Properties of syndiotacticity-rich poly(vinyl alcohol) thin film in water. I. Effect of the load on the extension of untreated thin film in water

The effect of the load on the extension of untreated thin film of syndiotacticity-rich poly(vinyl alcohol) (PVA_VTFA) derived from vinyl trifluoroacetate was examined in water. The untreated thin film obeys Hooke's law under a certain constant load at 25°C. Young's modulus of untreated PVA_VTFA film in water at 25°C was about 4.8 × 10^?4 GPa. The maximum elongation of PVA_VTFA film in water at 25°C is achieved for a short time under high load, whereas not under low load. The expansion of PVA_VTFA thin film by the elevation of temperature of water occurs mildly in the range of temperature of 45–55°C under low load, whereas not under high load. The temperature at break T_b is in the range of 70–90°C and increasing load roughly tends to decreasing T_b. The elongation at break decreased with the increase in load.     

Mechanical properties of films of poly(vinyl alcohol) derived from vinyl trifluoroacetate

In order to study the influence of the stereoreguralities of polymer chains on the mechanical properties of films of poly(vinyl alcohol) (PVA)_(VTFA) derived from vinyl trifluoroacetate, the strength of the film was measured. In the case of undrawn PVA_(VTFA) films, Young's modulus and strength at break were the smallest at the annealing temperature of about 100°C. It is considered to be due to the melt of small microcrystals and the increase in mobility of chains in amorphous parts. Young's moduli of undrawn PVA_(VTFA) films were in the range of 1.50–3.75 GPs and the values were higher than that (0.17–0.36 GPa) of undrawn film of commercial PVA with the low concentration of syndiotacticity and the high concentration of head-to-head bounds. In the case of drawn, annealed PVA_(VTFA) films, the maximum Young's modulus was about 20 GPa.     

Properties of syndiotacticity-rich poly(vinyl alcohol) thin film in water. IV. Elastic behavior of untreated thin film by repeated elongation and contraction in water

The activation energy ΔE_a for diffusion of water molecules into untreated thin film of poly(vinyl alcohol) (PVA_VTFA) derived from vinyl trifluoroacetate was estimated as 30.3 kcal/mol from the temperature dependence of the initiation time of swelling. The degree of equilibrium swelling increases with the increase in temperature in the range of 10–70°C, passing through the constant range between 30 and 50°C. Under the forced, repeated elongation and contraction for swollen PVA_VTFA thin film in water, the perfect elastic behavior is kept up to higher elongation with the increase in temperature and especially up to about three times equilibrium swelling length at 70°C. Young's modulus of swollen PVA_VTFA thin film in water was 6.47 × 10⁶ to 1.60 × 10⁶ dyn/cm² at 25–70°C. The molecular weight between junctions M_c increased with the increase in temperature; M_c was nearly equal to about one-sixth of the molecular weight of raw polymer M at 25°C and about one-third of M at 70°C. The interaction parameter between PVA_VTFA and water X₁, was 0.493–0.497 at 25–70°C.     

The production and properties of poly(aryletherketone) (PEEK) rods oriented by drawing through a conical die

Oriented poly(aryletherketone) (PEEK) rods have been produced by drawing isotropic polymer through a conical die. Room temperature Young's moduli were measured by three-point bending and ranged from 5 GPa at a draw ratio of about 2 to 11 GPa at a draw ratio of about 4. Dynamic mechanical properties were explored in the range ?150 to 200°C; two loss peaks were observed, with the higher corresponding to T_g.     

Microstructure evolution and mechanical behavior of a mullite fiber heat-treated from 1100 to 1300°C

In this paper, the effect of phase transformation on microstructure evolution and mechanical behaviors of mullite fibers was well investigated from 1100 to 1300°C. In such a narrow temperature range, the microstructure and mechanical properties showed great changes, which were significant to be studied. The temperature of the alumina phase transformation started at below 1100°C. The main phases in fibers were γ-Al₂O₃ and δ-Al₂O₃ with amorphous SiO₂ at 1150°C. The stable α-Al₂O₃ formed at 1200°C. Then the mullite phase reaction occurred. As the alumina phase reaction took place, the tensile strength increased with the increasing temperature. In particular, the filaments achieved the highest strength at 1150°C with 1.98 ± 0.17 GPa, and the Young's modulus was 163.08 ± 4.69 GPa, showing excellent mechanical performance. After 1200°C, the mullite phase reaction went on with the crystallization of orthorhombic mullite. The density of surface defects increased rapidly due to thermal grooving, which led to mechanical properties degrade sharply. The strength at 1200°C was 1.01 ± 0.15 GPa with a strength retention of 63.13%, and the Young's modulus was 184.14 ± 10.36 GPa. While at 1300°C, the tensile strength was 0.64 ± 0.14 GPa with a strength retention of only 40.00%.     

Effect of hot drawing on properties of wet‐spun poly(L,D‐lactide) copolymer multifilament fibers

Polylactide stereocopolymer multifilament fibers were prepared by wet spinning and subsequent hot drawing. The stereocopolymers were poly‐(L,D ‐lactide) [P(L,D )LA], L/D ratio 96/4, and poly‐(L,DL ‐lactide) [P(L,DL )LA], L/DL ratio 70/30. They were dissolved in dichloromethane and coagulated in a spin bath containing ethanol. The hot‐drawing temperature was 65°C. The draw ratios (DR) were upto 4.5 to the P(L,D )LA 96/4 filaments and upto 3 to the P(L,DL )LA 70/30 filaments. Wet spinning decreased crystallinities of both copolymers. Hot drawing increased the crystallinity of the P(L,D )LA 96/4 filament but not to the level of the original copolymer, whereas the as‐spun and the hot‐drawn P(L,DL )LA 70/30 filaments were amorphous. The filament diameter, tenacity, Young's modulus, and elongation at break were dependent on the DR. The maximum tenacity (285 MPa) and Young's modulus (2.0 GPa) were achieved with the P(L,D )LA 96/4 filament at the DR of 4.5. Respectively, the maximum tenacity of the hot‐drawn P(L,DL )LA 70/30 filament was 175 MPa and Young's modulus 1.3 GPa at the DR of 3. Hot drawing slowed down in vitro degradation rate of both stereocopolymer filaments. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and crosslinking behavior of a soluble,crosslinkable, and high young modulus poly(arylene ether nitriles) with pendant phthalonitriles

Poly(arylene ether nitriles) (PEN) with pendant phthalonitrile groups (PEN? CN) were obtained via the Yamazaki‐Higashi phosphorylation route of 4‐(4‐aminophenoxy)phthalonitrile (APN) with acid‐contained PEN (PEN? COOH) in the presence of CaCl₂. The chemical structure and molecular weight of PEN? CN were characterized by ¹H‐NMR, Fourier transform infrared spectroscopy, and Gel permeation chromatography. The synthesized PEN? CN had superior solubility in polar organic solvent and can be easily processed into thin films from the solutions of N‐methylpyrrolidone, dimethylsulfoxide, N,N′‐dimethylformamide, dimethylacetamide, and tetrahydrofuran. Compared with PEN? COOH, PEN? CN showed higher thermal stability with 5% weight loss temperatures (T_5%) up to 430°C. The glass transition temperature of PEN? CN was improved from 211 to 235°C measured by differential scanning calorimetry (DSC). In addition, it also exhibited excellent mechanical properties that Young's modulus reached to 3.5 GPa. Meanwhile, the effects of different aromatic amines and Lewis acid on the crosslinking behavior of PEN? CN were investigated by DSC. The results indicated that anhydrous Zinc chloride (ZnCl₂) was the best catalyst to lower the curing temperature among 2,6‐bis(4‐diaminobenzoxy) benzonitrile, 4,4‐diaminediphenyl sulfone, APN and ZnCl₂. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis of highly transparent and heat‐resistant polyimides containing bulky pendant moieties

A new diamine with bulky pendant biphenyl and ortho‐position dimethyl structures, 4,4′‐((1,1′‐biphenyl)‐4‐ylmethylene)bis(2,6‐dimethylaniline), was synthesized via a one‐pot reaction of 4‐biphenyl carboxaldehyde and 2,6‐dimethylaniline. The diamine was employed to polymerize with several dianhydrides via one‐step condensation under high‐temperature conditions. The light yellow or colorless polyimide (PI) films obtained were found to have cut‐off wavelengths in the range 286–358 nm and transmittance over 80% in the visible region (400–780 nm). Meanwhile, these PIs possessed excellent solubility in common organic solvents, even in low‐boiling‐point solvents such as chloroform (CHCl₃), dichloromethane (CH₂Cl₂) and tetrahydrofuran. The glass transition temperatures (T_g) of the PIs were determined to exceed 343 °C, even to 456 °C. All PI films were flexible with a tensile strength of 78–119 MPa, a Young's modulus of 2.0–2.5 GPa and elongation at break of 4.0%–8.2%. Therefore, these colorless PIs can be used as candidate materials for flexible display substrates. © 2019 Society of Chemical Industry     

Auxetic polypropylene films

Auxetic materials are those exhibiting negative Poisson's ratio (ν) behavior. Polymeric auxetic extruded products in the form of cylinders and fibers have previously been reported. This article reports the successful production of auxetic polypropylene films (～0.15‐mm thick) using a melt extrusion process. Video extensometry and tensile testing techniques have been used to measure the in‐plane Poisson's ratios and Young's moduli of the auxetic film, both on an Instron tensile testing machine and a Deben microtensile testing machine. The film is elastically anisotropic with the Poisson's ratio and Young's modulus along the extrusion (x) direction being ν_xy = ?1.12 ± 0.06 and E_x = 0.34 ± 0.01GPa, respectively, while the Poisson's ratio and Young's modulus in the transverse (y) direction to the extrusion direction are ν_yx = ?0.77 ± 0.01 and E_y = 0.20 ± 0.01GPa, respectively. POLYM. ENG. SCI., 45:517–528, 2005. © 2005 Society of Plastics Engineers     

Enhancing interfacial adhesion performance by using poly(vinyl alcohol) in (low‐density polyethylene)/(natural rubber)/(water hyacinth fiber) composites

The effects of (a) the chemical modification of water hyacinth fiber by poly(vinyl alcohol) (WHF‐_PVA) and (b) loading on the properties of low‐density polyethylene (LDPE)/(natural rubber (NR))/(water hyacinth fiber (WHF)) composites were studied. Mechanical properties, water absorption behavior, morphology, and thermal properties were examined; X‐ray diffraction and infrared spectroscopic analysis were done. The results indicated that LDPE/NR/WHF‐_PVA composites had higher values of tensile strength, Young's modulus, melting temperature, and water absorption resistance but lower elongation at break than LDPE/NR/WHF composites. The LDPE/NR/WHF‐_PVA composites had better interfacial adhesion between the matrix and the fibers than LDPE/NR/WHF composites, as shown by SEM results. The LDPE/NR/WHF‐_PVA composites exhibited lower interparticle spacing than LDPE/NR/WHF composites, a feature which enhanced the interparticle interaction between the water hyacinth fibers and the LDPE/NR matrix. J. VINYL ADDIT. TECHNOL., 19:47–54, 2013. © 2012 Society of Plastics Engineers     

High Stiffness Cellulose Fibers from Low Molecular Weight Microcrystalline Cellulose Solutions Using DMSO as Co‐Solvent with Ionic Liquid

There is a need to develop high‐performance cellulose fibers as sustainable replacements for glass fibers, and as alternative precursors for carbon filaments. Traditional fiber spinning uses toxic solvents, but in this study, by using dimethyl sulfoxide (DMSO) as a co‐solvent with an ionic liquid, a novel high‐performance fiber with exceptional mechanical properties is produced. This involves a one‐step dissolution, and cost‐effective route to convert high concentrations of low molecular weight microcrystalline cellulose into high stiffness cellulose fibers. As the cellulose concentration increases from 20.8 to 23.6 wt%, strong optically anisotropic patterns appear for cellulose solutions, and the clearing temperature (T _c) increases from ≈100 °C to above 105 °C. Highly aligned, stiff cellulose fibers are dry‐jet wet spun from 20.8 and 23.6 wt% cellulose/1‐ethyl‐3‐methylimidazolium diethyl phosphate/DMSO solutions, with a Young's modulus of up to ≈41 GPa. The significant alignment of cellulose chains along the fiber axis is confirmed by scanning electron microscopy, wide‐angle X‐ray diffraction, and powder X‐ray diffraction. This process presents a new route to convert high concentrations of low molecular weight cellulose into high stiffness fibers, while significantly reducing the processing time and cost.     

Carbazole‐based poly(aryl ether ketone) containing crosslinkable allyl groups on the side chains: synthesis,characterization and properties

This paper presents a feasible method for introducing crosslinkable groups into a polymer to achieve excellent chemical resistance and improved thermal stability. Here, 3,6‐bi(4‐fluorobenzenzoyl)‐N‐allylcarbazole, a novel allyl‐containing difluoroketone monomer, is synthesized and characterized. The resulting monomer is polymerized with phenolphthalein through the aromatic nucleophilic substitution reaction at 160 °C to provide the soluble poly(aryl ether ketone) (PAEK) with a pendant allyl group. The obtained PAEK is characterized using Fourier transform infrared spectroscopy, NMR and gel permeation chromatography. The crosslinking reaction of the polymer occurs at 270 °C, and it imparts excellent solvent resistance. DSC analysis shows that the glass transition temperature (T_g) of the cured polymer increases to 262–306 °C when the curing temperature is elevated or when the curing time is extended within certain limits. The rate of increase of T_g and the rate of the crosslinking reaction decrease as the curing time is extended under all of the investigated curing temperatures. The cured PAEKs possess good thermal stability with 5% weight loss temperatures up to 450 °C. The tensile strength and Young's modulus of the polymer film cured at 300 °C for 2 h are 65 MPa and 1.4 GPa, respectively. In addition, the polymer films before and after curing exhibit similar UV?visible absorption and blue light emission. © 2014 Society of Chemical Industry     

Properties of syndiotacticity-rich poly(vinyl alcohol) thin film in water. II. Effect of the annealing temperature on the extension of thin film in water

The effect of the annealing temperature on the extension of thin film of syndiotacticityrich poly(vinyl alcohol)(PVA_VTFA) derived from vinyl trifluoroacetate is investigated in water. For the samples annealed at the temperature of above 125°C, the time of initiation of elongation and Young's modulus increase steeply with the elevation of annealing temperature, and the time required to maximum elongation and the maximum elongation ratio decrease quietly. The elongation ratio at break during the elevation of temperature of water decreases with the increase in the annealing temperature, that is, from 6.5 to 1.5. Reversely, the temperature at break increases from 85 to 97°C, but it is minimum at the annealing temperature of 125°C.     

Superstructure and mechanical properties of nylon 66 microfiber prepared by carbon dioxide laser‐thinning method

Nylon 66 microfibers were obtained by a carbon dioxide (CO₂) laser‐thinning method. A laser‐thinning apparatus used to continuously prepare microfibers consisted of spools supplying and winding the fibers, a continuous‐wave CO₂‐laser emitter, a system supplying the fibers, and a traverse. The diameter of the microfibers decreased as the winding speed increased, and the birefringence increased as the winding speed increased. When microfibers, obtained through the laser irradiation (at a power density of 8.0 W cm^?2) of the original fiber supplied at 0.23 m min^?1, were wound at 2000 m min^?1, they had a diameter of 2.8 μm and a birefringence of 46 × 10^?3. The draw ratio calculated from the supplying and winding speeds was 8696×. Scanning electron microscopy showed that the microfibers obtained with the laser‐thinning apparatus had smooth surfaces not roughened by laser ablation that were uniform in diameter. To study the conformational transition with winding speed, the changes in trans band at 936 cm^?1 and gauche band at 1136 cm^?1 were measured with a Fourier transform infrared microscope. The trans band increased as the winding speed increased, and the gauche band decreased. Young's modulus and tensile strength increased with increasing winding speed. The microfiber, which was obtained at a winding speed of 2000 m min^?1, had a Young's modulus of 2.5 GPa and tensile strength of 0.6 GPa. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 802–807, 2006     

Effect of polyphenylene sulfide containing amino unit on thermal and mechanical properties of polyphenylene sulfide/glass fiber composites

Three kinds of high‐molecular‐weight compatibilizers [copoly(1,4‐phenylene sulfide)‐poly(2,5‐phenylene sulfide amine)] (PPS‐NH₂) containing different proportions of amino units in the side chain) were synthesized by the reaction of dihalogenated monomer and sodium sulfide via nucleophilic substitution polymerization under high pressure. The intrinsic viscosity of the obtained copolymers was 0.354–0.489 dL/g and they were found to have good thermal performance with melting point (T_m) of 271.3–281.0 °C and initial degradation temperature (T_d) of 490.0–495.7 °C. There was an excellent physical compatibility between PPS‐NH₂ and the pure industrial PPS. The results of dynamic mechanical analysis and macro‐ and micromechanical test showed that the selective compatibilizer PPS‐NH₂ (1.0) (1.0% mol aminated ratio) can improve the mechanical and interfacial properties of polyphenylene sulfide/glass fiber (PPS/GF) composite. The macro‐optimal tensile strength, Young's modulus, bending strength, and notched impact strength of 5%PPS‐NH₂ (1.0)/PPS/GF composite raised up to 141 MPa, 1.98 GPa, 203 MPa, and 6.15 kJ/m², which increased 12.8%, 9.4%, 4.1%, and 13.8%, respectively, comparing with the pure PPS/GF composite (125 MPa, 1.81 GPa, 195 MPa, and 5.40 kJ/m², respectively). © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45804.     

A Complete Solid Solution with Rutile‐Type Structure in SiO2–GeO2 System at 12 GPa and 1600°C

High pressure and temperature synthesis of compositions made of (Si_1?x,Ge_x)O₂ where x is equal to 0, 0.1, 0.2, 0.5, 0.7, and 1 was performed at 7–12 GPa and 1200–1600°C using a Kawai‐type high‐pressure apparatus. At 12 GPa and 1600°C, all the run products were composed of a single phase with a rutile structure. The lattice constants increase linearly with the germanium content (x), which indicates that the rutile‐type phases in the SiO₂–GeO₂ system form a complete series of solid solutions at these pressure and temperature conditions. Our experimental results show that thermodynamic equilibrium state was achieved in this system at 12 GPa and 1600°C, but not at 1200°C. At lower pressures (7 and 9 GPa) and 1600°C, we observed the decomposition of (Si_0.5,Ge_0.5)O₂ into SiO₂‐rich coesite and GeO₂‐rich rutile phases. The silicon content in the rutile structure increases sharply with pressure in the vicinity of the coesite–stishovite phase transition pressure in SiO₂.     

Synthesis and characterization of ternary‐copolymer of soluble fluorinated polyimides based on 1,4‐bis (4‐amino‐2‐trifluoromethylphenoxy) benzene

A series of novel ternary‐copolymer of fluorinated polyimides (PIs) were prepared from 1,4‐bis(4‐amino‐2‐trifluoromethylphenoxy)benzene (pBATB), commercially available aromatic dianhydrides, and aromatic diamines via a conventional two‐step thermal or chemical imidization method. The structures of all the obtained PIs were characterized with FTIR, ¹H‐NMR, and element analysis. Besides, the solubility, thermal stability, mechanical properties, and moisture uptakes of the PIs were investigated. The weight‐average molecular weight (M_w) and the number‐average molecular weight (M_n) of the PIs were determined using gel‐permeation chromatography (GPC). The PIs were readily dissolved not only in polar solvents such as DMF, DMAc, and NMP, but also in some common organic solvents, such as acetic ester, chloroform, and acetone. The glass transition temperatures of these PIs ranged from 201 to 234°C and the 10% weight loss temperatures ranged from 507 to 541°C in nitrogen. Meanwhile, all the PIs left around 50% residual even at 800°C in nitrogen. The GPC results indicated that the PIs possessed moderate‐to‐high number‐average molecular weight (M_n), ranging from 9609 to 17,628. Moreover, the polymer films exhibited good mechanical properties, with elongations at break of 8–21%, tensile strength of 66.5–89.8 MPa, and Young's modulus of 1.04–1.27 GPa, and low moisture uptakes of 0.54–1.13%. These excellent combination properties ensure that the polymer could be considered as potential candidates for photoelectric and microelectronic applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Phosphoric acid doped poly(2,5‐benzimidazole)‐based proton exchange membrane for high temperature fuel cell application

Undoped and doped poly(2,5‐benzimidazole) (ABPBI) membrane was prepared by solvent casting method using methane sulfonic acid as a solvent and phosphoric acid (H₃PO₄) as a doping agent. The concentration of H₃PO₄ was varied from 0 to 60 vol% to enhance the proton conductivity of the ABPBI membrane at higher temperature. Wide angle X‐ray diffraction analysis showed a decrease in crystallinity in ABPBI membrane with increase in H₃PO₄ doping concentration. The molecular signature and the presence of H₃PO₄ was observed in 1000–1500 cm^?1 in the Fourier transform infrared spectra, which was also supported by a corresponding weight loss at 180°C–200°C in the thermogravimetric analysis. Undoped ABPBI membrane registered the Young's modulus (E) and hardness (H) values of 2.46 and 0.92 GPa, respectively, and the corresponding E and H values for 1.65 doping level of 60 vol% H₃PO₄ doped ABPBI membrane were 0.14 and 0.067 GPa, respectively. The 60 vol% H₃PO₄ doped ABPBI membrane with doping level of 1.65 showed highest proton conductivity value of 2.2 × 10^?2 S/cm. The impedance spectroscopic analysis and the equivalent circuit model were discussed to understand the nature of proton conduction in H₃PO₄ doped ABPBI membrane. POLYM. ENG. SCI., 56:1366–1374, 2016. © 2016 Society of Plastics Engineers     

Characterization of jute fibers treated with soap–glycerol micelles

A tossa variety of jute fiber (Corchorus olitorious) treated with soap–glycerol micelles is characterized by infrared (IR) spectroscopy, X‐ray diffraction method, and tensilometry. The IR spectra for jute fibers treated with soap–glycerol micelles show a reduced absorption band due to O H stretching at a frequency of 3420 cm⁻¹ with almost absent OH bending frequencies, prominent CH₂ stretching and bending frequencies at 2915 and 1440 cm⁻¹ and reduced skeletal vibration at 1060 cm⁻¹. The percentage crystallinity measured by the X‐ray diffraction method increases from 45 to 53% on treated jute fibers. The tensile strength and strain percent at maximum load, Young's modulus, and work done per unit volume within an elastic limit (resilience) for treated fibers increased from 1.8 ± 0.2 to 3.43 ± 0.2 GPa, from 3.98 ± 0.1 to 4.75 ± 0.1, from 75 ± 2 to 113 ± 5 GPa, and from 26 ± 2 to 74 ± 3 MJ m⁻³, respectively. Using a stabilizing agent (2%) and a swelling agent (2% KOH), the tensile strength, strain percent, Young's modulus, and resilience increase to 4.02 ± 0.2 GPa, 4.85 ± 0.3, 154 ± 5 GPa, and 95 ± 4 MJ m⁻³, respectively. Under natural weathering at 12–30°C and 30–80% relative humidity over a prolonged period of 8 weeks, all the tensile properties for micelle‐treated fibers increase during the first 2 weeks of exposure and then decrease exponentially to the starting values. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 852–856, 2000     

Synthesis and characterization of novel soluble cardo poly(arylene ether ketone)s containing xanthene structures

9,9‐Bis(4‐hydroxyphenyl)xanthene (BHPX), a bisphenol monomer, was synthesized in 82% yield from xanthenone in a one‐pot, two‐step synthetic procedure. Four novel aromatic poly(ether ketone)s (PEKs) based on BHPX were prepared via a nucleophilic aromatic substitution polycondensation with four difluorinated aromatic ketones. The polycondensation proceeded in tetramethylene sulfone in the presence of anhydrous potassium carbonate and afforded the new cardo PEKs in nearly quantitative yields with inherent viscosities of 0.77–0.85 dL/g. High molecular weight PEKs having number‐average molecular weights (M_n's) in the range of 38,900–40,600 g/mol with the polydispersity index ranged from 1.97 to 2.06 are all amorphous and show high glass transition temperatures ranging from 210°C to 254°C, excellent thermal stability, and the temperatures at the 5% weight loss are over 538°C with char yields above 60% at 700°C in nitrogen. These new PEKs are all soluble in polar aprotic solvents such as N‐methyl‐2‐pyrrolidone and N, N′‐dimethylacetamide and could also be dissolved in chloroform and tetrahydrofuran. All the polymers formed transparent, strong, and flexible films with tensile strengths of 78–84 MPa, Young's moduli of 2.54–3.10 GPa, and elongations at break of 14–18 %. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009