bluuebunny/crossref_metadata_2025 huggingface dataset:
Immunopathology of secondary‐progressive multiple sclerosis
Authors: Prineas John W. , Kwon Eunice E. , Cho Eun‐Sook , Sharer Leroy R. , Barnett Michael H. , Oleszak Emilia L. , Hoffman Brad , Morgan Bryan P.
Published: August 2002

Twenty‐three plaques obtained at early autopsy from 2 patients with secondary‐progressive multiple sclerosis were examined immunohistochemically for microglia/macrophages, and for immunoglobulins and components of activated complement. Most of the lesions examined in both cases exhibited evidence of low‐grade active demyelination of an unusual type (frustrated phagocytosis) in periplaque white matter. This included linear groups of microglia engaging short segments of disrupted myelin that were associated with deposits of C3d, an opsonin formed during complement activation. Similar microglia/C3d/myelin profiles were not observed in newly forming lesions in cases of acute multiple sclerosis or other central white matter diseases. As C3d coupling is known to increase the immunogenicity of potential antigens enormously, present findings point to disrupted myelin close to plaques as a possible source of the putative multiple sclerosis antigen. Ongoing myelin destruction found in a high proportion of old, established plaques was surprising. It suggests that slowly expanding lesions (progressive plaques), in which ongoing myelin breakdown occurs in the absence of florid perivascular cell cuffing or other histological signs of acute inflammation, contribute to disease progression in cases of secondary‐progressive multiple sclerosis.
Estimation of arsenobetaine in the NIES candidate certified reference material no. 18 human urine by HPLC–ICP‐MS using different chromatographic conditions
Authors: Chatterjee Amit , Shibata Yasuyuki , Yoshinaga Jun , Morita Masatoshi
Published: August 2002

HPLC–ICP‐MS, employing a silica‐based LC‐SCX cation‐exchange column, styrene–divinylbenzene copolymer‐based PRP‐X100 anion exchange column, an ODS reversed‐phase and gel‐permeation (polyvinyl alcohol‐based resin) GS‐220 columns, has been used for the separation, identification, and quantification of arsenic compounds, particularly arsenobetaine (AB), present in NIES candidate certified reference material (CRM) no. 18 human urine. AB is the predominant arsenic species, followed by dimethylarsinic acid, methylarsonic acid and arsenic acid. The peak of each arsenic compound has been validated by spiking of the authentic standard solution to the urine sample and by using the above chromatographic systems. The high concentration of chloride that co‐elutes with the arsenic acid from the LC‐SCX and with the AB from the GS‐220 columns has interfered with the ion signals of arsenic acid and AB, by forming the molecular ions 40Ar35Cl+ and 38Ar37Cl+ in the plasma. Thus, the concentration of AB has been carefully estimated on the ­GS‐220 after extracting the chloride interference (37Cl:35Cl = 1:3.1271) by measuring the 40Ar37Cl+. The peak of AB overlapped with the peak of arsenous acid and hindered the estimation of AB on the ODS and PRP‐X100 columns. But AB has been baseline separated from the other arsenic compounds and also from the chloride with 20 mM pyridine at pH 2.60 on the LC‐SCX. So, the LC‐SCX column has been proven and used for the determination of AB in NIES candidate CRM no. 18 human urine. The concentrations of AB, estimated by the standard addition method and found using the LC‐SCX and GS‐220 columns, are 70.5 ± 5.5 (n = 20) and 71.5 ± 4 µgl−1 (n = 9). The concentration of AB thus found has been applied as the baseline value for the collaborative study to certify the AB in the NIES candidate CRM no. 18 human urine. Copyright © 2001 John Wiley & Sons, Ltd.
Determination of arsenic species in oyster tissue by microwave‐assisted extraction and liquid chromatography–atomic fluorescence detection
Authors: Vilanó Marc , Rubio Roser
Published: August 2002

A method for the determination of arsenic species in oyster tissue is established. The extraction of arsenic species is carried out by using low‐power microwaves. Quantitative extraction is obtained at a power of 40 W, and in 5 min, using the extracting agent methanol/water (1 + 1). The measurements are carried out using liquid chromatography–UV irradiation–hydride generation–atomic fluorescence detection (LC–UV–HG–AFS). Three arsenic species were detected in oyster tissue: arsenobetaine (AsBet) (87%), a probable arsenosugar (AsS) (4.9%), and dimethylarsinate (DMA) (4.7%). No influence of the clean‐up, the microwave field or the IR drying system on the stability of the arsenic compounds was observed. The extracts can be kept stable up to 3 days at 4 °C. The performance of the method is proved on fresh samples, as they are usually analysed in routine laboratories. Copyright © 2001 John Wiley & Sons, Ltd.
Preparation and pyrolysis of a blended precursor possessing TiN and AlN bonds
Authors: Cheng Fei , Sugahara Yoshiyuki , Kuroda Kazuyuki
Published: August 2002

The preparation and pyrolysis of a blended precursor possessing TiN and AlN bonds were investigated. The precursor was prepared by mixing (HAlN
iPr)
n, whose main compo‐nent was a cage‐type compound, and an aminolysis product of Ti(NMe2)4 with MeHNCH2CH2NHMe with a molar ratio of Ti:Al = 2:1. IR analysis of the products pyrolyzed under NH3–N2 indicated that a large proportion of the organic groups in the precursor were removed by an amine‐exchange reaction during the pyrolysis under NH3; thus, the products contained only a small amount of carbon. On the contrary, a considerable amount of carbon was present in the product pyrolyzed under Ar. Composites consisting of AlN and an NaCl‐type compound were obtained after pyrolysis of the precursor under both NH3–N2 and Ar. The composition of the NaCl‐type compound depended significantly on the pyrolysis atmosphere. Copyright © 2001 John Wiley & Sons, Ltd.
Continuous ultrasonic devulcanization of NR/SBR blends
Authors: Hong Chang Kook , Isayev A. I.
Published: August 2002

The ultrasonic devulcanization of sulfur‐cured natural rubber (NR)/styrene–butadiene rubber (SBR) blends was studied with the goal of understanding the devulcanization of rubber vulcanizates in which two networks of different natures were present. Also, similarities and differences in the devulcanization behaviors of NR, SBR, and their blends were found. During the devulcanization of cured NR/SBR blends, we observed that, as for NR, the ultrasonic power consumption for 75/25 and 50/50 (w/w) NR/SBR blends passed through a maximum at 7.5 μm. For SBR and 25/75 (w/w) NR/SBR blends, the power consumption increased with increasing ultrasonic amplitude. The higher power consumption led to a higher degree of devulcanization. The crosslink densities of the devulcanized 25/75, 50/50, and 75/25 (w/w) NR/SBR blends were lower than those of the devulcanized NR and SBR, possibly because of the reduced degree of unsaturation. The tensile properties of the revulcanized blends were lower than those of the virgin vulcanized blends. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 160–168, 2002
Preparation, characterization, and properties of unbleached, bleached, and grafted pulps from JRC‐321 variety jute fiber
Authors: Sahoo P. K. , Swain S. K. , Debsarkar N. L.
Published: August 2002

Graft copolymerization onto jute pulps opened the door to new concepts in pulp and paper research. Jute pulp from the JRC‐321 variety white jute fiber was prepared by the alkaline sulfite pulping process. The pulp obtained was bleached by the chlorination, extraction, and hypochlorite sequence technique to remove excess lignin for making bright and good quality paper. Special attention was focused on the graft copolymerization of acrylamide monomer onto the unbleached and bleached pulps by the use of a complex initiating system: Cu(II)/glycine/KHSO5 in aqueous solution. It was found that percentage grafting was high in the case of bleached pulp. The grafted pulps so obtained were characterized by FTIR and their thermal behavior was characterized by TGA. Their mechanical properties such as tensile strength, percentage elongation, and tenacity were measured and compared. The physical properties such as rot‐resistance and water‐retention capacity of the grafted and the ungrafted pulps were determined. The effect of the percentage grafting variation on the above mentioned properties was examined. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1963–1969, 2002
Catalytic reduction of residual styrene monomer in polystyrene
Authors: Kim Yongsin , Harwood H. James , Priddy Duane
Published: August 2002

Styrene monomer has a low taste and odor threshold, and its presence in the polystyrene used in food packaging applications must be as low as possible. Conventional devolatilization technology does not lower styrene contents to desired levels, so special costly devolatilization techniques have to be used. Attempts to employ scavengers for styrene to reduce residual monomer levels have been largely unsuccessful. This article evaluates the possibility that strong acids can be used to induce residual styrene to alkylate styrene units in polystyrene by Friedel–Crafts reactions. The results of studies evaluating this approach indicate its feasibility, but colored products are obtained when sulfonic acids are used and prohibitively high levels of acids must be used to be effective. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1786–1791, 2002
A comparison of tetraethylthiuram and tetramethylthiuram disulfide vulcanization. II. Reactions in rubber
Authors: Gradwell M. H. S. , Grooff D.
Published: August 2002

The reactions of tetraethylthiuram disulfide (TETD) with polyisoprene were investigated under vulcanization conditions. Samples of polyisoprene compounded with various combinations of TETD, sulfur, and ZnO were heated in a differential scanning calorimeter to various degrees of vulcanization. The crosslink density of the compounds was determined by swelling, and the extractable residual curatives and reaction products were analyzed with high‐performance liquid chromatography. TETD caused crosslinking to occur in the absence of added sulfur, as did tetramethylthiuram disulfide (TMTD), both sulfur donors. In the presence of sulfur, the formation of TETD polysulfides occurred immediately before the crosslinking reaction started. The TETD polysulfides were the initial crosslinking agents. The ready reaction between TETD and zinc oxide to form zinc diethyldithiocarbamic acid resulted in considerably higher crosslink densities. This greater reactivity between TETD and zinc oxide, compared with that between TMTD and zinc oxide, did not lead to any noticeable differences in the vulcanizate. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1119–1127, 2002
Synthesis and electroluminescence properties of a novel poly(paraphenylene vinylene)‐based copolymer with tri(ethylene oxide) segments on the backbone
Authors: Wang Haiqiao , Duan Lian , Qiu Yong , Wang Xiaogong , Liu Deshan
Published: August 2002

A novel light‐emitting copolymer [tri(ethylene oxide)–poly(paraphenylene vinylene) (TEO–PPV)] containing alternating rigid, conjugated distyrylbenzene [poly(paraphenylene vinylene) model oligomer] as light‐emitting units and flexible tri(ethylene oxide) as ionic conductive units was synthesized. The polymer was characterized with Fourier transform infrared, 1H‐NMR, ultraviolet–visible spectroscopy, differential scanning calorimetry, and gel permeation chromatography. TEO–PPV has excellent solubility in conventional organic solvents such as tetrahydrofuran, chloroform, benzene, and toluene. The estimated lowest unoccupied molecular orbital, highest occupied molecular orbital, and band gap are 2.35, 5.29, and 2.94 eV, respectively. Single‐layer and double‐layer light‐emitting diodes with indium tin oxide anodes and calcium cathodes were fabricated, and the photoluminescence (PL) and electroluminescence (EL) properties were investigated. The maximum EL emissive peak (475 nm) of the devices is essentially the same as that of PL. Anomalous current–voltage characteristics were observed in both devices. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2195–2200, 2002
Effect of dopant mixture on the conductivity and thermal stability of polyaniline/nomex conductive fabric
Authors: Kim Seong Hun , Seong Jea Hwan , Oh Kyung Wha
Published: August 2002

Electrically conductive polyaniline (PANI)/[poly(m‐phenylene isophthalamide)] Nomex composite fabric was prepared by in situ polymerization of aniline doped by a mixture of hydrochloride (HCl) and various sulfonic acids such as benzenesulfonic acid (BSA), sulfosalicylic acid (SSA), and dodecylbenesulfonic acid (DBSA); their effect on conductivity and physical properties were then investigated. PANI/Nomex composite fabrics doped by a mixture of protonic acids exhibited higher conductivity than those doped by other single dopants such as camphorsulfonic acid (CSA), p‐toluenesulfonic acid (TSA), BSA, SSA, and HCl. The conductivity of PANI/Nomex fabrics especially doped by a mixture of HCl and DBSA was evenly maintained up to 100°C without depression of mechanical properties of Nomex. Their conductivity was also maintained under extension of the composite fabric. In addition, electrical conductivity of PANI/Nomex fabrics was highly increased by ultrasonic treatment, which facilitated better diffusion and adsorption of aniline by cavitation and vibration. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2245–2254, 2002
Morphology structure study of polypropylene hollow fiber membrane made by the blend‐spinning and cold‐stretching method
Authors: Mei Li , Zhang Dasheng , Wang Qingrui
Published: August 2002

This paper proposes one of simplest ways to prepare polypropylene/easy hydrolytic degradation polyester (PP/EHDPET) microporous hollow fibers by blend spinning and cold stretch process. And it details and investigates the structure properties of as‐spun fibers, micropore formation mechanism, and pore structure of the hollow fiber membranes by the scanning electron microscope. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1390–1394, 2002; DOI 10.1002/app.10280
Effects of resin chemistry on redox polymerization of unsaturated polyester resins
Authors: Yang Huan , Lee L. James
Published: August 2002

Unsaturated polyester resins are the most widely used thermoset resins in the composite industry. In this study, three well‐defined unsaturated polyester resins were used. These resins have similar number‐average molecular weights, and they have different numbers of CC bonds per molecule. The reaction kinetics of unsaturated polyester resins was studied using a differential scanning calorimeter (DSC) and a Fourier transform infrared (FTIR) spectrometer. The glass transition temperature of the isothermally cured resin was also measured. Trapped radicals were observed in the cured polyester resin from electron spin resonance (ESR) spectroscopy. Considering the diffusion‐limitation effect, a simple kinetic model was developed to simulate the reaction rate and conversion profiles of polyester vinylene and styrene vinyl groups, as well as the total reaction rate and conversion. Experimental results from DSC and FTIR measurements compare favorably with the model prediction. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 211–227, 2002; DOI 10.1002/app.10317
Synthesis and characterization of emulsion copolymer of N‐cyclohexylmaleimide and methyl methacrylate
Authors: Yang Liting , Sun Donghai , Li Yanfang , Liu Guodong , Gao Jungang
Published: August 2002

Copolymers of N‐cyclohexylmaleimide (ChMI) and methyl methacrylate (MMA) were synthesized by the emulsion semibatch copolymerization method. The effects of the monomer mixture composition on the average molecular weight (Mn and Mw), glass transition temperature (Tg), degradation temperature, mechanical properties, and rheological behavior of the copolymers were investigated. The results show that Mn and Mw have maximum values when the ChMI feed content was about 20% (by wt). The degradation temperature and Tg of the copolymers increase with increasing ChMI moieties in the copolymer. The mechanical properties (tensile strength and impact strength) decrease with an increasing ChMI feed content. All copolymers in the melt show pseudoplastic behavior. The flow index n increases with an increasing ChMI feed content. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1070–1075, 2002; DOI 10.1002/app.10394
Effect of the compatibilization of linear low‐density polyethylene‐g‐acrylic acid on the morphology and mechanical properties of poly(butylene terephthalate)/linear low‐density polyethylene blends
Authors: Yang Jinghui , Shi Dean , Yao Zhanhai , Xin Zhirong , Yin Jinghua
Published: August 2002

A poly(butylene terephthalate) (PBT)/linear low‐density polyethylene (LLDPE) alloy was prepared with a reactive extrusion method. For improved compatibility of the blending system, LLDPE grafted with acrylic acid (LLDPE‐g‐AA) by radiation was adopted in place of plain LLDPE. The toughness and extensibility of the PBT/LLDPE‐g‐AA blends, as characterized by the impact strengths and elongations at break, were much improved in comparison with the toughness and extensibility of the PBT/LLDPE blends at the same compositions. However, there was not much difference in their tensile (or flexural) strengths and moduli. Scanning electron microscopy photographs showed that the domains of PBT/LLDPE‐g‐AA were much smaller and their dispersions were more homogeneous than the domains and dispersions of the PBT/LLDPE blends. Compared with the related values of the PBT/LLDPE blends, the contents and melting temperatures of the usual spherulites of PBT in PBT/LLDPE‐g‐AA decreased. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1059–1066, 2002; DOI 10.1002/app.10399
Chemical synthesis and characterization of some conducting polyaniline derivatives: Investigation of the effect of protonation medium
Authors: Gök Ayşegül , Sari Beki̇r
Published: August 2002

Poly(o‐toluidine) (POT) and poly(2‐chloroaniline) (P2ClAn) emeraldine salts were synthesized chemically by using formic (HCOOH), acetic (CH3COOH), propionic (C2H5COOH), and boric (H3BO3) acids. Ultraviolet‐visible absorption spectra (UV–Vis) analysis results indicated that POT has the better protonation effects than P2ClAn. Among the POTs synthesized using the four different acids, POT(H3BO3) showed the least protonation effect. The conductivities of prepared polymers were measured by a four‐probe technique. The highest conductivities were obtained in POTs synthesized by using formic, acetic, and propionic acids. Magnetic susceptibility measurements of the polymer salts were analyzed by using Gouy scale and it was found that POT(CH3COOH) and POT(C2H5COOH) salts are of bipolaron structure; other polymer salts are of polaron structure. The characterization of the polymers were investigated by Fourier infrared spectroscopy (FTIR), UV–Vis, thermogravimetric analysis, and scanning electron microscopy. It was observed from UV–Vis spectra of the emeraldine salt of POT that wavelengths belonging to π → π* transitions shifted to shorter wavelengths with increasing pKa values of acids. POT and P2ClAn synthesized in four different protonation media decomposed with three‐step and three‐ or two‐step weight loss, respectively. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1993–2000, 2002; DOI 10.1002/app.10487
Free radical copolymerization of tert‐butyl 3‐isopropenylcumylperoxide with styrene and grafting of methyl methacrylate onto the copolymers
Authors: Guo Xingpeng , Li Zhiang , Du Qiangguo , Yang Yuliang , Lin Mingde
Published: August 2002

Copolymers of tert‐butyl‐3‐isopropenylcumylperoxide (D‐120) with styrene (St) were prepared in bulk by using benzoyl peroxide as initiator at 80°C. The compositions of the copolymers were determined by 1H‐NMR analysis. The reactivity ratios of D‐120 and St were calculated by methods of Kelen–TüdÖs (K‐T), Fineman–Ross (F‐R), and Yezrielev‐Brokhina‐Roskin (YBR), respectively. Graft copolymers were obtained by grafting of methyl methacrylate (MMA) onto the copolymers during decomposition of peroxy bonds suspended in the backbone. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2318–2326, 2002
Visible light‐induced polymerization of monooxiranes and 1,5,7,11‐tetraoxaspiro[5.5]undecanes
Authors: Pinzino Charles S. , Chappelow Cecil C. , Holder Andrew J. , Morrill Jason A. , Harris C. David , Power Martin D. , Eick J. David
Published: August 2002

The visible‐light photohomopolymerization reactivities of several monofunctional oxiranes were evaluated using photodifferential scanning calorimetry (PDSC). Two oxiranes, styrene oxide and 1‐methoxy‐2‐methyl propylene oxide, were selected for copolymerization reactivity studies with five substituted 1,5,7,11‐ tetraoxaspiro[5.5]undecanes (TOSUs). Reaction mixtures contained a diaryliodonium salt photoacid initiator and a β‐diketone photosensitizer. Experimentally determined reaction enthalpies were compared with calculated theoretical values to assess percent conversion. Relative reactivities were evaluated by comparing induction and exotherm peak maximum times. Results of AM1 semiempirical quantum mechanical calculations of reaction energetics were compared to experimental findings for selected polymerizations. IR spectral changes were consistent with oxirane and TOSU ring opening. The effect of temperature on the photopolymerization reactivity characteristics of glycidyl methylphenyl ether alone and in combination with unsubstituted TOSU was also studied. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 159–168, 2002
Microporous membranes of polyoxymethylene from a melt‐extrusion process: (II) Effects of thermal annealing and stretching on porosity
Authors: Johnson Matthew B. , Wilkes Garth L.
Published: August 2002

A two‐part study utilizing polyoxymethylene (POM) was undertaken to investigate a three‐stage process (melt‐extrusion/annealing/uniaxial‐stretching) utilized to produce microporous films. In this report, the thermal annealing (second stage) and subsequent uniaxial‐stretching (third stage) results of selected POM films from two commercial resins, labeled D & F, are discussed. Specifically, the annealing and uniaxial stretching effects on film morphology, orientation, and other pertinent film properties are addressed. Additionally, sequential analysis was performed regarding the influence each stage had on the resulting microporosity. It was found that the melt‐extruded precursor morphology and orientation, as a consequence of the first stage extrusion parameters and resin characteristics, are crucial to controlling the membrane permeability. The annealing parameters were also deemed critical, where a temperature of 145°C applied for 20 min under no tension was the optimum annealing condition for producing a highly microporous film upon stretching. For the conditions studied, the stretching parameters that were found to be optimum for producing the desired characteristics in the final film were a cold temperature of 50°C and hot stretch temperature of 100°C. The optimum extension levels were concluded to be 90% for both the cold and hot stretch steps, and thus a total overall extension level of 180%. However, these results were only with respect to resin F films. Because the resin D melt‐extruded precursors possessed twisted lamellar morphologies and relatively low crystal orientation, their samples could not be produced into microporous films. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1762–1780, 2002; DOI 10.1002/app.10587
Polyurethane elastomers made from linear polybutadiene diols
Authors: Špírková Milena
Published: August 2002

Segmented polyurethane elastomers made from linear polybutadiene diols terminated with primary (Krasol LBH‐P) or secondary (Krasol LBH) hydroxy groups, alicyclic diisocyanate, and aliphatic chain extender were prepared and tested. The system was chemically crosslinked either through isocyanurate, that is, hexahydro‐1,3,5‐triazine‐2,4,6‐trione groups (formed by catalyzed cyclotrimerization of isocyanate groups), or by low molecular weight triols. The best balance of stress‐strain properties and reasonable thermal stability was obtained for systems in which only a small amount of chemical crosslinks was present in predominantly physically crosslinked networks. The influence of the type of polymer diol, chemical crosslinking, diisocyanate, and technique of preparation on mechanical, thermal, and swelling properties is discussed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 84–91, 2002
Synthesis and study of a new polyorganophosphazene
Authors: Li Feng , Wang Jingyuan , Xie Tengfeng , Wang Dejun , Tang Jun , Tang Xinyi
Published: August 2002

In this study, a new polyorganophosphazene with pendant carbazolyl groups was synthesized, and its structure was characterized by IR, 1H‐NMR, and 31P‐NMR spectroscopy. To understand its carrier photogeneration and transport property, we also studied fluorescence spectra and photovoltage spectra. Fluorescence spectra show that the polymer possesses properties dissimilar to those of PVK. There are only two emission peaks at ≈ 360 nm in its spectra, which coincides with that of the monomer model compound, 9‐ethylcarbazole. This may be because of the influence of the spacer. The results of SPS shows that band–band transition mainly comes from electron π–π* transition, and the polymer is a p‐type semiconductor. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1446–1451, 2001
Polymer mediated growth and morphology in MNA/PMMA guest/host microdispersed composites
Authors: Saujanya C. , Pathak G. , Radhakrishnan S.
Published: August 2002

The structure and morphology in the meta‐nitroaniline (MNA) dispersed poly(methyl methacrylate) (PMMA) guest/host system was investigated with respect to composition and different techniques of crystallization. Large changes in the intensities of various X‐ray diffraction peaks were observed for both solution grown (SC) and melt crystallized (MC) MNA/PMMA composite films. However, in the former case, the peak corresponding to (060) reflection had maximum intensity, while in the latter, the peak corresponding to (112) reflection was most prominent. At low concentrations, the films appeared to be amorphous and transparent, but electron diffraction studies revealed small ordered domains. Both solution and melt grown MNA/PMMA films contained two types of crystallites having different structures: one having the original orthorhombic structure (a = 6.51 Å, b = 19.35 Å, c = 5.07 Å) of bulk MNA, while the other crystallized in new monoclinic phase with a = 13.0 Å, b = 19.35 Å, c = 10.15 Å, and β = 64°. The presence of the new structure that formed could be due to a formation of complex between PMMA and MNA. This complex formation and new structure was further confirmed by differential scanning calorimeter (DSC) and infrared analysis (IR). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1547–1557, 2001
Tensile properties of elastomeric polyolefin thin films: The path to failure
Authors: Eckersley Sarah T. , Chaput A. Bruce
Published: August 2002

The tensile failure of thin films prepared from polyolefin elastomer dispersions was studied. The elastomer dispersions were composed of copolymers of ethylene and 1‐octene, dispersed in water at solids concentrations of approximately 50%. The density of the polyolefin resins ranged from 0.855 to 0.885 g cm−3. The melt index of the resins ranged between 0.5 and 5.0 g 10 min−1. As expected, the tensile strength of neat polyolefin films was found to be a strong function of the density and a weak function of the melt index. Dispersion blends were prepared from neat polyolefin dispersions. The film tensile properties were measured as a function of the blend ratio and the particle‐size ratio. The blend ratio was found to be the dominant factor. It was found that blending the dispersions had an antagonistic effect on the tensile properties. The ultimate tensile strength of the blend film was lower than expected from the arithmetic mean behavior (based on the weight fraction) of the two constituent resins. A similar result was observed for the ultimate elongation, that is, blending of the two elastomers gave inferior behavior. The relationship between the experimental tensile properties and the blend ratio fit a quadratic function. A Monte Carlo simulation was used to model film failure in two dimensions. The two particle types were assumed to pack randomly and failure was forced to occur by the lowest‐energy path. The simulated ultimate tensile strength was also found to be a quadratic function of the blend ratio, confirming the suitability of the model. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2545–2557, 2001
Solvent effects on the miscibility of poly(methyl methacrylate)/poly(bisphenol a carbonate) blends
Authors: Hsu Wen‐Ping
Published: August 2002

Blends of atactic or syndiotactic poly(methyl methacrylate) (designated as aPMMA or sPMMA) and poly(bisphenol A carbonate) (PC) were prepared from solution casting. Tetrahydrofuran (THF) and chloroform were used as solvent. Experimental results indicated that the as‐cast blends from THF were quite different from the chloroform‐cast ones. After film preparation, THF‐cast blends did not show any visible phase separation. However, chloroform‐cast blends formed a phase‐separated structure. The as‐cast PC from either solvent was not completely amorphous, and had a melting point at 239–242°C, indicating a certain degree of crystallinity. In contrast, the quenched samples of aPMMA/PC blends prepared from the two solvents behaved virtually the same. They both showed aPMMA dissolves better in PC, but PC solubility in aPMMA is very little. Using sPMMA instead of aPMMA to blend with PC, different results were obtained. The quenched sPMMA/PC blends cast from THF showed only one Tg. However, immiscibility (i.e., two Tgs) was found in the same blend system when cast from chloroform. THF was believed to cause the observation of single Tg due to the following kinetic reason. sPMMA and PC were still trapped together even after THF removal in a homogeneous, but nonequilibrium state below the glass transition. Therefore, the quenched sPMMA/PC blends were not truly thermodynamically miscible. From the results of aPMMA or sPMMA with PC, increasing syndiotacticity seemed to improve the miscibility between PMMA and PC. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2842–2850, 2001
Local polydispersity detection in size exclusion chromatography: Method assessment
Authors: Balke Stephen T. , Mourey Thomas H.
Published: August 2002

Local polydispersity is the term describing the variety of molecules present at the same retention volume in size exclusion chromatography (SEC) analysis. In the analysis of a linear homopolymer, local polydispersity is generally attributed to the effect of axial dispersion: it can cause molecular size variety (i.e., imperfect resolution) at each retention volume and thus local polydispersity in the molecular weight. In the analysis of polymer blends (copolymers and branched polymers), it is possible to have local polydispersity, even when the resolution is perfect, because molecules of different compositions (or degrees of branching) can have the same molecular size in solution. Conventional SEC interpretation assumes no local polydispersity if the axial dispersion effects are negligible. Three methods are currently available for detecting local polydispersity by using a combination of differential refractive index, light scattering, and viscometer detectors: the chromatogram comparison method, the conventional calibration curve comparison method, and the universal calibration comparison method. Here we experimentally assess these three methods using polymer blends and emphasize the chromatogram comparison method. All three are shown to be useful for assessing triple detector systems, but they are capable of detecting local polydispersity due to molecular heterogeneity only for very large differences in specific refractive index increments in the blend components. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 370–383, 2001
Natural rubber‐g‐methyl methacrylate/poly(methyl methacrylate) blends
Authors: Thiraphattaraphun L. , Kiatkamjornwong S. , Prasassarakich P. , Damronglerd S.
Published: August 2002

The grafting of the methyl methacrylate (MMA) monomer onto natural rubber using potassium persulfate as an initiator was carried out by emulsion polymerization. The rubber macroradicals reacted with MMA to form graft copolymers. The morphology of grafted natural rubber (GNR) was determined by transmission electron microscopy and it was confirmed that the graft copolymerization was a surface‐controlled process. The effects of the initiator concentration, reaction temperature, monomer concentration, and reaction time on the monomer conversion and grafting efficiency were investigated. The grafting efficiency of the GNR was determined by a solvent‐extraction technique. The natural rubber‐g‐methyl methacrylate/poly(methyl methacrylate) (NR‐g‐MMA/PMMA) blends were prepared by a melt‐mixing system. The mechanical properties and the fracture behavior of GNR/PMMA blends were evaluated as a function of the graft copolymer composition and the blend ratio. The tensile strength, tear strength, and hardness increased with an increase in PMMA content. The tensile fracture surface examined by scanning electron microscopy disclosed that the graft copolymer acted as an interfacial agent and gave a good adhesion between the two phases of the compatibilized blend. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 428–439, 2001
Peroxide modification of poly(butylene adipate‐co‐succinate)
Authors: Kim D. J. , Kang H. J. , Seo K. H.
Published: August 2002

We attempted to introduce crosslinking into poly(butylene adipate‐co‐succinate) (PBAS) to improve the properties, such as the mechanical strength and elasticity, by a simple addition of dicumyl peroxide (DCP). Prior to curing, the thermal stability of PBAS was investigated. Above 170°C PBAS was severely degraded, and the degradation could not be successfully stabilized by an antioxidant. The PBAS was effectively crosslinked by DCP, and the gel fraction increased as the DCP content increased. A major structure of the crosslinked PBAS was an ester and aliphatic group. The tensile strength and elongation of PBAS were improved with an increasing content of DCP, but there was little affect on the tear strength. The biodegradability of crosslinked PBAS was not seriously deteriorated. A higher degree of crosslinking gave a lower heat of crystallization and heat of fusion. However, the melt crystallization temperatures of the crosslinked PBAS were higher than that of PBAS. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 637–645, 2001
Durable press finish of cotton/polyester fabrics with 1,2,3,4‐butanetetracarboxylic acid and sodium propionate
Authors: Lee Eui So , Kim Hong Je
Published: August 2002

Sodium hypophosphite (SHP) is widely used as an effective catalyst for the esterification reaction of cellulose with 1,2,3,4‐butanetetracarboxylic acid (BTCA). However, catalysts containing phosphorus cause significant shade changes in dyed fabrics because of their reductive nature, and the effluents containing phosphorus cause eutrophication in rivers and lakes. Hence, their commercial application as catalysts in textile processing is limited. In this study sodium propionate and its catalytic activities as a nonphosphorous catalyst were investigated. The evidence for esterification and crosslinking of cellulose with BTCA in the presence of sodium propionate was shown by an improved wrinkle recovery angle and durable press rating of treated fabrics. The presence of ester groups in the treated fabrics was confirmed by FTIR analysis. The performance of sodium propionate as a catalyst for BTCA was comparable to that of SHP. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 654–661, 2001
Encapsulation of aluminum flakes by dispersion polymerization of styrene in a nonaqueous system with reactive surfactants
Authors: Kimura Isao , Taguchi Yoshinari , Yoshii Haruyuki , Tanaka Masato
Published: August 2002

Dispersion polymerization of styrene in ethanol was carried out to encapsulate aluminum flakes. The effects of three reactive surfactants, two anionic and one nonionic, were investigated. It was confirmed prior to encapsulation that these surfactants did not polymerize by themselves but did promote polymerization of styrene. The capsules obtained were characterized with respect to the morphology and mean size. The encapsulating efficiency of the polymer of the wall material, the wall thickness, and the molecular weight distribution were measured. The effects of the concentrations of styrene monomer and reactive surfactants on these characteristics were determined and discussed. Aluminum flakes were coagulated to form secondary particles and they were covered with fine polymer particles, which were precipitated in the continuous phase. To improve encapsulation, the auxiliary addition of nonionic surfactant was attempted. By controlling those concentrations, capsules covered with polymer layer were prepared. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 675–683, 2001
Rubber modeling using uniaxial test data
Authors: Bradley G. L. , Chang P.C. , Mckenna G. B.
Published: August 2002

Accurate modeling of large rubber deformations is now possible with finite‐element codes. Many of these codes have certain strain‐energy functions built‐in, but it can be difficult to get the relevant material parameters and the behavior of the different built‐in functions have not been seriously evaluated. In this article, we show the benefits of assuming a Valanis–Landel (VL) form for the strain‐energy function and demonstrate how this function can be used to enlarge the data set available to fit a polynomial expansion of the strain‐energy function. Specifically, we show that in the ABAQUS finite‐element code the Ogden strain‐energy density function, which is a special form of the VL function, can be used to provide a planar stress–strain data set even though the underlying data used to determine the constants in the strain‐energy function include only uniaxial data. Importantly, the polynomial strain‐energy density function, when fit to the uniaxial data set alone, does not give the same planar stress–strain behavior as that predicted from the VL or Ogden models. However, the polynomial form does give the same planar response when the VL‐generated planar data are added to the uniaxial data set and fit with the polynomial strain‐energy function. This shows how the VL function can provide a reasonable means of estimating the three‐dimensional strain‐energy density function when only uniaxial data are available. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 837–848, 2001
Synthesis and characterization of poly(butylene terephthalate‐co‐triethylene terephthalate) copolyesters
Authors: Lotti Nadia , Finelli Lara , Fiorini Maurizio , Righetti Maria Cristina , Munari Andrea
Published: August 2002

Poly(butylene terephthalate‐co‐triethylene terephthalate) random copolymers of various compositions and molecular weights were synthesized in bulk and characterized in terms of their chemical structure and thermal and rheological properties. At room temperature all the copolymers were partially crystalline and showed good thermal stability. The main effect of copolymerization was a decrease in the melting and glass‐transition temperatures with respect to the poly(butylene tere‐ phthalate) homopolymer. The fusion temperatures were well correlated with the composition by the Baur equation and the equilibrium melting temperature and the heat of fusion extrapolated values for poly(butylene terephthalate) were in good agreement with those reported elsewhere. Triethylene terephthalate units were found to influence the rheological behavior in the melt, the viscosity being significantly higher than that of the poly(butylene terephthalate‐co‐diethylene terephthalate) copolymers investigated previously. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 981–990, 2001
Modification of poly(butylene succinate) with peroxide: Crosslinking, physical and thermal properties, and biodegradation
Authors: Kim D. J. , Kim W. S. , Lee D. H. , Min K. E. , Park L. S. , Kang I. K. , Jeon I. R. , Seo K. H.
Published: August 2002

Prior to curing, we evaluated thermal stability of poly(butylene succinate) (PBS). Above 170°C, PBS was severely degraded and the degradation could not be successfully stabilized by an antioxidant. PBS was crosslinked effectively by DCP at 150°C, and the gel fraction was increased as DCP content increased. The major structure of crosslinked PBS is supposed to consist of an ester and an aliphatic group. The tensile strength and elongation of PBS were improved with increasing content of DCP, but tear strength was only slightly affected. The higher the crosslinking, the lower the heat of crystallization (ΔHc) and heat of fusion (ΔHf). However, the melt crystallization temperature (Tc) of crosslinked PBS was higher than that of PBS. The viscosity of crosslinked PBS increased and exhibited rubbery behavior as the content of curing agent increased. The biodegradability of crosslinked PBS did not seriously deteriorate. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1115–1124, 2001
pH‐reversible hydrogels. IV. Swelling behavior of the 2‐hydroxyethyl methacrylate‐co‐acrylic acid‐co‐sodium acrylate copolymeric hydrogels
Authors: Lee Wen‐Fu , Lin Yu‐Hung
Published: August 2002

A series of 2‐hydroxyethyl methacrylate (HEMA) and sodium acrylate (SA50) copolymeric gels were prepared from HEMA and the anionic monomer SA50 with various molar ratios. The influence of SA50 on the copolymeric gels on their swelling behavior in deionized water at different temperatures and various pH buffer solutions was investigated. Results indicated that the poly(2‐hydroxyethyl methacrylate) (PHEMA) hydrogels exhibited an overshooting phenomenon in their dynamic swelling behavior. The maximum overshooting value decreased with increasing of the temperature. The same results were also found in the HEMA/SA50 copolymeric gels with a lower SA50 content. On the contrary, the overshooting phenomenon for HEMA/SA50 copolymeric gels with a higher content of SA50 was exhibited only under higher temperature (over 35°C). These copolymer gels were used to assess drug release and drug delivery in this article. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1360–1371, 2001
A study of one‐bath alkali–amine hydrolysis and silk‐fibroin finishing of polyester microfiber crepe fabric
Authors: Wei Zhaohui , Gu Zhenya
Published: August 2002

In this study, the synergistic aminolysis (sodium hydroxide and ethylene diamine in one bath) mechanism of polyethylene terephthalate (PET) microfiber crepe fabric was preliminarily investigated. The results showed that not only active groups (i.e., NHR, COOH, and OH) but also considerable cracks and craters were introduced onto PET fibers, which provided locations for a subsequent crosslinking reaction and mechanical attachment and so facilitated the silk‐fibroin finishing. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1467–1473, 2001
Unsaturated polyester resin modified with poly(organosiloxanes). I. Preparation, dynamic mechanical properties, and impact resistance
Authors: Rosa Valéria M. , Felisberti Maria Isabel
Published: August 2002

Unsaturated polyester resins (UP) display a wide range of applications depending on the proper choice of raw materials and cure conditions. However, some applications are limited to their low‐impact resistance, which can be enhanced by the incorporation of modifiers that increase the flexibility of the network. This work aims to incorporate flexible poly(organosiloxane) segments in the UP network as a graft copolymer, as a way of minimizing the low adhesion between the resin and the modifier and enhance its flexibility. Because polyester and poly(organosiloxanes) are immiscible mixtures, the grafting copolymerization during the cure can promote compatibilization between both polymers. Hence, glycidyl methacrylate (GMA) is added to the resin network by radical reaction, as well as 1,3‐aminopropyltriethoxysilane (APTS), amino groups of which react with GMA. The addition of a siloxane (1,1,3,3‐tetramethyl‐1,3‐diethoxydisiloxane) allows the poly(organosiloxane) network to grow and the addition of water guarantees the hydrolysis and polycondensation during the cure. In this way it is possible to increase its flexibility. The grafting copolymerization is evaluated by dynamic mechanical analysis and the impact resistance of pure and modified polyester resins is evaluated by the Izod test. The grafting of a flexible segment in the UP chains enhances the impact resistance of the polyester resin at low‐modifier concentration. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3272–3279, 2001
A comparative study of polystyrene decomposition in supercritical water and air environments using diamond anvil cell
Authors: Fang Zhen , Koziński Janusz A.
Published: August 2002

Polystyrene (PS) decomposition in supercritical water (SCW) and in air was studied with the diamond anvil cell (DAC) technique coupled with microscopy and FTIR. Apparent concentrations were calculated by using digital imaging analysis. When PS + water systems (11.8–22.6 wt % PS) were rapidly heated at a rate of 2.3°C/s, the PS particle melted at 279.8–320.2°C. After formation of a globule at 409.3–452.5°C, the globule started to dissolve in color to yellow at 496.1°C. At 570.3°C and 742.5 MPa, solubility reached the maximum of 91.5 wt % (11.8 wt % PS). The soluble material was a styrenelike liquid, which was identified by IR after cooling. In isothermal runs at 400 and 450°C, two heterogeneous liquid phases consisting of water and decomposed PS were found. Styrenelike liquid products were identified after the reactions. PS decomposition stages in air consisted of melting, gas generation, liquid ring configuration, and finally yellow volatile products formation at 583.2°C. The results show conclusively that PS can be dissolved in SCW above 496.1°C and homogenous reaction is likely to occur above 570.3°C. Reactions in SCW at 400 and 450°C take place in heterogeneous liquid phases, while in the PS + air system, a formed liquid ring undergoes depolymerization. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3565–3577, 2001
Progress of synthesis and application of trans‐1,4‐polyisoprene
Authors: Song Jing‐She , Huang Bao‐Chen , Yu Ding‐Sheng
Published: August 2002

A new technology to synthesize trans‐1,4‐polyisoprene (TPI) with bulk precipitation polymerization in the presence of a supported Ti catalysts was introduced. The termination of polymerization, stabilization of the polymer, and the adjustment of the molecular weight of TPI and its quality index are discussed. The blending and covulcanization of TPI with natural rubber (NR), styrene butadiene rubber (SBR), and butadiene rubber (BR) were studied. The blending compounds had outstanding dynamic mechanical properties, especially the rolling resistance, heat buildup, and wet skid resistance. Tread and sidewall compounds that contained TPI had a higher modulus, longer fatigue life, better abrasion resistance, lower rolling resistance, and lower buildup, which indicates that TPI is suitable for high‐performance tire. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 81–89, 2001
Stress relaxation and inverse stress relaxation in silk fibers
Authors: Kothari V. K. , Rajkhowa R. , Gupta V. B.
Published: August 2002

Stress‐relaxation experiments on four varieties of Indian silk fiber show that stress relaxation is significantly greater in non‐Mulberry silks than in the Mulberry silk and that the differences among non‐Mulberry silk fibers are relatively small. All the fibers studied also exhibit inverse stress relaxation. It has been shown that the Maxwell–Wiechert model, with two Maxwell elements in parallel, can be used to analyze and explain both the stress‐relaxation and inverse stress‐relaxation behaviors. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1147–1154, 2001