bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of thermally stable aromatic poly(imide amide benzimidazole) copolymers
Authors: Wang Huei‐Hsiung , Wu Shu‐Ping 
Published: September 2003

Abstract3,3′‐Dinitrobenzidine was first reacted with excess m‐chlorophenyl acid to form a monomer with dicarboxylic acid end groups. Two types of aromatic dianhydrides (Pyromellitic diconhydride (PMDA) and 3,3′,4,4′‐sulfonyl diphthalic anhydride) were also reacted with excess 4,4′‐diphenylmethane diisocyanate to form polyimide prepolymers terminated with isocyanate groups. The prepolymers were further extended with the diacid monomer to form nitro groups containing aromatic poly(imide amide). The nitro groups in these copolymers were hydrogenated to form amine groups and then were cyclized at 180°C to form poly(imide amide benzimidazole) in poly(phosphoric acid), which acted as a cyclization agent. The resultant copolymers were soluble in sulfuric acid and poly(phosphoric acid), in sulfolane under heating to 100°C, and in the polar solvent N‐methyl‐2‐pyrrolidone under heating to 100°C with 5% lithium chloride. According to wide‐angle X‐ray diffraction, all the copolymers were amorphous. According to thermal analysis, the glass‐transition temperatures of the copolymers were 270–322°C. The 10% weight‐loss temperatures were 460–541°C in nitrogen and 441–529°C in air. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1435–1444, 2003
Online monitoring of the evolution of the number of particles in emulsion polymerization by conductivity measurements. I. Model formulation
Authors: Santos A. F. , Lima E. L. , Pinto J. C. , Graillat C. , McKenna T. 
Published: September 2003

AbstractA conductivity meter is an inexpensive instrument that can easily be installed in polymerization reactors. This instrument can be used to monitor ionic species without time‐consuming calibrations. A probe is inserted into the media, providing in situ measurements of conductivity in real time. For emulsion polymerization reactions, the conductivity meter can respond to changes in the ionic surfactant concentration, allowing the determination of surfactant dynamics in the media. The surfactant concentration can then be related to the changes in the surface area of the polymer particle phase, which can be linked to nucleation or coagulation phenomena. In this study, a conductivity meter was coupled to a calorimetric reactor to provide in situ and online measurements of conductivity during the emulsion polymerization of styrene, with sodium dodecyl sulfate as an anionic surfactant and with potassium persulfate as a free‐radical initiator. A semiempirical model was built to describe the conductivity signal as a function of the latex composition and the reactor temperature. The model was inverted and combined with the available conductivity signal, conversion, and temperature measurements and was able to accurately predict the number of polymer particles in the latex and the surfactant concentrations in the many phases, without online measurements of the particle size. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1213–1226, 2003
Thermal degradation kinetics of poly(propylene carbonate) obtained from the copolymerization of carbon dioxide and propylene oxide
Authors: Liu Binyuan , Zhao Xiaojiang , Wang Xianhong , Wang Fosong 
Published: September 2003

AbstractThe kinetics of the thermal degradation of poly(propylene carbonate) (PPC) were investigated with different kinetic methods with data from thermogravimetric analysis under dynamic conditions. The apparent activation energies obtained with different integral methods (Ozawa–Flynn–Wall and Coats–Redfern) were consistent with the values obtained with the Kinssinger method (99.93 kJ/mol). The solid‐state decomposition process was a sigmoidal A3 type in terms of the Coats–Redfern and Phadnis–Deshpande results. The influence of the heating rate on the thermal decomposition temperature was also studied. The derivative thermogravimetry curves of PPC confirmed only one weight‐loss step. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 947–953, 2003
Miscibility and properties of blend membranes of waterborne polyurethane and carboxymethylchitin
Authors: Zeng Ming , Zhang Lina , Wang Niangui , Zhu Zhichao 
Published: September 2003

AbstractWe prepared a series of blend membranes by blending waterborne polyurethane (WPU) and carboxymethylchitin (CMCH) in aqueous systems. The effects of CMCH content on the miscibility, morphology, thermal stability, and mechanical properties of the blend membranes were investigated by dilute solution viscometry (DSV), Fourier transform infrared spectroscopy, wide‐angle X‐ray diffraction (WXRD), scanning electron microscopy, dynamic mechanical analysis (DMA), thermogravimetric analysis, ultraviolet (UV) spectroscopy, and tensile testing. The miscibility parameter of the WPU/CMCH aqueous solution obtained by DSV predicted that the blends of WPU and CMCH were miscible or partially miscible. Moreover, the partial miscibility of the blend membranes over the entire composition range were confirmed by FTIR, WXRD, DMA, and UV spectroscopy to support the conclusion from DSV. New hydrogen bonds were formed between CMCH and WPU in the blend membranes, resulting in strong intermolecular interactions. By inducing the CMCH, we improved the tensile strength, thermostability, and organic solvent resistance of the blend membranes significantly. Therefore, this study not only provided a novel way to prepare an environmentally–friendly material but also expanded the application of chitin and CMCH. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1233–1241, 2003
Novel water sorption behavior of emulsion blends
Authors: Robeson Lloyd M. , Hyder Ingrid Z. 
Published: September 2003

AbstractAs waterborne emulsions continue to replace their solvent‐based counterparts in various applications, the water resistance of cast films is attracting significant interest. The characterization of the water sorption kinetics and structure–property relationships related to water sorption is, therefore, an important area for investigation. In this study, the water sorption kinetics of emulsion blends were compared with those of their blend components. The investigated blends were at equal weight (dry basis) fractions for each emulsion. The initial water sorption rate for immiscible emulsion blends was found to be significantly higher than composite values of the constituents. This behavior was due to percolation networks in the blends because thermodynamic constraints prevented diffusion across the interface bordering dissimilar particles, leaving a interface enriched with water‐sensitive species. The peak water sorption for the immiscible emulsion blends was lower than the composite values because of the ability of the water‐sensitive species to rapidly diffuse out of the samples due to the percolation network. This behavior existed for room‐temperature‐cast samples and persisted as the time and temperature exposure was increased. Atomic force microscopy results clearly showed the potential for percolation networks in the blends. Higher glass‐transition emulsion polymers [e.g., poly(vinyl acetate)] exhibited similar behavior, and this indicated poor film formation like that for the immiscible emulsion blends. These results indicated that the degree of film formation was critical with respect to the water sorption characteristics of emulsion films. Immiscible emulsion blends were compared with miscible emulsion blends for which all constituents exhibited excellent film formation (unblended). The immiscible blends exhibited a significant difference in water sorption compared with the miscible blends because of the existence of percolation networks. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 933–939, 2003
Atom transfer radical polymerization of lauryl methacrylate
Authors: Xu Wenjian , Zhu Xiulin , Cheng Zhenping , Chen Jianying 
Published: September 2003

AbstractThe atom transfer radical polymerization (ATRP) of lauryl methacrylate (LMA) with an ethyl 2‐bromobutyrate/CuCl/N,N,N′,N″,N″‐pentamethyldiethylenetriamine initiation system was successfully carried out in toluene, and poly(lauryl methacrylate) with a low polydispersity (1.2 < weight‐average molecular weight/number‐average molecular weight < 1.5) was obtained. Plots of ln ([M])0/([M]) versus time and plots of the molecular weight versus conversion showed a linear dependence, indicating a constant number of propagating species throughout the polymerization. The rate of polymerization was 0.56‐order with respect to the concentration of the initiator and 1.30‐order with respect to the concentration of the Cu(I) catalyst. In addition, the effect of the solvent on the polymerization was investigated, and the thermodynamic data and activation parameters for the solution ATRP of LMA were reported. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1117–1125, 2003
Preparation and properties of polyelectrolyte complex sponges composed of hyaluronic acid and chitosan and their biological behaviors
Authors: Lee Sang Bong , Lee Young Moo , Song Kang Won , Park Moon Hyang 
Published: September 2003

AbstractPolyelectrolyte complexes (PECs) composed of chitosan and hyaluronic acid (HA) were prepared in various pH regions and at different weight ratios. At low pHs, there was a strong ionic interaction between NH groups in chitosan and both COO− and COOH groups in HA due to the deprotonation of HA, whereas weak linkages were formed at high pHs because only the carboxyl groups of HA could interact with NH groups in chitosan. The formation of PECs resulted in a decrease in the crystallinity and thermal stability caused by the interactions between polyions. With variations in the degree of ionization of polyions at various pH conditions, novel PEC sponges were prepared by the freeze drying of PEC solutions. Furthermore, for the evaluation of the wound‐healing effect of PEC sponges with or without an antimicrobial agent (silver sulfadiazine), they were applied to a full‐skin defect of a Wistar rat in vivo. The histology and computerized morphometric analysis of the epidermal healing confirmed the proliferation of fibroblasts in the wound bed and a distinct reduction in infectious agents. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 925–932, 2003
Thermooxidative degradation of methyl methacrylate‐graft‐natural rubber
Authors: Li Si‐Dong , Wang Chen , Xu Kui , Peng Zheng 
Published: September 2003

AbstractThe thermooxidative degradation of methyl methacrylate‐graft‐natural rubber (MG) at different heating rates (B) has been studied with thermogravimetric analysis in an air environment. The results indicate that the thermooxidative degradation of MG in air is a one‐step reaction. The degradation temperatures increase with B. The initial degradation temperature (To) is 0.697B + 350.7; the temperature at the maximum degradation rate, that is, the peak temperature on a differential thermogravimetry curve (Tp), is 0.755B + 368.8; and the final degradation temperature (Tf) is 1.016B + 497.4. The degradation rates at Tp and Tf are not affected by B, and their average values are 46.7 and 99.7%, respectively. The maximum thermooxidative degradation reaction rate, that is, the peak height on a differential thermogravimetry curve (Rp), increases with B. The relationship between B and Rp is Rp = 2.12B + 7.28. The thermooxidative degradation kinetic parameters are calculated with the Doyle model. The reaction energy (E) and frequency factor (A) change with an increasing reaction degree, and the variational trends of the two kinetic parameters are similar. The values of E and A increase remarkably during the initial stage of the reaction, then keep relevantly steady, and finally reach a peak during the last stage. The velocity constants of the thermooxidative degradation vary with the reaction degree and increase with the reaction temperature. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1227–1232, 2003
Synthesis of new polymeric hindered amine light stabilizers: Performance evaluation in styrenic polymers
Authors: Singh R. P. , Patwa A. N. , Desai S. M. , Pandey J. K. , Solanky S. S. , Vishwa Prasad A. 
Published: September 2003

AbstractPolymeric hindered amine light stabilizers (HALSs), in which the HALS functionality was attached to the terminal isocyanate chain end of poly(styryl‐co‐styryl isocyanate), were synthesized by a two‐step process. First, cinnamoyl azide was prepared and copolymerized with styrene by a free‐radical copolymerization method. Polymeric low‐molecular‐weight and high‐molecular‐weight 2,2,6,6‐tetramethyl‐4‐pipridinol‐graft‐poly(styryl‐co‐styryl isocyanate) and 4‐amino‐2,2,6,6‐tetramethyl piperidine‐graft‐poly(styryl‐co‐styryl isocyanate) were synthesized by a grafting method. The photodegradation and stabilization of different grades of high‐impact polystyrene (HIPS) were studied at 55°C in air at different time intervals, and the photostabilizing efficiency of polymeric HALSs was compared with conventional light stabilizers, such as 2,2,6,6‐tetramethyl‐4‐pipridinol and bis(2,2,6,6‐tetramethyl‐4‐piperidinyl)sebacate. Polymeric HALSs showed significant improvements in the photostabilization of HIPS. The solubility and diffusion coefficient of polymeric HALSs were studied. The morphological changes in HIPS caused by photooxidation were also studied. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1126–1138, 2003
Modification of acrylonitrile–butadiene–styrene terpolymer by grafting with maleic anhydride in the melt. I. Preparation and characterization
Authors: Qi Rongrong , Qian Junling , Zhou Chixing 
Published: September 2003

AbstractThe graft copolymerization of maleic anhydride (MAH) onto acrylonitrile–butadiene–styrene terpolymer (ABS) was carried out with dicumyl peroxide (DCP) and benzoyl peroxide (BPO) as the binary initiators and with styrene as the comonomer in the molten state. IR spectra confirmed that MAH was successfully grafted onto the ABS backbone. A reaction mechanism was proposed: the grafting most likely took place through the addition of MAH radicals to the double bond of the butadiene region of ABS. Influences such as the MAH concentration, the initiators and their concentrations, the reaction temperature, the rotating speed, and the comonomer concentration were studied. The results indicated that using styrene as a comonomer and DCP/BPO as binary initiators was beneficial for the graft copolymerization. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1249–1254, 2003
Particle features of poly(vinyl chloride) resins prepared by a new heterogeneous polymerization process
Authors: Bao Y. Z. , Brooks B. W. 
Published: September 2003

AbstractThe heterogeneous polymerization of vinyl chloride monomer (VCM), with n‐butane as the reaction medium, was used to prepare poly(vinyl chloride) (PVC) resins. The particle features of the resulting resins and the particle formation mechanism of the polymerization process were investigated. The PVC resins prepared by the new polymerization process had a volume‐average particle size comparable to that of suspension PVC resins and a lower number‐average particle size. From scanning electron micrographs, it could be seen that the new PVC resins had a regular particle shape and a smooth surface with no obvious skin. They also had a high porosity. The new PVC resins were composed of individual and loosely aggregated primary particles. The diameter of the primary particles in the top layer of the grains was smaller than that of the primary particles in the center part of the grains. On the basis of the particle features of these PVC resins, a particle formation mechanism for the new polymerization process was proposed. PVC chains precipitate from a VCM/n‐butane mixed medium to form primary aggregates at a very low conversion, and the primary aggregates of the PVC chains aggregate to form primary particles, which further aggregate to form grains. The primary particles and grains grow by the capture of newly formed PVC chains and their primary aggregates and by polymerization occurring inside the aggregates. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 954–958, 2003
Effects of NCO/OH ratio and catalyst concentration on structure, thermal stability, and crosslink density of poly(urethane‐isocyanurate)
Authors: Semsarzadeh M. A. , Navarchian A. H. 
Published: September 2003

AbstractPoly(urethane‐isocyanurate)s were synthesized by reacting toluene diisocyanate and poly(propylene glycol) with various stochiometric ratios (1–3) in the presence of different concentrations of dibutyltin dilaurate (DBTDL) and ferric acetylacetonate (FeAA). The influence of the NCO/OH ratio and the catalyst type and concentration on the extent of urethane and isocyanurate formation were examined using Fourier transform IR spectroscopy. No trimer formation was observed in the presence of the FeAA catalyst. The percentage of the trimer group and the trimer/urethane content were found to be increased with increasing the stochiometric ratio or DBTDL concentration. The thermal decomposition of the copolyurethanes in an inert atmosphere was studied by means of thermogravimetry (TG). The TG curves showed three decomposition steps with the principal degradation temperature at about 355–385°C. The effects of the NCO/OH ratio, catalyst type and concentration, and heating rate on the thermal stability of the copolyurethanes were determined. The Flynn–Wall, Kissinger, and Ozawa methods were used to calculate the activation energies of thermal decomposition. The swelling behavior of solid copolyurethanes in toluene showed that, as the DBTDL concentration and/or NCO/OH ratio increased, the swelling ratio and average molecular weight between crosslinks were decreased whereas the crosslink density was increased. The sol fraction of solid copolyurethanes was examined and found to be reduced when the percentage of DBTDL or the stochiometric ratio was raised. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 963–972, 2003
Pressure‐dependent glass‐transition temperatures of poly(methyl methacrylate)/poly(styrene‐co‐acrylonitrile) blends
Authors: Wen Gangyao , An Lijia 
Published: September 2003

AbstractThe pressure‐dependent glass‐transition temperatures (Tg's) of poly(methyl methacrylate) (PMMA)/poly(styrene‐co‐acrylonitrile) (SAN) blends were determined by pressure–volume–temperature (PVT) dilatometry via an isobaric cooling procedure. The Gordon–Taylor and Fox equations were used to evaluate the relationships between the Tg's and compositions of the PMMA/SAN system at different pressures. The relationships were well fitted by the Gordon–Taylor equation, and the experimental data for Tg positively deviated from the values calculated with the Fox equation. Also, the influence of the cooling rate (during the PVT measurements) on Tg was examined. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 959–962, 2003
Hydrogenation of nitrile–butadiene rubber latex to form thermoplastic elastomer with excellent thermooxidation resistance
Authors: Xie Hong‐Quan , Li Xiao‐Dong , Guo Jun‐Shi 
Published: September 2003

AbstractHydrogenation of nitrile–butadiene rubber latex was carried out using hydrazine and hydrogen peroxide, with copper sulfate as catalyst and without pressurized hydrogen and organic solvent. A special inhibitor was used during hydrogenation to reduce gel formation. Various hydrogenation conditions were studied. The gel content of the hydrogenation product can be reduced to ∼15%, and hydrogenation degree can reach ∼87%. The hydrogenated product was characterized by infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, and differential scanning calorimetry. The hydrogenated product behaved as an oil‐resistant thermoplastic elastomer with excellent thermooxidation resistance, due to the absence of most double bonds and the presence of crystalline domains of polyethylene segments formed by hydrogenation of polybutadiene segments and nitrile groups. The higher the hydrogenation degree, the higher were the mechanical properties and thermooxidation resistance of the product. The product with a hydrogenation degree of 87% withstood thermooxidation quite well at 150°C for 65 h, maintaining ∼98% of its tensile strength and 96% of its ultimate elongation. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1026–1031, 2003
A novel catalyst for the glycolysis of poly(ethylene terephthalate)
Authors: Troev K. , Grancharov G. , Tsevi R. , Gitsov I. 
Published: September 2003

AbstractPoly(ethylene terephthalate) waste materials were depolymerized by ethylene glycol (EG), diethylene glycol (DEG), and propylene glycol (PG) in the presence of a novel catalytic system: titanium (IV)‐phosphate. The new catalyst was synthesized through a reaction of TiCl4 with triethyl phosphate (C2H5O)3P(O). It was found that the depolymerization of poly(ethylene terephthalate) fiber proceeds faster in the presence of titanium (IV)‐phosphate compared with compounds traditionally used in this process like Zn(OOCCH3)2. The oligomer distribution in the glycolysis products was studied by size‐exclusion chromatography. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1148–1152, 2003
Synthesis and characterization of novel copolymers of carboxyphenylmaleimide and methacrylates with trimethylsiloxy groups for deep‐UV photoresists
Authors: Chiang Wen‐Yen , Lee Ming‐Lo 
Published: September 2003

AbstractN‐(4‐Carboxyphenyl) maleimide (CPMI), with high thermal stability structure, was synthesized from maleic anhydride and p‐aminobenzoic acid. Free‐radical copolymerization of CPMI and three comonomers (M‐1, M‐2, and M‐3) bearing a trimethylsiloxy group was performed at 60°C in the presence of azobisisobutyronitrile as an initiator in 1,4‐dioxane. Two different processes were adopted to prepare resists using these copolymers. The first one was to mix the dissolution inhibitor, o‐nitrobenzyl cholate, into the new copolymers. The second approach was to react the new copolymers with o‐nitrobenzyl bromide using 1,8‐diazabicyclo[5.4.0]undeca‐7‐ene in dimethylformamide. The cyclic maleimide group was responsible for the high thermal stability. After irradiation by a deep‐ultraviolet light and development with aqueous Na2CO3 (0.01 wt %), the developed patterns showed positive images and exhibited good adhesion to the silicon wafer without the use of any adhesion promoter. The resolution of the resists was at least 0.8 μm and the most effective factor for improving the etching selectivity was to increase the silicon content. We found that suitable amounts of silicon (about 14%) can drastically lower the etching rates of organic polymers; that is, an oxygen–plasma etching rate of 1 : 7.92 compared with hard‐baked HPR‐204. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1032–1037, 2003