Thermal stability of polyurethane elastomers before and after UV irradiation

In this work, we investigated the thermal degradation behavior of segmented polyurethane (PUR) elastomers before and after UV irradiation. The thermal degradation of PUR elastomers was studied over the temperature range of 25–600°C in an atmosphere of nitrogen using thermal gravimetric analysis (TGA). Four series of PUR elastomers derived from poly(oxytetramethylene)glycol (PTMO) of 1000 and 2000 molecular weight and poly(caprolactone glycol) (PCL) of 1250 molecular weight, 4,4′‐diphenylmethane diisocyanate (MDI), and 4,4′‐dicyclohexylmethane diisocyanate (H₁₂MDI) and 1,4‐butanediol as an chain extender were synthesized by the prepolymer method. The derivative thermogravimetric (DTG) peaks observed in the experiments indicated that PUR elastomers degraded through two steps. We attributed the first step to degradation of the hard segment. The second degradation step could be ascribed to degradation of the soft segment. We found that the PUR elastomers based on poly(ester polyol) and aromatic diisocyanate exhibit better thermal stability than that of PUR elastomers based on the poly(ether polyol) soft segment in both steps of degradation. The thermal degradation is more prevalent in PUR elastomers based on cycloaliphatic diisocyanate. The higher values of the temperature of initial decomposition (Tⁱ) indicate a higher thermal stability of UV‐exposed elastomers on the beginning of degradation. This may be due to the formation of a crosslinking structure in the presence of UV irradiation. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 864–873, 2001     

Preparation and characterization of novel crosslinked poly[glycidyl methacrylate–poly(ethylene glycol) methyl ether methacrylate] as gel polymer electrolytes

In this study, glycidyl methacrylate was copolymerized with poly(ethylene glycol) methyl ether methacrylate to obtain a copolymer {poly[glycidyl methacrylate–poly(ethylene glycol) methyl ether methacrylate] [P(GMA–PEGMA)]}, which was crosslinked with α,ω‐diamino poly(propylene oxide) (Jeffamine) at various weight ratios and molecular weights to form novel gel polymer electrolytes (GPEs). The crosslinked copolymers were characterized by Fourier transform infrared spectroscopy and thermal analysis. The crosslinked polymers were amorphous in the pristine state and became crystallized after they were doped with lithium electrolyte. Furthermore, the crosslinking degree of the crosslinked polymers increased with increasing weight ratio of Jeffamine, and both the swelling properties and mechanical behaviors of the crosslinked polymers were heavily affected by the weight ratio and molecular weight of Jeffamine. The ionic conductivity (σ) of the GPEs from the crosslinked copolymers was determined by alternating‐current impedance spectroscopy. A higher molecular weight and increased weight ratio of Jeffamine resulted in a higher σ. The GPE based on P(GMA–PEGMA) crosslinked with an equal weight of Jeffamine D2000 exhibited the highest σ of 8.29 × 10⁻⁴ S/cm at 25°C and had a moderate mechanical strength. These crosslinked copolymers could be potential candidates for the construction of rechargeable lithium batteries. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

New thermoplastic segmented polyurethanes with hard segments derived from 4,4′‐diphenylmethane diisocyanate and methylenebis(1,4‐phenylenemethylenethio)dialcanols

New thermoplastic poly(ether–urethane)s and poly(carbonate–urethane)s were synthesized by a one‐step melt polymerization from poly(oxytetramethylene) diol (PTMO) and poly(hexane‐1,6‐diyl carbonate) diol (PHCD) as soft segments, 4,4′‐diphenylmethane diisocyanate, and 2,2′‐[methylenebis(1,4‐phenylenemethylenethio)]diethanol, 3,3′‐[methylenebis(1,4‐phenylenemethylenethio)]dipropan‐1‐ol or 6,6′‐[methylenebis(1,4‐phenylenemethylenethio)]dihexan‐1‐ol as unconventional chain extenders. The effects of the kind and amount of the polymer diol and chain extender used on the structure and properties of the polymers were studied. The polymers were examined by Fourier transform infrared (FTIR) spectroscopy, X‐ray diffraction analysis, atomic force microscopy, differential scanning calorimetry, thermogravimetric analysis (TGA), TGA coupled with FTIR spectroscopy, and Shore hardness and tensile testing. The obtained high‐molecular‐weight polymers showed elastomeric or plastic properties. Generally, the PTMO‐based polymers exhibited significantly lower glass‐transition temperatures (up to ?48.1 vs ?1.4°C), a higher degree of microphase separation, and ordering in hard‐segment domains in comparison with the corresponding PHCD‐based ones. Moreover, it was observed that the polymers with the PTMO soft segments showed poorer tensile strengths (up to 36.5 vs 59.6 MPa) but higher elongations at break. All of the polymers exhibited a relatively good thermal stability. Their temperatures of 1% mass loss were in the range 270–320°C. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Heat-resistant thermosetting polyimide matrix resins containing keto,ether, hexafluoroisopropylidene linkages and maleimido- and nadimido- end capped groups

Various heat-resistant thermosetting polyimides containing hexafluoroisopropylidene and keto and ether groups suitable for fiber-reinforced composites development have been synthesised by thermal polymerization of maleimido and nadimido end capped polymer precursors. Thermal polymerization involving addition reactions was performed at 225°C for 1.5 h and post-curing at 290°C for 0.5 h. Tough polymers XVIII to XXIII were obtained. The thermal polymerization was monitored using infrared spectroscopy. The polymer precursors were characterized by IR, ¹H-NMR, and elemental analysis. The synthesized polymers were evaluated for thermal stability using dynamic thermogravimetric analysis (TGA). All the polymers showed thermal decomposition temperatures in the range of 430–435°C in nitrogen and in air. The char yield of the polymers was in the range of 60–67% in nitrogen at 800°C. This study indicated that thermally synthesized polymers from hexafluoroisopropylidene, keto, and ether containing polymides are potential candidates for the development of advanced materials for aerospace and high-tech applications. © 1993 John Wiley & Sons, Inc.     

Synthesis and characterization of poly(ether carbonate)s by melt‐phase interchange reactions of dihydroxy compounds with alkylene and arylene diphenyl dicarbonates containing ether groups

A new method of synthesis of poly(ether carbonate)s based on interchange reactions of dihydroxy compounds with alkylene and arylene diphenyl dicarbonates containing ether group was presented. The diphenyl dicarbonate monomers were prepared from phenyl chloroformate and dihydroxy compounds containing ether group (e.g., diethylene glycol, bis(2‐hydroxyethyl ether) of bisphenol A, and 4,4′‐oxydiphenol). The process consisted of a precondensation step under a stream of dry argon followed by a melt polycondensation at 230 or at 250°C under vacuum. Four series of poly(ether carbonate)s were prepared using this approach. Using alkylene and arylene diphenyl dicarbonate‐containing ether groups as monomers, the polycondensation reaction with dihydroxy compounds led to the formation of poly(ether carbonate)s having inherent viscosity values up to 0.56 dL/g and high thermal stability. The glass transition temperature values of polycarbonates were in the range 7–122°C. The polymers were characterized by inherent viscosity and spectroscopic (Fourier transform infrared spectroscopy and ¹H‐NMR and ¹³C‐NMR) and thermal (differential scanning calorimeteric and thermogravimetric) methods. This approach may permit the use of diphenyl dicarbonates containing other organic functional groups for the synthesis of polycarbonates containing those groups. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Kinetic analysis of high-resolution TGA variable heating rate data

Isothermal and constant heating rate thermogravimetric analysis (TGA) experiments have been performed for examining decomposition of polymers and composites. In practice, low heating rates are necessary to obtain good resolution under nonisothermal conditions thus increasing the time required for experiments. A novel TGA mode, high-resolution TGA (Hi-Res^TM TGA), provides a means to remarkably increase the resolution while often decreasing the time required for experiments. In this variable heating rate mode of Hi-Res^TMTGA, the heating rate is continuously and dynamically varied to maximize resolution. Thus, traditional methods cannot be directly utilized to determine kinetic parameters. Accordingly, in this work, variable heating rate experiments were run on ethylene-vinylacetate (EVA) copolymer, poly(ether ether ketone) (PEEK), and carbon-fiber-reinforced bismaleimide (BMI), whose kinetics have been quantitatively described with traditional isothermal and nonisothermal experiments. Comparison of the different techniques led to the development of a simplified method by which the activation energy, preexponential factor, and reaction order can be extracted from variable heating rate TGA experiments. The technique, based on the principle that maximum weight loss rate is observed at minimum heating rate, gave kinetic results that were in excellent agreement with values that have been determined by traditional isothermal and dynamic experiments. © 1993 John Wiley & Sons, Inc.     

Application of thermogravimetric analysis to the thermal decomposition of polybutadiene

Thermogravimetric analysis (TGA) has been used extensively to determine the thermal stability of polymers. The present study indicates that the isothermal decomposition of polybutadienes (PBDs) is significantly different from that in the heat mode. The isothermal decomposition of PBDs is an exothermic reaction occurring at 350°–375°C. This decomposition is shown to be rapid and temperature specific. It appears to be related to the cyclization reaction reported previously by several investigators. Decomposition of PBDs in the heat mode (10°C/min) occurs at 447°–461°C. This is about 100°C higher than that observed in the isothermal mode. Further TGA experiments indicate that a period of slow heating stabilizes PBD and can eliminate the exothermic decomposition at about 360°C. This stabilization appears to be related to the ease with which both 1,2- and 1,4-PBDs thermally crosslink. Heating 1,4-PBD for 6 min at 270°C gives rise to 92% gel. 1,2-PBD is shown to crosslink more extensively. It is shown that polymers which do not thermally crosslink or cyclize, such as polystyrene, decompose similarly in the two modes of heating.     

Synthesis of poly(ether amide)s from p‐xylylene glycol and bis(ether nitrile)s

BACKGROUND: Poly(ether amide)s have been well studied in terms of improving the physical and thermal properties of aromatic polyamides. Poly(ether amide)s of high enough molecular weight to be useful for industrial purposes are generally difficult to prepare. The objective of this project was to introduce a simple and commercially feasible process to prepare poly(ether amide)s by a polymerization reaction at relatively low temperature. RESULTS: A series of poly(ether amide)s were prepared by direct polyamidation of p‐xylylene glycol with bis(ether nitrile)s via the Ritter reaction using concentrated H₂SO₄ in acetic acid. The synthesized poly(ether amide)s showed good solubility in polar aprotic solvents. The resultant poly(ether amide)s had inherent viscosities in the range 0.36–1.03 dL g^?1. The glass transition temperatures of the poly(ether amide)s were determined using differential scanning calorimetry to be in the range 190–258 °C. Thermogravimetric analysis data for these polymers indicated the 10% weight loss temperatures to be in the range 290–390 °C in nitrogen atmosphere. CONCLUSION: The Ritter reaction was applied for the synthesis of a variety of poly(ether amide)s with moderate to high molecular weights. This procedure provides a simple polymerization process for the convenient preparation of poly(ether amide)s in high yield at room temperature. Copyright © 2009 Society of Chemical Industry     

Synthesis and characterization of novel organosoluble biosourced poly(ester imide)s based on 1,4:3,6 -dianhydrohexitols suited for adhesives applications

A new series of poly(ester imide)s were prepared from the polycondensation of isosorbide and a series of synthesized diacyl chloride monomers based on a reaction between 1,2,4-Benzenetricarboxylic anhydride (TMA) and various diamines. The structures of the resulting polymers were confirmed by Fourier transform infrared spectroscopy (FTIR) and ¹³C NMR spectra. Inherent viscosities and size exclusion chromatography (SEC) measurements proved the formation of high molecular weight poly(ester imide)s. The thermogravimetric analysis (TGA) showed deterioration temperature in the range of 221–400 °C indicating a good thermal stability. The differential scanning calorimetry (DSC) measurements revealed high glass transition temperature in the range of 67–185 °C. Wide angle X-ray diffraction measurements showed that the studied poly(ester imide)s were semi-crystalline. Most of the synthesized poly(ester imide) exhibited a good adhesion ability and tensile strength values comparable to analogous polymers.     

Synthesis,characterization, and properties of co-poly(ether–urethane–urea)s containing lariat cryptand 22: Li<Superscript>+</Superscript> harvesting polymers

In this work, some segmented poly(ether–urethane–urea)s (PEUUs) containing aza crown ether (cryptand) were prepared and characterized. These polymers were synthesized via the reaction of kryptofix 22 with 2 mol excess of 4,4′-methylene-bis-(4-phenylisocyanate) (MDI), and different molecular weights of polyethylene glycols (PEGs). Morphology, thermal, and complexation properties of these polymers were studied by Fourier-transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), atomic absorption spectroscopy (AAS), and solid state NMR (S-NMR). The data confirmed complexation ability of these polymers for Li⁺ ion absorption and revealed the effect of Li⁺ ion complexation on the morphology and thermal behavior of the PEUUs.     

Poly(polyethylene glycol methyl ether methacrylate) as novel solid-solid phase change material for thermal energy storage

Poly(polyethylene glycol methyl ether methacrylate) as novel solid–solid phase change materials (PCMs) for thermal energy storage was prepared via the facile bulk polymerization of polyethylene glycol methyl ether methacrylate and was characterized by Fourier transform infrared, ¹³C-NMR, X-ray diffraction, differential scanning calorimetry, and thermogravimetric analysis measurements. Based on the results, it is indicated that the poly (polyethylene glycol methyl ether methacrylate) as novel PCM showed solid–solid properties with suitable transition temperature, high transition enthalpy, and good thermal stability, which was apt to crystallize due to the flexibility of long polyether side chain. This novel PCMs have advantages for the potential application in energy storage. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis and thermal properties of poly(acrylonitrile‐co‐allyl glycidyl ether)‐graft‐methoxypoly(ethylene glycol) copolymers as novel solid–solid phase‐change materials for thermal energy storage

We synthesized a series of poly(acrylonitrile‐co‐allyl glycidyl ether)‐graft‐methoxypoly(ethylene glycol) (PAA‐g‐MPEG) copolymers as novel polymeric solid–solid phase‐change materials by grafting methoxypoly(ethylene glycol) (MPEG) to the main chain of poly(acrylonitrile‐co‐allyl glycidyl ether) (PAA). PAA was the skeleton, and MPEG was a functional side chain, which stored and released heat during its phase‐transition process. Fourier transform infrared spectroscopy and ¹H‐NMR spectroscopy analysis were performed to investigate the chemical structures. The crystalline morphology and crystal structures were also measured with polarized optical microscopy and X‐ray diffraction. Moreover, the thermal‐energy‐storage properties, thermal stability, and thermal reliability of the PAA‐g‐MPEG copolymers were characterized by differential scanning calorimetry and thermogravimetric analysis (TGA) methods. These analysis results indicate that the MPEG chains were successfully grafted onto PAA, and we found that the PAA‐g‐MPEG copolymers had typical solid–solid phase‐transition temperatures in the range 11–54 °C and high latent heat enthalpies between 44 and 85 J/g. In addition, the as‐prepared PAA‐g‐MPEG copolymers showed reusability and thermal reliability, as shown by the thermal cycle testing and TGA curves. Therefore, the synthesized PAA‐g‐MPEG copolymers have considerable potential for thermal energy storage. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46641.     

Synthesis and characterization of poly(ether sulfone) and poly(ether sulfone ketone) copolymers

Poly(ether sulfone) and poly(ether sulfone ketone) copolymers (I–V) were synthesized by the nucleophilic substitution reaction of 4,4′-dihydroxy diphenyl sulfone (DHDPS, A) with various mole proportions 4,4′-difluoro benzophenone (DFBP, B) and 4,4′-difluoro diphenyl sulfone (DFDPS, C) using sulfolane as solvent in the presence of anhydrous K₂CO₃. The polymers were characterized by physicochemical and spectroscopic techniques. All polymers were found to be amorphous, and the glass transition temperature (T_g) was found to increase with the sulfonyl content of the polymers. ¹³C-nuclear magnetic resonance (NMR) spectral data was interpreted in terms of the compositional triads, BAB, BAC, CAC, ABA, and ABB, and indicate that transetherification occurs at high concentration of DFBP units in the polymer (IV). The good agreement between the observed and calculated feed ratios validates the triad analysis. Thermal decomposition studies reveal that the thermal stability of the polymers increases with increase in the carbonyl content in the polymer. Activation energies for thermal decomposition were found to be in the range of 160–203 kJ mol⁻¹ with the cleavage of ϕ SO₂ bond being the preponderant mode of decomposition and depended on the block length of the sulfonyl unit. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2113–2121, 1999     

Synthesis,optical, and thermal properties of polyimides containing flexible ether linkage

The goal of this article was to synthesize a series of flexible polyimides containing ether linkage in main chain and clarified the effect of this ether linkage on some physical properties such as optical and thermal decomposition. Also, different functional group effects such as carbonyl (? C?O), hexa‐fluoro‐isopropylidene [? C(CF₃)₂? ] and phenyl (? C₆H₅) on these physical properties were evaluated. The structural characterization of poly(ether imide)s was performed using Fourier transform infrared, ¹H‐nuclear magnetic resonance (NMR), and ¹³C‐NMR techniques. Optical band gap of polyimides was calculated in the range from 2.57 to 2.81 eV. Thermal characterization of poly(ether imide)s was carried out using thermogravimetry–differential thermal analysis and differential scanning calorimetry. Thermal stability of poly(ether imide)s was evaluated by initial decomposition temperature (T_on) and char. T_on value of polymers was determined in the range from 100 to 195 °C. In addition, glass transition temperatures of poly(ether imide)s were found between 144 and 148 °C. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46573.     

Preparation and characterization of long‐chain multimaleimide‐containing aralkyl group linkages

Poly(aralkyl maleimide) (PAMI) and poly(glycidyl ether of aralkyl novolac) resin (PANE) with phenyl‐methylene units were synthesized from the intermediates poly(aralkyl amino) resin (PAAR) and poly(aralkyl novolac) resin (PANR), which were obtained from the reactions of p‐xylylene glycol with aniline or phenol, respectively. The oligomers were characterized by ¹H‐NMR, Fourier transform infrared spectroscopy, gel permeation chromatography, and potentiometry. The corresponding PAMI and PANE were cured with 4,4′‐diaminodiphenylmethane (DDM) at an equal equivalent ratio, and their curing behaviors were investigated by differential scanning calorimetry. The reaction involved a major chain extension and a minor homopolymerization. The thermal, mechanical, and electric properties of the PAMI–DDM system were better than that of those PANE–DDM system. Furthermore, the PAMI–DDM has a low internal stress. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1066–1072, 2003     

Investigation of the thermal stability of nitroxide capped polystyrene by TGA and Py-GC/MS

The thermal stability of nitroxide capped polystyrene is examined by TGA and pyrolysis-GC/MS. As opposed to technical polystyrene, these polymers (M_n > 30000 g mol^–1) show a characteristic decomposition step at 230–250°C. The volatile product of this step is mainly styrene, which results from retropolymerization. For some PS-N adducts terminator fragments can be identified. Prolonged isothermal treatment of PS-N adducts at their step temperature yields polystyrene without nitroxides. The loss of molecular weight is in the range of technical PS by the same treatment, but the polymers keep a narrow molecular weight distribution.     

Thermal stability,solubility, and fluorescence property of poly(arylene ether ketone)s bearing <Emphasis Type="Italic">N</Emphasis>-arylenebenzimidazole units

A series of novel random poly(arylene ether ketone)s containing N-arylenebenzimidazolyl groups with precise structures in high yields were synthesized from 2-(2′-hydroxyphenyl) benzimidazole and 4,4′-dihydroxybenzophenone with 4,4′-difluorobenzophenone via nucleophilic substitution polycondensation reaction using sulfolane as a solvent. The reaction was carried out at 210 °C in the presence of anhydrous potassium carbonate. The structures of the resulted polymers were characterized by means of FT-IR, ¹H NMR spectroscopy, and elemental analysis, and the results were largely consistent with the proposed structure. X-ray diffraction studies revealed that the incorporation of N-arylenebenzimidazolyl groups decreased the crystallinity of the resulted polymers. As the benzimidazole unit content in the copolymer increased, the solubility and thermal behavior of the prepared polymers improved. The novel poly(arylene ether ketone)s exhibited glass transition temperatures (T _gs) in the range 188–237°C, and there was a good linearity relationship between T _g values and the content of benzimidazolyl groups. The 5% decomposition temperatures were within the range of 512–539 °C in nitrogen and 496–540 °C in air indicating their good thermal stability. Tensile tests of the films showed that these polymers have desirable mechanical properties. Moreover, the resulting polymers showed good fluorescence properties.     

Effect of silicon and phosphorus on the degradation of polyurethanes

A series of polyurethanes containing silicon and phosphorus was prepared from 4,4′‐diphenylmethane diisocyanate (MDI), poly(tetramethylene ether glycol) (PTMG), diphenylsilanediol (DSiD), and methylphosponic acid (MPA). ¹H‐NMR spectra determined the qualitative and quantitative characteristics of these polymers. The thermal stability and activation energy for thermal degradation of these polymers were measured by thermogravimtry and compared with pure polyurethane (PU). The DSiD incorporated into the main chain of the polymer improved the thermal stability of PU, while the phosphorus‐containing polyurethane (P–PU) displayed a lower thermal stability than that of pure PU. The activation energies at various degradation stages for the pure PU, silicon‐containing polyurethane (Si–PU), and P–PU polymers were calculated by the Ozawa method. The activation energies of the Si–PU polymers were higher than were those of pure PU and increased according to the increase in the DSiD content. However, the P–PU polymers' activation energies were smaller than were those of pure PU, and they decreased with increasing phosphorus content in the range of 0.1 ≤ conversion ≤ 0.5, whereas the reverse was true between 0.6 and 0.9. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 881–899, 2001     

Thermal properties,adhesive strength,and optical transparency of cyclolinear poly(aryloxycyclotriphosphazenes)

Four cyclolinear poly(aryloxycyclotriphosphazenes) derived from poly[4,4′‐(isopropoylidene)diphenoxytetrachlorocyclotriphosphazene] and poly[4,4′‐(hexafluoroisopropylidene)diphenoxytetrachlorocyclotriphosphazene] were synthesized from the reaction of hexachlorocyclotriphosphazene (HCP) with 4,4′‐(isopropylidene)diphenol (bisphenol A) or 4,4′‐(hexafluoroisopropylidene)diphenol (bisphenol AF) in molar ratio 1 : 1 via a one‐step condensation polymerization. Subsequent reaction of the resulted chlorine‐bound polymers with adequate amount of the sodium salts of 4‐methoxycarbonylphenoxide or 4‐propoxycarbonylphenoxide yielded the corresponding chlorine‐free polymers, [poly(tetra‐4‐methoxycarbonylphenoxy)‐4,4′‐(isopropoylidene)diphenoxy cyclotriphosphazene] (MBACP), [poly(tetra‐4‐propoxycarbonylphenoxy)‐4,4′‐(isopropoylidene)diphenoxycyclotriphosphazene] (PBACP), [poly(tetra‐4‐methoxycarbonylphenoxy)‐4,4′‐(hexafluoroisopropylidene)diphenoxycyclotriphosphazene] (MBAFCP), [poly(tetra‐4‐propoxycarbonylphenoxy)‐4,4′‐(hexafluoroisopropylidene)diphenoxycyclotriphosphazene] (PBAFCP), respectively. The chemical structures were characterized by Fourier transformer infrared, ¹H, and ¹³C‐NMR. Thermal properties of polymers were investigated using DSC and TGA analysis. The obtained polymers were thermoplastic, having moderate T_g values in the range of 26–78°C and good thermal stability up to 350°C in N₂ and O₂ gases. The thermal decomposition of the isopropylidene‐containing polymers is a one‐step process, while that of hexafluoroisopropylidene‐containing polymers is a two‐step process. However, presence of the latter group in the polymers backbone showed negligible effects on the thermo‐oxidative stability. The adhesive strength was measured by lap‐shear strength test on glass–glass bonded joint and found to be in the range of 1.78–2.62 MPa, this property may be attributed to the physical interactions between glass–glass interfaces and the polar‐pendant units present at the polymers backbone. The products showed high optical transparency when they applied between two glass surfaces, the adhesive layers were colorless, with the UV cut‐off wavelength of 300–302 nm, and the maximum transparency of about 90% was observed within the wavelengths range of 400–700 nm. Because of their properties, the cyclolinear poly(aryloxycyclotriphosphazenes) synthesized in this study are recommended as potential candidates for high thermally stable, transparent adhesives required in industrial applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

Crosslinked monosulfonated poly(arylene ether) using cyclodimerization of trifluorovinyl ether groups for fuel cell applications

A crosslinker and crosslinkable sulfonated poly(arylene ether)s with trifluorovinyl ether groups were synthesized via reaction of 4‐trifluorovinyloxyphenol for application in fuel cells. Crosslinked poly(arylene ether) membranes were prepared by thermal irradiation, and the cyclodimerization of the trifluorovinyl ether groups in the polymers as well as the crosslinker was confirmed using differential scanning calorimetry and infrared measurements. These crosslinked membranes showed a low swelling ratio, comparable to that of Nafion 112. The proton conductivity of the crosslinked membranes was 0.17 and 0.3 S cm^?1 at 30 and 80 °C, respectively, much higher than that of Nafion 112 under the same conditions. The excellent dimensional stability and high conductivity of the crosslinked membranes can be attributed to this new type of crosslinking system (end‐group crosslinking) as well as the chemical structure of crosslinked (multi‐block) polymers. Copyright © 2011 Society of Chemical Industry