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Showing papers in "Journal of Polymer Science Part A in 1996"


Journal ArticleDOI
TL;DR: In this paper, the sulfonation of arylene polymers with an ion exchange capacity of 0.5 to 3.2 mequiv SO3H/g polymers has been investigated.
Abstract: A new process has been developed for the sulfonation of arylene polymers which can be lithiated, like polysulfone Udel®. The sulfonation process consists of the following steps: (1) lithiation of the polymer at temperatures from −50 to −80°C under argon, (2) gassing of the lithiated polymer with SO2; (3) oxidation of the formed polymeric sulfinate with H2O2, NaOCl, or KMnO4; (4) ion-exchange of the lithium salt of the sulfonic acid in aqueous HCl. The advantages of the presented sulfonation procedure are: (1) in principle all polymers which can be lithiated can be subjected to this sulfonation process; (2) by this sulfonation procedure the sulfonic acid group is inserted into the more hydrolysis-stable part of the molecule; (3) this process is ecologically less harmful than many common sulfonation procedures. The sulfonated polymers were characterized by NMR, titration and elemental analysis, by IR spectroscopy, and by determination of ionic conductivity. Also the hydrolytic stability of the sulfonated ion-exchange polymers was investigated. Polymers with an ion-exchange capacity of 0.5 to 3.2 mequiv SO3H/g Polymer have been synthesized and characterized. The following results have been achieved: membranes made from the sulfonated polymers show good conductivity, good permselectivity (>90%), and good hydrolytic stability in 1N HCl and water at temperatures up to 80°C. © 1996 John Wiley & Sons, Inc.

195 citations


Journal ArticleDOI
TL;DR: In this article, the soft-hard segment phase separation in response to variations of composition and structure of PU has been studied from the dynamic mechanical measurements of the emulsion cast films, and the structural variation included ionic and hard segment content, molecular weight of NCO-terminated prepolymer, and type and length of the soft segment.
Abstract: Anionomer-type waterborne polyurethanes (PUs) were obtained from poly(β-methyl-δ-valerolactone) glycol (PMVL) and isophorone diisocyanate, following a prepolymer mixing process. The soft-hard segment phase separation in response to the variations of composition and structure of PU has been studied from the dynamic mechanical measurements of the emulsion cast films. The structural variation included ionic and hard segment content, molecular weight of NCO-terminated prepolymer, and type and length of the soft segment. It was found that phase separation is more sensitive to the soft segment length, rather than the soft segment content. With only phase separation, the rubbery modulus was significant even with lower hard segment content. Phase separation was much more pronounced with PU from poly(tetramethylene adipate) glycol, rather than from PMVL and poly(caprolactone) © 1996 John Wiley & Sons, Inc.

171 citations


Journal ArticleDOI
TL;DR: A series of cycloaliphatic diepoxides with cleavable acetal links were synthesized and characterized in this paper, which can extend the utility of thermosetting epoxies by preserving their positive attributes while eliminating their well known intractability after curing.
Abstract: A series of cycloaliphatic diepoxides with cleavable acetal links were synthesized and characterized. These materials were shown to undergo thermosetting reactions with cyclic anhydride in very similar fashion to a commercial cycloaliphatic epoxide, but cured samples were easily dissolved in a variety of acid-containing solvent mixtures. Such materials can extend the utility of thermosetting epoxies by preserving their positive attributes while eliminating their well known intractability after curing. The latter property is particularly a problem for manufacturers designing products for disassembly at end of use in order to facilitate recycling. © 1996 John Wiley & Sons, Inc.

143 citations


Journal ArticleDOI
TL;DR: In this article, the surface characterization of polystyrene microspheres was performed by x-ray photo-electron spectroscopy and critical surface tension measurements, and the correlation between the surface composition and wett ability properties of the particles surface and their size and size distribution was also demonstrated.
Abstract: Polystyrene microspheres were prepared by dispersion polymerization of styrene in a mixture of ethanol and 2-methoxy ethanol. Surface characterization of the formed particles was performed by x-ray photoelectron spectroscopy and critical surface tension measurements. The influence of different reaction parameters, i.e., monomer concentration, stabilizer type (polyvinylpyrrolidone, copolymers of vinylpyrrolidone and vinylacetate and polyvinylace tate), stabilizer concentration and molecular weight, and initiator type and concentration, on the molecular weight and on the size and size distribution of the formed polystyrene microspheres was investigated. The correlation between the surface composition and wett ability properties of the particles surface and their size and size distribution was also demonstrated. © 1996 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 34:1857–1871, 1996

141 citations


Journal ArticleDOI
TL;DR: In this article, two new diglycidyl ester compounds containing preformed imide rings for better thermal stability were prepared to be used as chain extenders for PET and PBT.
Abstract: Two new diglycidyl ester compounds containing preformed imide rings for better thermal stability were prepared to be used as chain extenders for PET and PBT. The preparation of these compounds was carried out in two steps. In the first step, diimidodiacids were prepared from pyromellitic anhydride and 3-aminopropanoic acid or 4-(aminomethyl)benzoic acid. From these diimidoacids, in a second step, diimidodiepoxides were obtained by reaction with epichlorohydrin. The aforementioned diimidodiepoxides were used as chain extenders for poly(ethylene terephthalate) (PET) and poly(butylene terephthalate) (PBT) with satisfactory results. The polyester samples obtained from various residence times in the reactor, were characterized by solution viscosity measurements, carboxyl, and hydroxyl end-group determination. Starting from a PET having intrinsic viscosity ([η]) of 0.60 dL/g and carboxyl content (CC) of 42 equiv/106 g, one could obtain PET with [η] of 1.16 and CC below 5 equiv/106 g. The typical reaction condition for the coupling of PET was its heating with the chain extender under argon atmosphere above its melting temperature (280°C) for several minutes. Analogous results were obtained for PBT. The hydroxyl content in all cases was increased. © 1996 John Wiley & Sons, Inc.

130 citations


Journal ArticleDOI
TL;DR: In this paper, a set of polyvinyl alcohol-vinyl benzoate copolymers with different degrees of modification were crosslinked to study how the percentage of remaining hydroxylic groups affects the crosslinking process.
Abstract: The reaction of acid chlorides with poly(vinyl alcohol) (PVA) leads to vinyl alcohol-vinyl ester copolymers. The esterification by Schotten-Baumann enables degrees of modification to be reached which depend on the chemical structure of the pendant unit introduced. High degrees of modification were obtained in the reaction with water-stable acid chlorides such as benzoyl or cinnamoyl chloride. The copolymers obtained were characterized by spectroscopic techniques, elemental analysis, thermal methods, and viscosity determinations. Since in all cases they were only partially modified, the remaining hydroxyl groups were reacted with difunctional hardeners, Epiclon B-4400, hexamethylene diisocyanate, and tolylene 2,4-diisocyanate, to obtain tridimensional networks. Vinyl alcohol-vinyl benzoate copolymers with different degrees of modification were crosslinked to study how the percentage of remaining hydroxylic groups affects the crosslinking process. The exotherm maximum of the curing process was lower when diisocyanates were used as hardeners and the degree of crosslinking was higher when hexamethylene diisocyanate was used according to the observed increase in T g values. Whereas the TGA curves of linear polymers only showed one degradation, in crosslinked polymers two degradation steps were detected, suggesting several degradation mechanisms.

109 citations


Journal ArticleDOI
TL;DR: The polyaddition of L-lysinol and 1 was also carried out in NMP to afford higher molecular weight of optically active polyurethane 3 bearing hydroxy group in quantitative yield as mentioned in this paper.
Abstract: The polyaddition of L-lysine hydrochloride and bifunctional five-membered cyclic carbonate 1 was carried out in DMAc in the presence of 1 equiv of DBU or 2 equiv of sodium hydride for 24 h to afford optically active polyurethane 2 bearing hydroxy and carboxyl group. The polyaddition of L-lysinol and 1 was also carried out in NMP to afford higher molecular weight of optically active polyurethane 3 bearing hydroxy group in quantitative yield. These polyurethanes reacted with cupric acetate, sodium tetrahydroborate, and titanium tetraisopropoxide to afford the corresponding crosslinked gels immediately. © 1996 John Wiley & Sons, Inc.

101 citations


Journal ArticleDOI
TL;DR: An automated reaction calorimeter was used to directly monitor the rate of emulsion polymerization of styrene using different emulsifier (sodium lauryl sulfate) and initiator (potassium persulfate) concentrations.
Abstract: An automated reaction calorimeter was used to directly monitor the rate of emulsion polymerization of styrene using different emulsifier (sodium lauryl sulfate) and initiator (potassium persulfate) concentrations. By using this technique in conjunction with off-line measurements of the evolution of the particle size distributions, important details of the process were observed. The classical constant rate period (Interval II) often reported for the batch emulsion polymerization of styrene was not seen in this work. Instead, the experimental results suggest that the end of nucleation and the disappearance of monomer droplets take place at approximately the same conversion (36-40%). From the polymerization rate data, important parameters such as the monomer concentration in the polymer particles and the average number of radicals per particle were calculated.

84 citations


Journal ArticleDOI
TL;DR: In this paper, hyperbranched polyurethanes, with varying oligoethyleneoxy spacer segments between the branching points, have been synthesized by a one-pot approach starting from the appropriately designed carbonyl azide that incorporates the different spacer segment.
Abstract: Hyperbranched polyurethanes, with varying oligoethyleneoxy spacer segments between the branching points, have been synthesized by a one-pot approach starting from the appropriately designed carbonyl azide that incorporates the different spacer segments. The structures of monomers and polymers were confirmed by IR and 1 H-NMR spectroscopy. The solution viscosity of the polymers suggested that they were of reasonably high molecular weight. Reversal of terminal functional groups was achieved by preparing the appropriate monohydroxy dicarbonyl azide monomer. The large number of terminal isocyanate groups at the chain ends of such hyperbranched macromolecules caused them to crosslink prior to its isolation. However, carrying out the polymerization in the presence of 1 equiv of a capping agent, such as an alcohol, resulted in soluble polymers with carbamate chain ends. Using a biphenyl-containing alcohol as a capping agent, we have also prepared novel hyperbranched polyurethanes with pendant mesogenic segments. These mesogen-containing polyurethanes, however, did not exhibit liquid crystallinity probably due to the wholly aromatic rigid polymer backbone.

83 citations


Journal ArticleDOI
TL;DR: In this paper, the free radical polymerization of a polyNIPAAm macromonomer and styrene in ethanol was used to obtain poly(N-isopropylacrylamide)-coated polystyrene microspheres.
Abstract: Thermosensitive microspheres with 0.4–1.2 μm diameter consisting of a polystyrene core and poly(N-isopropylacrylamide) (polyNIPAAm) branches on their surfaces were prepared by the free radical polymerization of a polyNIPAAm macromonomer and styrene in ethanol. Electron spectroscopy for chemical analysis (ESCA) of the microsphere surface suggested that polyNIPAAm chains were favorably located on the surface of the microspheres. The morphology of the microspheres was observed by transmission electron micrograph (TEM) and the particle size of was estimated by submicron particle analyzer. The molecular weight of the polyNIPAAm macromonomer, the ratio of the macromonomer and styrene, and the polymerization temperature affected the particle size. Thermosensitive properties of polyNIPAAm-coated polystyrene microspheres were evaluated by the turbidity of their dispersion solutions and the hydrodynamic size of the miocrospheres. The transmittance in dispersion solutions changed clearly, similar to oligoNIPAAm and polyNIPAAm macromonomers. In addition, the particle size of microspheres decreased with rising temperature. These results were explained by the thermosensitivity of polyNIPAAm branches on the microsphere surface. © 1996 John Wiley & Sons, Inc.

82 citations


Journal ArticleDOI
TL;DR: In this article, high-random copolymers of ϵ-caprolactone (CL) and D,L-lactide (LA) were synthesized by a new catalyst system, rare earth chloride-propylene oxide (PO) system.
Abstract: Highly random copolymers of ϵ-caprolactone (CL) and D,L-lactide (LA) were synthesized by a new catalyst system, rare earth chloride–propylene oxide (PO) system. In the presence of propylene oxide, all rare earth chlorides tested are highly effective for the copolymerization. The influences of reaction conditions on the copolymerization catalyzed by the NdCl3-5PO system have been investigated in detail. The reactivity ratios of ϵ-caprolactone and D,L-lactide were determined and show that the copolymerization with this new rare earth catalyst is closer to ideal copolymerization than reported for other catalysts. The microstructure of copolymer analyzed by 13C-NMR shows that the monomer units in the copolymer is near to completely random distribution with a short average monomer sequence length. The DSC measurement confirms the high randomness of the chain structure. The mechanism studied by NMR indicates that the rare earth alkoxide generated by the reaction of rare earth chloride with propylene oxide initiates the copolymerization, and then proceeds via a “coordination-insertion” mechanism with acyl-oxygen bond cleavage of CL and LA. © 1996 John Wiley & Sons, Inc.

Journal ArticleDOI
TL;DR: In this paper, a new type of H-bonded host-guest liquid-crystalline copolymers with mesogenic acrylate and 4-vinylpyridine units was reported.
Abstract: Supramolecular liquid–crystalline polymeric complexes based on a backbone that contains vinyl pyridine units and azobenzene or biphenyl derivatives that posses alkyl chains terminated by carboxylic acid have been obtained by the formation of intermolecular hydrogen bonds between the carboxylic acid and the pyridyl moieties. The polymeric complexes behave as side-chain liquid–crystalline polymers and exhibit smectic phases. A new type of H-bonded host-guest liquid–crystalline system is also reported. The liquid–crystalline host copolymers contain both mesogenic acrylate and 4-vinylpyridine units. The guest molecule is an azobenzene that has a carboxylic acid moiety at one of its extremities. The H-bonded polymeric host–guest complexes exhibit nematic phases. Sequential UV and visible light irradiation of the polymeric complex causes reversible photochemically induced phase transitions. The isothermal nematic–isotropic and isotropic–nematic transitions result from the trans-cis and cis-trans photoisomerization of the guest azobenzene in the host–guest system. © 1996 John Wiley & Sons, Inc.

Journal ArticleDOI
TL;DR: In this article, the synthesis and characterization of new liquid crystalline thermosets having a twin structure was described, and an epoxy-terminated monomer based on a 1,4-bis(benzoyloxy)phenylene mesogen was synthesized to determine the effect of the position of the mesogen on the final network structure.
Abstract: This article describes the synthesis and characterization of new liquid crystalline thermosets having a twin structure. Nematic epoxy-terminated monomers based on a phenyl benzoate twin mesogen connected by an alkylene spacer were synthesized for these studies. In addition, an epoxy-terminated monomer based on a 1,4-bis(benzoyloxy)phenylene mesogen was synthesized to determine the effect of the position of the mesogen on the final network structure. The diepoxy monomer made with phenyl benzoate twin mesogens connected with an alkylene spacer formed a smectic-like network when cured with diamines. This smectic organization appeared even though the diepoxy monomer itself showed only a nematic mesophase over a narrow temperature range. The presence of crosslinks at both ends of the mesogens helped to retain a uniform spacing between crosslinking sites during the curing reaction, and aided formation of the smectic layer arrangement. The epoxy monomer possessing a 1,4-bis(benzoyloxy)phenylene mesogen and two epoxidized alkylene end groups on both sides of the mesogen formed a stable nematic mesophase. However, in contrast to the twin epoxies, the latter epoxy when reacted with diamines tended to produce a nematic-like network which was retained as the crosslinking reaction proceeded.

Journal ArticleDOI
TL;DR: In this article, a comparison of microwave induced reactions with thermal methods, therefore, must also specify the microwave power used, and the results indicate a similar comparable temperature of about 80°C irrespective of the microwave powers used.
Abstract: Styrene was cured by microwave radiation at two different powers: 300 and 500 W. The temperature profile of the sample during the microwave curing process was determined to select a suitable temperature for comparison with the conventional method of cure. The results indicate a similar comparable temperature of about 80°C irrespective of the microwave power used. The percentage conversion of the cure was followed by Fourier transform infrared (FTIR) spectroscopy. The thermal polymerization at 79(±1)°C displayed a gradual increase in the rate of reaction at the gel effect from about 30 to 50% conversion of the reaction. The microwave cure at 300 and 500 W displayed a large and sharp gel effect from about 20 to 69 and 64% conversion of the reaction, respectively. The limiting conversion decreased with increase in microwave power which was also observed in the polymerization of methyl methacrylate (MMA). Based on similarity in temperature and reaction conditions, the 500 W cure was found to show a reaction rate enhancement of 190% and the 300 W cure 120%. A comparison of microwave induced reactions with thermal methods, therefore, must also specify the microwave power used. © 1996 John Wiley & Sons, Inc.

Journal ArticleDOI
TL;DR: In this article, the effects of transesterification on the miscibility of poly(ethylene terephthalate)/poly (ethylene 2,6-naphthalate) were studied and the physical blends and transesterified products were analyzed by wideangle x-ray scattering, differential scanning calorimetry, and nuclear magnetic resonance spectroscopy.
Abstract: The effects of transesterification on the miscibility of poly(ethylene terephthalate)/poly(ethylene 2,6-naphthalate) were studied. Blends were obtained by solution precipitation at room temperature to avoid transesterification during blend preparation. The physical blends and transesterified products were analyzed by wide-angle x-ray scattering, differential scanning calorimetry, and nuclear magnetic resonance spectroscopy. It was found that the physical blends are immiscible and when the extent of transesterification reaches 50% of the completely randomized state, independent of blend composition, the blends are not crystallizable and show a single glass transition temperature between those of starting polymers. The interchange reactions were significantly influenced by annealing temperature and time but negligibly by blend composition.

Journal ArticleDOI
TL;DR: In this article, a membranous copolymer crosslinked with divinylbenzene reacted with N, N,N,N′, N′-tetra-methylethylenediamine, NN, N',N',N'tetramethyl-1,3-propanediamine.
Abstract: A membranous copolymer crosslinked with divinylbenzene reacted with N,N,N′,N′-tetra-methylethylenediamine, N,N,N′,N′-tetramethyl-1,3-propanediamine, and N,N,N′,N′-tetramethyl-1,6-hexanediamine to prepare highly crosslinked anion exchange membranes. More than 80% of both tertiary amino groups of the diamines reacted with chloromethyl groups of the membrane to form crosslinkage. After formation of the high crosslinkage of the membrane was confirmed with dialysis of a neutral molecule, electrochemical properties of the obtained membranes (mainly, relative transport number between two anions in electrodialysis) were evaluated: nitrate ions to chloride ions, sulfate ions to chloride ions, fluoride ions to chloride ions, and bromide ions to chloride ions. Though larger anions, in general, were difficult to permeate through the membranes due to high crosslinkage, the number of methylene groups of the diamines (which means the increase in hydrophobicity of anion exchange groups) also affected the relative transport number between two anions. The lower the hydration of anions, the higher the relative transport number of the anions through the membranes with the hydrophobic anion exchange groups. © 1996 John Wiley & Sons, Inc.

Journal ArticleDOI
TL;DR: In this article, the effects of the concentration of surfactant, cosurfactant, and initiator on the number of particles were determined systematically in ways that indicate predominant droplet nucleation in these systems.
Abstract: Miniemulsions of methyl methacrylate with sodium lauryl sulfate as the surfactant and dodecyl mercaptan (DDM) as the cosurfactant (or hydrophobe) were prepared and polymerized. The emulsions were of a droplet size range common to miniemulsions and exhibited long-term stability (greater than 3 months). Results indicate that DDM retards Ostwald ripening and allows the production of stable miniemulsions. When these emulsions were initiated, particle formation occurred predominantly by monomer droplet nucleation. The effects of the concentration of surfactant, cosurfactant and initiator were determined. Rates of polymerization, monomer droplet sizes, polymer particle sizes, molecular weights of the polymer, and the effect of initiator concentration on the number of particles vary systematically in ways that indicate predominant droplet nucleation in these systems. © 1996 John Wiley & Sons, Inc.

Journal ArticleDOI
TL;DR: In this paper, a new type of epoxy resin which contained cyclic phosphine oxide group in the main chain was synthesized, and the structure of the new epoxy resins was confirmed by elemental analyses (EA), infrared spectroscopy (IR), and 1H-NMR and 13C NMR spectroscopies.
Abstract: A new type of epoxy resin which contained cyclic phosphine oxide group in the main chain was synthesized. The structure of the new type of epoxy resin was confirmed by elemental analyses (EA), infrared spectroscopy (IR), and 1H-NMR and 13C-NMR spectroscopies. In addition, compositions of the new synthesized cyclic phosphine oxide epoxy resin (EPCAO) with three curing agents, e.g., bis(3-aminophenyl)methylphosphine oxide (BAMP), 4,4′-diamino-diphenylmethane (DDM), and 4,4′-diaminodiphenylsulfone (DDS), were used for making a comparison of its curing reactivity, heat, and flame retardancy with that of Epon828 and DEN438. The reactivities were measured by differential scanning calorimetry (DSC). Through the evaluation of thermal gravimetric analysis (TGA), those polymers which were obtained through the curing reactions between the new epoxy resin and three curing agents (BAMP, DDM, DDS) also demonstrated excellent thermal properties as well as a high char yield. © 1996 John Wiley & Sons, Inc.


Journal ArticleDOI
TL;DR: In this article, the authors used Fourier transform infrared (FT-IR) spectroscopy to investigate the formation of five-membered cyclic anhydride intermediates on cotton fabric by different polycarboxylic acids.
Abstract: Polycarboxylic acids have been used as crosslinking agents for cotton cellulose. In our previous research, we used Fourier transform infrared (FT-IR) spectroscopy to investigate the formation of five-membered cyclic anhydride intermediates on cotton fabric by different polycarboxylic acids. In this research, we found that those polycarboxylic acids capable of forming both five- and six-membered cyclic anhydrides form only five-membered cyclic anhydrides. We compared the effectiveness of the polycarboxylic acids with different molecular structures for esterifying cellulose. Those polycarboxylic acids, which have their carboxyl groups bonded to the adjacent carbons of their molecular backbones and are capable of forming five-membered cyclic anhydrides, are more effective for esterifying cellulose than those polycarboxylic acids having their carboxyl groups bonded to the alternative carbons. The only six-membered cyclic anhydride identified is the anhydride formed on the cotton fabric treated with poly(acrylic acid). © 1996 John Wiley & Sons, Inc.

Journal ArticleDOI
TL;DR: The first homopolymerization of pure maleic anhydride was reported in this paper at 190 degrees C, during the melt-functionalization of polypropylene, either with or without organic peroxide, in vacuum-sealed glass vials.
Abstract: The homopolymerization of maleic anhydride was attempted at 190 degrees C, during the melt-functionalization of polypropylene, either with or without organic peroxide using a Brabender plastograph. The free radical homopolymerization of pure maleic anhydride was also attempted either with or without organic peroxide, at 190 degrees C, in vacuum-sealed glass vials. In all cases, free low molecular weight maleic anhydride oligomers were observed by low molecular weight size exclusion chromatography (SEC). This maleic anhydride homopolymerization tends to prove that the ceiling temperature of poly(maleic anhydride) probably lies above the previously published value of 160 degrees C for these specific experimental conditions. (C) 1996 John Wiley & Sons, Inc.

Journal ArticleDOI
TL;DR: Using a plasma-induced graft polymerization technique, which is well known as a surface modification method, the grafted polymer was formed in pores of the porous material and examined the filling mechanism as discussed by the authors.
Abstract: Using a plasma-induced graft polymerization technique, which is well known as a surface modification method, the grafted polymer was formed in pores of the porous material This study examined the filling mechanism Five thin porous films were sandwiched together, and employed as the substrate The substrate was treated by plasma, and the change in surface tension and radical formation was measured for each sheet after the sheet was separated The only surface on which surface-tension change was detected, was that of the sheet directly exposed to the plasma Although plasma treatment made polymer radicals primarily on the outer surface of the sheet, the treatment also formed a few radicals inside the sheets The radicals inside the sheets reacted with methylacrylate and grafted polymer formed in the pores The location of grafted polymer depended on the balance between monomer diffusivity and reactivity The grafting rate depended on which monomer solvent was used for the polymerization Thus, the grafted membrane morphology could be controlled by varying the grating solvent composition © 1996 John Wiley & Sons, Inc

Journal ArticleDOI
TL;DR: In this paper, a bis(phenoxy)naphthalene-containing diamine, 1,6-bis(4-aminophenoxy) naphthalenes, was synthesized in two steps from the condensation of 1, 6-dihydroxynaphthien with p-chloronitrobenzene in the presence of potassium carbonate.
Abstract: A new bis(phenoxy)naphthalene-containing diamine, 1,6-bis(4-aminophenoxy)naphthalene, was synthesized in two steps from the condensation of 1,6-dihydroxynaphthalene with p-chloronitrobenzene in the presence of potassium carbonate, giving 1,6-bis(4-nitrophenoxy)naphthalene, followed by hydrazine hydrate/Pd-C reduction. A series of polyamides were synthesized by the direct polycondensation of the diamine with various aromatic dicarboxylic acids in the NMP solution containing dissolved metal salts such as CaCl 4 or LiBr using triphenyl phosphite and pyridine as condensing agents. The polymers were obtained in quantitative yield with inherent viscosities of 0.78-3.72 dL/g. Most of the polymers were soluble in aprotic solvents and they could be solution-cast into transparent, flexible and tough films. The casting films had tensile strength of 102-175 MPa, elongation at break of 8-42%, and tensile modulus of 2.4-3.8 GPa. The polymers derived from rigid dicarboxylic acids such as terephthalic acid and 4,4'-biphenyldicarboxylic acid exhibited some crystalline characteristics. The glass transition temperatures of the polyamides were in the range of 238-337 o C, and their 10% weight loss temperatures were above 487 o C in nitrogen and above 438 o C in air

Journal ArticleDOI
TL;DR: In this paper, a hot-melt method was used to extract siloxane-incorporated epoxy (ESDG) copolymers and the structures were determined using IR, 1H- and 13C-NMR to determine the structures.
Abstract: Siloxane-incorporated epoxy (ESDG) copolymers were prepared by a hot-melt method. IR, 1H- and 13C-NMR are used to determine the structures. The data on the molecular properties indicate that reaction proceeded with a random polycondensation without involving the opening of the oxirane ring in the epoxy structure. Lowering Tgs with increasing siloxane content in copolymers are observed except for the copolymer modified with PDMS siloxane oligomer. Thermal stability data indicate that siloxane moiety exerts its thermal stability on the copolymer through dissipation of the heat, thus delaying thermal degradation of copolymers. Increasing impact strengths in J/M in the range of 22.0–59.0 are observed for copolymers and the improvement of the impact strength is closely related to the structure and content of siloxane oligomers in copolymers. A rough surface was observed by SEM examination on the propagation surface of the copolymeric impact specimen, while a smooth surface is observed on the unmodified epoxy specimen. The EDX analysis reveals these protruded features are Si-rich segments. The morphological observations suggest the siloxane segment may act as a toughening agent in the epoxy networks, thus contributing to the impact improvement of the copolymers. © 1996 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 34:1907–1922, 1996

Journal ArticleDOI
TL;DR: In this paper, polyacrylic acid was grafted onto the surface of silicone rubber membrane (SR) by plasma-induced graft copolymerization (PIP), and the surface properties of SR were measured by ATR-FTIR, ESCA, and SIMS.
Abstract: Polyacrylic acid (PAA) was grafted onto the surface of silicone rubber membrane (SR) by plasma-induced graft copolymerization (PIP). Ar-plasma was used to activate the surface of SR. Also, a determination was made of the influences of plasma treatment power, pressure, time, grafted copolymerization reaction time, and monomer concentration on polymerization yield. The surface properties of SR were measured by ATR-FTIR, ESCA, and SIMS. In those analyses, the elemental composition and different carbon bindings on the surface of SR were examined by ESCA with the amount of O1s/C1s being approximately 0.7 at 60 s by Ar-plasma treatment (60 W, 200 mtorr). The peroxide group introduced on SR was measured via 1,1-diphenyl-2-picryhydrazyl (DPPH). The optimum amount of peroxide groups was 6.85 × 10−8 mol/cm2 at 60 s of Ar-plasma treatment. The peroxide group (33D peak) was introduced onto the surface of SR by negative spectra of SIMS analysis after SR treatment by Ar-plasma. An increase was obtained in grafted polymerization yield with a region of 5 to 50% (v/v) of acrylic acid aqueous solution. Both sites of polyacrylic acid were detected after staining by toluidine blue O. That is, a homobifunctional membrane was developed via this surface modification method. © 1996 John Wiley & Sons, Inc.

Journal ArticleDOI
TL;DR: In this paper, 1,3-Diaminoadamantane (I) was used as a monomer with various aromatic dicarboxylic acyl chlorides and dianhydrides to synthesize polyamides and polyimides, respectively.
Abstract: 1,3-Diaminoadamantane (I) was used as a monomer with various aromatic dicarboxylic acyl chlorides and dianhydrides to synthesize polyamides and polyimides, respectively. Polyamides having inherent viscosities of 0.10-0.27 dL/g were prepared by low-temperature solution polycondensation. The polyamides were soluble in a variety of solvents such as N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), pyridine, dioxane, and nitrobenzene. These polyamides had glass transition temperatures in the 179-187°C range and 5% weight loss temperatures occurred at up to 354°C. Polyimides based on diamine I and various aromatic dianhydrides were synthesized by the two-stage procedure that included ring-opening to form polyamic acids, followed by thermal conversion to polyimides. The polyamic acids had inherent viscosities of 0.14-0.38 dL/g. The glass transition temperature of these polyimides were in the 245-303°C range and showed almost no weight loss up to 350°C under air and nitrogen atmosphere.

Journal ArticleDOI
TL;DR: In this article, the structure and some physico-chemical properties of radiation grafted FEP-g-polystyrenesulfonic acid proton exchange membranes were studied as a function of the degree of grafting.
Abstract: The structure and some physico-chemical properties of radiation grafted FEP-g-polystyrenesulfonic acid proton exchange membranes were studied as a function of the degree of grafting. The distribution of grafted polymer across the membrane thickness was obtained from microprobe measurements. It was found that for low levels of grafting (ca. 3%), polystyrene chains are located near the membrane surface only, and the interior of the membrane remains ungrafted. With the increasing degree of grafting, polystyrene chains were incorporated into the interior of the membrane as well. An almost homogeneous distribution of grafts in the membrane was obtained at a graft level of > 13%. The influence of the degree of grafting on membrane properties, such as ion exchange capacity, swelling, and specific resistivity was studied. Three different states of water, viz., freezing free, freezing bound, and nonfreezing water have been identified in noncrosslinked membranes. However, the nature and the amount of crosslinker had a profound influence on the states of water in a membrane

Journal ArticleDOI
TL;DR: A fluorine-containing diamine, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane (BAPPH) (II), was synthesized in two steps on condensation of BAPPH with p-chloronitrobenzene in the presence of potassium carbonate as mentioned in this paper.
Abstract: A fluorine-containing diamine, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane (BAPPH) (II), was synthesized in two steps on condensation of 2,2-bis(4-hydroxyphenyl)hexafluoropropane with p-chloronitrobenzene in the presence of potassium carbonate, giving 2,2-bis[4-(4-nitrophenoxy)phenyl]hexafluoropropane (I), followed by reduction with hydrazine monohydrate/Pd—C. Fluorine-containing polyamides and copolyamides having inherent viscosities 0.41–0.88 dL g−1 were prepared by direct polycondensation of BAPPH with various aromatic diacids or with mixed diacids, by triphenyl phosphite and pyridine in N-methyl-2-pyrrolidinone (NMP). The polyamides were examined by elemental analysis, IR spectra, inherent viscosity, x-ray diffraction, solubility, DSC, and TGA. The diffractogram showed that the polyamides were crystalline except IVb, IVc, IVf, and Vc. Almost all polyamides were soluble in polar aprotic solvents. The polymers obtained from BAPPH lost no mass below 350°C, with 10% loss of mass being recorded above 467°C in nitrogen. These aromatic polyamides had glass transition temperatures in the 221–253°C range. © 1996 John Wiley & Sons, Inc.

Journal ArticleDOI
TL;DR: In this paper, an increase in homogeneity of the composite material after the irradiation of HEMA, and a chemical linkage of the monomer with the surface has been observed.
Abstract: Hydroxyethylmethacrylate (HEMA) monomer in different contents was used in the preparation of transparent organic-inorganic hybrid sol-gel matrices. The matrices were studied by analytical techniques before and after irradiation. An increase in the homogeneity of the composite material after the irradiation of HEMA, and a chemical linkage of the monomer with the surface has been observed. Photopolymerization processes were studied by differential scanning calorimetry (DSC). Details of the irradiation times, polymerization rates, and DSC related parameters of HEMA in the sol-gel matrices are reported. © 1996 John Wiley & Sons, Inc.

Journal ArticleDOI
TL;DR: In this article, the excited state interactions occurring when a three-component system of thioxanthene derived dye TXD/amine/additive (diphenyliodonium salt, CBr 4, benzoyl peroxide, cumene hydroperoxide) is subjected to sensitization processes in the visible range, were investigated through time-resolved absorption spectroscopy, spectrofluorometry, and photolysis.
Abstract: The excited state interactions occurring when a three-component system of thioxanthene derived dye TXD/amine/additive (diphenyliodonium salt, CBr 4 , benzoyl peroxide, cumene hydroperoxide) is subjected to sensitization processes in the visible range, were investigated through time-resolved absorption spectroscopy, spectrofluorometry, and photolysis. The rate constants of the various operative processes were measured together with the values of the fluorescence quantum yields (e.g. ? f = 0.75 ± 0.07 in methanol) and the lifetimes of the singlet excited state of the dye (e.g. 6 ns in methanol). Singlet state quenching by methyldiethanolamine (MDEA) occurs with a rate constant k = 10 9 M -1 s -1 in methanol. The reactivity of the triplet excited state of the dye is very low (k = 5.6 X 10 4 M -1 s -1 for the TXD/MDEA interaction). The ketyl radicals that arise from the interaction of the singlet state of the dye with the amine, are quenched by such additives as CBr 4 (k = 6.7 X 10 5 M -1 s -1 ), or the onium salts (k = 5.7 X 10 5 M -1 s -1 ). The calculations of the yields of interaction of the singlet state of the dye with the two components of the system demonstrate that the process of quenching by the amine is the main one ( ? int = 0.5) compared to that by, e.g., an onium salt ( ? int = 0.07). Sensitivity of 0.3 mJ cm -2 obtained in a laser scanning system is also reported.