Journal of Polymer Research

Published by Springer Verlag
Online ISSN: 1572-8935
Print ISSN: 1022-9760
Radical ring opening polymerisation behaviour of 5,6-Benzo-2-methylene-1,3-dioxepane (BMDO) during its copolymerisation with 2,3,4,5,6-pentafluorostyrene (PFS) is reported using t-butyl peroxide (TBPO) conventional radical initiator. The reactivity behaviour of PFS for its copolymerisation is compared with that of the corresponding non-fluorinated monomer styrene. The presence of five fluorine atoms affected the course of polymerisation and led to the synthesis of well defined copolymers as compared to the formation of only homo poly styrene. Structural characterisation of the copolymers was done using 1D and 2D NMR spectroscopic techniques. The microstructural characterisation showed the formation of gradient copolymers with increased reaction time and/or increased amount of BMDO in the feed. The reactivity ratios for the copolymerisation of BMDO and PFS were determined using Kelen-Tüdos method and was found to be r BMDO = 0.35 and r PFS = 9.9. Thermal stabilities of copolymers are also compared with that of the homopolymers.
A diamine, 1,3-bis(4-aminophenoxy) benzene (II), was synthesized in two steps; fist from the condensation of resorcinol with p-chloronitrobenzene in the presence of potassium carbonate, producing I ,3-bis(4-nitrophenoxy) benzene (I), followed by hydrazine hydrate/Pd-C reduction. A two imide rings-preformed dicarboxylic acid, 1,3-bis(4-trimellitimidophenoxy)benzene (III), was prepared from the condensation of diamine II and trimellitic anhydride in 1:2 molar ratio. A series of structurally new polyamide-imides (Va-p) were directly synthesized from the diacid III and various aromatic diamines (IVa-p). The resultant polyamide-imides had inherent viscosities between 0.56–1.39 dl/g. All polymers, except some derived from diamines with p-phenoxy structure, showed excellent solubility. Some polymer resulted in tough or flexible transparent films. Dynamic TG data indicated that all polymers possess excellent thermal stability with no significant weight loss up to the temperature of approximately 450 C in nitrogen, and their 10% weight loss temperature was recorded in the range of 489–577 C. Measurements of wide-angle X-ray diffraction revealed that some polymers derived from p-phenoxy group-containing diamines showed crystalline patterns.
Poly(2,3-Dimethyl-1,3-butadiene) (PDMB) with varying contents of 1,4-and 1,2-structures has been anionically synthesized using either n-butyllithium or sec-butyllithium as an initiator. The addition of tetrahydrofuran could enhance the rate of synthesis and effect the microstructure. The Tm was higher for PDMB with a lower content of 1,2-structure, and the Tg was lower. This PDMB was then hydrogenated with a nickelocene/n-butyllithium catalyst system leading to the formation of HPDMB. The trans 1,4-structure unit was more difficult to hydrogenate due to its steric hindrance. Repetitive hydrogenation was necessary in order to achieve a high degree of hydrogenation. The hydrogenated PDMB is an amorphous elastomeric material. The Tg’s were found to decrease with an increase in the degree of hydrogenation, concurrent with a gradual disappearance of the Tm’s. Since a HPDMS with a low content of 1,2-structure resembles a head-to-head polypropylene, our data suggest that the Tg of an atactic head-to-head polypropylene lie between −30 and −35 °C.
a shows an XRD pattern of the TiO 2 nanoneedles, which were harvested from a silicon wafer by ultrasonic vibration. These needlelike nanostructured TiO 2 nanoneedles exhibit a clearly tetragonal structure (rutile) by comparison with the JCPDS card file mo. 75-1757 (also shown in the figure). b shows the typical HRTEM images of the TiO 2 nanostructure and the inset shows a selective-area electronic diffraction pattern. It reveals that TiO 2 has a rutile crystal structure. The lattice spacing is about 3.2 A ˚ between adjacent lattice planes of the TiO 2 needles, corresponding to the distance between (110) crystal planes of the rutile phase. The dispersion of TiO 2 nanoneedles in MEH-PPV was further analyzed by TEM. The samples for TEM study were prepared by directly coating the TiO 2 /MEH-PPV solution on a C-Cu grid. The TEM images of TiO 2 /MEH-PPV containing different amounts of TiO 2 are shown in Figure 3a-c, and they show that the TiO 2 nanoneedles were well dispersed in MEH- PPV. The percolation network geometry of TiO 2 increases, while the percentage of incorporated TiO 2 in the composites increases. The enlarged image shown in Figure 3d reveals that the TiO 2 nanoneedles formed a percolation network geometry in MEH-PPV. These TiO 2 nanoneedles are about 100 nm in length and 30 nm in width, terminating with a sharp pinnacle.  
(a) Model and experimental JYE curves of MEH-PPV and TiO 2 nanoneedles/MEH-PPV composites. The dotted line is a fit to the data. (b) Hole barrier height from cyclic voltammetry (CV) and FowlerYNordheim (FN ) fitting vs the amount of TiO 2 incorporated in MEH-PPV.  
(a) X-ray diffraction curves of TiO 2 nanoneedles and (b) a highresolution transmission electron microscopy (TEM) image of TiO 2 nanoneedles.  
We demonstrated that in a nanocrystalline TiO2/poly(2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylene vinylene) (MEH-PPV) composite, electroluminescence of this composite is enhanced via addition of TiO2 nanoneedles. The TiO2 nanoneedles enhance the partial crystallization of MEH-PPV around TiO2, which in turn causes a decrease in the hole barrier height and an increase in hole mobility. The I–V measurement was established on an indium tin oxide/MEH-PPV:TiO2/Al device to identify the electrical properties of the composites.
1,4-pentadien-3-one-1,5-bis(p-hydroxyphenyl) (PBHP) was synthesized by reacting p-hydroxybenzaldehyde and acetone in the presence of HCl gas. 1,4-pentadien-3-one-1-p-hydroxyphenyl-5-p-phenyl acrylate (HPA) was prepared by reacting PBHP with acryloyl chloride in ethyl methyl ketone (EMK) medium at 0C. Copolymerization of different feed compositions of HPA with glycidyl methacrylate (GMA) was carried out using benzoyl peroxide (BPO) as initiator in EMK solvent under nitrogen atmosphere at 701C. Polymers thus synthesized were characterized by IR and NMR (1H/13C) spectroscopic techniques. Reactivity ratios of the monomers were calculated from the 1H NMR data by applying linearization methods such as Fineman–Ross, Kelen–Tudos and extended Kelen–Tudos methods. Photocrosslinking property of the polymer samples was studied using the solvent method. Thermal stability of the polymers were measured using thermogravimetric analysis. Molecular weights (M w and M n) and polydispersity value of the polymer were determined using gel permeation chromatographic technique.
An imide ring containing dicarboxylic acid, 1,4-bis(4-trimellitimidophenoxy)benzene (III), was prepared by the condensation of 1,4-bis(4-aminophenoxy)benzene and trimellitic anhydride. A series of new poly(amide-ether-imide)s were prepared by the direct polycondensation of diimide-diacid III with various aromatic diamines using triphenyl phosphite and pyridine as condensing agents inN-methyl-2-pyrrolidone (NMP) in the presence of calcium chloride. The highest inherent viscosity value of a poly(amide-ether-imide) obtained was 1.78 dL/g (inN,N-dimethylacetamide, DMAc, at 30 C). Flexible films with excellent tensile properties were cast from DMAc solutions. Glass transition temperatures of these poly(amide-ether-imide)s were recorded in the range of 248–297 C. These polymers do not show obvious weight loss before 400C; the decomposition temperatures at which 10% weight loss in nitrogen and in air were observed for these poly(amide-ether-imide)s in the range of 521–564C and 501–539C, respectively. The polymers derived fromp-phenylenediamine or the diamines containing 1,4-bisphenoxy units exhibited a higher degree of crystallinity and higher initial decomposition temperatures but poor solubility in organic solvents.
A new series of N,N′-(bicyclo[2,2,2]oct-7-ene-tetracarboxylic)-bis-L-amino acids 3a–g were synthesized by the condensation reaction of bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride 1 with two equimolars of various amino acids such as L-alanine 2a, L-valine 2b, L-leucine 2c, L-isoleucine 2d, L-phenyl alanine 2e, L-2-aminobutyric acid 2f and L-histidine 2g in an acetic acid solution. Also 1,5-bis(4-aminophenyl)penta-1,4-dien-3-one 7 was synthesized by using a two-step reaction. At first 1,5-bis(4-nitrophenyl)penta-1,4-dien-3-one 6 was prepared from the reaction of two equimolars 4-nitrobenzaldehyde 5 and one equimolar acetone 4 in ethanol and NaHCO3 and dinitro compound 6 was reduced by using Na2S. Then seven new photosensitive and optically active organo-soluble poly(amide–imide)s (PAIs) 8a–g with good inherent viscosities were synthesized from the direct polycondensation reaction of new N,N′-(bicyclo[2,2,2]oct-7-ene-tetracarboxylic)-bis-L-amino acids 3a–g with 1,5-bis(4-aminophenyl)penta-1,4-dien-3-one 7 by two different methods such as direct polycondensation in a medium consisting of N-methyl-2-pyrrolidone (NMP)/triphenyl phosphite (TPP)/calcium chloride (CaCl2)/pyridine (py) and direct polycondensation in a tosyl chloride (TsCl)/pyridine (py)/N,N-dimethylformamide (DMF) system. The polymerization reactions produced a series of photosensitive and optically active organo-soluble PAIs with high yield and good inherent viscosity. The resulted polymers were fully characterized by means of FTIR and 1H-NMR spectroscopy, elemental analyses, inherent viscosity, specific rotation, solubility tests, UV-vis spectroscopy, differential scanning calorimeter (DSC), thermogravimetric analysis (TGA), and derivative of thermaogravimetric (DTG). These macromolecules exhibited maximum UV-vis absorption at around 370 and 265nm in a DMF solution. KeywordsPhotosensitive-Optically active-Organo-soluble-Poly(amide–imide)
Phase behaviorof ternary blends of polystyrene (PS), tetramethylbisphenol-A polycarbonate (TMPC), and poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) at two different temperatures (i.e., 210 and 300 C, respectively) was studied by means of differential scanning calorimetry. Miscibility of the ternary blends at either temperature was found restricted to limited compositions, in agreement with simulated spinodal curves based on published values of interaction parameters. The limited ability of PS, which is separately miscible with TMPC and PPO at 210 C, to act as a common solvent for the immiscible TMPC/PPO pair at this temperature was explained in terms of the disparity in PS/TMPC and PS/PPO pair interactions (i.e., the "ΔX effect").
In this work, a kind of aliphatic biodegradable polyesteramide (PEA) copolymer based on 6-aminocaproic acid, adipic acid, and 1,6-hexane diol was synthesized by melt polycondensation method, and was characterized by 1H-NMR, FTIR and DSC. The PEA fiber was prepared by melt-spinning method. Tensile properties of the as-spun and hot-drawn fibers were also investigated. Hydrolytic degradation behavior of PEA copolymer chips and fibers were evaluated by weight loss in PBS solution with different pH value. The alkaline degradation behavior of fiber was also studied on change of diameter and surface morphology. During alkaline degradation, the PEA fiber underwent surface erosion.
Films of Polypyrrole/Montmorillonite (PPy/MT) clays were electropolymerized potentiostatically on aluminium alloy 1100, using sodium dodecylbenzenesulfonate (SDBS) as a dopant. Two clay species were used: Na+-Montmorillonite (MT-Na) and modified-Montmorillonite (MT-M). The characterization of the PPy/MT films performed by XRD and TEM shows that the exfoliation method employed, as well the electrochemical polymerization method used in this work, allow nanocomposite materials to be obtained. The PPy/MT films were found to have less electrical conductivity than pure PPy. The corrosion protection of aluminium alloy 1100 covering PPy/MT was evaluated by electrochemical techniques in 0.05molL−1 NaCl medium. The electrochemical parameters derived from the polarization curves, together with the EIS data, revealed that the corrosion resistance of PPy/clay coatings depends on the type and concentration of Montmorillonite employed. The best performance in the corrosion protection of the aluminum was achieved with PPy/MT films containing 1% of clay. KeywordsPolypyrrole-Montmorillonite-Aluminium-Corrosion
Using self-consistent field theory, we investigate the ordered microstructures self-assembled from A 2m + 1 B m C m comblike copolymers. We find that the architectures, volume fractions of the components and the interaction parameters dramatically influence the phase behavior. By systematically changing above factors, we obtain six kinds of regular structures. They are hexagonal lattice phase, two interpenetrating tetragonal lattice, core shell hexagonal lattice phase, two-phase lamellar structure, hexagonal phase with beads inside and three-phase lamellar structure. Further we construct the phase diagrams to clarify the phase regions where the different microstructures exist. The results may be helpful in the design of the desired microstructures. KeywordsMicrostructures–Self-assembly–Comblike copolymers–Self-consistent field theory
A new trifluoromethyl-substituted diamine monomer, 2,2-bis[4-(4-amino-2-trifluoromethylpenoxy)phenyl]sulfone (II), was prepared through the nucleophilic substitution reaction of 2-chloro-5-nitrobenzotrifluoride and 4,4’-sulfonyl diphenol in the presence of potassium carbonate, followed by catalytic reduction with hydrazine and Pd/C. Novel fluorinated polyimides Va–f having inherent viscosities ranging from 0.74 to 1.14 dL/g were synthesized from the diamine II with various aromatic dianhydrides via thermal imidization of poly(amic acid). Most of V series were soluble in the all test solvents, except Vb(H). These polyimide films had strengths at yield of 94–119 MPa, tensile strengths of 90–118 MPa, elongations to break of 10–16%, and initial moduli of 2.0–2.4 GPa. The glass transition temperature (Tg) of these polymers were in the range of 244–297 ○C, their 10% weight loss temperatures were above 520 ○C under ether nitrogen or air atmosphere, and left more than 45 wt% residue even at 800 ○C in nitrogen. Compared with polyimides VII based on 4,4’-bis(3-aminophenoxy)diphenyl sulfone (II’), V showed better solubility and lower color intensity, dielectric constant, and moisture absorption. Their films had cutoff wavelengths between 355–402 nm, b* values ranging from 6.8 to 32.9, dielectric constants of 3.32–4.27 (1 MHz), and moisture absorptions in the range of 0.27–0.62 wt%.
Inherent viscosities, film quality, and tensile properties of the poly(ester-amide)s and poly(ester-imide)s
Average molecular weights of the poly(ester-amide)s and poly(ester-imide)s
Elemental analysis data for the poly(ester-amide)s and poly(ester-imide)s
FT-IR spectrum of a thin film of the copoly(ester-amide) m-5j  
Typical DSC and TMA thermagrams of the poly(ester-amide) p-5i: DSC, heating rate of 20 °C/min; TMA, heating rate of 10 °C/min and applied force of 10 mN
Two new naphthalene-ring-containing bis(ester-amine)s, 2,3-bis(4-aminobenzoyloxy)naphthalene (p-2) and 2,3-bis(3-aminobenzoyloxy)naphthalene (m-2), were prepared from the condensation of 2,3-dihydroxynaphthalene with 4-nitrobenzoyl chloride and 3-nitrobenzoyl chloride, respectively, followed by catalytic hydrogenation. The novel aromatic poly(ester-amide)s and poly(ester-imide)s having 2,3-linked bis(benzoyloxy)naphthalene units have been synthesized from the polycondensation reactions of bis(ester-amine)s (p-2 and m-2) or an equimolar mixture of 4,4′-oxydianiline and p-2 or m-2 with various aromatic dicarboxylic acids and dianhydrides. The synthesis of the poly(ester-amide)s was achieved by the phosphorylation polyamidation reaction by means of triphenyl phosphate, and the synthesis of the poly(ester-imide)s included ring-opening polyaddition to give poly(amic acid)s followed by chemical imidization to polyimides. Most of the poly(ester-amide)s were readily soluble in various organic solvents. Six poly(ester-amide)s and two poly(ester-imide)s derived from less rigid diacids and dianhydrides, respectively, were amorphous and could be solution-cast into transparent and tough films with good mechanical properties. Most of the poly(ester-amide)s displayed discernible glass-transition temperatures (T gs) between 192 and 223°C in the DSC traces. All of the poly(ester-imide)s, except for one sample, showed clear T g values between 225 and 265°C by DSC. These poly(ester-imide)s showed excellent thermal stability with 10wt% loss temperatures above 460°C in nitrogen or air.
Thin-film FTIR spectra of poly(amide-imide)s 4c and 4d. 
TMA thermograms of poly(amide-imide)s 4c (curve A) and 4e (curve B) with a heating rate of 10 ◦ C/min. 
TGA curves of poly(amide-imide) 4f with a heating rate of 20 ◦ C/min. 
2,4-diaminotriphenylamine (2) was synthesized via the cesium fluoride-mediated aromatic substitution reaction of 1-fluoro-2,4-dinitrobenzene with diphenylamine, followed by palladium-catalyzed hydrazine reduction. A series of poly(amide-imide)s (PAIs) with inherent viscosities of 0.38–0.46 dL/g were prepared by triphenyl phosphite-activated polycondensation from the diamine monomer 2 with various monoimide- and diimide-dicarboxylic acids. All of the PAIs were readily soluble in a variety of organic solvents and formed strong and tough films via solution casting. These PAIs have moderately high glass transition temperatures in the range of 168–274 ○C and 10 % weight loss temperatures in excess of 447 ○C in nitrogen or in air.
2,6-bis[1-(cis)-myrtanylimino)ethyl]pyridineiron(II) chloride (2) and 2,6-bis[(1-phenylimino)ethyl]pyridineiron(II) chloride (3) were investigated as novel complexes for iron-mediated atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) and tert-butyl acrylate (tBA) using toluene as the solvent, and ethyl 2-bromoisobutyrate as the initiator. A catalyst/initiator molar ratio as low as 0.1/1 was used in order to reduce catalyst contamination to the polymers. Both complexes produced PMMA and PtBA polymers with controlled structures and very low molecular weight distributions as low as 1.07, in particular for complex 3. High to moderate conversions (30–45%) were obtained in 20h, although very diluted amount of catalyst was used and in the absence of any reducing agent which indicates an efficient catalyst system. The resulting polymers were characterized by NMR, GPC, and DSC. Syndio-rich atactic poly(t-BA) and poly(MMA) with relatively high [rr] diads (50%, 42%, respectively) were isolated. KeywordsATRP-Bis(imino)pyridineiron(II) complexes-tert-Butylacrylate-Methyl methacrylate-Tacticity-Molecular weight distribution
A series of new aromatic polyimides containing bis(phenoxy)naphthalene units were synthesized from 2,6-bis(4-aminophenoxy)naphthalene (2,6-BAPON) and various aromatic tetracarboxylic dianhydrides by the conventional two-stage procedure with thermal imidization of poly(amic acid) films. The intermediate poly(amic acid)s obtained had inherent viscosties of 1.60–3.31 dL/g, and they could be solution cast and thermally converted into transparent, flexible, and tough polyimide films. The resulting polyimide films had tensile moduli of 1.5–2.3 GPa, tensile strengths of 105–124 MPa, and elongations at break of 7–22%. The polyimide derived from 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) was readily soluble in polar aprotic solvents. The glass-transition temperatures of these polyimides, except for that from pyromellitic dianhydride (PMDA), were recorded between 255 and 295C by differential scanning calorimetry (DSC). The softening temperatures of all the polyimide films stayed within 246–286C according to thermomechanical analysis (TMA). Thermogravimetic analyses (TGA) established that these polymers were fairly stable up to 500C, and the 10% weight loss temperatures were recorded in the range of 543–563C in nitrogen and 535–563C in air atmosphere.
1 H-NMR spectrum of PEHFV prepared by Horner-Emmons coupling
TGA and DSC thermograms of PEHFV prepared by HornerEmmons coupling
Photoluminescence of PEHFV in solid form (powder) at room temperature (excitation at 370 nm) 
Current and electroluminescence versus voltage profile of the ITO/PEDOT:PSS/PEHFV emitting layer/Al device 
The π-conjugated light-emitting polymer poly(9,9-bis(2-ethylhexyl)fluorene-2,7-vinylene) (PEHFV), was synthesized in defect-free form via Horner-Emmons coupling. The structure and properties of the polymer were characterized by 1H NMR, 13C NMR, UV-vis, photoluminescence (PL), and electroluminescence (EL) spectroscopies as well as gel permeation chromatography (GPC) and thermogravimetric analysis (TGA). The weight-average molecular weight (Mw) and polydispersity of the PEHFV were 34,000g/mol and 2.3, respectively. The UV-vis spectra showed absorption maxima at 425 and 452nm, and the PL emission spectra showed a maximum at 505nm with a shoulder at 541nm. The polymer was soluble in common organic solvents and easily spin-coated on indium-tin oxide (ITO)-coated glass substrates. A double-layer light-emitting device with an ITO/PEDOT:PSS/PFV/Al configuration was fabricated. The turn-on voltage for the PEHFV device was observed at 3.0V. KeywordsPolymer light-emitting diode (PLED)-Poly(fluorene vinylene)(PFV)-Defect-free-Electroluminescence
The effects of structure and stereochemistry on NMR spectrum of the synthesized PVAc-b-PMA and PVAc-b-PMMA block copolymers via ATRP were studied by 1D (13C and distortionless enhancement by polarization transfer, DEPT-135) and 2D heteronuclear single quantum coherence (13C-1H HSQC) and 2D total correlation spectroscopy (1H-1H TOCSY) NMR. The carbonyl carbons of vinylacetate (VAc), methyl acrylate (MA) and methyl methacrylate (MMA) units resonated separately and were found to be sensitive to the configuration through different coupling between carbonyl carbon and protons of methylene, methin and α-methyl. The DEPT-135 helped in separation of the overlapping peaks of methylene carbon signals from the methin and α-methyl carbon resonances. The total spectral assignment of triad level of methin of MA and quaternary carbon of MMA units, tetrads level of methylene of VAc, MA and MMA units and pentads level of methin of VAc unit were studied by 13C NMR and Bernoullian statistics also proved the assignments. The probability (Pm) to length average (Nm) values of meso addition in PVAc, PMA and PMMA segments were also calculated to be 0.455/2.86, 0.208/1.08 and 0.249/1.31. 2D HSQC NMR was used in accurate assignment of CH2 backbone, α-CH3 and CH carbon resonances and study of stereochemical effect on the splitting of signals. 2D TOCSY NMR played an important role in studying the vicinal and geminal couplings between the protons of methylene and methin.
Novel bioengineering copolymers were synthesized by radical copolymerization of N-isopropylacrylamide (NIPA) and 3,4-2H-dihydropyran (DHP) with 2,2′-azobisisobutyronitrile as an initiator in acetone solution at 70 °C under nitrogen atmosphere. Structure, tacticity and compositons of the copolymers prepared in a wide range of monomer feed were confirmed by FTIR, 1H{13C} NMR-DEPT and elemental analyses. The monomer reactivity ratios (r 1 and r 2) were detected using known two methods: r 1 (NIPA) = 1.25 and r 2 = 0.035 (DHP), and r 1 (NIPA) = 0.97 and r 2 = 0.022 (DHP) by Kelen-Tüdös and Jaacks methods, respectively. It was demonstrated that the studied monomer pair has a tendency to form H-bonding beween amide/ether groups through −NH...O< complexation which played an important role in the stereoselective chain growth, and significant decrease of allyl degradative chain transfer reactions. This phenomenon is also confirmed by the observed relatively high molecular weights of copolymers (M v ). The synthesized water-soluble stimuli-responsive poly(NIPA-co-DHP)s exhibit thermal stability, higher glass-transition temperature, polyelectrolyte, pH- and temperature-sensitive behavior and can be attributed to the class of bioengineering functional copolymers useful for various bio- and gene-engineering, and drug delivery applications.
Electrodeposition of poly(3,4-ethylenedioxythiophene) by electrochemical polymerization of 3,4-ethylenedioxythiophene has been performed on steel electrodes rather than on the typically used inert electrodes (Pt, Au, graphite carbon). The polymer was generated by cyclic voltammetry, chronopotentiometry and chronoamperometry from a 10mM monomer solution in acetonitrile with 0.1M LiClO4. Elemental analysis of the generated polymer indicated that the monomeric units support 0.54 positive charges balanced with CIO4 14− counterions. Electrochemical, electrical and structural properties of the prepared material have been characterized. The good adherence of films combined with its excellent properties indicate that poly(3,4-ethylenedioxythiophene) can be a suitable material for anticorrosion applications.
A novel fluorinated diimide dicarboxylic acid, 4,4′-bis(4-trimellitimido-2-trifluoromethylphenoxy)biphenyl (III), was synthesized from the condensation of 4,4′-bis(4-amino-2-trifluoromethylphenoxy)biphenyl (I) and trimellititc anhydride. A series of soluble poly(amide-imide)s (PAI) Va–h having inherent viscosities of 0.56–0.97 dL/g were prepared from reacting III with an equivalent amount of diamines by direct polycondensation using triphenyl phosphite and pyridine as condensing agents. The polymer V series afforded tough, transparent, and flexible films. They had tensile strengths ranging from 88 to 112 MPa, elongations at break from 8 to 31%, and initial moduli from 1.9 to 2.7 GPa. The glass-transition temperature (T g) of the polymers was recorded at 235–300 ○C. They had 10% weight loss at a temperature above 502 ○C and left more than 54% residue even at 800 ○C in nitrogen. In comparison with the nonfluorinated PAI VI series, the fluorinated V exhibited better solubility.
A diamime monomer with ether-ketone group, 4,4'-Bis(4-aminophenoxy)benzophenone (II) was prepared through the nucleophilic substitution reaction of 1-chloro-4-nitrobenzene with 4,4'-Dihydroxybenzophenone in the presence of potassium carbonate in N,N-dimethylformamide, followed by catalytic reduction with hydrazine and Pd/C. Polyimides (PI) V a–f (H), V a–f (C) and copolyimides (co-PI) V b–d/m(e–f) were synthesized from II and six kinds of commercial aromatic dianhydrides (III a–f )via thermal or chemical imidization method. Poly(amic acid) (IV a–f )had inherent viscosities range from 0.81 to 0.98 dL/g. PI of thermal imidization method was showed poor solubility even sulfuric acid. But PI of chemical imidization method V e,f (C) and (co-PI(C)) could be dissolved. The reason is that the ketone group of poly(amic acid) segments linked with the terminal amino group of polymer chains during thermal imidization. PI films V a–f (H) had tensile strengths of 101–118 MPa, elongations to break of 11–32%, and initial moduli of 2.1–2.8 GPa. The glass transition temperatures of V series were in the range of 252–278C, and the temperatures of 10% weight loss (T 10) were above 529C and their residues more than 50% at 800C in nitrogen. V series also measured the color, dielectric constants and moisture absorptions. Their films had cutoff wavelengths between 378–421 nm, b * values ranging from 16.4 to 77.1, dielectric constants of 3.47–3.85 (1 MHz), and moisture absorptions in the range of 0.31–0.46 wt%.
A new monomer (2-N,N-dimethylamino-4,6-Bis (2-thienyl)–pyrimidine) was synthesized and its homopolymer was successfully prepared by using Ferric trichloride (FeCl3) as an oxidant. The structure of the polymer and monomer was fully characterized by 1H–NMR, FTIR, UV-vis, Fluorescent spectroscopy and X-ray diffraction pattern. The polymer gives rise to a band at λ max = 391nm. The polymer showed the PL spectrum, gave a peak at 507nm.We have observed that the polymer was sensitive to inorganic acids and the acidochromism behavior was investigated applying organic acid such as CF3COOH. The corresponding UV-Vis peaks were observed at 464nm and 357nm respectively. X-ray diffraction data shows that polymer has a certain crystallinity. The polymer exhibited an [η] value of 0.26dLg−1 at 25°C in H2SO4 (w = 98%). KeywordsPolymer-Optical properties-Acidochromism
A novel class of interesting polyurea derivatives 6 a-c and 7 a-c was synthesized using solution polycondensation technique by the interaction of 1 mole of bis (2-aminothiazol-4-ylbenzylidene)cycloalkanones monomers 3 a,b with one moles of diisocyanate compounds in pyridine. The model compounds 4 and 5 were synthesized by the interaction of one mole of monomers 3 a or 3 b with two moles of phenylisocyanate in pyridine and their structures were confirmed by correct elemental and spectral analyses. The resulting polymers were characterized by elemental and spectral analyses, beside solubility and viscometry measurements. X-ray analysis showed these polymers having high degree of crystallinity in the region 2θ = 5–60°. In addition, the morphological properties of selected examples were tested by SEM, and the electrical properties of these polymers were measured. Moreover the corrosion inhibition behavior of diarylidenecycloalkanone monomers and selected examples of polyurea derivatives were carried out on steel in 0.5 M H2SO4 at 40°C giving cathodic, anodic and mixed inhibition.
Fatigue behavior of carbon fiber reinforced poly etheretherketone (PEEK) laminated composite was investigated. The [45]4s AS-4/PEEK laminated composites under static tensile measurement at various test temperatures were conducted. Three tension-tension fatigue loading frequencies, 1 Hz, 5 Hz and 10 Hz, were selected to study the effect of frequency on the fatigue behavior of [45]4s AS-4/PEEK laminate. The survival probability of experimental fatigue life data under different stress amplitude tests were estimated and analyzed by the median rank order-statistic cumulative-distribution function and the Weibull distribution function. The S-N curves at different fatigue loading frequencies exhibited a trend of two-segment straight line curves. The increase in surface temperature of specimens was found and the thermal stress history was also investigated by thermo-image techniques during fatigue life testing. The fatigue failure mechanism was investigated by X-ray radiography.
This investigation focused on the research of 4A zeolite on the properties of intumescent flame retardant (IFR) agent filled natural rubber (NR) systems. The first part focused on the evaluation of such characteristics as cure characteristics, tensile property, abrasion loss, and cross-linking density of NR composites. Experimental results demonstrated that the addition of 4A zeolite could increase the cross-linking density of the NR systems. The incorporation of 0.3phr of 4A zeolite with 50phr of IF Ragent could improve the elongation value from 480 to 610%, probably 27% increase. Also, the abrasion loss was decreased from 0.95 to 0.70cm3, nearly 26%. The second part focused on the study of flame-retardant (FR) properties of 4A zeolite filled NR systems. The properties and structure of these composites were characterized by limited oxygen index (LOI), thermogravimetric analysis (TGA), and cone calorimeter. It was proved that the addition of 0.3phr of 4A zeolite into the IFR filled NR systems could lead to an increase of LOI value and thermal stability, together with a decrease of mass loss ration, rate of heat release (RHR), carbon monoxide (CO) evolution and carbon dioxide (CO2) evolution, and so on, in a word, an improvement of FR properties.
Acetophenone based oligomer was synthesized by condensation of 2-hydroxy-4-ethoxyacetophenone with 1,3-propane diol in the presence of polyphosphoric acid as a catalyst at 145°C for 10h. The synthesized oligomer was used to study its ion exchange efficiency and to synthesize its polychelates with 4f-block elements. The oligomer and its polychelates were characterized on the basis of elemental analyses, electronic spectra, magnetic susceptibilities, FTIR, NMR and Thermogravimetric analyses. The Number Average Molecular Weight ([`(M)] n\overline M n) was determined using Vapor Pressure Osmometry (VPO) method. Ion-exchange studies at different electrolyte concentrations, pH and rate have been carried out for 4f-block elements. Antimicrobial activity of polychelates against Escherichia coli, Bacillus subtilis, Staphylococcus aureus (bacteria) and Saccharomyces cerevisiae (yeast) were measured Catalytic activity of only selected polychelates was examined for organic synthesis. It is observed that, oligomer can be used as an ion – exchanger and polychelates act as an efficient catalysts and antimicrobial agents.
Nylon-6,6 fibers, spun from the polyamide (polyhexamethylene diamine adipate), are increasingly required to be dyed with high washing fastness. Nylon-6,6 were dyed with hydrophobic reactive dyes synthesized in our laboratory, using supercritical carbon dioxide as the solvent system. Structures of four hydrophobic reactive dyes and their covalent force with nylon-6,6 fibers were confirmed by FTIR, MS and NMR analysis. Nylon-6,6 were also dyed with C.I. disperse red 2 to compare the result with specimen dyed by hydrophobic reactive yellowish red dye (dye I), which further demonstrated that covalent force was formed between dye-fiber interaction. Dye uptake was moderate to good and the dyed fabrics had very good fastness properties. Results of the latter studies indicated that dyeing nylon-6,6 in supercritical carbon dioxide is feasible.
Styrene-acrylonitrile-glycidyl methacrylate (SAG) copolymers with various glycidyl methacrylate (GMA) contents have been used to compatibilize the incompatible blends of acrylonitrile-butadiene-styrene (ABS) and nylon 6,6 (N66) by varying the blending sequences. When the epoxy group of SAG copolymer makes contact and reacts with the amine endgroup of N66, the resultant grafted products, SAG-g-N66, tend to reside at interface and act as compatibilizers of the blends. For a SAG copolymer with lower GMA content (SG2), a better compatibilized blend is achieved by sequential blending of the SAG2 with N66 then with ABS. When a higher GMA content SAG (SAG 10) is employed, on the contrary, a better compatibilized blend is obtained by preblending SAG10 with ABS then with N66. A grafted SAG-g-N66 molecule is considered as an effective compatibilizer when it anchors along the interface with the ungrafted SAG, or the SA segments, penetrating into the ABS phase while the branched N66 chains protruding into the N66 phase. The conventional one-step three-component blending usually results in less compatibilized blend than the properly selected sequential blending. The trend of mechanical properties observed closely match the compatibility of the blend in terms of domain size. However, the overall improvement of the resultant mechanical properties of the compatibilized blend over the uncompatibilized one is not substantial.
60Co γ rays induced styrene emulsion polymerizations were carried out with sodium undec-10-enoate (UDNa) as emulsifier at room temperature and the different kinetics was discussed. The influence of absorbed dose rate, monomer concentration and emulsifier concentration on kinetics and latex particles was studied. The polymerization kinetics relation was found as R P ∝ D 0.37· M 0.75· E 0.70 (R P , maximum polymerization rate; D, absorbed dose rate; M, monomer concentration; E, emulsifier concentration). The particles’ diameter increases and particle size distribution (PSD) becomes narrower with the decrease of absorbed dose rate and increase of monomer content. The effect of UDNa content on particles’ diameter and particle size distribution is the same as that of emulsifier in conventional emulsion system. This type of emulsion polymerization can easily form monodisperse particles.
The effect of service temperature on chemical structure and mechanical properties of polyamide 6 & 66 tyre cords was studied over the broad range of 50–200°C and for a period of 16h. The heat treatment of cords at below 100°C and above 120°C was found to reduce their tensile properties considerably. The changes in properties above 120°C were caused by increase in width of the molecular weight distribution curve as ascertained by gel permeation chromatography (GPC) studies and increase in irregularity of the polymeric chains as ascertained by birefringence studies; this appears to be due to the fact that, by raising the temperature, both chain folding and chain scission occur. Since there was deformation of the amorphous regions as ascertained by FTIR spectroscopy and birefringence studies, the changes in properties below 100°C were attributed mainly to the effectiveness of thermal oxidation and annealing in the amorphous phase. In other words, the degree of crystallinity increased, the tyre cord became brittle, and breaking load and elongation at break were decreased. The lower reduction of tensile properties at an intermediate temperatures of 100–120°C was caused by the lower polydispersity and irregularity in the polymeric chains, in comparison with higher temperatures and less crystallinity than lower temperature treatments. KeywordsHeat treatment–Tyre cord–Polyamide–Mechanical properties–Molecular weight distribution
Eight 7,7-coumarinyl polymethylene dicarboxylates have been successfully synthesized by solution condensation of 7-hydroxycoumarin (umbelliferone) or 7-hydroxy-4-methylcoumarin (4-methylumbelliferone) with various polymethylene diacid chlorides. Upon benzophenone-sensitized irradiation with 350 nm light, the terminal coumarin chromophores dimerize to form intermolecular cycloadducts or intermolecular polyesters with three kinds of cyclobutanes (syn head-to-head,anti head-to-head,anti head-to-tail), depending on structure of the dicarboxylates and reaction conditions. The structures of the cycloadducts and polyesters have been characterized by1H NMR spectra. When the methylene units exceed seven, intermolecular reaction becomes predominant and result inanti-rich configuration photo-cyclized products with higher viscosity. Lower polar solvents and 4-methyl substitution in coumarin chromophores also promote intermolecular reaction. The highest viscosity (red = 0.42 dL/g) is obtained with polyester from 7,7-(4-methyl coumarinyl) decamethylene decarboxylate. Irradiation of the polyesters with 254 nm light leads to symmetric cleavage of the cyclobutane linkage in the main chain.
The electrochemical copolymerization of aniline (ANI) with 1-amino-9,10-anthraquinone (1-AAQ) was carried out in 4M sulfuric acid by potential cycling in the potential range of −0.1V to 1.3V vs. SCE. Copolymer films were grown from different feed ratios of ANI and 1-AAQ (0.2:0.8, 0.4:0.6, 0.5:0.5, 0.6:0.4, 0.8:0.2) on a glassy carbon electrode (GCE). Studies on the effect of scan rate on the conductivity of the copolymer film confirmed the formation of a stable conducting copolymer film. The FTIR spectrum recorded for the copolymer film provides concrete evidence of copolymer formation, since it indicates the presence of quinone units in the copolymer backbone. XRD data (particle size: 47nm) and SEM (grain size: 100nm) micrographs provide a clear picture of the nano-sized polymeric particles formed. It is envisaged that the newly reported copolymer could be a useful material for performing the catalytic reduction of oxygen in an acidic medium—a useful process for fuel cell applications. Keywords1-Amino-9,10-anthraquinone–Electropolymerization–Cyclic voltammetry–X-ray diffraction–Copolymer
Present work deals with findings on dielectric behaviour and a.c. conduction in a ferrite doped polymer nano composite electrolyte system, namely [(100−x) PEO + xNH4SCN]: ferrite. The formation of nano composite and structural behavior of electrolyte was studied by XRD and SEM images. The effect of salt and ferrite on conductivity behaviour of PEO based nano composite polymer electrolyte has been investigated by the impedance spectroscopy at room temperature. The variation of dielectric permittivity and dielectric loss with frequency was carried out at ambient temperature. The a.c. conductivity seems to follow the universal power law.
Poly(HEMA) hydrogel is usually prepared by using 1,1,1-trimethylol propane trimethacrylate and ethylene glycol dimethacrylate as the crosslinkers. Another method using PVA-AA (polyvinyl alcohol partially esterified with acryloyl chloride) as the cross linker is reported here. Two hydrogels, co-A1H9 and co-A2H8, were prepared by the polymerization of HEMA in the presence of 10% and 20% PVA-AA, respectively. The presence of PVA-AA reduced the water content from 32% to 25% in the resultant copolymer, whereas Tg did not change significantly. Co-A1H9 had an elastic modulus of 6.3 Mpa, which is much higher than 3.9 MPa and 3.7 MPa for poly(HEMA) and co-A2H8, respectively. The interfacial energies of poly(HEMA), co-A1H9 and co-A2H8 were calculated to be 0.52, 0.65 and 0.71 dyne/cm2, respectively, whereas the fractional polarities of these three hydrogels were all about 0.74. Thus a HEMA-based hydrogel with surface properties similar to poly(HEMA) but with stronger mechanical strength was successfully prepared. This copolymeric hydrogel could provide a choice other than the conventionally cross linked poly(HEMA) for various applications.
Two series of novel rod–coil block copolymers, poly(ɛ-caprolactone)-b-poly{2,5-bis[(4-methoxyphenyl) oxycarbonyl] styrene} (PCL-b-PMPCS) and poly{2,5-bis[(4-methoxyphenyl) oxycarbonyl] styrene}-b-poly(ɛ-caprolactone)-b-poly{2,5-bis[(4-methoxyphenyl) oxycarbonyl] styrene} (PMPCS-b-PCL-b-PMPCS), were successfully synthesized via atom transfer radical polymerization in chlorobenzene solution using macro-initiator and CuBr/Sparteine complex as catalyst. The results show that the number average molecular weight M n increased versus the monomer conversion and that the polydispersity M w/M n was quite narrow (<1.35), which were the character of controlled polymerization. The structure of the block copolymers was experimentally confirmed by 1H NMR. And the liquid crystalline behavior of them was studied using DSC and POM. The data obtained implied that the block copolymers with low molar percentage of PMPCS block could show T m of PCL. While only the copolymers with long rigid segment PMPCS could form liquid crystalline phase, which was quite stable with a high clearing point.
To improve the miscibility and tensile strength of the ABCPs material, we conducted a study in which maleimide end-capped polyurethane was prepared from the PU prepolymer and maleimide by reacting 4,4′-diphenylmethane diisocyanate (MDI) with poly(tetramethylene oxide) (PTMO), whose molecular weights were Mn=600∼700 (PA650), Mn=900∼1050 (PA1000) and Mn=1900∼2100 (PA2000). AB crosslinked polymers (ABCPs), synthesized from the PU prepolymer and the novolac resin, were studied. The study confirmed the occurrence of phase mixing. Further investigation through dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC) and transmission electron microscopy (TEM) revealed that the tensile strength and phase mixing were,improved.
Well-defined diblock copolymer based on polyhedral oligomeric silsesquioxane (POSS) was synthesized by atom transfer radical Well-defined diblock copolymer based on polyhedral oligomeric silsesquioxane (POSS) was synthesized by atom transfer radical polymerization (ATRP) using POSS/PMMA-Cl as a macroinitiatior. POSS/PMMA-Cl was prepared by POSS-Cl initiating the polymerization polymerization (ATRP) using POSS/PMMA-Cl as a macroinitiatior. POSS/PMMA-Cl was prepared by POSS-Cl initiating the polymerization of MMA in the presence of CuCl, 2, 2, - bipyridine at 110 °C. The structure of the block copolymer had been characterized of MMA in the presence of CuCl, 2, 2, - bipyridine at 110 °C. The structure of the block copolymer had been characterized by FTIR, 1H NMR and GPC, which all agreed well with the theoretical values. XRD measurements revealed that POSS molecules were successfully by FTIR, 1H NMR and GPC, which all agreed well with the theoretical values. XRD measurements revealed that POSS molecules were successfully monodispered in the hybrid composite. monodispered in the hybrid composite.
Multicomponent compatibilized blends of polyamide 6 (PA6) and styrene-butadiene-acrylonitrile (ABS) with co-continuous morphology are among commercial alloys with an interesting combination of properties. To further enhance the properties different amounts of nanoclay were incorporated into these blends through a one step melt mixing process. The effect of nanoclay addition on rheological, thermal stability, crystallization and morphological properties of the nanocomposites were investigated and compared with those of the neat blends. The nanoscale dispersion of the clay layers in the blends were confirmed through X-ray diffraction and transmission electron microscopy methods. Rheological investigation indicated an increased viscosity and melt elasticity for the nanocomposite systems. The viscosity of nanocomposites followed a shear thinning flow behavior and decreased with increasing shear rates. The changes in the rheological properties were accompanied by refinement of the co-continuous morphology. For thermal degradation under N2 atmosphere, the onset and maximum of degradation temperatures for the nanocomposites were as high as the neat blends, while significant improvement in thermal stability (about 60 °C by 3wt% clay addition) was observed in the air environment. In addition agglomerated clay particles did not significantly affect thermal stability of the polymer matrix. Non-isothermal crystallization results indicated that the clay layers had a retarding effect on the crystal growth rate and facilitated the formation of α crystalline form. In addition no nucleation effect was observed during the crystallization process due to incorporation of nanoclay into the blends. KeywordsBlend nanocomposites–PA6/ABS–Crystallinity–Thermal properties–Rheology
Large articles of polymeric materials which can not be molded require welding to join the components. Weld zones result in a morphology that differs from the adjacent areas. This difference in structure represents a defect in the article that can result in premature failure during service. Experiments with a Pulse 830 (a polycarbonate/acrylonitrile-butadiene-styrene blend) engineering resin showed that weld zones made using hot plate techniques, retained only 30% of the unwelded tensile strength, while 80% was retained if vibration welding was applied. Examination of the weld zone by transmission electron microscopy (TEM) revealed a dramatic difference in the microstructure.The weld zone morphology in Pulse" 830 engineering resin by hot plate welding is highly laminar and oriented while a much more homogeneous structure, similar to that in the bulk, is produced by vibration welding. This morphology difference accounts for the variation of the tensile strength of the joints.
Superabsorbent polyaspartic acid (PASP) resin was prepared from high molecular weight polysuccinimide (PSI), which was synthesized from l-aspartic acid by thermal polycondensation. The effects of the reaction temperature, the reaction time, the concentration of the solvent, the molecular weight of PSI, the concentration of the cross-linking agent, the hydrolysis conditions, and the drying temperature on the swelling ratio of PASP resin were investigated. The swelling ratios of PASP resin in deionized water and saline solution were measured, and the biodegradability of PASP hydrogel was evaluated. The results show that the swelling ratios of PASP resin in deionized water were 100–1,120g/g depending on the preparation conditions. The swelling ratio of PASP resin in saline solution reached 143g/g, and PASP resin was a kind of biodegradable material with high water absorbency, so this PASP resin can be used as agricultural and horticultural water-holding material, and in manufacturing of diapers, sanitary napkins, medical products, etc.
for the sample codes
Structural features and physical constants of the alcohols a used as the swelling media in this work
Scheme 1 Structural repeating units of poly(AA-AMPS) alcohol absorbents prepared in the present work (y=0.06-0.4)
Scheme 3 Steric hindrance of the neighboring groups in opposition to hydrogen bonding of hydroxyl group of a n-propanol and b isopropanol. Intra-and inter-molecular hydrogen bonding in c propylene glycol and d 1,3-propanediol. e Inter-molecular hydrogen bonding in 1,3-propanediol with linear form
Alcohol-specific superabsorbing gels (super-alcogels) based on non-neutralized acrylic acid (AA, 60–94mol%) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS) were prepared via solution polymerization in water. Polyethylene glycol dimethacrylate and potassium persulfate were used as crosslinker and initiator, respectively. Characterization of samples was performed using FTIR, 1H-NMR and thermomechanical analyses. Glass transition temperature and modulus of dried samples were found to be directly changed with their AA content. The gels exhibited enormous ability for absorbing and retaining a variety of mono- and poly-hydric alcohols. For example, in lieu of one gram of a typical sample composing 25mol% AMPS, its absorption capacity was measured to be 53.0g methanol, 42.1g ethanol, 12.1g n-propanol, 3.4g iso-propanol, 41.2g ethylene glycol, 20.7g propylene glycol, 37.8g 1,3-propanediol and 32.9g glycerol. The absorbencies were superior to those of a known commercial poly(AA) sample, Carbopol. The alcohol absorbency was improved with increase of AMPS incorporated. It was recognized to be dependant on the alcohol characteristics such as H-bonding ability, OH/C ratio, electronic features (e.g. dielectric constant), steric hindrance of the neighboring groups of the solvent OH group, as well as the solvent viscosity. Normal phase transitions were observed in the gel swelling behavior in the alcohol-water binary mixtures. Rheological measurements of the water-swollen gel showed that more AMPS content resulted in gels with inferior storage modulus. All the empirical observations were discussed based on the related physicochemical principles. KeywordsGel–2-acrylamido-2-methylpropane sulfonic acid–Acrylic acid–Alcohol absorbency
The bicomponent fibers were prepared for the radar absorbing and infrared camouflage. The fibers were melt-spun by co-extrusion of polypropylene (PP) and PP/fillers master-batches using general conjugate spinning. Master-batches were made up of mixture of PP chips and inorganic particle. The radar absorbing property was evaluated by an arch method. The fibers filled with the barium ferrite, Mn–Zn ferrite and bronze fillers had good radar absorbing effect. The input of infrared camouflage fillers in the sheath-part showed a limited effect on the radar wave absorbing properties of the bicomponent fibers. For the characterization, differential scanning calorimetry (DSC) and mass specific electrical resistance apparatus (MSERA) were used for analysis of thermal and crystallization behavior and electric performance of the spun-fibers. Scanning electron microscopy (SEM) was carried out to observe particle distribution on the bicomponent fibers.
A two-stage moisture absorption behavior for the cured 4,4-dicyanato 1,1-diphenolethane (DCDPE) resins was found when they were exposed to 60C/100%RH environment. The first stage followed the Fickian diffusion, whereas the secondary stage was a swelling-controlled diffusion in that the diffusion coefficient was decreased with time. With increasing the sample thickness, the two-stage absorption behavior became less discernible. After long term exposure to moisture, DCDPE resins were prone to hydrolysis to form voids in the networks. When chromium acetylacetonate (Cr(acac)3) was incorporated in the resin formulations as a curing accelerator, it also accelerated the hydrolysis, facilitating the formation of voids.
The theoretical geometries and electronic properties of fluorene (F) based alternating donor–acceptor conjugated copolymers and their model compounds were studied by the density function theory (DFT) at the B3LYP level with 6–31G or 6–31G** basis set. The acceptors investigated in this study include thiazole (TZ), thiadiazole (TD), thienopyrazine (TP), thienothiadiazole (TT), thiadiazolothienopyrazine (TTP), quinoxaline (Q), benzothiadiazole (BT), pyrazinoquinoxaline (PQ), thiadiazoloquinoxaline (TQ), and benzobisthiathiadiazole (BB). The torsional angle, bridge bond length, bond length alternation, and intramolecular charge transfer were simulated and correlated with the electronic properties, i.e., HOMO, LUMO level, and band gap. The geometries of fluorene-based donor–acceptor alternating copolymers and their model compounds are significantly affected by the structure of acceptors, particularly the ring size on the backbone. The electronic properties of the polymers and their model compounds are well correlated with the acceptor strength, coplanarity of the backbone, and intramolecular charge transfer. The theoretical study suggests that the electronic properties of alternating fluorene–acceptor conjugated copolymers could be tuned by the geometries or acceptor strength. Hence, these proposed copolymers could have potential applications as light-emitting diodes (LEDs), transparent conductor, or photovoltaic devices.
LOI and UL-94 results of flame retardant EVM/SPDV composites
Residual mass curves versus burning time for EVM/SPDV composites
Original residues of EVM/SPDV composites after cone calorimeter test: a EVM-SPDV 0 phr; b EVM-SPDV 20 phr; c EVM-SPDV 30 phr; d EVMSPDV 40 phr
A novel flame retardant (SPDV) containing phosphorus and silicon elements at the same time was synthesized. Spirocyclic pentaerythritol bisphosphorate disphosphoryl chloride (SPDPC) synthesized through simple dehydrochlorination reaction of pentaerythritol (PER) and phosphorus oxychloride (POCl3) was introduced into 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO)/ vinylmethyldimethoxy silane (VMDMS) oligomer (DV) to form a novel flame retardant. The structure and properties of SPDPC, DV and SPDV were characterized by FT-IR, NMR and TGA. After blended with EVM, the flame retardance of EVM/SPDV composites was estimated by cone calorimeter, limited oxygen index (LOI) and UL-94, and thermal stability was investigated using TGA. The morphological structure of the char formed after combustion in cone calorimeter was investigated by Scanning Electron Microscopy (SEM). The results indicate that the flame retardant and thermal stability were improved by incorporation of SPDV. The rich foamed char layers were observed in the residues after combustion in cone calorimeter test, which exactly benefits the thermal stability and flame retardant of EVM materials. KeywordsFlame retardant-Cone calorimeter-EVM-Phosphorus-Silicone
FT-IR spectrum of solid superacid catalysts SO 4 2j /ZrO 2 .
FT-IR spectra of cellulose acetate prepared by SO 4 2j /ZrO 2 catalysis in solvent-free process at different reaction times.
Herein a novel process to synthesize cellulose acetate (CA) is reported in a solvent-free ball-milling reactor in the presence of solid superacid SO4 2−/ZrO2 as green catalyst. FT-IR and H1-NMR spectra reveal that the maximum degree of substitution (DS) of formed cellulose acetate can achieve 1.8, and the DS depends on the reaction time. This method provides a new environmental benign and simple way to synthesize cellulose acetate.
A redox initiation system based on potassium persulfate/acetone sodium bisulphite (KPS/ASBS) was developed to initiate the graft copolymerization of vinyl acetate (VAc) monomer onto corn starch in aqueous solution. The grafting reaction was studied with respect to grafting yield (GY), grafting efficiency (GE) and total conversion (TC) and results obtained were compared with those a well-established redox initiation system namely potassium persulfate/sodium bisulphite (KPS/SBS). The effect of reaction variables such as redox initiator concentration, liquor ratio, reaction time and temperature as well as VAc concentration were investigated. The GY, GE and TC increased significantly with increase of the redox initiation concentration up to 8/16 mmol/l irrespective of the initiation system used. Moreover, optimal grafting was obtained at 60 ○C for KPS/ASBS redox system and 70 ○C for KPS/SBS redox system. Saponification of poly (vinyl acetate)-starch graft copolymers were effected using NaOH in three different bath media (n-hexane, acetone or methanol) to convert starch-g-poly(vinyl acetate) to starch-g-poly(vinyl alcohol). Higher extent of solubility in hot water of the saponified form was achieved by using a bath containing n-hexane/sodium hydroxide; however, increasing the graft yield higher than 26.3% decreases the solubility. The structures and thermal stability of starch, grafted starch copolymer and saponified grafted starch copolymer were characterized by infrared spectroscopy and thermogravimetric analysis. Moreover, the rheological behavior as well as sizing performance of the saponified grafted starch copolymers were evaluated and compared with the native starch and commercial polyvinyl alcohol.
The dynamic mechanical behaviour of uncrosslinked and crosslinked styrene butadiene rubber/poly (ethylene-co-vinyl acetate) (SBR/EVA) blends was studied with reference to the effects of blend ratio, crosslinking systems, a compatibilizer viz. maleic-anhydride grafted poly [styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS-g-MA), frequency and temperature. The two separate tan δ peaks, obtained during DMA, indicated the immiscibility of SBR/EVA system. The damping properties increased with SBR content for uncrosslinked and crosslinked blends. In the case of crosslinked systems, depending upon the type of crosslinking agent used, the glass transition temperature (T g) of SBR phase has been found to be shifted to higher temperatures. The damping characteristics of the blends were observed to be affected by the variations in frequency. The addition of the compatibilizer improved the storage modulus and reduced the damping properties. These results have been correlated with the morphology of the blends, attested by scanning electron micrographs. The activation energy for glass transition has been computed. The experimental data on storage modulus were compared with theoretical predictions.
Isotactic polypropylenes (iPP) with different melt flow indexes were melt blended with cellulose acetate butyrate (CAB) and then prepared into microspheres or nanofibers following a novel process of producing well dispersed CAB/iPP immiscible blends and subsequent removal of the CAB matrix. The morphologies of iPP microspheres were investigated by a scanning electron microscopy, and the dimensions of iPP microspheres were evaluated. The melt viscosities of iPP, CAB, and CAB/iPP blends were measured by using a capillary rheometer. The influences of the viscosity, viscosity ratio, and composition ratio of iPP/CAB on the morphology formation of iPP in CAB matrix were studied. KeywordsImmiscible polymer blends–Polypropylene–Viscosity ratio–Micro-spherical beads
Top-cited authors
R.B. Mathur
  • National Physical Laboratory - India
Dr. Tejendra Kumar Gupta
  • Amity University
Bhanu Pratap Singh
  • National Physical Laboratory - India
  • University of Tabriz
Hassan Namazi
  • University of Tabriz