bluuebunny/crossref_metadata_2025_split huggingface dataset:
Scanning electron microscopy study of raw and chemically modified sisal fibers
Authors: Martins Maria Alice , Kiyohara Pedro Kunihiro , Joekes Inés 
Published: October 2004

AbstractMercerization and acetylation treatments were applied to sisal fibers to enhance adhesion with polymer matrices in composites. The structures of the untreated and treated fibers were assessed with scanning electron microscopy. The waste from sisal‐fiber decortication consisted of mechanical, ribbon, and xylem fibers, and their ultimate cells varied considerably in size and shape. After mercerization and acetylation, the fibers and conductive‐vessel surfaces were successfully changed. The parenchyma cells were partially removed, and the fibrils started to split, because of the alkali action. This increased the effective surface area available for contact with the matrix. The mercerized and acetylated fibers were coated with cellulose acetate by the grafting of the acetyl group in the fibrils. The treatment used to remove lignin and hemicellulose caused changes in the fiber surface but did not damage the fiber structure because the fibrils remained joined in a bundle. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2333–2340, 2004
Structure and properties of polyurethane acrylate prepolymers based on hydroxy‐terminated polybutadiene
Authors: Henry Isabelle , Pascault Jean‐Pierre , Taha Mohamed , Vigier Gérard , Flat Jean‐Jacques 
Published: October 2004

AbstractPrecursors of polyurethane acrylate based on hydroxy‐terminated polybutadiene (HTPB) soft segments, different diisocyanate and hydroxy ethyl acrylate (HEA) as hard units, were synthesized in bulk or in solution in methyl methacrylate. During precursor synthesis (in bulk), microphase separation was observed by small‐angle X‐ray scattering (SAXS). Diffusing particles are around 50 Å in size and are assumed to be assembling of hard segments. From these morphologies, it can be deduced that some isocyanate groups were trapped/or buried in hard domains. At a larger scale, around millimeters, hard segment crystallites were observed. Properties such as molar masses, melting and glass‐transition temperatures, and viscosities were correlated with precursor structure and morphology. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 225–233, 2002
Synthesis of graft copolymeric membranes of poly(vinyl alcohol) and polyacrylamide for the pervaporation separation of water/acetic acid mixtures
Authors: Aminabhavi Tejraj M. , Naik Huchchuraya G. 
Published: October 2004

AbstractGraft copolymers of poly(vinyl alcohol) (PVA) with polyacrylamide were prepared and membranes were fabricated at 48 and 93% grafting of acrylamide onto PVA. These membranes were used in the pervaporation separation of water/acetic acid mixtures at 25, 35, and 45°C. The permeation flux, separation selectivity, diffusion coefficient, and permeate concentration were determined. The highest separation selectivity of 23 for neat PVA at 25°C and the lowest value of 2.2 for 93% acrylamide‐grafted PVA membranes were observed. A permeation flux of 1.94 kg m−2 h−1 was found for the 93% grafted membrane at 90 mass % of water in the feed mixture. The diffusion coefficients in a water/acetic acid mixture had an effect on the membrane permselectivity. The Arrhenius equation was used to calculate the activation parameters for permeation as well as for the diffusion of water and of acetic acid. The activation energy values for the permeation flux varied from 97 to 28 kJ/mol. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 244–258, 2002
Miscibility of blends of ethylene‐propylene‐diene terpolymer and polypropylene
Authors: Xiao Han‐Wen , Huang Shi‐Qiang , Jiang Tao , Cheng Shi‐Yuan 
Published: October 2004

AbstractThe miscibility of polymers is not only an important basis for selecting a proper blending method, but it is also one of the key factors in determining the morphology and properties of the blends. The miscibility between ethylene‐propylene‐diene terpolymer (EPDM) and polypropylene (PP) was explored by means of dynamic mechanical thermal analysis, transmission electron microscopy (TEM), and differential scanning calorimetry (DSC). The results showed that a decrease in the PP content and an increase of the crosslinking density of EPDM in the EPDM/PP blends caused the glass‐transition temperature peaks of EPDM to shift from a lower temperature to higher one, yet there was almost no variance in the glass‐transition temperature peaks of PP and the degree of crystallinity of PP decreased. It was observed that the blends prepared with different mixing equipment, such as a single‐screw extruder and an open mill, had different mechanical properties and blends prepared with the former had better mechanical properties than those prepared with the latter. The TEM micrographs revealed that the blends were composed of two phases: a bright, light PP phase and a dark EPDM phase. As the crosslinking degree of EPDM increased, the interface between the phases of EPDM and PP was less defined and the EPDM gradually dispersed in the PP phase became a continuous phase. The results indicated that EPDM and PP were both partially miscible. The mechanical properties of the blends had a lot to do with the blend morphology and the miscibility between the blend components. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 315–322, 2002
Effect of synthesis parameters on thermal behavior of phenol–formaldehyde resol resin
Authors: Park Byung‐Dae , Riedl Bernard , Yoon Soo Kim  , So Won Tek 
Published: October 2004

AbstractDifferential scanning calorimetry (DSC) was used to investigate the influence of resin synthesis parameters on the thermal behavior of low molecular weight phenol–formaldehyde (PF) resol resins prepared with different formaldehyde/phenol (F/P) molar ratios, different sodium hydroxide/phenol (NaOH/P) molar ratios, and different catalysts. As the F/P molar ratio increased, the molecular weight and activation energy increased while the gel time, peak temperature, resin pH, and nonvolatile solids content decreased. By contrast, the molecular weight, gel time, resin pH, resin solids content, and peak temperature increased with an increasing NaOH/P molar ratio. However, the activation energy decreased with an increasing NaOH/P molar ratio. The polydispersity increased with both F/P and NaOH/P ratios. Calcium hydroxide gave a faster curing resin compared to sodium and potassium hydroxides. All DSC thermograms of this study showed just a single exothermic peak for the resins that were used. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1415–1424, 2002
Tribological action of metallic fillers in poly(tetrafluoroethylene) composites
Authors: Yan Feng‐Yuan , Xue Qun‐Ji , Wang Xiaobo 
Published: October 2004

AbstractThe tribological behavior of poly(tetrafluoroethylene) composites filled with various metallic particles was investigated under the extreme friction conditions of a heavy load and reciprocation with a small amplitude. Two obviously distinct friction stages corresponding to the contact conditions were found. The phenomena of the accumulation of fillers on the contact surface and extrusion wear of the poly(tetrafluoroethylene) matrix were also observed. Based on the experimental results, the actions of metallic fillers on the transfer film formation were analyzed. It was noted that the transfer and accumulation of fillers could actually be considered to be an assimilating process of the friction pairs. Accordingly, the physical model of the transfer film formation process was described and some suggestions on the mechanism of load‐supporting actions of hard fillers were also proposed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1832–1840, 2002
Kinetics of the nonstationary photopolymerization of diacrylates
Authors: Bratus A. , Turovki A. , Medvedevskikh Yu. , Zagladko E. , Zaikov G. 
Published: October 2004

AbstractThe kinetics of non‐stationary photopolymerization (post‐polymeryzation) of some diacrylates at the wide range of initial conversions was investigated. All kinetic curves has two regions: quick and short, slow and long. Experimental results were compared with the kinetic model of the photoinitial three‐dimensional photopolymerization. It was determined that kinetic model allows us to describe the process of the post‐polymerization in the whole range of conversions. The rate constants of the linear break of the primary and secondary chains in the interphase layer were estimated. The increasing rate constants in the interphase are the similar for investigated diacrylates and do not depend on the glicol chain. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1892–1895, 2002
Influence of electron donors on the initial stage of cyclopolymerization of 1,5‐hexadiene with MgCl2‐supported Ziegler catalysts analyzed by temperature rising elution fractionation
Authors: Kono Hiroyuki , Mori Hideharu , Terano Minoru , Nakatani Hisayuki , Nishiyama Isa 
Published: October 2004

AbstractAdditive effects of donors on the initial polymerization of 1,5‐hexadiene with the MgCl2‐supported Ziegler catalysts were investigated by using the stopped‐flow method, temperature rising elution fractionation (TREF) analysis, and kinetic study. The cyclopolymerization of 1,5‐hexadiene proceeded within an extremely short period (≤ 0.2 s) and yielded a unique poly(methylene‐1,3‐cyclopentane). cis ring content and cis–cis unit in meso dyad of the resulting polymer were increased by the addition of electron donors. The influence of internal and external donors was examined by the estimation of kinetic parameters and TREF analysis. Because the addition of the internal donor caused an obvious change in one of the kinetic parameters and the microstructure, an isospecific active site was considered to be formed by the addition of the internal donor. In the case of the external donor, the additive effects on the stereospecificity were weaker than those of the internal donor. It was expected from TREF measurements that the external donor modified an aspecific active site into a lower isospecific active site. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2976–2983, 2002; DOI 10.1002/app.2326
Preparation and evaluation of some novel organo‐phosphorus compounds as antioxidants and antifatigue agents in rubber
Authors: Ismail M. N. , Yehia A. A. , Korium A. A. 
Published: October 2004

AbstractSix organo‐phosphorus compounds were synthesized and incorporated in NR and SBR mixes. The rheometric characteristics of the green rubber mixes were determined using the oscillating disc rheometer. The prepared compounds were evaluated as antioxidants and antifatigue agents in NR and SBR vulcanizates. It was found that the prepared compounds are good antioxidant and antifatigue agents and their efficiency was better than that obtained by 4‐methyl‐2,6‐di‐tert‐butyl phenol, which is used in the rubber industry. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2984–2992, 2002; DOI 10.1002/app.2327
Study on pH‐sensitive and thermosensitive polymer networks containing polyacetal segments
Authors: Du Juan , Peng Yuxing , Zhang Tingting , Ding Xiaobin , Zheng Zhaohui 
Published: October 2004

AbstractA series of pH‐sensitive and thermosensitive polymer networks were first obtained by copolymerization of telechelic poly(1,3‐dioxolane) (PDXL) with acrylic acid (AA), acrylamide (AM), and N‐isopropylacrylamide (NIPAM), respectively. The copolymerization of PDXL diacrylate (PDXLDA) with AA, AM, or NIPAM is expected to lead to polymer networks in which homopolymeric segments of the monomer are connected by polyacetal segments. As a combination of these two parts, these polymer networks can have some interesting physical properties. For example, the copolymer networks of poly(AA‐b‐DXL) showed pH sensitivity, and both the copolymer networks of poly(AM‐b‐DXL) and poly(NIPAM‐b‐DXL) showed temperature sensitivity. Moreover, because of the low ceiling temperature of polyDXL, the networks containing polyacetal segments (PDXL) can degrade by treatment with a trace of appropriate cationic initiator. The polymer networks prepared were characterized by Fourier transform infrared, differential scanning calorimetry, and swelling data. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 3002–3006, 2002; DOI 10.1002/app.2329
Reactivity ratios of free monomers and their charge‐transfer complex in the copolymerization of N‐butyl maleimide and styrene
Authors: Zhao Youliang , Li Huaming , Liu Pengsheng , Liu Hongwei , Jiang Jing , Xi Fu 
Published: October 2004

AbstractAs for the charge‐transfer complex (CTC) formed by N‐butyl maleimide (NMBI) and styrene in chloroform, the complex formation constant was determined by 1H‐NMR of Hanna–Ashbaugh. The copolymerization of NBMI (NBMI, M1) and styrene (St, M2) in chloroform using AIBN as an initiator was investigated. On the basis of the kinetic model proposed by Shan, the reactivity ratios of free monomers and CTC in the copolymerization were calculated to be r12 = 0.0440, r21 = 0.0349, r1C = 0.00688, r2C = 0.00476, and the ratios of rate constants were obtained to be k1C/k12 = 6.40, k2C/k21 = 7.33. In addition, the copolymer was characterized by IR, 1H‐NMR, DSC, and TGA. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 3007–3012, 2002; DOI 10.1002/app.2330
Characterization of virgin and postconsumer blended high‐impact polystyrene resins for injection molding
Authors: Xu Guojun , Qiao Jianhong , Kuswanti Christiana , Koelling Kurt , Stuart Julie Ann , Lilly Blaine 
Published: October 2004

AbstractThis article focuses on the mechanical and rheological properties of virgin and recycled high‐impact polystyrene (HIPS) materials and describes our progress in evaluating the viability of reusing postconsumer and virgin polymer blends of HIPS from electronics equipment housings. Plastics reuse challenges are briefly reviewed, and experimental results, such as the rheological properties, mechanical properties, molecular weight, and morphology of different blends, are summarized and discussed for reuse of HIPS from printer and monitor housings. It is found that all blends have similar molecular weight and polydispersity. Furthermore, the recycled resin and virgin resin consist of almost the same components. However, the morphology of the rubber phases is different. The mechanical properties are similar for the ASTM specimens molded with either set of blends. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1–8, 2002; DOI 10.1002/app.2339
A kinetic investigation of thermally initiated emulsion copolymerization of styrene and methylmethacrylate without conventional initiators
Authors: Du Yong‐Zhong , Ma Guang‐Hui , Nagai Masatoshi , Omi Shinzo 
Published: October 2004

AbstractThe thermally initiated emulsion copolymerization of styrene (ST) and methyl methacrylate (MMA) was carried out in the absence of conventional initiators. The hydroperoxide (HPO) concentration in the monomers, sodium dodecyl sulfate (SDS), deionized water, and the formulation of those for emulsion copolymerization were measured. The HPO concentration in ST and MMA increased with the storage time, and were considered to be the major sources of HPO. The thermal decomposition of hydroperoxide in monomers, the thermal initiation of ST by Mayo mechanism, and the complex formation between SDS and the monomers were proposed to be three main sources of the radical generation. It was confirmed that new polymer particles were generated throughout the polymerization process, and consequently resulted in a broader distribution of polymer particle size, compared with that for conventional emulsion polymerization. Approximately 80 wt % of monomer conversion was obtained in the presence of SDS at 373 K in 24 h. The initiation rate of the 30 wt % monomer charge was faster than those of 10 wt % and 20 wt % monomer charge. The latex instability at higher solid content was improved by adding electrolyte to promote the electrostatic repulsion force between the polymer particles. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 455–467, 2002; DOI 10.1002/app.2343
Continuous distribution kinetics for the thermal degradation of LDPE in solution
Authors: Kumar G. Sanjay , Kumar V. Ravi , Madras Giridhar 
Published: October 2004

AbstractPolymer degradation in solution has several advantages over melt pyrolysis. The degradation of low‐density polyethylene (LDPE) occurs at much lower temperatures in solution (280–360°C) than in conventional melt pyrolysis (400–450°C). The thermal degradation kinetics of LDPE in solution was investigated in this work. LDPE was dissolved in liquid paraffin and degraded for 3 h at various temperatures (280–360°C). Samples were taken at specific times and analyzed with high‐pressure liquid chromatography/gel permeation chromatography for the molecular weight distribution (MWD). The time evolution of the MWD was modeled with continuous distribution kinetics. Data indicated that LDPE followed random‐chain‐scission degradation. The rapid initial drop in molecular weight, observed up to 45 min, was attributed to the presence of weak links in the polymer. The rate coefficients for the breakage of weak and strong links were determined, and the corresponding average activation energies were calculated to be 88 and 24 kJ/mol, respectively. © 2002 John Wiley & Sons, Inc. J Appl Polym Sci 84: 681–690, 2002; DOI 10.1002/app.2344
Cure kinetics modeling and process optimization of the vialux 81 epoxy photodielectric dry film (PDDF) material for microvia applications
Authors: Dunne Rajiv C. , Sitaraman Suresh K. , Luo Shijian , Wong C. P. , Estes William E. , Periyasamy Mookkan 
Published: October 2004

AbstractThe cure kinetics of a photodielectric dry film (PDDF) material called ViaLux 81 has been studied, with the aim of understanding and optimizing its curing schedule for the fabrication of sequentially built‐up (SBU) high‐density‐interconnect printed wiring boards (HDI‐PWB). Initial dynamic differential scanning calorimetry (DSC) scans on the material revealed a two‐stage curing mechanism due to the long lifetime of the photoinitiator catalyst, which could not be separated at lower heating rates. On the other hand, the heat flow exotherm from isothermal DSC experiments showed a rapid reaction rate at the beginning with only a single peak. Therefore, to capture the complexity of the process, the faster multiple heating rate DSC experiments are used to predict the degree‐of‐cure (DOC) evolution. Two approaches have been developed based on the dynamic DSC data: (1) a “model‐free” approach, which only requires information about the cure‐dependence of the activation energy; and (2) a practical scheme to deconvolute the two curing peaks. Excellent agreement is observed for the heating rate experiments, but the methods are inadequate for predicting the DOC evolution under isothermal conditions. Therefore, a modified autocatalytic model with temperature‐dependent kinetic parameters has been developed based on the isothermal DSC data. This model predicts the DOC evolution for isothermal curing profiles very well. However, some discrepancy is evident in predicting the DOC evolution for heating rate experiments, due to the underestimation of the activation energy. With appropriate corrections, excellent predictive capability is illustrated for complex cure schedules with combined heating rate and isothermal segments. In addition, a cure process optimization strategy has been suggested, and the fabrication of fine features and microvias is demonstrated. © 2002 John Wiley & Sons, Inc. J Appl Polym Sci 84: 691–700, 2002; DOI 10.1002/app.2345
Resin‐vulcanized NBR: Suitability of rheometric parameters for the calculation of cure kinetic constants
Authors: Sousa Ana M. F. , Peres Augusto C. C. , Nunes Regina C. R. , Visconte Leila L. Y. , Furtado Cristina R. G. 
Published: October 2004

AbstractSeveral mechanisms can be used to describe the vulcanization process, and study of the reactions that actually take place can be done through different techniques. In this work, two methods that used rheometric parameters to calculate the kinetic constant were compared for the cure of nitrile rubber with a system of phenolic resin, polychloroprene, and zinc oxide. The formulations and data analysis were based on a complete factorial experiment design. The results enabled the identification of the influence of each parameter involved in the vulcanization process and the suitability of the two methods used. © 2002 John Wiley & Sons, Inc. J Appl Polym Sci 84: 505–513, 2002; DOI 10.1002/app.2354
Relationship between the composition of polycarbonate copolymers and the refractive index
Authors: Okamoto Masaya 
Published: October 2004

AbstractWith a polycarbonate (PC)–poly(methyl methacrylate) (PMMA) graft copolymer and a PC–poly(dimethyl siloxane) (PDMS) block copolymer, the relationship between the composition of PC copolymers and the refractive index (nD) was investigated. According to the results, with a PMMA content of 38 wt %, the nD value of the PC–PMMA graft copolymer was nearly the same as that of electrical (E) glass (nD = 1.545), and with a PMMA content of 6 wt %, it was nearly the same as that of electrical corrosion resistance (ECR) glass (nD = 1.579). However, with a PDMS content of 19 wt %, the nD value of the PC–PDMS block copolymer was nearly the same as that of E glass, and with a PDMS content of 2 wt %, it was nearly the same as that of ECR glass. The combination of the PC–PDMS block copolymer and the glass fibers (GFs) of ECR glass led to haze values of 8 and 16% with GF contents of 10 and 20%, respectively. © 2002 John Wiley & Sons, Inc. J Appl Polym Sci 84: 514–521, 2002; DOI 10.1002/app.2355
Effect of chlorination of ground rubber tire on its compatibility with poly(vinyl chloride): Dielectric studies
Authors: Naskar Amit K. , Khastgir D. , Bhowmick Anil K. , De S. K. 
Published: October 2004

AbstractDielectric analysis (DEA) of molded ground waste rubber tire (GRT) and its chlorinated derivatives (Cl‐GRT) was undertaken. Dielectric spectra of Cl‐GRT show formation of a biphasic structure consisting of the rubbery phase and a hard phase whose relaxation occurs in the high‐temperature region. DEA of plasticized poly(vinyl chloride) (PVC) containing GRT and PVC containing Cl‐GRT was also undertaken. It is observed that PVC containing Cl‐GRT exhibits a higher loss factor in the high‐temperature region than does the PVC compound containing GRT, due to enhanced interaction between Cl‐GRT and PVC. While the activation energy for dielectric relaxation of PVC does not change when compounded with GRT, it does decrease when PVC is compounded with Cl‐GRT due to dipolar interaction. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 993–1000, 2002; DOI 10.1002/app.10320
Synthesis and characterization of fluorocarbon‐containing, hydrophobically associative poly(acrylic acid‐co‐Rf‐poly(ethylene glycol) macromonomer)
Authors: Zhang Yunxiang , Liu Shouping , Du Libin , Zhuang Dongqing , Chen Junyan , Jiang Ming , Hogen‐Esch Thieo E. , Wu Shuguang , Swift Graham 
Published: October 2004

AbstractFluorocarbon‐ or hydrocarbon‐end‐capped poly(ethylene glycol) (PEG) macromonomers were prepared with coupling methods. Several factors affecting the synthesis were studied, and the optimal condition was ascertained. The critical micelle concentrations of these macromonomers were determined with the fluorescence method. Novel fluorocarbon‐containing, hydrophobically modified, alkali‐soluble copolymers were made by the copolymerization of fluorocarbon‐ or hydrocarbon‐alkyl‐end‐capped PEG macromonomers with acrylic acid in an organic solvent. The effects of the macromonomer contents, polymerization conditions, spacer, temperature, shear rate, pH, and addition of salt and various surfactants on the solution viscosity were preliminarily investigated. A very strong hydrophobic association was found for these copolymer solutions. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1035–1047, 2002; DOI 10.1002/app.10393