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Preparation and performance of an immiscible PVC-HDPE blend compatibilized with maleic anhydride (MAH) via in-situ reactive extrusion
Abstract
The mechanical and thermal properties of an uncompatibilized blend, i.e., polyvinyl chloride-high-density polyethylene (PVC-HDPE), can be improved by introducing maleic anhydride (MAH) into the blend polymer. The impact of this compati-bilizer was investigated using Fourier Transform Infrared (FTIR) spectroscopy and density functional theory (DFT) calculations , which revealed that MAH forms bridges between the PVC and HDPE polymers. Scanning electron microscopy (SEM) showed the single-phase morphology of a (PVC-HDPE)-g-MAH blend, demonstrating improved adhesion between the two immiscible polymers. Further, thermogravimetric analysis (TGA) indicated that incorporating MAH increased the initial thermal degradation temperature (Tonset) of the blend at approximately 31 °C. Moreover, dynamical mechanical analysis (DMA) and differential scanning calorimetry (DSC) results showed a clear increase in the glass transition temperature (Tg) due to the incorporation of MAH in the polymer blend. This increase in the Tg value indicates that the addition of MAH into the PVC-HDPE blend enhances the thermodynamic compatibility of the blend. Finally, the addition of MAH increased the tensile modulus by more than 17%, improved the flexural modulus up to 25%, and increased the complex viscosity of the PVC-HDPE blend.
... Mixed plastic waste blends have been compatibilized through various techniques, including in situ reactive compatibilization by using coupling agents such as MAH and BPO or dicumyl peroxide (DCP) [24,[37][38][39]. Gao et al. incorporated wood fibers after modifying PP/PE blends with MAH using DCP in a twin-screw extruder to enhance the mechanical properties of composites [40]. ...
... Minor peaks may indicate the presence of impurities and additives. Figure 3 illustrates the proposed reaction scheme of in situ compatibilization where new grafted phases such as PP-g-PE, PP-MAH-PE, PP-g-MAH, and PE-g-MAH are formed during the in situ reaction in the internal mixer [38,46,47]. Maleic anhydride grafted compatibilizers are produced through a free radical grafting reaction initiated by benzoyl peroxide (BPO). ...
This study entails in situ reactive compatibilization of post‐consumer mixed plastic waste using two different coupling agents. The mixed plastic waste was compatibilized through melt mixing using maleic anhydride (MAH) and bisphenol A (BPA) epoxy as coupling agents by adding benzoyl peroxide (BPO) as an initiator. The compatibilized blends comprising low‐density polyethylene (LDPE), high‐density polyethylene (HDPE) and polypropylene (PP) showed significant improvement in mechanical and thermal properties when characterized using tensile, impact, hardness, heat deflection temperature testing, and thermogravimetric analysis (TGA). MAH content was varied from 0.5% to 2.0%, where compatibilized blends showed a 58% increase in tensile strength, a 112% increase in elongation at break, and an increase in other properties as well. The TGA of compatibilized blends showed a significant increase in degradation temperatures as compared to uncompatibilized blends. FTIR spectroscopy confirmed the grafting of coupling agents as compatibilizing phase, whereas SEM images showed a homogeneous dispersed phase morphology on compatibilization. Reaction schemes are proposed for in situ compatibilization, and interaction among phases is depicted schematically explaining the properties improvement. An optimum loading (i.e., 1.5%) of MAH was suggested for maximum mechanical properties, showing a saturation loading content of compatibilizer. This study showed in situ compatibilization as a promising technique for upcycling mixed plastic waste.
... On the other hand, the thermophysical effects of date palm fibers and acrylonitrile butadiene rubber on polyvinylchloride/low density polyethylene blend were recently reported [27]. Finally, it is worth to notice that polyvinylchloride/high density polyethylene blends are equally extensively studied [28][29][30]. ...
This research was aimed to study various PVC/LDPE blends in order to valorize the PVC and LDPE wastes by blending them. Indeed, this homopolymers constitute an important part of the plastic industry production in the world. The polymer blends were prepared by melt blending followed by extrusion. The obtained results showed that the mechanical properties were weak and an improvement of these properties occurs when the morphology evolves from matrix/droplets towards co-continued structure. The morphology is greatly related to the viscosity/volume ratio of each blend component. The increase of PVC onset first step degradation temperature Td1 as function of of the increase of LDPE concentration is assigned to macromolecular cross recombination reactions between PVC and LDPE radicals that occur during the heating. This study had allowed getting a composition blend of interesting mechanical and thermal properties despite the no use of a compatibilizer.
... Several researchers. [7][8][9] confirmed the use of thermoplastic polymers grafted to maleic anhydride (MAH) as a compatibilizer to promote the compatibility of polymer blends and composites. As a result, the quality and performance of the PP composite was weakened. ...
Polypropylene (PP) is a strong, tough, crystalline thermoplastic material with high performance. Because of its diverse thermo-physical and mechanical properties, it is utilized in a wide variety of disciplines.. In this study, the impact of free quenching on the thermos-physical characteristics of PP/calcium carbonate (CaCO 3) composites was examined. Three distinct heating procedures were used. First, composites were cooled from their melting phase temperature to ambient temperature. Second, composites were cooled from 130°C to a predetermined and controlled temperature (T: 0°, 20°, 30°, 40°, 50°, 60°, 70°, 80°C). Third, composites were temperature-tested using annealing. The findings suggest that the elongation at break and impact strength may be improved following an initial quenching process from the melting phase to ambient temperature. On the other hand, a second quenching process at 0°C produces superior results, and a correlation between mechanical and thermal characteristics is noted; however, while these qualities are increased, others, such as flexibility, density, Vicat softening temperature (VST), and heat distortion temperature (HDT) are negatively impacted.
... The use of anhydride maleic (MAH) as a compatibilizer to promote the interaction between immiscible polymers was also explored. [14,15]. The evolution of morphology during melt blending is another important consideration for immiscible polymer blends [16]. ...
... Melt blending processes can be used for mixing PVC with different percentages of polyethylene (PE) [22], low density polyethylene (LDPE) [23], recycled low density polyethylene (r-LDPE) [24], high-density polyethylene (HDPE) [25], polypropylene (PP), and polystyrene (PS). An efficient strategy to overcome the compatibility and adhesion issues is the introduction of small quantities of a third component used as a compatibilization agent, this component serves as the bridge linking the polymer-polymer interfaces for blend compatibilization and/or bio-reinforcement to the polymer matrix [25,26], which may markedly alter the mechanical characteristics of the polymer blends. Xu and collaborators [27], investigated the effect of the acrylonitrile butadiene rubber (NBR) concentration (33.5-36.5 wt.%) on the characteristics of a PVC/LDPE blend, as well as its synergism with dicumyl peroxide (DCP). ...
Date palm tree leaf-reinforced polymer composites have important advantages, such as sustainability and low-cost. In the present study, ternary blend composites of polyvinyl chloride (PVC), low-density polyethylene (LDPE), and acrylonitrile butadiene rubber (NBR) copolymer (LDPE/PVC: C0, LDPE/PVC/NBR:C1) as well as reinforced composites with 10, 20, and 30 wt.% of alkali treated date palm fiber (TDPF) (C2, C3 and C4 respectively) were fabricated using a melt blending extrusion process. TDPF and the NBR copolymer were used to improve the interfacial bonding, compatibility, and thermomechanical properties of the composite, yielding the highest tensile strength of 32 MPa for the composite containing 10 wt.% TDPF. Moreover, the morphological analysis showed that the incorporation of the NBR copolymer enhanced the compatibility of the blend. Mechanical testes revealed that the hardness of the TDPF/PVC/LDPE/NBR composite increased in the order C2 (450 MPa) < C3 < C4 (540 MPa). In addition, the flexural and tensile moduli of the composite increased with increasing TDPF content, with the highest values (534 and 1585 MPa, respectively) observed for composite C4. Thermal analysis revealed increased T onset and T 10% values, indicating an improved thermal stability of the composite. This study clearly demonstrates that the (DPF/PVC/LDPE/NBR) composites can be used in various high-tech engineering applications, which require excellent properties.
... The stress-strain behavior and morphology of partially compatible PVC/CPE blends were studied by Zhang and Peixin [6]. The mechanical and thermal properties of an uncompatibilized blend of (PVC/HDPE) were studied by Maou et al. [7]. They showed that MAH formed bridges between the PVC and HDPE polymers improved adhesion between the two immiscible polymers, increased the initial thermal degradation temperature of the blend at approximately 31 • C, and increased the glass transition temperature. ...
The experimental solubility data of polyvinyl chloride (PVC) and high-pressure polyethylene (HPPE) in organic solvents (toluene, dichloromethane, and chloroform) at temperatures ranging from 308.15 to 373.15 K at atmospheric pressure are reported in the present paper. The solubility of the polymers (PVC and HPPE) in organic solvents (toluene, dichloromethane, and chloroform) was studied at temperatures between 298 and 373 K. The supercritical SEDS dispersion of PVC and HPPE polymer blends at pressures between 8.0 and 25 MPa and at temperatures from 313 to 333 K are reported in the present work. The kinetics of crystallization and phase transformation in polymer blends obtained by blending in a melt, and using the supercritical SEDS method, have been studied. The effect of the HPPE/PVC ratio on the thermal and mechanical characteristics of the polymer blends has been studied. For all studied polymer blends and pure polymers obtained using the SEDS method, the heat of fusion ΔfusH exceeds the values obtained by blending in the melt by 1.5 to 5) times. The heat of fusion of the obtained polymer blends is higher than the additive value; therefore, the degree of crystallinity is higher, and this effect persists after heat treatment. The relative elongation decreases for all polymer blends, but their tensile strength increases significantly.
To demonstrate the upcycling of thermoplastic waste with good thermo‐physical properties, high density polyethylene (HDPE; 80 phr) and polyvinyl chloride (PVC; 20 phr) are mixed as the matrix using maleic anhydride (MAH) reinforced with unmodified and modified date palm fibers (DPFs; 30 phr). The effects of in situ grafting of MAH onto the DPFs‐HDPE‐PVC composites upon the resultant thermo‐physical characteristics are investigated and analyzed via Fourier transform infrared spectroscopy and scanning electron microscopy. Thus, the effective compatibilizing of both the HDPE‐PVC component and the grafted HDPE‐PVC blend with the modified DPFs are confirmed. In addition, the results of dynamical mechanical analysis and differential scanning calorimetry indicate that the glass transition temperature (Tg) of the composite is enhanced by the incorporation of modified DPFs. The thermal, mechanical, and water uptake properties of the composites are also improved. Rheological analysis at low frequency reveals that the introduction of hydrolyzed DPFs results in a higher complex viscosity (1.94 × 10⁶ Pa s) and storage modulus (119,844 MPa) for the obtained composite (designated G‐Hydro). Overall, the G‐Hydro composite exhibits the best performance, making it ideal for a variety of construction and building purposes.
Properties of polyethylene terephthalate (PET) and polypropylene (PP) can be enhanced by blending both in a specific proportion to get combined superior properties. To make a homogeneous blend, maleic anhydride functionalized PP (PP-g-MAH) was used as a compatibilizer in 60% PET blends. In all blends, PET’s percentage crystallinity was reduced as compared to pure PET because there were hindrances in chains packing because of the presence of PP chains. The addition of compatibilizer in PET and PP blend enhanced interactions resulted in a homogeneous blend with fewer voids. 2.5% of PP-g-MAH was observed to be the optimum value of compatibilizer in the blend of PET and PP. The decrease in free space inside the blend hindered water molecules' passage through the sheets. Owing to this, water vapor permeability of the blend was less compared to pure PET. The addition of the nonpolar PP also influenced the water transmittance rate of blended sheets.
Acrylonitrile‐butadiene‐styrene (ABS) functionalization is industrially important since it can wide the ABS application range. However, grafting of functional groups must be effective. This work aimed evaluating the effectiveness of ABS functionalization in an internal mixer, using maleic anhydride (MA) and dicumyl peroxide (DCP) as initiator, at 2.5% and 5.0%; and 0.3% and 0.5% contents respectively. Torque rheometry, melt flow rate (MFR), titration, Fourier transform infrared spectroscopy (FTIR), contact angle, thermogravimetry (TG), differential scanning calorimetry (DSC), and X‐ray diffraction (XRD) were used to collect the main parameters of produced compounds. For ABS with 5% MA and 0.5% DCP, an efficiency of 62% was reached with the degree of grafting 3.1% MA. FTIR spectra confirmed new band in ABS chain in 1780 cm⁻¹ due to the carbonyl group. Reduction in contact angle and thermal stability were verified, whereas MFR and torque rheometry suggested that viscosity decrease is most due to the molecular weight reduction. In general, MA grafted ABS presented proper functionalization with great potential for applications as reactive compatibilizer.
Over the past 50 years demand for plastics drastically increased worldwide resulting in plastic wastes causing serious environmental problems. The main market sector of European plastics industry is the packaging industry most of which are polyolefins and poly(ethylene-terephtalate). In the EU, 29.1 million tonnes of plastic waste were collected in 2018, of which 32.5% was recycled, 42.6% was recovered for energy, and 24.9% was landfilled (Plastics-the Facts, 2019). Although landfilling of collected waste in the EU is steadily declining, there is still too much unused waste. Polymer blends based on waste resources can solve the issues of recycling. The main purpose of the research was to produce polymer blends from waste based PET that have appropriate mechanical properties and rheological behaviour as well in order to find application areas where product requirements are not strict. Blends containing waste based PET were extrusion moulded and calenderd producing extrusion strings and films. Rheological and tensile properties of three types of PET/engineering thermoplastic blends (PET/PC, PET/PA and PET/ABS) were studied. Miscibility of components of the blends is limited leading to weak mechanical properties such as low tensile strength and/or elongation at break. Due to that phenomenon compatibilizing additives are also required. As compatibilizing additives olefin-maleic-anhydride copolymer based additives have been used in our experiments. Structure of additives differed from each other both in ratio and length of carbon chains of compounds linked to maleic-anhydride groups. Blends have been studied with PET content ranging from 10 to 90%. As an outstanding result improving of mechanical properties was achieved, for example almost 40% growth was observed in elongation at break of extruded 80/20 PET/PA blends in the presence of 0.2% compatibilizing additive compared to the sample without additive, meanwhile its strength has also improved.
Graphic Abstract
The most common type of extruded power cable insulation is based on cross-linked polyethylene (XLPE), which cannot be recycled as a thermoplastic material. Hence, thermoplastic insulation materials currently receive considerable attention because they would allow recycling through re-melting. In particular blends of polyethylene (PE) and polypropylene (PP) would be a compelling alternative to XLPE, provided that the poor compatibility of the two polymers can be overcome. Here, we establish an alternative approach that exploits the in situ formation of a PE–PP-type copolymer through reactive compounding. Ternary blends of an ethylene-glycidyl methacrylate copolymer, a maleic anhydride-grafted polypropylene, and up to 70 wt % low-density polyethylene (LDPE) are compounded at 170 °C. Covalent bonds form through reaction between epoxy and carboxyl groups, leading to a PE–PP-type copolymer that shows good compatibility with LDPE. The in situ generated PE–PP copolymer arrests creep above the melting temperature of LDPE, mediated by a continuous network that is held together by PP crystallites. Recyclability is confirmed by reprocessing at 170 °C. Furthermore, the here investigated formulations feature a low direct-current electrical conductivity of ∼4 × 10–14 S m–1 at 70 °C and 30 kV mm–1, on a par with values measured for LDPE and XLPE. Evidently, in situ formation of a PE–PP-type copolymer through reactive compounding is a promising approach that may enable the design of thermoplastic insulation materials for power cables.
Plastic wastes are environmentally problematic and costly to treat, but they also represent a vast untapped resource for the renewable chemical and fuel production. Pyrolysis has received extensive attention in the treatment of plastic wastes because of its technical maturity. A sole polymer in the waste plastic is easy to recycle by any means of physical or chemical techniques. However, the majority of plastic in life are mixtures and they are hard to separate, which make pyrolysis of plastic complicated compared with pure plastic because of its difference in physical/chemical properties. This work focuses on the synergistic effect and its impact on chlorine removal from the pyrolysis of chlorinated plastic mixtures. The pyrolysis behavior of plastic mixtures was investigated in terms of thermogravimetric analysis, and the corresponding kinetics were analyzed according to the distributed activation energy model (DAEM). The results show that the synergistic effect existed in the pyrolysis of a plastic mixture of LLDPE, PP, and PVC, and the DAEM could well predict the kinetics behavior. The decomposition of LLDPE/PP mixtures occurred earlier than that of calculated ones. However, the synergistic effect weakened with the increase of LLDPE in the mixtures. As for the chlorine removal, the LLDPE and PP hindered the chlorine removal from PVC during the plastic mixture pyrolysis. A noticeable negative effect on dechlorination was observed after the introduction of LLDPE or PP. Besides, the chlorine-releasing temperature became higher during the pyrolysis of plastic mixtures ([LLDPE/PVC (1:1), PP/PVC (1:1), and LLDPE/PP/PVC (1:1:1)]. These results imply that the treatment of chlorinated plastic wastes was more difficult than that of PVC in thermal conversion. In other words, more attention should be paid to both the high-temperature chlorine corrosion and high-efficient chlorine removal in practical. These data are helpful for the treatment and thermal utilization of the yearly increased plastic wastes.
Maleic anhydride (MAH) grafting to different polyolefins with similar grafting degree can have different effects on crystallization, crystal structure, and mechanical and thermal properties. The grafting leads to a smaller crystal size, less ordered lamellar structure, and a shorter long period for HDPE, LLDPE, and PP. The grafting makes PP lamellar packing less ordered the most and almost no effect to LLDPE. The grafting does not have that much impact on the crystallization ability of the HDPE, LLDPE, and HDPE/PP blend, but appreciably reduces the crystalline ability of PP-g-MAH, due to a dramatical drop in its molecular weight during the grafting process. As a result, the grafting makes PP a very brittle material with a lowered average melting point than the corresponding neat PP, but the grafting has almost no effect on elongation at break for LLDPE and some effect on HDPE (decreased by one-third). However, the PP degradation due to MAH grafting can be avoided in the presence of PE component, i.e., making the grafting of PP and PE at the same time with HDPE/PP blend. The grafted HDPE/PP blend shows a significantly improved compatibility, which leads to overall appreciably better mechanical properties than the neat HDPE/PP blend.
Maleic anhydride (MA) grafted with poly(trimethylene terephthalate) (PTT)—abbreviated as PTT-g-MA—can be used as a compatibilizing agent to improve the compatibility and dispersion of nanofillers and a dispersed polymer phase into PTT matrix. This work suggests the preparation of PTT-g-MA using a mixture of PTT, MA, and benzoyl peroxide (BPO) by a reactive extrusion process. PTT-g-MA was characterized to confirm the grafting reaction of maleic anhydride on PTT chains by Fourier transform infrared (FTIR) spectroscopy. Thermal properties (differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA)) and rheological analysis (parallel plates rheology) were used to prove the changes that occurred after the graphitization reaction. The reactive processing route allowed the production of the compatibilizing agent (PTT-g-MA) with good thermal properties and with lower viscosity compared to neat PTT, and this could be an alternative for the compatibilization of polymer blends, as example for PTT/ABS (acrylonitrile butadiene styrene) blends and nanocomposites based on PTT matrix.
Incineration of plastic materials for the energy generation is one of the types of polymer recycling, however the composition of the atmosphere used in this process must be controlled, since the products generated during the incineration and released into the atmosphere can be harmful to environment. Combination of different polymers and the mixing of this with other municipal solid wastes can generate varied products, accentuating the toxicity of the evolved gases. Thus, in this work, mass loss, amount of main stages and the gases evolved during polyethylene (PE) and polyvinyl chloride (PVC) thermolysis, as well as the physical mixture of both polymers, were analyzed by the evolved gas analysis using hyphenated techniques Thermogravimetry and Infrared Spectroscopy. Analyzes were conducted under inert and oxidizing atmosphere and showed that the products formed in the samples thermolysis were chemically different in the two atmospheres. During the thermogravimetric analysis under oxidizing atmosphere, even O2 is present in a significant amount, the products formed are dependent on the temperature of the thermolysis process, being able to generate carbon dioxide and carbonylated, carboxylated compounds, carbon monoxide and others products.
This article investigates the mechanical, morphological, and thermal properties of poly(vinyl chloride) (PVC) and low‐density polyethylene (LDPE) blends, at three different concentrations: 20, 50, and 80 wt% of LDPE. Besides, composite samples that were prepared from PVC/LDPE blend reinforced with different date palm leaf fiber (DPLF) content, 10, 20, and 30 wt%, were also studied. The sample in which PVC/LDPE (20 wt%/80 wt%) had the greatest tensile strength, elongation at break, and modulus. The good thermal stability of this sample can be seen that T10% and T20% occurred at higher temperatures compared to others blends. DPLF slightly improved the tensile strength of the polymer blend matrix at 10 wt% (C10). The modulus of the composites increased significantly with increasing filler content. Ageing conditions at 80°C for 168 h slightly improved the mechanical properties of composites. Scanning electron microscopic micrographs showed that morphological properties of tensile fracture surface are in accordance with the tensile properties of these blends and composites. Thermogravimetric analysis and derivative thermogravimetry show that the thermal degradation of PVC/LDPE (20 wt%/80 wt%) blend and PVC/LDPE/DPLF (10 and 30 wt%) composites took place in two steps: in the first step, the blend was more stable than the composites. In the second step, the composites showed a slightly better stability than the PVC/LDPE (20 wt%/80 wt%) blend. Based on the above investigation, these new green composites (PVC/LDPE/DPLF) can be used in several applications. J. VINYL ADDIT. TECHNOL., 25:E88–E93, 2019. © 2018 Society of Plastics Engineers
The rheologies, morphologies, crystallization behaviors, mechanical and thermal properties of poly(lactic acid) (PLA)/polypropylene (PP) blends and PLA/PP/maleic anhydride-grafted PP (MAPP) blends were investigated. The results showed that the complex viscosities of PLA/PP blends were between those of neat PLA and neat PP, and MAPP had a thinning effect on those of the blends. PLA/PP blends exhibited the distinct phase separation morphologies due to the limited partial miscibility of the blend components. MAPP slightly improved the miscibility between PLA and PP. Both the cold crystallization of PLA component and melt crystallization of PP component were enhanced, probably because PLA and PP were reciprocal nucleating agents. The tensile strength and flexural modulus decreased, while the tensile strain at break and heat deflection temperature (HDT) increased with the increasing PP content. MAPP had the positive effects on the notched impact strength and HDT of PLA-rich blends and also increased the flexural modulus of the binary blends. The thermal stability of the blend was improved by PP, and the incorporation of MAPP further enhanced the thermal stability.
This paper reports excellent electrical properties in polypropylene grafted with maleic anhydride (PP-g-MAH) and a related mechanism of the enhanced electrical properties. The chemical structure of PP-g-MAH was analyzed and its effect on space charge accumulation, electrical breakdown strength and DC conductivity was studied. Compared with pure PP, the PP-g-MAH exhibits remarkably suppressed space charge accumulation, enhanced electrical breakdown strength and reduced conduction current. The mechanism enhancing the electrical properties was studied by measuring the trap level distribution. It can be explained that abundant deep traps are introduced in PP-g-MAH with the introduction of polar groups in MAH, which reduces the charge mobility and raises the charge injection barrier so as to suppress space charge accumulation. This investigation would contribute to propose a new material modification strategy for designing high-voltage direct current insulation material in addition to the inclusion of nanoparticles.
Blending of polyamide 6/high density polyethylene (PA6/HDPE=70/30 wt%) was prepared by melt compounding using a twin screw extruder followed by injection molding using HDPE-g-MAH served as compatibilizer. A series combination of PA6/HDPE with HDPE-g-MAH were blended with varied composition of 100/0, 98/2, 96/4, 94/6 and 92/8. The mechanical properties of the samples such as tensile test, flexural test and elongation at break were measured by universal tensile machine while hardness was measured using the Zwick Roell hardness tester. The composites were characterized by Fourier Transform Infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC) and Thermogravimetric Analyzer (TGA). The addition of HDPE-g-MAH (2wt%) showed increased in modulus, strength and hardness but elongation at break decreased. DSC tests showed similar trend for all compositions. All mechanical tests also showed that composition of 98% PA6/HDPE with 2% HDPE-g-MAH has the highest value indicated best formulation for this research.
Date Palm Fiber (DPF) is one of the most available natural fibers in the Middle East, especially in Iran and the Persian Gulf region. This research provides a new insight into DPF, with consideration of morphological, chemical characteristics, and bulk density, as well as morphological and mechanical properties of DPF/HDPE wood plastic composite. There are three parts of date palm that are used for producing fiber, the trunk, rachis, and petiole. Results indicated that there is significant difference between trunk and petiole on fiber length but rachis has no significant differences relative to the other parts. The aspect ratios have significant differences among of three parts, with the highest and lowest values measured for the petiole and trunk, respectively. The chemical composition of various parts of the date palm tree differed significantly; with the highest amounts of cellulose and lignin content belong to rachis. Bulk density was measured for three parts of date palm, and the lowest amount was 0.082 g/cm 3 . The highest strengths were achieved in composites with 30 and 40% fiber content, depended on which original parts of the tree were used.
Algerian palm groves, a key component of oasis ecosystems, generate significant volumes of natural waste. In the present study, leaflet and rachis derived date palm fibers (DPFs) produced from the pruning of date palm trees were used as an effective filler to reinforce composites consisting of polyvinyl chloride and high-density polyethylene (PVC-HDPE) (20:80). Composites with an untreated and treated DPFs loading of 30 wt.% were prepared using a twin-screw extruder and compression molding. The DPFs surface was modified using various treatments, including NaOH, 3-aminopropyltriethoxysilane, combined alkali-silane, bleaching with NaClO2, and H2O2+HNO3. The successful surface modification of the DPFs, including delignification and the extraction of cellulose microcrystals (CMCs), was verified using infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric analysis (TG). The results revealed an improvement in the morphological, thermal, mechanical, dynamical-mechanical, rheological, and water uptake performance of the composites with the addition of the modified DPFs. It was concluded that it was the CMCs that primarily enhanced the thermo-physical properties of the PVC-HDPE composites, making them suitable for several industrial applications.
Chemical mixture (C-M) of low density polyethylene (LDPE) and electronic waste made of acrylonitrile butadiene styrene (ABS) have been prepared via one step reactive extrusion. The morphology of prepared crosslinked blends has been investigated. Single phase morphology has been found in C-M as opposed to two phase morphology in physical blend. The extent of crosslinking has been observed by determining gel content through solvent extraction. The structural changes have been confirmed by FTIR and solid state ¹³C NMR spectroscopy. The C-M have been tested using DSC and TGA and have found to be thermally stable. The chemical mixture has showed excellent mechanical properties like increment in Young’s modulus, ultimate tensile strength. The flexural properties have also been investigated and C-M has found to have enhanced flexural modulus and flexural stress. For C-M to be used in practical heat exposure conditions heat distortion temperature tests have been performed and C-M has shown better properties than pure LDPE and physical blend.
In the last several years, the electronic waste, especially printed circuit boards have significantly increased over the world, generating one of the highest rates of solid waste. The recycling process of the printed circuit boards implies mainly the recovery of metals and glass fibers, while the reuse of the polymeric support has remained largely in the phase of research. In this paper, the non-metallic part of printed circuit boards was used as filler (up to 30%), but also to improve the fire resistance of thermoplastic composites based on recycled polypropylene and diene block-copolymers. The synergy between the elastic effect of elastomers and the reinforcing effect of the waste powder into the thermoplastic matrix was studied by mechanical and dynamo-mechanical analysis, X-ray diffraction, optical micro-scopy, micro-calorimetry and thermo-gravimetrical analysis. Improved mechanical properties, especially impact strength was observed. The compatibization of components considering the interactions between the ethylene-butylene blocks from the hydrogenated and maleinized styrene-butadiene block-copolymer and recycled polypropylene, respectively between the MA groups and the functionalities of the waste powder, evidenced by FTIR, was highlighted by changes in the X-ray pattern and an increased fire resistance and thermal stability.
Polypropylene-graft-maleic anhydride (PP-g-MAH) ionically modified with zinc(II) (PP-g-MAHZn) in varying amounts of ionic associations were prepared via melt reaction. Absorption bands in FTIR-ATR and shifted binding energy in X-ray photoelectron spectroscopy showed the formation of zinc carboxylates in PP-g-MAHZn. Decreased crystallinity, gradually increased viscosities, and storage modulus with the increment of zinc carboxylates in the PP-g-MAHZn were investigated by thermal and rheological analysis, which were attributed to the restriction of chain mobility via ionic interactions between polymer chains and aggregations of ionic domains. Furthermore, PP-g-MAHZn was introduced to polypropylene as an additive to promote foamability, and the PP/PP-g-MAHZn blends displayed higher viscosities and storage modulus compared with pristine PP in rheological measurements. In addition, the PP/PP-g-MAHZn blends were foamed by supercritical CO2 and cryogenically fractured surfaces were observed by scanning electron microscope. PP/PP-g-MAHZn foams presented high closed-cell content, uniformity of cells, and increasing cell density owing to the combined effects of rheological properties, while maintaining the cell structures and good dispersion of the PP-g-MAHZn as nucleating sites. These results reveal that PP-g-MAHZn is a suitable additive to produce high melt strength PP for foam production.
The pyrolysis reactions of styrene trimer as polystyrene (PS) model compound were researched through using density functional theory (DFT) method M06-2X with the 6-311G(d) basis set to clarify the evolution mechanisms of PS pyrolysis products. The kinetic and thermodynamic parameters in all reactions (including bond cleavage, β-scission, hydrogen transfer, radical addition and disproportionation) were calculated. The calculation results of bond dissociation energies (BDE) indicate that the BDE values of C-C on the backbone are obviously lower than those of C-Caromatic of branched chain, and the structure of syndiotactic PS is more stable than that of isotactic and atactic PS. PS can be decomposed into a methylene-end radical and a benzyl-end radical through the main-chain homolytic reaction, and these radicals further decompose to generate styrene through the end-chain β-scission reaction, or generate α-methylstyrene through the mid-chain β-scission after 1,2-hydrogen transfer reaction, or generate dimer through the mid-chain β-scission after 1,3-hydrogen transfer reaction. The kinetic analysis indicates that styrene is the major pyrolysis product, and α-methylstyrene and dimer are the main competitive products.
Polyvinyl chloride (PVC) is a widely consumed plastic material and may lead various environmental pollutions. China produces and consumes the largest amount of PVC material in the world, owing to its rapid urbanization and economic growth. Herein, we establish a dynamic material flow analysis methodology for quantifying PVC stocks and flows in China, including material input, manufacturing and consumption distribution, and waste management stage. We examine the material flow of PVC in China from 1980 to 2015. The PVC trajectory analysis from 2016 to 2050 is based on the historical PVC material consumption data and scenario analysis. Total amount of PVC consumption in all types of products dramatically increased from 0.4 Mt (0.4 kg/capita) in 1980 to 14.5 Mt (10.7 kg/capita) in 2015, with a cumulative amount of 173.7 Mt. The rapid increase of PVC consumption in China significantly accelerated the PVC waste accumulation, reaching 66.3 Mt, accounting for 38.2% of total PVC use from 1980 to 2015. Building & construction sector has the largest PVC in-use stock, while consumer goods sector generated the largest PVC waste. In recent fifteen years, mechanical recycling, chemical recycling, incineration, and landfill of PVC waste ratios are 25.5%, 0.8%, 9.3%, and 36.0%, respectively. The PVC trajectory analysis shows that by the end of 2050, the accumulative PVC waste in China will be 508.6 Mt in the limited growth scenario and 562.0 Mt in the business as usual scenario. Based on the MFA results, policies for improving PVC recycling system were analyzed in this work.
In order to study the relationship between the interfacial adhesion and preparation technology, nano CaCO3 impregnation modification (IM) as an efficient way was reported for improving the interfacial interactions, using three preparation technologies which include hot press molding (HPMP), extrusion molding (EMP) and injection molding process (IMP) to produce the bamboo pulp fiber (BPF) reinforced HDPE composites. Fractal theory and dynamic mechanical analysis were used to investigate the interfacial interactions quantificationally. The fractal dimension D of composites was different, indicating the D did characterize the difference among the different complicated fracture surfaces. A poor correlation (R² = 0.4563) was observed between three preparation technologies and D, indicating there are remarkable difference between HPMP, EMP and IMP. The apparent activation energy was lower in the IM-BPF/HDPE composites (e.g. 115.99 kJ/mol for EMP-2 <124.88 kJ/mol for EMP-1). The least potential energy was needed to change the structure of the composites prepared by EMP, which indicated that the interfacial adhesion of composites prepared by EMP was the best while the HPMP was the worst. It can be concluded that IM had an interactive effect with preparation technology on interfacial interactions of the composites and IM worked more effectively on composites prepared by EMP.
Plant fiber reinforced polymer composites are experiencing rapid growth in terms of applications where they may be subject to corrosion and wear. The present work explores the possibility of reinforcing polyvinyl chloride (PVC)/sorghum straw (SS) composites with micro-silica (MS) and poly(acrylonitrile-styrene-acrylate) (ASA) for developing a new corrosion and wear-resistant material. Sea water (salinity 3.5%, temperature 55 °C) and acid rain (pH 2.5, temperature 55 °C) were utilized to simulate extreme cyclic corrosion conditions. The results revealed that the wear and corrosion resistance of the PVC/SS composites was significantly enhanced by the addition of 6 wt% MS (particle size 2.6 μm) and 34% ASA, which was attributed to that the MS and ASA could render the PVC matrix with the improved toughness, strength, and heat resistance.
The enhancement of mechanical properties of immiscible blend, i.e. polypropylene/ cyclic natural rubber (PP/CNR), could be achieved by incorporating a compatibilizer into the blend system. The main challenge is how to compatibilize the two materials with distinct characteristic of saturated and apolar structures. As compatibilizers, copolymer of maleic anhydride-grafted polypropylene (POLYBOND 3002 and POLYBOND 3200) and maleic anhydride-grafted cyclic natural rubber (CNR-g-MA) were incorporated with PP/CNR (80/20 wt.%) blends in different weight ratios. The impact of those compatibilizers were analysed using Scanning Electron Microscope (SEM), which shows a homogenous phase of PP matrix indicating a homogenous dispersion of CNR into PP matrix. Thermogravimetry (TGA) analysis confirmed that the addition of compatibilizers improved the thermal stability of blends. The Differential Scanning Calorimetry (DSC) curve shows that the glass transition temperature (Tg) was significantly decreased due to the maleic anhydride-grafted polymers incorporation. The decrease of CNR’s Tg value implies that the incorporation of maleic anhydride-grafted polymer into PP/CNR blends can improve blend compatibility. The compatibilization was further confirmed by an increase in tensile strength of compatibilized blends.
This study focuses on creating an optimal grafting compatibilizer for blends of polypropylene carbonate (PPC) and polybutylene succinate (PBS). PPC and PBS were blended separately with different amounts of maleic anhydride (MAH) and with and without dicumyl peroxide (DCP) to aid the free‐radical grafting. Titration analysis evidenced that MAH reacted with the polymers terminal groups and backbones using free‐radical functionalization. Thermogravimetric analysis (TGA) and gas permeation chromatography (GPC) results demonstrated how the thermal stability of PPC improves with the addition of MAH. Proton NMR proved that, in both PPC and PBS formulations, ring‐opening reactions and grafting of the intact MAH ring occur, as well as interchain grafting producing network structures. The rheological analysis showed that small quantities of MAH and DCP increase the viscosity of the resins. The compatibilizer that was determined to be most reactive and stable of all the formulations analyzed was PPC with 2% MAH and DCP and its effect in the morphology of PPC‐PBS blends was proven successful by a reduction of the PPC droplet size. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47553.
Raman and Fourier Transform infrared spectroscopy were used to study the vibrational spectra in commercial polyvinyl chloride (PVC) flexible films. In order to have insights of the PVC and the plasticizer structures, density functional theory calculations were conducted via B3LYP hybrid functional. The Infrared and Raman calculations took into account geometry optimization of the PVC film, the plasticizer DEHA and the convolution of both. The convoluted spectra were then compared with the experimental data. Finally, the thermal stability of the PVC films was checked through one-hour thermal treatment of the samples comprising temperatures ranges from 50 to 200 °C.
We have studied the effect of thermally reduced graphene oxide (TRG) on the properties of polypropylene/maleic anhydride-grafted-ethylene vinyl acetate (PP/EVA-g-MA) blends. In blends without TRG, EVA-g-MA was dispersed as droplets in PP. At low TRG content, the sheets located in the EVA-g-MA phase. At 5 wt. %, the morphology was co-continuous and the domain sizes of EVA-g-MA were small, while TRG sheets were randomly distributed in the blend. The electrical percolation threshold was between 3 and 5 wt. %. Melt rheological analysis revealed that PP/EVA-g-MA/TRG nanocomposites exhibited a viscous behavior of up to 3 wt. %, but showed a solid-like behavior at 5 wt. %. The addition of TRG into PP/EVA-g-MA blend up to 3 wt. % enhanced the tensile strength and modulus of PP/EVA-g-MA blend, while not adversely affecting its impact strength. PP/EVA-g-MA/TRG nanocomposites exhibited higher electrical and thermal conductivities compared to PP or PP/EVA-g-MA blends.
Polylactic acid (PLA) was modified with poly (butylene adipate-co-terephthalate) (PBAT) and carbon nanotubes (CNTs-COOH) with carboxyl groups by using the melt blending technique. Ethylene-butyl acrylate-glycidyl methacrylate (E-BA-GMA) was used as a compatibilizer which can bond the CNTs-COOH nanoparticles with PLA/PBAT matrix through interaction between the epoxy and carboxyl groups. The effects of the CNTs-COOH content on the mechanical properties, thermal properties, crystallinity and morphology of PLA/CNTs-COOH nanocomposites were investigated. The results showed that the tensile strength, elongation at break and impact strength of PLA could be simultaneously increased by incorporating CNTs-COOH nanoparticles. PLA/CNTs-COOH nanocomposites possessed higher thermal stability than pure PLA. The glass transition temperature and initial degradation temperature of PLA/CNTs-COOH increased as the CNTs-COOH content increased. When the CNTs-COOH content was low (≤0.5 wt%), CNTs-COOH nanoparticles could uniformly disperse in the PLA matrix. In general, CNTs-COOH was an effective filler to reinforce and toughen PLA simultaneously, and the PLA/CNTs-COOH nanocomposite with 0.5 wt% CNTs-COOH exhibited a good combination of strength and toughness.
The studies on the pyrolysis mechanisms of waste PVC contribute to development and application of pyrolysis technology for mixed waste plastics. In the article, the thermal decomposition mechanisms of model compound of poly(vinyl chloride) (PVC) have been investigated by employing density functional theory methods at M06-2X/6-31++G(d,p) level in order to illuminate the elimination of HCl and the formation of hydrocarbons. Various possible pyrolysis paths for the formation of main products were proposed, and the thermodynamic and kinetic parameters in every path were calculated. The calculation results show that the HCl elimination can occur through the concerted reaction and the energy barrier of HCl elimination changes from 167.4 to 243.3 kJ/mol; allyl group can obviously reduce the activation energy of HCl elimination, and the branched-chain can lower the energy barrier of HCl elimination at the carbon sites near the branch chain; a free radical is more easily converted into aromatic compound through a series of isomerizations, cyclization and dehydrogenation; the conjugated polyene could be decomposed in parallel reaction channels: one is the evolution of aromatics, another is the formation of small molecule products. The above analysis is consistent with previous experimental results and analysis.
This study focuses on the mechanical recycling of polymeric waste that is produced in considerable amount from the cable industry. Every year large amounts of cables become waste; wires recycling has traditionally focused on metal recovery, while the polymer cover has just been considered as a residue, being landfilled or incinerated. Nowadays, increasingly restrictive regulations and concern about environment make necessary to reduce landfilling as much as possible. Main novelty of the study is that the material used in the research is a post-consumer material and the entire residual material is used, without a previous purification, in contrast with similar studies. Characterization of this residue was performed by thermal analysis, showing that the material is mainly made up of a heavy fraction (84% of the residue), which is not able to melt, fact what makes recycling more difficult. Once characterized, the material was ground, blended with virgin polyethylene and reprocessed by rotational moulding. The influence of the amount of residue and parts structure (1, 2 and 3 layers) was assessed, studying the mechanical behaviour of obtained parts (tensile, flexural and impact properties). It has been found that although mechanical properties get reduced with the increased amount of residue, up to a 35% of residue can be used without an important decrease in mechanical properties. On the other hand, the use of multiple layers in the mouldings allowed obtaining a better external appearance without compromising the mechanical properties.
Density functional theory methods (DFT) M062X have been used to investigate the thermal degradation processes of model compound of bisphenol A polycarbonate (MPC) and to identify the optimal reaction paths in the thermal decomposition of bisphenol A polycarbonate (PC). The bond dissociation energies of main bonds in MPC were calculated, and it is found that the weakest bond in MPC is the single bond between the methylic carbon and carbon atom and the second weakest bond in MPC is the single bond between oxygen atom and the carbonyl carbon. On the basis of computational results of kinetic parameters, a mechanism is proposed where the hydrolysis (or alcoholysis) reaction is the main degradation pathways for the formation of the evolved products, and the homolytic cleavage and rearrangement reactions are the competitive reaction pathways in the thermal degradation of PC. The proposed mechanism is consistent with experimental observations of CO2, bisphenol A and 1,1-bis(4-hydroxyphenyl)-ethane as the main degradation products, together with a small amount of CO, alkyl phenol and diphenyl carbonate.
In this study, mechanically stable and recyclable superhydrophobic materials were prepared from polyvinylchloride (PVC) and kaolin nanoparticles modified by stearic acid using a simple and low-cost drop-coating. The obtained materials displayed liquid-repellent toward water and several other liquids of daily life (such as orange juice, coffee, milk, coca cola and ink). These superhydrophobic materials showed remarkable robustness against sandpaper abrasion, UV-irradiation and ultrasonication test, while retaining its superhydrophobicity even after 60 abrasion cycles loaded of 500 g with sandpaper, 7 days UV-irradiation or 120 min ultrasonication test. The excellent durability against complex conditions was attributed to the hierarchical structure and strong interfacial adhesion of the materials. More significantly, the materials used in the coating could be recycled and reconstructed without losing its superhydrophobicity. The current superhydrophobic materials tolerate rigorous environment, opening a new avenue to a variety of practical applications.
The effects of tannin-cadmium complex on the thermal and oxidation stability of PVC were investigated. Tannin-cadmium complex has been successfully synthesized and characterized by Fourier transform infrared spectroscopy, scanning electron microscopy and energy-dispersive X-ray analysis techniques. Thermal degradation and thermal oxidation–degradation behaviors of PVC formulations obtained by thermal mixing method were evaluated by thermogravimetric analysis (TG) and differential scanning calorimetry (DSC) under inert and oxidizing atmospheres, respectively. The obtained results such as the onset, maximum and final degradation temperatures as well as the degradation rates from TG and DTG curves revealed that the tannin-cadmium has significant impact on the thermal stability of PVC. The experimental data of PVC thermal degradation obtained by DSC studies also clearly showed that the stabilizing efficiency of tannin-cadmium is superior to that of synthetic thermal stabilizer applied as reference. Due to the HCl scavenging and antioxidation activities of tannin-cadmium, the global thermal and morphological properties of PVC stabilized by this product proved the best in morphology and stabilization properties both against thermal and thermal oxidation–degradations.
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In this report, melt grafting of maleic anhydride (MAH) and epoxy resin onto polypropylene (PP) by peroxide-initiated reactive extrusion has been investigated. As evidenced by Fourier transform infrared spectroscopy, both MAH and epoxy resin were successfully grafted onto PP through the reactions of MAH with PP and epoxy resin with MAH. It was found that tetramethyl thiuram disulfide could promote the grafting of MAH and inhibit the degradation of PP, as revealed by chemical titration and melt flow experiments, through prolonging the lifetime of the macroradical; meanwhile, epoxy resin could reduce the sublimation of MAH and the maximum grafting degree of MAH. Furthermore, the introduction of grafted products was found to enhance the mechanical properties of PP/glass fiber composites, and this influence was very significant at high grafting degrees with a high content of epoxy resin, which could be interpreted in terms of improved compatibility and adhesion at the interface. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43422.
A fluidized bed incineration experiment was performed by means of refuse-derived fuel (RDF) from source-classified garbage to study the emission characteristics of hydrogen chloride (HCl) pollutants and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCCD/Fs). This study analyzed the influence of the materials ratio, incineration temperature, and additive volume of calcium oxide (CaO) on the emission characteristics of HCl and the dioxins. Results show that plastics in garbage are direct factors for the emission of HCl and PCCD/Fs. The HCl yield significantly increases when the plastic component ratio increases from 35% to 45%. The RDF containing 45% plastics releases the highest toxicity concentration of total dioxins, whereas the RDF of 35% plastics releases the lowest dioxin toxicity concentration. The optimal incineration temperature is 850 °C, the emission concentrations of HCl and PCCD/Fs are significantly reduced at 850 °C. Adding CaO to combustible solid waste can effectively reduce the emission concentrations of HCl and PCDD/Fs in flue gas. This journal is
The formation of core-shell morphology for composite droplet polymer-blend systems containing a polyamide-6 (PA6) matrix, MAH grafted ethylene-propylene-diene rubber (EPDM-g-MAH) shell and high-density polyethylene (HDPE) core was studied. Core-shell morphology with various shell thickness of blends was controlled via adding EPDM-g-MAH with varying grafting degree. Smaller size of core-shell composite droplets and thicker EPDM-g-MAH shell are formed in PA6/EPDM-g-MAH/HDPE ternary blends with lower grafting degree of EPDM-g-MAH and the corresponding Izod impact strength reaches a optimal value of 35.7 kJ/m2, which is almost 9-10 times higher than pure PA6 (3.6 kJ/m2). Further, the toughening mechanism was proposed and the results showed that the thicker EPDM-g-MAH shell can better transfer the stress between polymer matrix and dispersed phase particles, resulting in easier fibrillation progress of dispersed phase particles, which absorbs a significant amount of impact energy. However, for the blends with higher grafting degree of EPDM-g-MAH, during impact processing the easier deformation of the thinner EPDM-g-MAH shell caused overlarge cavitations and naked/debonding fiber or spherical dispersed particles, which reduces the Izod impact strength of blends.
Bi-functional co-agent, diallyl phthalate (DAP), −assisted melting free-radical grafting of maleic anhydride (MAH) on polypropylene (PP) is carried out by reactive extrusion. The PP/recycled polyethylene terephthalate (rPET) blends with and without PP-g-MAH/DAP (PP grafted with both MAH and DAP) are conducted on a twin-screw extruder. It reveals that the introduction of DAP can significantly enhance the grafting degree of MAH and decrease the chain scission of PP. The maximum extent of MAH grafting (1.5 wt.%) is obtained when DCP and MAH contents are 0.5 and 6.0 wt.%, respectively, and the DAP/MAH molar ratio is 0.3. Besides, differential scanning calorimetry (DSC) analysis shows that the crystallization temperature of grafted PP is higher than that of pure PP due to the nucleation of grafted groups. Fourier transform infrared spectroscopy (FTIR) analysis proves that chemical reactions take place between PP-g-MAH/DAP and rPET. In particular, scanning electron microscopy (SEM) observations demonstrate that, the PP/rPET blends compatibilized with PP-g-MAH/DAP show enhanced adhesion at the interface comparing with the binary PP/rPET blend, which is also proved by DSC measurements, dynamic mechanical analysis (DMA) and mechanical properties.
The pyrolysis and co-pyrolysis behaviors of polyethylene (PE), polystyrene (PS) and polyvinyl chloride (PVC) under N2 atmosphere were analyzed by Thermal gravimetric/Fourier transform infrared (TG/FTIR). The volatile products were analyzed to investigate the interaction of the plastic blends during the thermal decomposition process. The TGA results showed that the thermal stability increased followed by PVC, PS and PE. The pyrolysis process of PE was enhanced when mixed with PS. However, PS was postponed when mixed with PVC. As for PE and PVC, mutual block was happened when mixed together. The FTIR results showed that the free radical of the decomposition could combine into a stable compound. When PE mixed with PVC or PS, large amount of unsaturated hydrocarbon groups existed in products while the content of alkynes was decreased. The methyl (CH3) and methylene (CH2) bonds were disappeared while PVC mixed with PE.
Processing and post-processing thermal stability of poly(vinyl chloride) compounds, plasticized with di(ethyl hexyl) phthalate (DEHP) and epoxidized soybean oil (ESO), using several ratios of calcium/zinc stearates are reported here. Two series of compounds were prepared, varying the DEHP or ESO concentrations. The compounds were prepared as follows: (1) preheating stearates, (2) dry-blending the compound components, (3) pelletizing the dry-blend and (4) extruding the pellets to obtain a ribbon geometry. Processing thermal stability was determined by: (a) mechanical characterization and (b) visual color comparison of samples. Post-processing thermal stability was followed by: (a) measurement of HCl release from heated pellets and (b) color changes in heated ribbon samples. Thermal stability was improved by the presence of DEHP and ESO. In addition, improved color stability was achieved with intermediate CaSt2/ZnSt2 ratios, and minimal HCl release was achieved in formulations without ZnSt2. Results can be directly applied to design a formulation for a specific application.
A graft copolymer, composed of malefic anhydride as side group and high-density polyethylene as backbone, was synthesized by a new method, in-situ chlorinating graft copolymerization. The result of Fourier Transform Infrared scans indicated the existence of anhydride polyethylene even if the chlorine content of the products was low (about 3%). Reactive degree of anhydridisation of polyethylene (AD), which was up to 1.4 wt%, was measured by chemical titration. The crystal behavior of graft copolymer was characterized by X-Ray diffraction and differential scanning calorimetry. The results of gel content and viscosity average molecular weight showed the modified polyethylene had no cross-link and degradation. Scanning electron microscope indicated that the compatibility between graft copolymer and polar polymers, such as poly (vinyl chloride), increased greatly compared with high-density polyethylene. As is highlighted in this paper, the preparation of anhydride polyethylene could be carried out efficiently and simply via in-situ chlorinating graft copolymerization.
Evidence is presented which suggests that during high temperature processing of LDPE/PVC blends with limited air access, cross-phase chemical interaction occurs to give LDPE/PVC graft copolymers. A similar process also appears to occur during photo-oxidation of LDPE/PVC blends, leading to improvement in blend properties (tensile strength).During thermal oxidation, stabilised PVC acts as a heat stabiliser for LDPE/PVC blends, whereas unstabilised PVC acts as a thermal sensitiser. The latter process is believed to be due to the formation of HCl which catalyses the decomposition of LDPE macroperoxides to free radicals.
In the presented study, polypropylene (PP) and high density polyethylene (PE) were blended at the ratios of 80/20 and 20/80 to simulate recycled waste thermoplastic mixtures. The effects of in situ grafting of PP/PE blends with maleic anhydride through the extruder on the mechanical and rheological properties of resulting wood/plastic composites were investigated. Different ratios of PP and PE in the blends created distinct properties in the resulting composites. Grafting of PP and PE blends improved the tensile and flexure properties of the resulting composites. The composites exhibited a reduced water uptake and resultant dimensional swelling due to grafting with maleic anhydride. Grafting of the blends also considerably improved the interfacial bonding and enhanced the dispersion of wood in the matrix, as evidenced by theological analysis and scanning electron microscopy. (C) 2011 Elsevier Ltd. All rights reserved.
High density polyethylene (HDPE)/nylon6 (PA6) blends were prepared by means of melt extrusion and using ethylene – octane copolymer graft maleic anhydride (POE-g-MAH) as a reactive compatibilizer. Phase morphology, rheological and thermoresponsive shape memory properties of the blends had been studied. The results showed that addition of POE-g-MAH could increase compatibility and phase-interfacial adhesion between HDPE and PA6, decrease the temperature sensitivity of the melt, improve the shape memory property and processability of HDPE/PA6 blends. The shape recovery rate of HDPE/PA6/POE-g-MAH (80/20/10) blend is 96.5% when the stretch ratio is 75% and optimal shape recovery response temperature is 135°C.
In this article, we report on the influence of reactive compatibilization on the morphological and rheological properties of blends of polyamide 6 (PA 6) and a styrene−acrylonitrile copolymer (SAN). PA 6/SAN blends with two different composition ratios (70/30 and 30/70) and varying concentration of a styrene acrylonitrile maleic anhydride terpolymer (SANMA) were prepared. During melt mixing, the amino end groups of PA 6 react with the maleic anhydride groups of SANMA. The objective of this work is to study the elastic and viscous properties of the blends in shear and elongation as a function of compatibilizer concentration. The composition ratio of the blends (PA 6 or SAN matrix) has a strong influence on the morphology and rheology of the blends, in particular for large SANMA concentrations. We explain this phenomenon by the asymmetric properties of the reactively compatibilized interface which originates from the comblike architecture of the in situ generated interfacial agent. In linear viscoelastic shear oscillations, the reactively compatibilized PA 6/SAN blends with a PA 6 matrix depict for large SANMA concentrations the power laws G′ G′′ ωn with n ≈ 0.58 whereas the blends with a SAN matrix display a solidlike low frequency behavior. In melt elongation, the extensional viscosity of the PA 6/SAN blends exceed its linear viscoelastic prediction for large SANMA concentrations. Furthermore, our AFM investigations of elongated and subsequently quenched samples reveal that the stretch ratio of spherical SAN domains in the PA 6 matrix increases with SANMA concentration. In recovery, these stretched SAN domains recover more slowly to an isotropic shape when the SANMA concentration was increased.
Thermal degradation mechanism and mechanical properties of poly(vinyl chloride) (PVC) in PVC–polyethylene (PE) mixtures with varying types, contents, and melt flow indexes of the PE were studied. The degradation behavior was investigated in terms of decomposition temperature and glass transition temperature, polyene index, and morphology of the PVC in the mix. The results suggested that adding small amounts of PE (5 phr) in PVC-PE mixtures could thermally stabilize the PVC, as noted by an increase in its decomposition temperature. At higher PE loading, the PVC encountered more degradation as a result of a consumption of the heat stabilizer by PE radicals and the dehydrochlorination reaction. A radical transfer reaction was proposed to explain the degradation mechanism of the PVC in the PVC-PE melt, specifically a progressive increase of the glass transition temperature of the PVC in the mix as a result of increasing PE content. The PVC-PE blend using HDPE with high MFI exhibited more pronounced thermal and structural changes of PVC. The mechanical properties of the PVC-PE blend were very much dependent on the PE content, but slightly affected by the type and MFI value of the PE. The dispersion level of the PE in the PVC phase was found to play an important role in affecting the mechanical properties of the PVC-PE mixtures. J. VINYL. ADDIT. TECHNOL. 12:115–123, 2006. © 2006 Society of Plastics Engineers
This paper investigates the structural changes of polyvinyl chloride (PVC) in melt-blends of a low-density polyethylene (LDPE) and polyvinyl chloride (PVC), and the effects of LDPE content and number of extrusion passes. These effects were examined in terms of changes in weight average molecular weight and number average molecular weight, polyene and carbonyl indices, color changes of the blend, and the variations in glass transition and decomposition temperatures. It was found that loading LDPE into PVC led to the formation of short-chain LDPE grafted PVC (s-LDPE-g-PVC) copolymers, via a macro-radical cross-recombination reaction, which had greater weight average molecular weight with unchanged number average molecular weight, increased decomposition temperature, lower glass transition temperature, as compared to the pure PVC sample. The dehydrochlorination reaction of PVC was suppressed by the macro-radical cross-recombination reaction with addition of LDPE, the effect being more pronounced at 13.0 wt% LDPE. For a given LDPE content, the macro-radical cross-recombination and dehydrochlorination reactions competed with one another, thus causing the increases in molecular weight average and molecular weight number up to the 4th extrusion pass. At the 5th extrusion pass, the dehydrochlorination reaction was predominant owing to a depletion of LDPE content to be grafted onto PVC molecular chains. The glass transition and decomposition temperature decreased with increasing number of extrusion passes. Polym. Eng. Sci. 44:487–495, 2004. © 2004 Society of Plastics Engineers.
This article aimed to investigate the mechanical, morphological and thermal properties of PVC/LDPE blend with and without the addition of compatibilizers. The effects of LDPE content, compatibilizer type and rubber-wood sawdust loading on the properties of the blend were evaluated. The experimental results suggested that as the LDPE content was increased the mechanical properties of PVC-LDPE blend progressively decreased due to poor interfacial adhesion. The continuity and compatibility between PVC and LDPE phases could be improved through three different types of compatibilizers which included chlorinated polyethylene (CPE) poly(methyl-methacrylate-co-butyl acrylate) (PA20) and poly(ethylene-co-methacrylate) (Elvaloy). The PA20 was found to be the most suitable compatibilizer for the blend. A radical transfer reaction was proposed in this work to explain the structure and thermal changes of the PVC in PVC-LDPE blend. The decomposition temperature of PVC in the blend decreased with the loading of the PA20 and the wood sawdust. As the sawdust content was increased the tensile and flexural moduli increased with considerable decreased in the tensile, flexural and impact strength, a slight improvement being achieved if the PA20 was incorporated in the composite. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 598–606, 2006