDP) in PC/ABSPTFE blend. The comprehensive study was carried out using
thermogravimetry (TG); TG coupled with Fourier transform infrared spectrometer (TGFTIR);
the Underwriters Laboratory burning chamber (UL 94); limiting oxygen index
(LOI); cone calorimeter at different irradiations; tensile, bending and heat distortion temperature
tests; as well as rheological studies and differential scanning calorimeter (DSC).
With respect to pyrolysis, TMC-BDP works as well as BDP in the PC/ABSPTFE blend by
enhancing the cross-linking of PC, whereas BEP shows worse performance because it
prefers cross-linking with itself rather than with PC. As to its fire behavior, PC/ABSPTFE +
TMC-BDP presents results very similar to PC/ABSPTFE + BDP; the blend PC/ABSPTFE + BEP
shows lower flame inhibition and higher total heat evolved (THE). The UL 94 for the materials
with TMC-BDP and BDP improved from HB to V0 for specimens of 3.2 mm thickness
compared to PC/ABSPTFE and PC/ABSPTFE + BEP; the LOI increased from around 24% up to
around 28%, respectively. BEP works as the strongest plasticizer in PC/ABSPTFE, whereas
the blends with TMC-BDP and BDP present the same rheological properties. PC/ABSPTFE +
TMC-BDP exhibits the best mechanical properties among all flame-retarded blends.
... E' at 30 C of r-PC/r-ABS/FR blends are higher than E' of r-PC/r-ABS blend (Table III), suggesting a reinforcing effect of the FRs BDP, TPP, and OPE at this temperature, which is characteristic of better compatibility and miscibility of phases ascribed to improved interactions between constituents of blends. Such an effect was already reported for virgin PC/ABS blends with 10 wt % of aryl phosphates, 40 phosphorus-containing POSS/PC composites, 41,42 and short glass fiber-reinforced PC/ABS composites with phosphorus-based FRs. 43 The FRs used enhance the storage modulus of r-PC/r-ABS/FR blends at 30 C differently, in the following order: BDP (2.25 GPa) < OPE (2.38 GPa) < TPP (2.49 ...
... These temperature shifts indicate a stabilizing effect of MBS on ABS phase and its compatibilization effect to the r-ABS/r-PC/OPE blend. Figure 7 shows the linear plots log r versus 1/T at different mass losses (10,20,30,40,50, 60, and 70%, and for r-PC/r-ABS/OPE/MBS blend also at 5, 15, 25, 45, 55, and 65% mass loss), where r is the heating rate (5, 10, 15, and 20 C min −1 ), T is absolute temperature (K), and R is universal gas constant (8.314 J mol −1 K −1 ). ...
The effects of three commercial aryl phosphate flame retardants (FRs; bisphenol A bis(diphenyl diphosphate) [BDP], triphenyl phosphate (TPP), and a proprietary oligomeric phosphate ester (OPE)) and a compatibilizer (methacrylate‐butadiene‐styrene copolymer [MBS]) on the thermal and mechanical properties of FR‐recycled PC/acrylonitrile‐butadiene‐styrene copolymer (r‐PC/r‐ABS) blends are investigated. The addition of FRs to r‐PC/r‐ABS blends increases the storage, tensile, and flexural moduli, indicating a reinforcing effect. However, at elevated temperatures, FRs reduce the glass transition temperature and act as plasticizers. The thermal stability of r‐PC/r‐ABS/FR blends at 10% mass loss increases in the following order: r‐PC/r‐ABS/TPP < r‐PC/r‐ABS/BDP < r‐PC/r‐ABS/OPE < r‐PC/r‐ABS/OPE/MBS. Kinetics of thermal decomposition of the FR r‐PC/r‐ABS blends is studied calculating the thermal decomposition activation energies by the Flynn–Wall–Ozawa method. Scanning electron microscopy shows that r‐PC/r‐ABS/OPE blend is only partly miscible, while homogeneous structure is formed in the r‐PC/r‐ABS/OPE/MBS blend, which is supported by its good mechanical and thermal properties. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48377.
... The effect of different phosphorus-based FRs, such as triaryl phosphates, resorcinol bis (diphenyl phosphate) (RDP), bisphenol A bis (diphenyl phosphate) (BDP) and red phosphorus (RP), in ABS blends are well-reported [11,12]. The flame-retardant efficiency of ammonium polyphosphate (APP) with the incorporation of other flame retardants such as pentaerythritol (PER) [13], poly-(4-nitrophenoxy)-phosphazene (DPP) [14], montmorillonite (MMT) [15] and aluminum diethylphosphinate (AlPi) [16] in ABS has been also previously studied. ...
The present work proposes to investigate the effect of an ultrahigh molecular weight silicone rubber (UHMW-SR) and two ethylene methyl acrylate copolymers (EMA) with different methyl acrylate (MA) content on the mechanical and fire performance of a fireproof acrylonitrile butadiene styrene copolymer (ABS) composite, with an optimum amount of ammonium polyphosphate (APP) and aluminum diethyl phosphinate (AlPi). ABS formulations with a global flame retardant weight content of 20 wt.% (ABS P) were melt-compounded, with and without EMA and UHMW-SR, in a Brabender mixer. During this batch process, ABS P formulations with UHMW-SR and/or EMA registered lower torque values than those of ABS P. By means of scanning electron microscopy (SEM), it was possible to observe that all ABS composites exhibited a homogenous structure without phase separation or particle agglomeration. Slightly improved interfacial interaction between the well-dispersed flame-retardant particles in the presence of EMA and/or UHMW-SR was also noticed. Furthermore, synergies in mechanical properties by adding both EMA and UHMW-SR into ABS P were ascertained. An enhancement of molecular mobility that contributed to the softening of ABS P was observed under dynamic mechanical thermal analysis (DMTA). An improvement of its flexibility, ductility and toughness were also registered under three-point-bending trials, and even more remarkable synergies were noticed in Charpy notched impact strength. Particularly, a 212% increase was achieved when 5 wt.% of EMA with 29 wt.% of MA and 2 wt.% of UHMW-SR in ABS P (ABS E29 S P) were added. Thermogravimetric analysis (TGA) showed that the presence of EMA copolymers in ABS P formulations did not interfere with its thermal decomposition, whereas UHMW-SR presence decreased its thermal stability at the beginning of the decomposition. Although the addition of EMA or UHMW-SR, as well as the combination of both in ABS P increased the pHRR in cone calorimetry, UL 94 V-0 classification was maintained for all flame-retarded ABS composites. In addition, through SEM analysis of cone calorimetry sample residue, a more cohesive surface char layer, with Si-O-C network formation confirmed by Fourier transform infrared (FTIR), was shown in ABS P formulations with UHMW-SR.
... The total heat evolved per total mass loss (THE/TML), a measure for the effective heat combustion of volatiles, was multiplied by the combustion efficiency during the cone calorimeter test. [20][21][22] a flame inhibition effect acted as the main fire retardancy mechanism, and an increase gas phase action was presented with the increase in the number of the aryl groups. The sequence of flame inhibition action was H-FR3 > H-FR2 > H-FR1. ...
The increased integration interaction of bis 9,10‐dihydro‐9‐oxa‐ 10‐phospaphenanthrene‐10‐oxide (DOPO) phosphonate (abbreviated as FR) including ethyl‐(FR1), phenethyl‐(FR2), naphthalene‐(FR3) with the aryl group and hexa‐phenoxy‐cyclotriphosphazene (HPCP) on flame‐retardant polyamide 6 (PA6) were investigated. The role of the aryl group in FR on flame‐retarding PA6 was analyzed. Results showed that PA6 composites with greatly reduced fire hazards possessed a high‐limiting oxygen index value of 34% and achieved a UL‐94 V‐0 rating and sharply decreased peak heat release rate by simultaneously adding FR and HPCP. Flame inhibition effect acted as the main mechanism for FR and HPCP in flame‐retarding PA6. Gas phase action increased with the number of aryl groups. HPCP played a catalytic effect in the condensed phase. Particularly, the result of residue analysis after cone test implied that char surface with network structure was formed, and the structure became compact and continuous with the increase in the number of aryl groups. Furthermore, the aryl group played an important role in aiding the PA6 composites in the construction of a network protective char layer on the surface during combustion.
... As portrayed in Figure 6, adding AHPP and DOPO into EP increases the char yield and strength. As is well-known, flame-retardant efficiency is not only dependent on the number of char residues but also their quality [44]. The spectra of char residue exhibit a similar shape including two peaks at 1590 and 1360 cm −1 . ...
Epoxy resin (EP) has widespread applications in thermosetting materials with great versatility and desirable properties such as high electrical resistivity and satisfactory mechanical properties. At present, 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) is widely applied to EP matrix for high flame resistance. Nevertheless, EP/DOPO composites acquire highly toxic decomposition products and smoke particles produced during combustion due to the gaseous fire-inhibition mechanism, which will be a major problem. To address this concern, an effective hyper-branched aluminum phosphonate (AHPP) was rationally designed and then coupled with DOPO into EP matrix to fabricate the fire-safe epoxy resin composites. On the basis of the results, significant increment in limiting oxygen index value (an achievement of 32% from 23.5% for pristine EP) and reduction in peak heat release rate and total heat release (59.4% and 45.6%) with the DOPO/AHPP ratio of 2:1 were recorded. During the cone calorimeter test, both the smoke production and total CO yield of EP-4 composite with the DOPO/AHPP ratio of 1:2 were dramatically decreased by 42.7% and 53.6%, which was mainly associated with the excellent catalytic carbonization of AHPP submicro-particles for EP composite. Future applications of submicro-scaled flame-retardant with various phosphorus oxidation states will have good prospects for development.
... These can be seen clearly from As the formation of a char protective layer is not only affected by its quantity but also controlled by its properties. 39 To further reveal the structure of the char residues, the Raman spectra are shown in Char (%) 5.2 7.7 8.0 ...
Multifunctional epoxy resins with excellent, thermal, flame‐retardant, and mechanical properties are extremely important for various applications. To solve this challenging problem, a novel highly efficient multielement flame retardant (PMSBA) is synthesized and the flame‐retardant and mechanical properties of modified epoxy resins are greatly enhanced without significantly altering their and thermal properties by applying the as‐synthesized PMSBA. The limiting oxygen index value reaches up to 29.6% and could pass the V‐0 rating in the UL‐94 test with even low P content (0.13%). Furthermore, cone calorimetry results demonstrate that 30.3% reduction in the peak heat release rate for the sample with 10.0 wt% PMSBA is achieved. X‐ray photoelectron spectroscopy and scanning electron microscopy indicate that Si‐C, Si‐N, and phosphoric acid derivative can be transformed into a multihole and intumescent char layer as an effective barrier, preserving the epoxy resin structure from fire. More importantly, mechanical properties such as impact strength, tensile strength, and flexural strength are also increased by 63.86%, 33.54%, and 15.65%, respectively, which show the incorporation of PMSBA do not deteriorate the mechanical properties of modified epoxy resins. All the results show that PMSBA is a promising strategy for epoxy resin with satisfactory, thermal, flame‐retardant, and mechanical properties.
... The graphitic structure of condensed-phased products of EP composites is characterized by Raman spectroscopy (Wawrzyn et al., 2012). Fig. 11 exhibits the Raman spectra of the exterior residues of EP and EP/AHPP composites. ...
... In forced flaming conditions, this trend was not clearly visible. However, as has been proven in previous experiments, 29 the residue yields of pure FRs in TGA experiments do not necessarily correlate with the residue yields of flame-retarded resins. Specifically, the interactions between FR and matrix govern the residue yield. ...
Flame retardants (FR) are inevitable additives to many plastics. Halogenated organics are effective FRs, but are controversially discussed, due to the release of toxic gases during a fire or their persistence if landfilled. Phosphorus-containing compounds are effective alternatives to halogenated FRs and have potential lower toxicity and degradability. Further, nitrogen-containing additives were reported to induce synergistic effects with phosphorus-based FRs. However, no systematic study on the gradual variation on a single phosphorus FR containing both P-O and P-N-moieties and their comparison to the respective blends of phosphates and phosphoramides was reported. This study developed general design principles for P-O and P-N-based FRs and will help to design effective FRs for various polymers. We synthesized a library of phosphorus FRs that only differ in their P-binding pattern from each other and studied their decomposition mechanism in epoxy resins. Systematic control over the decomposition pathways of phosphate (P=O(OR)3), phosphoramidate (P=O(OR)2(NHR)), phosphorodiamidate (P=O(OR)(NHR)2), phosphoramide (P=O(NHR)3) and their blends were identified, e.g. by reducing cis-elimination and the formation of P-N-rich char with increasing nitrogen content in the P-binding sphere. Our FR-epoxy resins can compete with commercial FRs in most cases, but we proved that the blending of esters and amides outperformed the single-molecule amidates/diamidates due to distinctively different decomposition mechanisms acting synergistically when blended.
... All polymers present good thermal stability in this study. Thermal decomposition region of these polymers matched with PC/ABS [10]. They may be a good flame retardant for PC/ABS alloy. ...
To overcome the disadvantage of liquid-phase flame retardant bisphenol A bis(diphenyl phosphate) (BDP) on processing and handling, two bisphenol A-derived solid polyphosphates, poly-phenoxyl bisphenol A phosphate (S-BDP) and poly-p-tolyl phenoxyl bisphenol A phosphate (PTPBP), were designed and synthesized from bisphenol A and dichlorophosphate by melting polymerization. PTPBP was different from S-BDP in a side-chain methyl group. The structures of polymers were characterized with FTIR, 1H-, 13C- and 31P-NMR. The molecular weight was determined by GPC. Thermal stabilities of polymers were studied by TGA. The results show that both polymers present good thermal properties. PTPBP is more stable than S-BDP at the beginning of decomposition, whereas at higher temperature the latter behaves better than the former. Furthermore, PTPBP gives more residue than S-BDP at the end of decomposition. It can, therefore, be concluded that thermal properties and char yield of compounds could be improved by increasing molecular weight and side-chain substituent. This knowledge will be helpful to design novel flame retardant.
Graphical abstract
Polyphosphate flame retardant can be prepared by simple melting polymerization. A side-chain methyl group will influence molecular weight and thermal stability of polymer. The phosphates represent good thermal stability under low-heat environment and maintain their structure up to 300 °C in this study. Open image in new window
... As shown in Fig. 7(A), besides the cut wavenumber range, the methane (CH 4 , $3016 cm À1 and $1304 cm À1 ), phenol derivatives ($3652 cm À1 for C aromatic -OH, $1603 cm À1 for C aromatic ]C aromatic , $1511 cm À1 for C aromatic -H, $1176 cm À1 for C aromatic -O), and carbonyl-containing substances ($1792 cm À1 for C]O, and $1236 cm À1 for C carbonyl -O) were the dominating products of decomposing neat PC within 30 wt% mass loss. 36,37 Among them, the ammable CH 4 and carbonyl-containing substances supplied fuels for the combustion of PC materials. Fortunately, as shown in Fig. 7(B), the addition of TDBA dramatically suppressed the production of CH 4 and carbonylcontaining substances from decomposing 10% TDBA/PC. ...
A multi-phosphaphenanthrene compound (TDBA) was incorporated into polycarbonate (PC) to prepare a flame retardant composite. TDBA improved the flame retardancy of the PC material effectively. The PC composite comprising 10 wt% TDBA passed the UL94 V-0 level with a LOI value of 33.7%. The incorporation of TDBA effectively inhibited the combustion intensity of the TDBA/PC composite via reducing the production of flammable methane and carbonyl-containing substances, suppressing the oxidative process of combustible pyrolysis products, and promoting the PC matrix to form large-scale smoke particles. All these were caused by releasing phosphaphenanthrene fragments, PO, and phenoxyl free radicals from pyrolyzed TDBA. As an additive-type flame retardant with multiple phosphaphenanthrene groups, TDBA was verified to exert its effect mainly in the gaseous phase during flame retarding of PC materials.
... The thermal degradation of printed ABS started at a lower temperature when impregnated with MA or MA/CNC mixture into printed ABS ( Fig. 5a and b), due to the relatively lower thermal stability of MA resin compared to ABS [32,33]. The onset temperature of impregnated ABS improved when adding CNC into the MA resin, compared to that without CNC, which can be attributed to the reaction between MA and CNC. ...
To improve the mechanical properties and reduce the heterogeneous properties of 3D printed materials, a novel structure inspired by wood microstructure was designed. A methacrylate (MA)/cellulose nanocrystal (CNC) mixture was impregnated into the structure (infill density controllable 3D printed structure) and cured at elevated temperature. The specific tensile strength and modulus increased considerably after impregnation, especially at 80% infill density. The morphology of printed composites indicated that good interfacial adhesion was obtained by impregnation of MA/CNC mixture and curing at elevated temperature. Thermal stability of the printed composites was also improved, as shown by increases in the temperature at maximum rate of weight loss and the glass transition temperature. Nanoindentation measurement showed that the printed sample was more homogeneous, as evidenced by the comparable elastic modulus and hardness at different positions of the sample.
... Nevertheless, if the phosphate esters are released into the gas phase instead of reacting with the decomposing polymer, they show high flame inhibiting effects [25,26]. Thus, phosphate flame retardants such as bisphenol-A bis(diphenyl phosphate) (BDP), triphenyl phosphate (TPP) and resorcinol bis(diphenyl phosphate) (RDP) have different flame inhibition effectiveness, due to variations in decomposition behavior and releasability [25,27]. Despite its flammability hazard, red phosphorus is used as a flame retardant as well. ...
Phosphorus-based flame retardants were incorporated into different, easily preparable matrices, such as polymeric thermoset resins and paraffin as a proposed model for polyolefins and investigated for their flame retardancy performance. The favored mode of action of each flame retardant was identified in each respective system and at each respective concentration. Thermogravimetric analysis was used in combination with infrared spectroscopy of the evolved gas to determine the pyrolysis behavior, residue formation and the release of phosphorus species. Forced flaming tests in the cone calorimeter provided insight into burning behavior and macroscopic residue effects. The results were put into relation to the phosphorus content to reveal correlations between phosphorus concentration in the gas phase and flame inhibition performance, as well as phosphorus concentration in the residue and condensed phase activity. Total heat evolved (fire load) and peak heat release rate were calculated based on changes in the effective heat of combustion and residue, and then compared with the measured values to address the modes of action of the flame retardants quantitatively. The quantification of flame inhibition, charring, and the protective layer effect measure the non-linear flame retardancy effects as functions of the phosphorus concentration. Overall, this screening approach using easily preparable polymer systems provides great insight into the effect of phosphorus in different flame retarded polymers, with regard to polymer structure, phosphorus concentration, and phosphorus species.
... The thermal degradation of printed ABS started at a lower temperature when impregnated with MA or MA/CNC mixture into printed ABS ( Fig. 5a and b), due to the relatively lower thermal stability of MA resin compared to ABS [32,33]. The onset temperature of impregnated ABS improved when adding CNC into the MA resin, compared to that without CNC, which can be attributed to the reaction between MA and CNC. ...
... However, the formation of a protective layer is not only controlled by its amount but also determined by its properties. 38 Even the properties of the char residues are more important than their amount at some level. To further investigate the graphitic structure of char residues, the spectra of the exterior char residues of EP composites are shown in Figure 9. ...
A novel flame retardant (FR) DOPO-PEPA, which was synthesized via Atherton-Todd reaction between 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10- oxide (DOPO) and 1-oxo-4-hydroxymethyl-2,6,7-trioxa-l-phosphabicyclo[2.2.2] octane (PEPA), was used as an additive-type FR in epoxy resin (EP). The results of the limiting oxygen index (LOI), vertical burning test, and cone calorimeter test indicated that the flame retardance of FR EP composites dependent on the chemical structure of phosphorus-based FRs. EP/DOPO-PEPA shows pretty good mechanical properties and a relatively high degree of crosslinking. Furthermore, the synergy as DOPO-PEPA was more efficient than DOPO or PEPA alone to flame retardant EP. When the FR additives were 9.1%, the EP/DOPO-PEPA acquired a LOI value of 35%, UL94 V-0 rating, and the lowest peak of heat release rate (PHRR) of 595 kW/m2. Furthermore，its continuous and firm char residue layer also reinforced this kind of action.
... Table 2 indicated that both T 5% and T max of PC/PhS decreased comparing with those of virgin PC, inferring that the addition of PhSs to PC lead to earlier thermal degradation of PC/PhS composites. GPC result showed that Mw of virgin PC before processing, virgin PC after processing and PC/PhS-1 (10 phr) was 2.85 Â 10 4 Da, 2.26 Â 10 4 Da and 1.939 Â 10 4 Da, inferring that in contrast to virgin PC, degradation of PC was caused in PC/PhS composites by the phosphonium sulfonates during processing, which may also contribute to the earlier thermal degradation of PC/PhS composites [42]. The residual at 700 C of PC/PhS was a little but not obviously higher comparing with that of virgin PC. ...
Phosphonium sulfonates (PhSs) as flame retardants have been synthesized from organic sulfonates and triphenylphosphine as starting materials. The PhSs revealed good thermal stability and efficient flame retardancy for polycarbonate (PC). The LOI values increased with the increase of PhS-1 contents to PC and reached 33.7 when the PhS-1 content is 10 phr, and the V-0 rating can be achieved when only 5 phr PhSs are added. The cone calorimeter analysis indicated that the HRR and THR were reduced with the addition of PhSs to the PC matrix. The PhS bearing alkene group revealed highest LOI values and lowest peak HRR (pHRR) values for PC. The morphology of the residual chars after LOI test and the element content of the chars after CONE test were also investigated by SEM and EDX.
... It shows that matching the decomposition temperature of PC promotes char formation from PC in the pyrolysis zone. 19,20 Marie-Claire Despinasse et al. found that using an aryl phosphate mixture of BDP and HDP to match the decomposition temperature of PC is possible to enhance the charring of PC in the condensed phase. 21 The temperature matching is also likely by varying the structure of the bridging unit or the end group of the aryl phosphate oligomers. ...
A novel series of flame retardants (FRs) containing phosphate moieties attached to a bridgehead-substituted adamantane, 1-(diphenyl phosphate) adamantane (DPAd), 1,3-bis(diphenyl phosphate) adamantane (BDPAd), 1,3,5-tris(diphenyl phosphate) adamantane (TDPAd) and 1,3,5,7-tetrakis(diphenyl phosphate) adamantane (TKDPAd), were systematically synthesized in an attempt to develop efficient FRs for polycarbonate (PC). Their chemical structures were confirmed by Fourier Transform Infrared Spectroscopy (FTIR), Nuclear Magnetic Resonance (1H and 31P NMR), elemental analysis and melting point measurements. The flame-retarding efficiencies of the FRs were evaluated by Limited Oxygen Index (LOI), UL-94 vertical burning experiments, Scanning Electron Microscopy (SEM), Cone Calorimeter Test (CCT), Thermogravimetric Analysis (TGA), FTIR and TGA-FTIR. For TKDPAd, thermal decomposition took place in a sharply two-step mechanism at high temperature above 381.5 °C. A significant improvement of flame-retardant performance in PC/TKDPAd among the PC/FR was observed with an addition of 8 wt% TKDPAd in the presence of an anti-dripping agent (0.1 wt%). High thermal stability and phosphorus content of flame retardant are believed to be of great importance for efficient flame-retardant action of adamantane-based phosphates.
... The peaks in the range of 7.0-7.8 ppm were attributed to the aromatic protons of diphenyl phosphate (Wawrzyn et al. 2012). The methyl protons of cellulose mixed ester appear at 1.8-2.1 ppm. ...
Using ionic liquid 1-allyl-3-methylimidazolium chloride as reaction medium, a series of novel cellulose esters containing phosphorus including cellulose diphenyl phosphate (C-Dp) and cellulose acetate (CA)–diphenyl phosphate mixed esters was synthesized homogeneously. The degree of substitution was well controlled by altering reaction conditions, such as the molar ratio of the acylating reagents/anhydroglucose unit and reaction time. The structure and thermal properties of cellulose esters were characterized by FTIR, NMR, wide-angle X-ray powder diffraction and differential scanning calorimetry. All the products possessed excellent solubility in some common organic solvents, and transparent films of cellulose esters were obtained by solution casting. In contrast to C-Dp, CA–diphenyl phosphate mixed esters showed clear glass transitions. More interestingly, these cellulose mixed esters exhibited thermoplastic behavior and could be processed by traditional melt processing methods.
... The shear stress versus shear rate and thus viscosity of PC/ ABS + BDP compared to PC/ABS as well as of PC/ABS + BDP + PTFE compared to PC/ABS + PTFE decrease by more than a factor of 4. For the analysis of dripping behaviour, the region of low shear rates is of principal interest. Only in this region does the addition of PTFE influence the curve shape, considerably changing the melt flow and dripping behaviour without deteriorating the improved processability [27]. Without PTFE, the shear stress decreases with decreasing shear rates. ...
An experimental and numerical investigation of the effect of bisphenol A bis(diphenyl phosphate) (BDP) and polytetrafluoroethylene (PTFE) on the fire behaviour of bisphenol A polycarbonate/acrylonitrile butadiene styrene (PC/ABS) in the vertical UL 94 scenario is presented. Four PC/ABS blends were discussed, which satisfy different UL 94 classifications due to the competing effects of gasification, charring, flame inhibition and melt flow/dripping. For numerical investigation, the particle finite element method (PFEM) is used. Its capability to model the complex fire behaviour of polymers in the UL 94 is analysed. The materials' properties are characterised, in particular the additives impact on the dripping behaviour during thermal exposure. BDP is an efficient plasticiser; adding PTFE prevents dripping by causing a flow limit. PFEM simulations reproduce the dripping and burning behaviour, in particular the competition between gasification and dripping. The thermal impact of both the burner and the flame is approximated taking into account flame inhibition, charring and effective heat of combustion. PFEM is a promising numerical tool for the investigation of the fire behaviour of polymers, particularly when large deformations are involved. Not only the principal phenomena but also the different UL 94 classifications and the extinction times are well predicted. Copyright © 2014 John Wiley & Sons, Ltd.
This investigation investigates the effects and mechanisms of mixed‐dimensional palygorskite clay (MDPal) on the thermal stability, flame retardancy and smoke suppression of polycarbonate/acrylonitrile‐butadiene‐styrene (PC/ABS) composites. MDPal, comprising palygorskite and illite as its main mineral components, is characterized by its interwoven morphology and the presence of Fe ions in its octahedral framework, making it highly promising for enhancing the fire safety of flammable composites. The incorporation of MDPal at a 10 wt% dosage leads to significant improvements in the fire safety of PC/ABS composites, including the reduction of 29.8% in peak heat release rate, 9.9% in total heat release, 34.5% in peak smoke production rate and 15.7% in total smoke production compared to pure PC/ABS. Besides, there is a notable increase of 31.5% in tensile strength and 80.4% in elongation at break when the content is 5 wt%. This research offers valuable insights into the application of MDPal for enhancing the thermal stability, flame retardancy and smoke suppression of flammable polymers.
Highlights
MDPal plays dual functions in gas and condensed phases as a flame retardant.
MDPal effectively reduces the heat and smoke release of PC/ABS composites.
MDPal improves the thermo‐stability and tensile strength of PC/ABS composites.
The flame‐retardant and smoke‐suppression mechanisms of PALC are elucidated.
This work investigates the effect of four different compatibilizers on the mechanical and thermal properties (impact, tensile strength, elongation, flexural modulus, and heat deflection temperature) of polycarbonate (PC)/acrylonitrile-butadiene-styrene (ABS) blends. The compatibilizers studied were styrene-ethylene-butylene-styrene (SEBS) grafted (g) with maleic anhydride (MAH), polystyrene (PS)-g-MAH, ABS-g-MAH, and ethylene-vinyl acetate (EVA)-g-MAH. The compatibility of the improved sample was also studied using scanning electron microscope images. In addition, the flammability of the improved sample with 8 % decabromodiphenyl ethane (DBDPE) as a flame-retardant (FR) additive was measured by limiting oxidation index and UL 94. The blends with a 70/30 ratio of PC/ABS and varying percentages of compatibilizers (1, 3, and 6 %) were prepared using a twin-screw extruder, and samples for mechanical tests were produced by injection molding. The mechanical properties indicated that PS-g-MAH was better than other compatibilizers. Compared with pure PC and ABS, the PC30P3-FR blend was an economical and versatile compound with potential applications in the electrical and electronic industries.
To investigate the effect of the distribution state of phosphophenanthrene groups within the branched structure on the flame retardant efficiency, the hyperbranched ester macromolecules Bz-DQMC-n (n = 1, 2, 3) capped with benzene rings were synthesized. The aggregation effect of phosphaphenanthrene groups in Bz-DQMC-n enhanced the flame retardancy of epoxy resins (EPs). At the same phosphorus contents of EPs, the Bz-DQMC-n/EP passed the V-0 rating, except for 2-(6-oxid-6H-dibenzo[c,e][1,2]oxaphosphorin-6-yl)-1,4-benzenediol (DOPO-HQ)/EP without aggregated phosphaphenanthrene groups, which only reached the V-1 rating in UL 94 test. The Bz-DQMC-2 showed a better flame inhibition effect. The limiting oxygen index (LOI) value of the Bz-DQMC-2/EP reached to 39.3%, and the peak heat release rate (pk-HRR) value was 563 kW/m², which decreased by 62.5% compared to neat EP. In addition, the total heat release (THR), and average effective heat of combustion (av-EHC) values of EP with Bz-DQMC-2 were also lower than that with Bz-DQMC-1 and Bz-DQMC-3 in the cone calorimetry test. The mechanism demonstrated that the aggregated phosphophenanthrene groups and benzene rings in Bz-DQMC-2 jointly promoted the formation of high-quality residue with more aromatic structures. Meanwhile, the concentrated release feature caused by group aggregation slightly enhanced the quenching effect in the gas phase. The aggregation effect of phosphophenanthrene groups in specific structures provides guidance for the development of high-efficiency DOPO-based flame retardants.
In the emerging applications of optoelectronics and mobile, it has always been an urgent problem in fire safety field to ensure the excellent transparency, water resistance and mechanical properties of flame retardant polycarbonate (PC). Unfortunately, the high-efficiency flame retardants used in PC often endow it with satisfied flame retardancy at the cost of the mechanical properties, transparency of composites. Hence, in this work, the high-quality pentaerythritol phosphate flame retardant (PBPP) was successfully prepared by novel synthesis method. The results indicated that the introduction of only 2 wt% PBPP and 0.1 wt% polytetrafluoroethylene (PTFE) enabled PC to obtain a UL-94 V-0 rating and the melt dripping of PC composites was inhibited during combustion. Meanwhile, the PC/PBPP composites still maintained its original transparency. With the introduction of PBPP, the PHRR and THR of PC/PBPP were reduced by 36.0% and 11.4%, respectively. This was mainly attributed to the catalytic charring and gas-phase suppression effect of PBPP. To our surprise, the introduction of PBPP obviously increased the tensile properties and ductility of PC composites. Besides, the PC/PBPP composites still retained excellent flame retardancy and mechanical performance before and after water resistance tests due to the hydrophobicity of PBPP and its excellent compatibility with the PC matrix. This work provided a simple and effective method to prepare PC composites with excellent water resistance, flame retardancy, transparency and mechanical enhancement, which possessed great significance for the application of PC composites in emerging fields.
A novel phosphorus-nitrogen-containing flame retardant (DOPT) has been successfully synthesized via the substitution reaction of cyanuric chloride, pentaerythritol phosphate and 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide. The chemical structure of DOPT was confirmed by ¹ H, ³¹ P and ¹³ C nuclear magnetic resonance, Fourier transform infrared spectroscopy and elemental analysis. Then, flame retardants were added to epoxy resin to prepare epoxy resin composites by pouring method. Thermal properties, flame retardancy, and combustion behavior of epoxy resin composites were evaluated by thermogravimetric analysis, vertical burning, limiting oxygen index and cone calorimeter test. Thermogravimetric analysis test showed that the carbon residue rate of DOPT at 800°C reached 52.53%, which indicated that the introduction of high-efficiency char-forming agent triazine and pentaerythritol phosphate groups could significantly improve its char-forming performance and thermal stability. The epoxy resin composite achieved vertical burning V-0 grade and the limiting oxygen index value reached 35.5% when 7 wt% DOPT was incorporated. Furthermore, the cone calorimeter test results manifested that the addition of DOPT stimulated degradation of the epoxy resin matrix during the combustion process and accelerated the formation of an expanded and dense carbon layer. Additionally, the incombustible gas produced during the decomposition of DOPT had played a flame-retardant effect in the gas phase. Hence, compared with neat epoxy resin, the total heat release and total smoke production of the EP-7 wt% DOPT composite decreased by 14.0% and 25.3%, respectively. Moreover, owing to the excellent compatibility and the strong interface effect between DOPT and epoxy resin, the addition of DOPT also enhanced the mechanical and fire resistance properties of the epoxy resin composite. Therefore, it is proposed that DOPT could be exploited as an economical and high-efficiency flame retardant, and it has considerable prospects in flame retardant epoxy resin composites.
In this study, the toxicity of combustion gases of polycarbonate/acrylonitrile butadiene styrene (ABS) blends that include aryl phosphates as flame‐retardants (FRs) was analyzed according to the European railway standard EN 45545‐2 (NBS chamber + FTIR). FRs have a significant influence on the evolution of the toxicity of gases generated during the combustion process. In the experiment, the asphyxiant hydrogen cyanide (HCN) was detected at the beginning of combustion (4 min of testing) as a product of ABS degradation. CO was generated throughout the test (8 min) because of the incomplete combustion of both the ABS and PC fractions. The presence of aryl phosphates promoted the inhibition of the flame. The reaction of PO·radicals in the gas phase resulted in OH·scavenging and a higher release of HCN and CO. The results suggest that aryl phosphates act in the first 4 min and do not have an effect later. FRs with lower thermal stability exhibited lower heat release and flame propagation but generated more toxic gases. This effect is attributed to the higher activity of the flame‐retardant in the gas phase. Further, additional fire performance parameters, including thermal stability (thermogravimetric analysis), flammability (UL94), and heat and smoke generation (cone calorimeter), were studied. It was found that aryl phosphates reduced the fire hazard, prevented the spread of the flame, reduced heat generation, increased the time to ignition, and, at the same time, promoted the emission of toxic gases that differ in function of the selected flame‐retardant.
Research focuses on developing a novel flame-retardant filament utilizing acrylonitrile–butadiene–styrene (ABS) and ammonium polyphosphate (APP) by the numerical approach using finite element analysis (FEM)-based software, COMSOL Multiphysics to overcome nozzle clogging and establish optimal three-dimensional (3D)-printing parameters. The developed FEM model enabled the numerical testing of differently shaped nozzles and proven the benefit of using a low-convergence angle (60°) nozzle because of the greater magnitude of pressure drop at nozzle tip compared with that of a high-convergence angle (120°) nozzle, a slightly better temperature distribution at the nozzle region, and smoother flow of the melted filament. Experimental tests results demonstrated the feasibility of using fused filament fabrication 3D printing to apply on ABS composite directly, and the printed samples retain their properties. An improvement in the burning test showed a V0 rating, thermal stability 13% at 800 °C, and the heat release rate of ∼390 W/g compared with neat ABS (∼501 W/g).
The pursuit of highly efficient phosphorous flame retardants for polymer-matrix composites is of great sense in industrial and academic community. In the contribution, a phosphorous-phosphorous (P-P) synergy between structurally well-defined phosphonium sulfonates (PhS) and triphenyl phosphate (TPP) or bisphenol A bis (diphenyl phosphate) (BDP) was specifically revealed in PC/ABS alloy. Compared with TPP and BDP loadings of respective 14 wt% and 12 wt% to pass UL-94 V-0, the mere 8 wt% FRs was required via an exceptional synergy of 2% allyl-substituted PhS and 6 wt% TPP (or BDP). In parallel, the studied P-P synergy reduced heat release rate and total heat release significantly. Deep mechanism analysis by solid NMR and Py/GC-MS unveiled a concurrent optimization of condensed-phase and vapor-phase effect. Additionally, the multifunctional reinforcement of tensile property, thermal resistance and hydrolytic resistance was sysmatically investigated. In perspective, the P-P synergy between structurally tailored PhSs and phosphates exploits a pathway for highly efficiently fire-safe polymers.
A range of flame retardant vinyl ester resins (VERs) samples have been produced containing different contents of PEPA (1‐oxo‐4‐hydroxymethyl‐2,6,7‐trioxa‐l‐phosphabicyclo[2.2.2]octane), APP (ammonium polyphosphate), and MoO3 (molybdenum trioxide). By investigating the flame retardancy of VER samples such as limiting oxygen index and UL‐94, the synergistic flame retardance of APP, PEPA, and MoO3 has been revealed. The cone calorimeter is an instrument that measures the combustion data of samples. In the VER composites on fire, the synergistic smoke suppression effect of the APP, PEPA, and MoO3 was detected. The gas and condensed phase of VER composites with APP, PEPA, and MoO3 were tested by the thermogravimetric analysis (TGA)–Fourier transform infrared spectroscopy (FTIR) and FTIR. The char residues of samples have been studied at length by scanning electron microscopy and FTIR. The results show that the presence of MoO3 can promote the formation of PO and PO structures.
We synthesized a library of phosphorus-based flame retardants (phosphates and phosphoramides of low and high molar mass) and investigated their behavior in two epoxy resins (one aliphatic and one aromatic). The pyrolytic and burning behavior of the two resins (via TGA, TG-FTIR, Hot stage FTIR, Py-GC/MS, PCFC, DSC, LOI, UL-94, Cone calorimeter) are analyzed and compared to the results of flame retardant (FR)-containing composites. A decomposition pathway incorporating the identified modes of action and known chemical mechanisms is proposed. The overlap of decomposition temperature (Tdec) ranges of matrix and FR determines the efficacy of the system. Low molar mass FRs strongly impact material properties like Tg but are very reactive, and high molar mass variants are more thermally stable. Varying P–O and P–N content of the FR affects decomposition, but the chemical structure of the matrix also guides FR behavior. Thus, phosphates afford lower fire load and heat release in aliphatic epoxy resins, and phosphoramides can act as additives in an aromatic matrix or a reactive FRs in aliphatic ones. The chemical structure and the structure-property relationship of both FR and matrix are central to FR performance and must be viewed not as two separate but as one codependent system.
Molybdenum disulfide (MoS2) with two‐dimensional (2D) lamellar structure was functionalized with melamine‐cyanuric acid (MCA) hybrids via a facile way. A core‐shell composite particle (MoMA) was obtained. Acting as one kind of synergistic flame retardant, it was mixed with traditional intumescent flame retardant (IFR) to prepare the flame retardant poly(lactic acid) composites by melt blending. UL‐94 V‐0 rating and LOI value of 29.8% for PLA composites were achieved while the total amount of flame retardants was 12 wt%, with the optimal weight ratio of IFR to MoMA 3:1. The inclusion of MoMA can enhance the amount of char residue and suppress the pyrolysis rate. The thermal degradation kinetic studies indicated that more pyrolysis conversion energy was needed. Finally, the investigation of char residue further confirmed that the addition of MoMA can improve the continuity and thermal stability of intumescent char layer and promote its graphitization degree. The condensed phase mechanism was mainly responsible for the improved flame retardant performance. This work suggests a novel strategy for improving flame retardant performance of PLA by combination of MoMA with IFR. The mechanical properties were studied as well. POLYM. COMPOS., 2018. © 2018 Society of Plastics Engineers
Flame retarded thermoplastic elastomers (TPE-S) based on styrene-ethylene-butylene-styrene, polypropylene, and mineral oil are a challenging task, due to their very high fire loads and flammability. A promising approach is the synergistic combination of expandable graphite (EG) and ammonium polyphosphate (APP). Cone calorimeter, oxygen index, and UL 94 classification were applied. The optimal EG:APP ratio is 3:1, due to the most effective fire residue morphology. Exchanging APP with melamine-coated APPm yielded crucial improvement in fire properties, whereas replacing EG/APP with melamine polyphosphate did not. Adjuvants, such as aluminum diethyl phosphinate (AlPi), zinc borate, melamine cyanurate, titanium dioxide, dipentaerylthritol, diphenyl-2-ethyl phosphate, boehmite, SiO2, chalk, and talcum, were tested. All flame retardants reinforced the TPE-S. The combination with AlPi is proposed, since with 30 wt% flame retardants a MARHE below 200 kWm-2 and aV-0 rating was achieved. Multicomponent EG/APP/adjuvants systems are proposed as a suitable route to achieve efficient halogen-free flame retarded TPE-S.
In this study, we report influence of exfoliated graphene nanoplatelets on the flame retardancy and thermal properties of hybrid kenaf flour graphene nanoplatelets polypropylene nanocomposites. Mass loss calorimeter, Limiting oxygen index and Universal laboratories-94-V fire test instruments were employed for flammability investigations. Fire results revealed improved flame retardancy of composites through enhanced fire performance index, prolonged time to ignition and reduced fire growth index. Heat release rate, peak heat release rate, time to peak heat release rate, mass loss rate and total heat release rate essential for the protection of human lives and properties during actual fire scenario were enhanced. Incorporation of graphene nanoplatelets improved flame retardancy of the materials. The GNP char structure improved flame retardancy by acting as heat shield and protective layering on surface of the materials thereby hindering transfer of oxygen and heat from the fire region to the underlying matrix while simultaneously inhibiting the penetration of flammable gases from underlying matrix to the combustion zone thereby cutting-off the fire track.
Two flame retardants, aluminium poly-hexamethylenephosphinate (APHP) and bisphenol-A bis(diphenyl phosphate) (BDP), were incorporated into diglycidyl ether of bisphenol A (DGEBA) thermoset with 4,4'-diaminodiphenyl sulfone (DDS) as curing agent, and then the synergistic flame-retardant behaviors of the cured thermosets were investigated. Compared with thermosets containing 10 wt% APHP and 10 wt% BDP alone, the sample with 3.3 wt% APHP and 6.7 wt% BDP (3.3%APHP/6.7%BDP/EP; EP is DGEBA/DDS) possessed a better flame-retardant effect since its limited oxygen index reached 35.0% and in the UL94 test it passed the V-0 rating. The cone calorimeter test revealed that the 3.3%APHP/6.7%BDP/EP sample generated less gaseous fragments and more smoke particles instead of fuels and verified that APHP and BDP exhibited an outstanding synergistic effect on the barrier effect. Macroscopic digital photos and micrographs from scanning electron microscopy further disclose that BDP facilitated the formation of a flexible film covering holes in the residue. The flexible film was combined with aluminium phosphate particles which were produced by decomposed APHP, thereby forming a char layer with increased barrier effect. The synergistic barrier effect from APHP and BDP imposed a better flame-retardant performance for epoxy thermosets.
Hexakis(4-nitrophenoxy) cyclotriphosphazene (HNTP) and oligomeric bisphenol A bis(diphenyl phosphate) (BDP), phosphorous-containing flame retardant, were mixed into polycarbonate (PC) together as intumescent flame retardancy (IFR) system. The flame retardancy and thermal decomposition behavior of composites were studied with the limiting oxygen index(LOI), UL-94 vertical burning test, microscale combustion calorimeter(MCC) and thermogravimetric analysis(TGA). The results showed the LOI of IFR system increased by 1.68 times compared with pure PC. The addition of HNTP and BDP accelerated the first decomposition peak but weaken the second decomposition peak to improve the flame retardancy of PC. Furthermore, TGA coupled with fourier transform infrared(TGA/FTIR) was used to research the gaseous products. Scanning electron microscopy (SEM) analyses and FTIR spectroscopy were used to study the structure of residual char. The results showed that HNTP and BDP formed continuous bubbles on the surface of PC during burning and exhibited synergistic effects on thermal stability of PC.
In this study, a halogen-free phosphorous-nitrogen synergistic flame retardant, poly-N-aniline-phenyl phosphamide (PDPPD), was synthesized. Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, and elemental analysis data confirmed the structure of PDPPD. The essential FR PA66 was polymerized with PA66 pre-polymer and PDPPD pre-polymer, prepared from PDPPD and adipic acid. The limit oxygen index and UL-94 test results of FR PA66 reached 28% and V-0, respectively, when the contents of PDPPD pre-polymer were 4.5 wt%. The thermo-gravimetric and differential scanning calorimetry results demonstrated that the initial decomposition temperature of FR PA66 was 43 °C lower than that of pristine PA66 from 385 to 342 °C; however, the peak decomposition temperature was 36 °C higher than that of pure PA66 from 437 to 473 °C, when the contents of PDPPD pre-polymer reached 4.5 wt%. Flame retardant mechanism was studied by cone calorimeter testing and SEM-EDX, confirming that the heat release rate (HRR), total heat release (THR), and total smoke product (TSP) decreased slightly, and PDPPD followed the gas phase flame retardant mechanism. Copyright
Pyrolysis, flammability, fire behavior, melt viscosity, and gas diffusion of bisphenol A polycarbonate/acrylonitrile-butadiene-styrene (PC/ABS) were investigated, with bisphenol A bis(diphenyl phosphate) (BDP), with 10 wt.% talc and with BDP in combination with 5, 10 and 20 wt.% talc, respectively. Compared to PC/ABS, PC/ABS + BDP results in an increased decomposition temperature of PC, a higher char yield, a significantly increased LOI, a V-0 classification in UL 94, a reduced peak heat release rate (pHRR), and a reduced total heat release (THR) in the cone calorimeter. This efficient flame retardancy is due to mechanisms in both the gas and condensed phases. PC/ABS + 10 wt.% talc shows a decrease in the PC decomposition temperature. The fire behavior is improved in part compared to PC/ABS, with an increased LOI and reduced pHRR. PC/ABS + BDP + 10 wt.% talc shows a strong synergism in LOI, a V-0 classification, and a decrease in pHRR, whereas THR is slightly increased compared to PC/ABS + BDP. Talc decreases the gas diffusion and enhances the flow limit for low shear rates, both of which influence the pyrolysis and flammability results. Further, talc improves the protection properties of the fire residues. Nevertheless it also partly suppresses flame inhibition and the charring effect of BDP. The synergism between BDP and talc in LOI is obtained even for low talc loadings in PC/ABS + BDP + talc, whereas for higher loadings saturation is observed.
A novel phosphorus-containing compound diphenyl-(1, 2-dicarboxylethyl)-phosphine oxide defined as DPDCEPO was synthesized and used as a flame retardant curing agent for epoxy resins (EP). The chemical structure of the prepared DPDCEPO was well characterized by Fourier transform infrared spectroscopy, and 1H, 13C and 31P nuclear magnetic resonance. The DPDCEPO was mixed with curing agent of phthalic anhydride (PA) with various weight ratios into epoxy resins to prepare flame retardant EP thermosets. The flame retardant properties, combustion behavior and thermal analysis of the EP thermosets were respectively investigated by limiting oxygen index (LOI), vertical burning tests (UL-94), cone calorimeter measurement, dynamic mechanical thermal analysis and thermogravimetric analysis (TGA) tests. The surface morphologies and chemical compositions of the char residues for EP thermosets were respectively investigated by scanning electron microscopy and X-ray photoelectron spectroscopy (XPS). The water resistant properties of the cured EP were evaluated by putting the samples into distilled water at 70°C for 168hr. The results revealed that the EP/20wt% DPDCEPO/80wt% PA thermosets successfully passed UL-94 V-0 flammability rating and the LOI value was as high as 33.2%. The cone test results revealed that the incorporation of DPDCEPO effectively reduced the combustion parameters of the epoxy resin thermosets, such as heat release rate and total heat release. The dynamic mechanical thermal analysis test demonstrated that the glass transition temperature (Tg) decreased with the increase of DPDCEPO content. The TGA results indicated that the incorporation of DPDCEPO promoted the decomposition of epoxy resin matrix ahead of time and led to a higher char yield and thermal stability at high temperatures. The surface morphological structures and analysis of the XPS of the char residues of EP thermosets revealed that the introduction of DPDCEPO benefited the formation of a sufficient, compact and homogeneous char layer with rich flame retardant elements on the epoxy resin material surface during combustion. The mechanical properties and water resistance of the cured epoxy resins were also measured. After water resistance tests, the EP/20wt% DPDCEPO/80wt% PA thermosets retained excellent flame retardancy, and the moisture adsorption of the EP thermosets decreased with the increase of DPDCEPO content in EP thermosets because of the existence of the P-C bonds and the rigid aromatic hydrophobic structure in DPDCEPO.
Condensed-phase mechanisms play a major role in fire-retardant polymers. Generations of development have followed the concept of charring to improve fire properties. Whereas the principal reactions are believed to be known, the specific description for multicomponent systems is lacking, as is the picture across different systems. A two-step approach is proposed in general, and also presented in greater detail. The second step covers the specific reactions controlling charring, whereas the actual reactants are provided in the preceding step. This model consistently incorporates the variety of structure–property relationships reported. A comprehensive case study is presented on seven phosphorus flame retardants in two epoxy resins to breathe life into the two-step approach.
PC/ABS nanocomposites have been developed using a mixture of acid functionalized multiwalled carbon nanotubes (f-MWCNT) and aminoproply triethoxysilane-treated cenospheres. The mechanical and flammability characteristics have been determined as per ASTM standards. The addition of a small quantity (∼1%) of MWCNT further enhanced the compressive strength by 70% while the compressive modulus doubled. The use of macrofiller in combination with the nanofillers led to synergism as observed by reduction of mean heat release rates for these composites. The formation of char residues and a uniform char layer has also been observed by thermogravimetric analysis and cone calorimetry. Both fillers were surface treated which in turn led to improved interfacial adhesion as analyzed by micromechanical models. POLYM. COMPOS., 2015. © 2015 Society of Plastics Engineers
Tri(2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane-1-oxo-4-hydroxymethyl) phenylsilane (TPPSi) was employed as a flame retardant and polydimethylsiloxane-g-styrene-g-methyl methacrylate copolymer (PSM) as a compatibilizer in polycarbonate-acrylonitrile-butadiene-styrene (PC-ABS) blends. The effect of TPPSi and PSM on the flame retardancy and compatibilization of PC-ABS was investigated by UL-94 vertical burning tests, DMA and SEM. The results indicated that the PC-ABS blend with 8 wt% TPPSi and 5 wt% PSM possessed both high flame retardancy and impact strength. It was found that PSM played an effective compatibilization role in the PC-ABS-TPPSi blend and elevated the thermal stability of the blend. A synergistic flame-retardant mechanism between phosphorus and silicon was presented by TGA, SEM/EDX analysis, FT-IR and Raman spectra of the residue.
A structurally novel hyperbranched halogen-free poly(phosphoester) (hbPPE) is proposed as a flame retardant in poly(ester)s and epoxy resins. hb polymeric flame retardants combine several advantages that make them an extraordinary approach for future flame retardants. hbPPE was synthesized by olefin metathesis polymerization according to a straightforward two-step protocol. The impact of hbPPE on pyrolysis, flammability (reaction-to-small-flame), and fire behavior under forced flaming conditions (cone calorimeter) was investigated for a model substance representing poly(ester)s, i.e. ethyl 4-hydroxybenzoate, and an epoxy resin of bisphenol A diglycidyl ether cured with isophorone diamine. The flame retardancy performance and mechanisms are discussed and compared to a commercial bispenhol A bis(diphenyl phosphate) (BDP). Both hbPPE and BDP combined gas-phase and condensed-phase activity; hbPPE is the more efficient flame retardant, and is proposed to be efficient in a greater variety of polymeric matrices. The hydrolysis of hbPPE is suggested to produce phosphorous acids, which, when available at the right temperatures, enhance the charring of the polymer in the condensed phase. The better fire protection behavior of the hbPPE is due not only to its higher phosphorus content, but also to the higher efficiency of the phosphorus it contains
Herein, we examine the influence of adding functionalized graphene (FG), distinct expanded graphites and carbon nanofillers such as carbon black and multiwall carbon nanotubes on mechanical properties, morphology, pyrolysis, response to small flame and burning behavior of a V‐2 classified flame‐retarded polypropylene (PP). Among carbon fillers, FG and multilayer graphene (MLG) containing fewer than 10 layers are very effectively dispersed during twin‐screw extrusion and account for enhanced matrix reinforcement. In contrast to the other fillers, no large agglomerates are detected for PP‐FR/FG and PP‐FR/MLG, as verified by electron microscopy. Adding FG to flame‐retardant PP prevents dripping due to reduced flow at low shear rates and shifts the onset of thermal decomposition to temperatures 40°C higher. The increase in the onset temperature correlates with the increasing specific surface areas (BET) of the layered carbon fillers. The reduction of the peak heat release rate by 76% is attributed to the formation of effective protection layers during combustion. The addition of layered carbon nanoparticles lowers the time to ignition. The presence of carbon does not change the composition of the evolved pyrolysis gases, as determined by thermogravimetric analysis combined with online Fourier‐transformed infrared measurements. FG and well‐exfoliated MLG are superior additives with respect to spherical and tubular carbon nanomaterials. Copyright © 2013 John Wiley & Sons, Ltd.
In this study, standard test specimens with flame-retarded short glass fiber-reinforced PC/ABS materials were fabricated under rapid thermal cycle injection molding condition by selecting a potassium perfluorobutane sulfonate flame retardant specially used for PC, FR2025, and two kinds of aryl phosphorus halogen-free flame retardants, UN707 and PX-220. The flame-retardancy effect of the above different flame retardants on the studied systems was compared through combustion tests of the specimens. Meanwhile, the thermal and mechanical properties of flame-retarded composites were studied by using the thermogravimetry analysis, dynamic mechanical thermal analysis (DMTA), and universal testing machine. The results show that the “candlewick effect” of fibers exacerbates the fire behavior of composites. With the increase of the aryl phosphorus halogen-free flame retardants, the flame-retardancy effect of composites is obviously improved, and the maximum thermal degradation rate of composites is significantly decreased. The UL94 combustion rating is improved, and the time of residual flame is substantially reduced with the increase of PC content under the same content of flame retardant. The DMTA results show that the flame retardants have a reinforcement action on PC/ABS matrix. However, the macroscopic mechanical properties are slightly decreased in the glass fiber-reinforced composites because of the destructive effect of the flame retardants on the interface compatibility between matrix and fibers; the scanning electron microscopic micrographs of tensile fracture fully prove this action mechanism of flame retardants. In addition, the addition of toughener and antidripping additive significantly affects the flame retardancy and mechanical properties of composites. POLYM. COMPOS., 2014. © 2014 Society of Plastics Engineers
The characteristic influences of increasing concentrations of graphene, expanded graphite (EG), carbon black (CB), and multiwall carbon nanotubes (MWNT) are investigated on pyrolysis, reaction to small flame, burning behavior, and on electrical, thermal, and rheological properties of flame retarded polypropylene (PP-FR). The property-concentration dependency is different for the various material properties, as threshold, linear, and leveling off functions were observed. Increasing concentrations of carbon nanoparticles resulted in a decrease in the electrical resistivity of the polymer by crossing the percolation threshold. The developing nanoparticle network changes melt flow behavior for small shear rates, increases thermal conductivity and therefore, affects the UL 94 classification and oxygen index. The onset temperature of PP decomposition is shifted to temperatures up to 37°C higher; the peak heat release rate is reduced by up to 74% compared to PP-FR. Both effects leveled off with increasing particle concentration. Among the four carbon nanomaterials tested, graphene presents superior influence on composite properties over the tested concentration range and outperforms commercial CB, MWNT, and EG. POLYM. COMPOS., 2014. © 2014 Society of Plastics Engineers
The pyrolysis and fire performance of bisphenol A polycarbonate/acrylonitrile-butadiene-styrene (PC/ABS) flame-retarded by a mixture of two aryl bisphosphates were investigated by thermogravimetry-coupled with FTIR, oxygen index (LOI), UL 94 and cone calorimeter. Both flame retardants, bisphenol A bis (diphenyl phosphate) BDP and hydroquinone bis (diphenyl phosphate) HDP, show gas-phase and condensed-phase actions. When mixed together at different ratios, a synergy is observed in terms of pyrolysis and fire residues as well as in effective heat of combustion (THE/ML). The synergisms were quantified and confirmed mathematically by the evaluation of the synergistic effect index (SE). All LOI values for the flame-retarded blends are between 29% and 32%, as opposed to 23% for PC/ABS, and UL94 testing results in V-0 at 1.6 mm instead of HB. Investigations on the binary system BDP + HDP reveal that BDP and HDP interact with each other, yielding stable intermediate products which are proposed to increase the thermal stability of the PC/ABS + BDP/HDP blends. Oligomeric phosphate esters are presumed to form via transesterification.
The polycarbonates, intrinsically rather flame retardant, have been further flame retarded with various bromoaromatic additives, such as tetrabromobisphenol-A polycarbonate. Other bromine additives used include brominated epoxy condensates and brominated polystyrenes. Sodium or potassium sulfonates, such as potassium perfluorobutylsulfonate, potassium diphenylsulfonesulfonate and sodium trichlorobenzenesulfonate are effective in very low loadings to meet less stringent flame retardancy. The first two allow for transparency. The blends of polycarbonate and poly(acrylonitride butadiene styrene) (ABS) are widely used for flame-retardant electrical and electronic enclosures. The major flame retardants used at present in the blends are tetraphenyl resorcinol diphosphate and tetraphenyl bisphenol-A diphosphonate (both with oligomers).
Different kinds of additive and reactive flame retardants containing phosphorus
are increasingly successful as halogen-free alternatives for various polymeric materials and
applications. Phosphorus can act in the condensed phase by enhancing charring, yielding
intumescence, or through inorganic glass formation; and in the gas phase through flame
inhibition. Occurrence and efficiency depend, not only on the flame retardant itself, but also
on its interaction with pyrolysing polymeric material and additives. Flame retardancy is
sensitive to modification of the flame retardant, the use of synergists/adjuvants, and changes
to the polymeric material. A detailed understanding facilitates the launch of tailored and
targeted development.
There is little consensus within the fire science community on interpretation of cone calorimeter data, but there is a significant need to screen new flammability modified materials using the cone calorimeter. This article is the result of several discussions aiming to provide guidance in the use and interpretation of cone calorimetry for those directly involved with such measurements. This guidance is essentially empirical, and is not intended to replace the comprehensive scientific studies that already exist. The guidance discusses the fire scenario with respect to applied heat flux, length scale, temperature, ventilation, anaerobic pyrolysis and set-up represented by the cone calorimeter. The fire properties measured in the cone calorimeter are discussed, including heat release rate and its peak, the mass loss and char yield, effective heat of combustion and combustion efficiency, time to ignition and CO and smoke production together with deduced quantities such as FIGRA and MARHE. Special comments are made on the use of the cone calorimeter relating to sample thickness, textiles, foams and intumescent materials, and the distance of the cone heater from the sample surface. Finally, the relationship between cone calorimetry data and other tests is discussed. Copyright © 2007 John Wiley & Sons, Ltd.
The role played by inorganic chemical additives in fire retardancy and flame inhibition is considered. Particular attention is given to the molecular level aspects of commercially important systems containing compounds of antimony, halogens, and phosphorus. The flame inhibiting function of metal containing additives is also discussed.
En se basant sur le fait que la Tg d'un polycarbonate aromatique est inversement proportionnelle a la mobilite conformationnelle du fragment carbonate, les homo- et copolycarbonates du 4,4'-(3,3,5-trimethylcyclohexylidene) diphenol (1) et du bisphenol A sont prepares. Le polycarbonate de (1) a une Tg superieure de 60 o C a celle du polycarbonate du bisphenol A. Les homo- et copolymeres presentent aussi de bonnes proprietes mecaniques, rheologiques et une bonne stabilite aux UV
The thermal degradation of polycarbonate under nitrogen was studied using TGA/FTIR, GC/MS and LC/MS as a function of mass loss. The gases evolved during degradation were inspected by in situ FTIR and then the evolved products were collected and analysed using FTIR, GC–MS and LC–MS. The structures of the evolved products are assigned on the basis of FTIR and GC/MS results. The main thermal degradation pathways follow chain scission of the isopropylidene linkage, and hydrolysis/alcoholysis and rearrangement of carbonate linkages. In the case of chain scission, it was proposed that methyl scission of isopropylidene occurs first, according to the bond dissociation energies. The presence of carbonate structures, 1,1′-bis(4-hydroxyl phenyl) ethane and bisphenol A in significant amounts, supports the view that chain scission and hydrolysis/alcoholysis are the main degradation pathways for the formation of the evolved products.
The thermal degradation of acrylonitrile-butadiene-styrene (ABS) terpolymer has been studied by TGA/FTIR. The degradation of ABS is compared with that of polystyrene, polybutadiene, polyacrylonitrile (PAN), and styreneacrylonitrile (SAN) copolymer. A small amount of acrylonitrile monomer is eliminated from PAN, SAN, and ABS. The grafting of butadiene on to SAN stabilizes the butadiene structure, since the evolution of butadiene begins 50 °C higher than in the homopolymer. The evolution of aromatics begins about 20 °C lower in ABS than in SAN, so the presence of the butadiene destabilizes SAN. The evolution of acrylonitrile begins at essentially the same temperature in ABS as in SAN. There are some significant effects on the degradation produced by grafting SAN onto polybutadiene but the degradation may be understood by considering the degradation of its components.
Polycarbonate together with the acrylonitrile/butadiene/styrene copolymers, and the poly amides constitute the leading groups of engineering thermoplastics; for polycarbonate in particular, continued dynamic growth is prophesized.
The underlying reason for this lies not only in its outstanding combination of technical properties and excellent price/performance balance, but also in the chemical and physical potential inherent in the basic structure of polycarbonate. The following review demonstrates with examples how this potential can be used in the development of new polycarbonates through the incorporation of alternative monomers, changes in the linear structure, end group variation, addition of special additives, and blending. The main emphasis of this articles lies in the development of polycarbonates resistant to high temperature, with a good balance of technologically valuable properties. For scientific and practical interests a new criterion is offered for polycarbonates having both high-temperature stability and impact strength.
“One must not only make a discovery, but also realize that a discovery has been made.”
Hermann Schnell [1]
A comparison is drawn between the thermal behaviour of poly-[2,2-propane-bis-(4-phenyl carbonate)] and the model compound diphenyl carbonate. On this basis a rearrangement mechanism is suggested to account for the main chemical and physical features of the degradation of the polymer between 300 and 389°.
Although a wide range of aromatic polycarbonates has been synthesized and examined [1–3], the term polycarbonate usually refers to the commercially available poly[2,2-propane-bis(4-phenyl carbonate)], i.e., and this polymer is discussed exclusively in the present review.Polycarbonate possesses a number of attractive mechanical properties [1,3] e.g., high impact strength, high elastic modulus, and creep resistance. These features, coupled with the fact that the polymer is almost unaffected by water and many inorganic and organic solvents, permit its use in a variety of applications. In such applications the mechanical properties may alter with time because of the viscoelastic nature of the material.
The pyrolysis and flame retardancy of a bisphenol A polycarbonate/silicon rubber/bisphenol A bis(diphenyl
phosphate) (PC/SiR/BDP) blend were investigated and compared to those of PC/BDP and PC/SiR. The impact modifier SiR consists mainly of poly(dimethylsiloxane) (PDMS> 80 wt %). The pyrolysis of PC/SiR/BDP was studied by thermogravimetry (TG), TG-FTIR to analyze the evolved gases, and a Linkamhot stage cellwithin FTIR aswell as 29SiNMR and 31PNMRto analyze the solid residue. The fire performance was determined by PCFC, LOI, UL 94, and a cone calorimeter under different external irradiations. The fire residues were studied by using ATR-FTIR as well as the additional binary systems PC + PDMS, PC + BDP, and BDP + PDMS, focusing on the specific chemical interactions. The decomposition pathways are revealed, focusing on the competing interaction between the components. Fire retardancy in PC/SiR/BDP is caused by both flame inhibition in the gas phase and inorganiccarbonaceous residue formation in the condensed phase. The PC/SiR/BDP does not work as well superimposing the PC/SiR and PC/BDP performances. PDMS reacts with PC and BDP, decreasing BDP’s mode of action. Nevertheless, the flammability (LOI > 37%, UL 94 V-0) of PC/SiR/BDP equals the high level of PC/BDP. Indeed, SiR in PC/SiR/BDP is underlined as a promising impact modifier in flame-retarded PC/impact modifier blends as an alternative to highly flammable impact modifiers such as acrylonitrile� butadiene�styrene (ABS), taking into account that the chosen SiR leads to PC blends with a similar mechanical performance.
Bisphenol A polycarbonate/acrylonitrile–butadiene–styrene (PC/ABS) with and without bisphenol A
bis(diphenyl phosphate) (BDP) and 5 wt.% zinc borate (Znb) were investigated. The pyrolysis was studied
by thermogravimetry (TG), TG-FTIR and NMR, the fire behaviour with a cone calorimeter applying
different heat fluxes, LOI and UL 94. Fire residues were examined with NMR.
BDP affects the decomposition of PC/ABS and acts as a flame retardant in the gas and condensed phases.
The addition of Znb results in an additional hydrolysis of PC. The fire behaviour is similar to PC/ABS, aside
from a slightly increased LOI and a reduced peak heat release rate, both caused by borates improving
the barrier properties of the char. In PC/ABS + BDP + Znb, the addition of Znb yields a borate network and
amorphous phosphates. Znb also reacts with BDP to form alpha-zinc phosphate and borophosphates
that suppress the original flame retardancy mechanisms of BDP. The inorganic–organic residue formed
provides more effective flame retardancy, in particular at low irradiation in the cone calorimeter, and
a clear synergy in LOI, whereas for more developed fires BDP + Znb become less effective than BDP in
PC/ABS with respect to the total heat evolved.
In this first of two papers, the thermal decomposition of bisphenol A bis(diphenyl phosphate)-flame
retarded polycarbonate (PC) blends with different impact modifiers was studied. The impact modifiers
were an acrylonitrile–butadiene–styrene (ABS), a poly(n-butyl acrylate) (PBA) rubber with a poly(methyl
methacrylate) (PMMA) shell and two silicone–acrylate rubbers consisting of PBA with different amounts
of polydimethylsiloxane (PDMS) and different shells (PMMA and styrene–acrylonitrile, SAN). The focus of
this work was to study the impact of the acrylate and silicon–acrylate rubbers with respect to pyrolysis
and flame retardancy in comparison to common ABS. Thermogravimetry (TG) was performed to
investigate the pyrolysis behaviour and reaction kinetics. TG in combination with FTIR identified the
pyrolysis gases. Solid residues were investigated by FTIR-ATR. PC/ABS shows two-step decomposition,
with PC decomposing independently from ABS at higher temperatures. Pure acrylate rubber destabilises
PC due to interactions between the rubber and PC, which leads to earlier decomposition of PC. Using
silicone–acrylate rubbers led to similar results as PC/ABS with respect to pyrolysis, reaction kinetics and
analysis of the solid residue; hence the exchange of ABS for the silicone–acrylate rubbers is possible.
The pyrolysis of polycarbonate (PC) and PC/acrylonitrile-butadiene-styrene (PC/ABS) with and without arylphosphates (triphenylphosphate
TPP, resorcinol-bis(diphenyl phosphate) RDP and bisphenol A bis(diphenyl phosphate) BDP) is investigated by thermal analysis
as key to understanding the flame retardancy mechanisms and corresponding structure–property relationships. The correspondence
between the decomposition temperature range of arylphosphates and PC is pointed out as prerequisite for the occurrence of
the reaction between arylphosphate and structures that are typical for the beginning of PC decomposition. Resulting cross-linking
enhances charring in the condensed phase and competes with the alternative release of phosphate in the gas phase and thus
flame inhibition. Flame inhibition was identified as the main flame retardancy mechanism. The additional condensed phase mechanisms
optimise the performance.
The influence of nano-dispersed 5 wt.% boehmite (AlOOH) and 5 wt.% AlOOH combined with bisphenol A bis(diphenyl phosphate) (BDP) in bisphenol A polycarbonate/acrylonitrileebutadieneestyrene (PC/ABS) þ poly(tetrafluoroethylene) (PTFE), and 1 wt.% AlOOH with and without BDP, resorcinol bis(diphenyl phosphate) (RDP), and triphenyl phosphate (TPP), on PC/ABS þ PTFE has been investigated. Possible
flame retardancy mechanisms are revealed. Thermogravimetry (TG) and evolved gas analysis (TG-FTIR) are used to study pyrolysis, a cone calorimeter applying different external heat fluxes is used to investigate fire behaviour, and LOI and UL 94 are used to investigate flammability. Fire residues were investigated using ATR-FTIR. Adding 5 wt.% AlOOH decreases the peak heat release rate, as also has been reported for polymer nanocomposites with other layered structures. AlOOH releases water, and adding 5 wt.% AlOOH crucially influences thermal decomposition by enhancing the hydrolysis of PC and of BDP. For PC/ABS þ PTFE þ BDP þ 5 wt.% AlOOH, the formation of AlPO4, for instance, results in antagonistic effects on the charring of PC þ BDP, whereas synergy is observed in LOI. When only 1 wt.% AlOOH is added to the PC/ABS þ PTFE with and without BDP, RDP and TPP, respectively, no significant influence is observed on thermal decomposition, UL 94, LOI or performance in the cone calorimeter.
A comparative study of the fire-retardant efficiency of three commercial aryl phosphates—triphenyl phosphate (TPP), resorcinol bis(diphenyl phosphate) (RDP) and bisphenol A bis(diphenyl phosphate) (BDP)—in PC/ABS blends was carried out. The thermal and hydrolytic stability of the fire-retardant resins, as well as their physical properties, was also studied. The use of RDP and BDP is preferred over TPP because of superior properties, whereas BDP shows better fire-retardant efficiency, hydrolytic stability, and thermal stability than RDP.
A review of literature was undertaken to ascertain the current knowledge of the nature of the thermal decomposition products generated from ABS and the toxicity of these evolved products in toto. The literature review encompasses English language publications available through June 1984. This literature surveyed showed that the principal ABS thermooxidative degradation products of toxicologic importance are carbon monoxide and hydrogen cyanide. The experimental generation of these and other volatile products is principally dependent upon the combustion conditions and the formulation of the plastic. The toxicity of ABS thermal degradation products has been evaluated by fire methods. The LC50 (30 min exposure + 14 day post-exposure period) values for flaming combustion ranged from 15.0 mgl−1 to 28.5 mgl−1. In the non-flaming mode of combustion, the LC50 values ranged from 19.3 Mgl−1 to 64.0 mgl−1. Therefore, no apparent toxicological difference exists between the flaming mode and the non-flaming mode. The toxicity of ABS degradation products was found to be comparable with the toxicity of the thermal decomposition products of other common polymeric materials.
Mechanical properties of polycarbonates (PCs) and elastomer-modified polycarbonates with various molecular weights (MW) are investigated. Higher MW PCs show slightly lower density, yield stress, and modulus. The ductile–brittle transition temperature (DBTT) of the notched impact strength decreases with the increase of PC MW and with the increase of elastomer content. The elastomer-modified PC has higher impact strength than does the unmodified counterpart if the failure is in the brittle mode, but has lower impact strength if the failure is in the ductile mode. The critical strain energy release rate (Gc) measured at −30°C decreases with the decrease of PC MW. The extrapolated zero fracture energy was found at Mn = 6800 or MFR = 135. The Gc of the elastomer-modified PC (MFR = 15, 5% elastomer) is about twice that of thee unmodified one. The presence of elastomer in the PC matrix promotes the plane–strain localized shear yielding to greater extents and thus increases the impact strength and Gc in a typically brittle fracture. Two separate modes, localized and mass shear yielding, work simultaneously in the elastomer-toughening mechanism. The plane–strain localized shear yielding dominates the toughening mechanism at lower temperatures and brittle failure, while the plane–stress mass shear yielding dominates at higher temperatures and ductile failure. For the elastomer-modified PC (10% elastomer), the estimated extension ratio of the yielding zone of the fractured surface is 2 for the ductile failure and 5 for the brittle crack. A criterion for shifting from brittle to ductile failure based on precrack critical plastic-zone volume is proposed.
The flame retardancy mechanisms of three aryl phosphates, triphenyl phosphate (TPP), resorcinol bis(diphenyl phosphate) (RDP) and bisphenol A bis(diphenyl phosphate) (BDP), in a polycarbonate/acrylonitrile–butadiene–styrene (PC/ABS) blend are investigated and compared. Further, the influence of polytetrafluorethylene (PTFE) on viscosity and thermal decomposition is discussed in the systems PC/ABS and PC/ABS + BDP. Mechanisms are proposed based on the results of various methods. Thermogravimetric analysis, Fourier transform infrared spectroscopy and kinetics are used to study the pyrolysis. The fire behaviour is studied by means of cone calorimeter measurements at different heat fluxes and the flammability is specified by limiting oxygen index (LOI) and UL 94. Rheology measurements are used to illuminate the changed dripping behaviour due to PTFE. TPP shows only a gas phase action. RDP shows mainly a gas phase action and some condensed phase action. BDP shows a crucial condensed phase action in addition to a gas phase action. TPP and RDP are somewhat superior in terms of flammability (LOI), whereas BDP shows superior performance in forced flaming combustion (cone calorimeter). Synergistic effects between PTFE and BDP are found. Copyright © 2007 Society of Chemical Industry
This paper presents an overview of the recent literature on flame retardancy of polycarbonate (PC) and polycarbonate-based resins. A brief survey of the major mechanisms of thermal decomposition of PC is also presented because it gives insight in the mechanisms of flame retardant action. Mostly industrial laboratories are involved in the development of new flame retardants for PC and, to a much lesser extent, academic laboratories are doing research on the mechanistic aspects of flame retardancy. The number of patents published annually on the flame retardancy of PC and its blends significantly exceeds the number of patents on flame retardancy of any other polymer. Because PC is a naturally high charring polymer, the condensed phase active flame retardants, in particular phosphorus-based ones, are widely used in PC-based blends. Plain PC can pass stringent flame retardant tests with very low additions of some sulfur- or silicone-based flame retardants. Copyright © 2005 Society of Chemical Industry
The thermal decomposition of polycarbonate (PC), PC containing resorcinol bis(diphenyl phosphate) (RDP), and PC—acrylonitrile–butadiene–styrene (PC–ABS) blend containing RDP was studied by thermogravimetry. Volatile and solid products of thermal decomposition were collected at different steps of thermal decomposition and characterized either by gas chromatography–mass spectrometry or infrared and chemical analysis. It was found that phosphorus accumulates in the condensed phase. Upon combustion of the fire-retardant mixture PC–ABS + RDP, accumulation of phosphorus is observed in the charred layer, at the surface of the burning specimens. It is suggested that PC undergoes a Fries-type rearrangement upon thermal decomposition, and RDP reacts with the formed phenolic groups through a trans-esterification mechanism. Kinetic analysis of the thermal decomposition of PC containing RDP supports the proposed mechanism. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1863–1872, 1999
Akzo Nobel Chemicals has recently introduced on the market an aromatic oligomeric phosphate (BDP) based on Bisphenol A. This product shows higher thermal and hydrolytic stability than other aryl phosphates. It provides similar or better fire retardant performance than an oligomeric phosphate (RDP) based on resorcinol. Fire retardant formulations with BDP based on polycarbonate/ABS plastic (PC/ABS) blend, polyphenylene oxide/high impact polystyrene (PPO/HIPS) blend, and HIPS alone show similar or better physical properties than those obtained with RDP. Upon thermal decomposition of the fire retarded polymers containing BDP, phosphorus tends to accumulate in the solid residue, a result which indicates that the primary fire retardant action of BDP is likely to occur in the condensed phase.