bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hygrothermal aging of rubber‐modified and mineral‐filled dicyandiamide‐cured DGEBA epoxy resin. III. Dielectric spectroscopy investigation
Authors: Ivanova Katya I. , Pethrick Richard A. , Affrossman S. 
Published: August 2002

AbstractThe effects of moisture absorption on the dielectric properties of a rubber‐modified, mineral‐filled, epoxy resin based on the diglycidyl ether of bisphenol A cured with dicyandiamide are reported. Samples of the resin were aged by immersing in deionized water, or 5% w/w NaCl solution, at elevated temperatures. Dielectric measurements were carried out over the frequency range 10−1 to 6 × 105 Hz. A featureless dielectric spectrum was observed with both real and imaginary dielectric permittivity increasing with the amount of absorbed water. The change in the dielectric properties with absorption of water was independent of presence of salt, temperature of exposure, and aging history, although a hysteresis of the hydration–dehydration process was observed at low frequencies. Two types of absorbed water were observed—water molecularly dispersed within the epoxy matrix and clustered water in spherical microcavities. The time dependence of the real dielectric permittivity measured at 10 kHz was found to closely resemble that of the water absorption, which allowed the activation energy of diffusion to be calculated from both dielectric and gravimetric data. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1011–1024, 2002; DOI 10.1002/app.10368
Study on the phase separation of thermoplastic‐modified epoxy systems by time‐resolved small‐angle laser light scattering
Authors: Zheng Qiang , Tan Kuitian , Peng Mao , Pan Yi 
Published: August 2002

AbstractReaction‐induced phase‐separation behavior of an epoxy (E‐ 51) system modified by thermoplastics, namely, polyetherimide (PEI) and polycarbonate (PC), isothermally cured with 4,4′‐ diaminodiphenylsulfone (DDS) at various temperatures, was investigated by the time‐resolved small‐angle laser light‐scattering (SALLS) technique. It was found that the morphology evolution of this E‐51 curing system was controlled by the competition between the curing reaction and the phase separation. It was verified that the phase separation of these systems followed the spinodal decomposition mechanism through analyzing the scattering pattern evolution and the cocontinuous morphology observed by optical microscopy. The curing temperatures and compositions of these epoxy systems were considered to be the determining factors for the domain size and the phase‐separation behavior. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 950–956, 2002
Swollen behavior of crosslinked network hydrogels based on poly(vinyl alcohol) and polydimethylsiloxane
Authors: Shin Mi‐Seon , Kim Seon Jeong , Kim In Young , Kim Nam Gyun , Song Chul Gyu , Kim Sun I. 
Published: August 2002

AbstractPoly(vinyl alcohol) (PVA) was dissolved in the water to make a 10 wt % aqueous solution, and polydimethylsiloxane (PDMS) was mixed with 1 wt % 2,2‐dimethyl‐2‐phenylacetophenone (DMPAP) and 0.5 mol % methylenebisacrylamide (MBAAm) in isopropyl alcohol. This mixture was added to a PVA aqueous solution and heated at 90°C for 7 h. Various crosslinked networks were prepared at different molar ratios of PVA/PDMS (1:1, 1:3, and 3:1). The characterization of PVA/PDMS crosslinked networks was determined by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), a universal testing machine (UTM), and the equilibrium water content (EWC). The DSC melting endotherms showed, at 219.49°C, a sharp endothermic peak of PVA, and PVA/PDMS crosslinked networks had melting peaks close to this point. The value of EWC increased with the content of PVA in the crosslinked networks, simultaneously depending on the temperature. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 957–964, 2002
Manufacture and properties of chitosan/N,O‐carboxymethylated chitosan/viscose rayon antibacterial fibers
Authors: Li Zhi , Liu Xiaofei , Zhuang Xupin , Guan Yunlin , Yao Kangde 
Published: August 2002

AbstractChitosan/N,O‐carboxymethylated chitosan/viscose rayon antibacterial fibers (CNVFs) were prepared by blending chitosan emulsion, N,O‐carboxymethylated chitosan (N,O‐CMC), and viscose rayon together for spinning. The fibers were characterized by transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA). TEM micrographs showed that chitosan microparticles dispersed uniformly along the oriented direction with the mean size ranging from 0.1 to 0.5 μm. DSC spectra of these fibers showed that no significant change in thermal property was caused by adding chitosan and N,O‐CMC into the viscose rayon. TGA spectra showed that the good moisture retentivity was not affected by the addition of chitosan and N,O‐CMC. Both DSC and TGA suggested that the decomposing tendency of the viscose rayon above 250°C seemed to be weakened by the chitosan. The fibers' mechanical properties and antibacterial activities against Escherchia coli,
Staphylococcus aureus, and Candida albicans were measured. Although the addition of chitosan slightly reduced the mechanical properties, the antibacterial fibers' properties were obtained and were found to meet commercial requirements. CNVF exhibited excellent antibacterial activity against E. coli,
S. aureus, and C. albicans. The antibacterial activity increased along with the chitosan concentration and was not greatly affected by 15 washings in water. Scanning electron microscopy (SEM) was used to observe the morphology of bacteria cells incubated together with the antibacterial or reference fibers. SEM micrographs demonstrated that greater amounts of bacteria could be adsorbed by the antibacterial fiber than by the reference fiber; these bacteria were overwhelmingly destroyed and killed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2049–2059, 2002; DOI 10.1002/app.10501
Interface modification on the properties of sisal fiber‐ reinforced polypropylene composites
Authors: Fung K. L. , Li R. K. Y. , Tjong S. C. 
Published: August 2002

AbstractShort sisal fiber (SF)‐reinforced polypropylene (PP) composites were prepared by melt blending followed by injection molding. To improve the interfacial bonding between SF and PP, the PP matrix was maleated (MAPP) by blending PP and maleic–anhydride‐grafted‐PP in the weight ratio of 9/1. It was found that the SF/MAPP composites have lower melt viscosity (as reflected by torque rheometer measurements) than the SF/PP composites at the respective sisal fiber contents. In terms of mechanical properties, PP maleation has the effect of improving the tensile strength. This can be explained in terms of the improved SF/matrix interfacial bonding when MAPP was used. However, the impact strength was reduced when the PP matrix was maleated. The improved SF/matrix interfacial bonding prevented fracture mechanisms such fiber/matrix debonding and fiber pullout from taking place. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 169–176, 2002
Comparison of tetraethyl‐ and tetramethylthiuram disulfide vulcanization. I. Reactions in the absence of rubber
Authors: Gradwell M. H. S. , Grooff D. 
Published: August 2002

AbstractThe reactions of tetraethylthiuram di‐ and monosulfide (TETD and TETM, respectively) were investigated in the absence of rubber and compared with those reported previously for tetramethylthiuram compounds. The reactions of TETM, TETD, and zinc diethyldithiocarbamic acid with zinc oxide and sulfur were investigated by differential scanning calorimetry, and the reaction products analyzed by high performance liquid chromatography. TETM was shown to be more stable at vulcanization temperatures (±150°C), but also less reactive with sulfur than tetramethylthiuram disulfide (TMTD). The reactions of TETD are very similar to those of TMTD, the TETD reacting slower than the TMTD to form analogous products. In the presence of zinc oxide, the formation of the zinc compound of TETD, zinc diethyldithiocarbamic acid, occurred readily. TMTD does not react readily with zinc oxide. The reaction of TETD with sulfur lead to the formation of polysulfidic accelerator species, although the concentrations formed in the absence of rubber were considerably less than that formed by the corresponding TMTD system. These differences in reactivity would affect the vulcanization reactions that take place in the rubber. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2292–2299, 2001
Study on the tribological characteristics of solid lubricants embedded tin‐bronze bearings
Authors: Li Tongsheng , Tao Jiang , Cong Peihong , Liu Xujun 
Published: August 2002

AbstractThe friction and wear characteristics of graphite, MoS2, and PTFE embedded tin‐bronze bearings were studied using a pin‐on‐disc tester. The results indicated that solid lubricants decreased and stabilized the friction coefficient, and decreased the wear rate by two to three orders of magnitude. When the content of solid lubricants, PTFE mixed with graphite, was 20–40%, the performance of the solid lubricants embedded bearing (SLEB) was the best. Wear scar was analyzed by means of X‐ray diffraction (XRD), Auger electron spectroscopy (AES), and scanning electron microscopy (SEM). The results show that the transfer films of solid lubricants reduce adhesion between the SLEBs and the mating material, and the wear mechanism of SLEBs changes to fatigue and adhesive wear. The main reason for fatigue wear is microcracks expanding at Pb points in SLEBs. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2394–2399, 2001
Blends of acrylonitrile–butadiene–styrene/waste poly(ethylene terephthalate) compatibilized by styrene maleic anhydride
Authors: Paul S. , Kale D. D. 
Published: August 2002

AbstractWaste poly(ethylene terephthalate) (PET) from thin bottles was blended with acrylonitrile–butadiene–styrene (ABS) copolymer in different proportions, up to 10 wt %. Styrene maleic anhydride (SMA) copolymer was used as a compatibilizer. The tensile strength and heat deflection temperature of the blend were higher than that of virgin ABS. Flexural modulus remained unaffected, although a slight decrease in impact property was observed. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2593–2599, 2001
Mechanical properties of flame retardant filled polypropylene composites
Authors: Tai C. M. , Li Robert K. Y. 
Published: August 2002

AbstractThe flammability performance and mechanical behaviors for halogen‐based and non‐halogen‐based flame retardant (FR) filled polypropylene (PP) composites were investigated in this study. The halogen‐based FR system consisted of a mixture of brominated phosphate ester and antimony trioxide (BR), and the halogen‐free FR was a magnesium hydroxide (MH). It was found from limiting oxygen index measurements that 60 wt % of MH was needed in order to achieve the same degree of flammability as the composite containing only 30 wt % of BR. Scanning electron microscopy examinations of the fractured specimens indicated that the interfacial bond strength between PP and MH was stronger than that for PP and BR. The notched Charpy impact strength and the impact fracture toughness were measured and compared. The discrepancies between the two impact test results could be correlated after kinetic energy correction was applied to the Charpy impact strengths. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2718–2728, 2001
Properties of films made from ternary blends of metallocene and conventional polyolefins
Authors: Majumdar A. , Kale D. D. 
Published: August 2002

AbstractThin films were blown from a composition of 75% linear low density polyethylene (LLDPE) and 25% LDPE. The LLDPE content was made up of different % of metallocene‐based and conventional octene‐based LLDPE. Tensile strength, dart impact strength, hot tack strength, heat seal strength, and the barrier properties of these films were measured. All the properties showed significant improvement when conventional LLDPE (cLLDPE) was replaced by metallocene‐based LLDPE (mLLDPE), even to the extent of only 25%. The blends of 50% mLLDPE and 50% LDPE showed attractive properties. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 53–57, 2001
Electrical behavior and structure of polypropylene/ultrahigh molecular weight polyethylene/carbon black immiscible blends
Authors: Mironi‐Harpaz I. , Narkis M. 
Published: August 2002

AbstractThis study investigates the electrical behavior, which is the positive temperature coefficient/negative temperature coefficient (PTC/NTC), and structure of polypropylene (PP)/ultrahigh molecular weight polyethylene (UHMWPE)/carbon black (CB) and PP/γ irradiated UHMWPE (XL‐UHMWPE)/CB blends. As‐received UHMWPE or XL‐UHMWPE particles are chosen as the dispersed phase because of their unusual structural and rheological properties (extremely high viscosity), which practically prevent CB particles penetration. Because of their stronger affinity to PE, CB particles initially form conductive networks in the UHMWPE phase, followed by distribution in the PP matrix, thus interconnecting the CB‐covered UHMWPE particles. This unusual CB distribution results in a reduced electrical percolation threshold and also a double‐PTC effect. The blends are also investigated as filaments for the effect of shear rate and processing temperature on their electrical properties using a capillary rheometer. Because of the different morphologies of the as‐received and XL‐UHMWPE particles in the filaments, the UHMWPE containing blends exhibit unpredictable resistivities with increasing shear rates, while their XL‐UHMWPE containing counterparts depict more stable trends. The different electrical properties of the produced filaments are also related to differences in the rheological behavior of PP/UHMWPE/CB and PP/XL‐UHMWPE/CB blends. Although the flow mechanism of the former blend is attributed to polymer viscous flow, the latter is attributed to particle slippage effects. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 104–115, 2001
Evaluation of thermo‐viscosity parameters of dextran in polar and nonpolar solvent
Authors: Mahapatra A. P. , Samal R. K. , Samal R. N. , Roy G. S. 
Published: August 2002

AbstractSome thermo‐viscosity parameters like Viscosity‐molecular weight constant (K), the short‐range parameter, (A) and long‐range parameter (B) have been evaluated for the polymer “Dextran” of three different molecular weights (M̄w = 19,500, 75,000, and 250,000) in three different solvents like 6 (M) aqueous urea, 2 (M) aqueous glycine, and 50% aqueous glucose at temperatures ranging from 25 to 50°C. The study reveals that the viscosity‐molecular weight constant (K) decreases with increase in temperature for polar solvents like aqueous urea and aqueous glycine. The value of “K” increases with the rise in temperature within the range of 25 to 35°C in case of a nonpolar solvent aqueous glucose and then “K” decreases with the increase in temperature within the range of 40 to 50°C for the nonpolar solvent aqueous glucose. The short‐range parameter (A) shows the same trend as shown by “K” and the long‐range parameter “B” exhibits no definite trend with the variation of temperature. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 440–452, 2001
Carbon black‐filled PET/HDPE blends: Effect of the CB structure on rheological and electric properties
Authors: Mallette Javier G. , Quej Luis M. , Marquez Alfredo , Manero Octavio 
Published: August 2002

AbstractThe rheological and electric properties of blends of poly(ethylene terephthalate) (PET) and high‐density polyethylene (HDPE) filled with various types of carbon black (CB) were analyzed in detail in this project. Four types of CB samples with available values of surface area, particle size, porosity, density, and maximum packing fraction were considered. Blends were prepared using an internal mixing chamber at two different rotational speeds, prior to mold compression of the samples. The rheological properties of the blends with varying polymer composition and a constant amount of CB were recorded in terms of torque variation with time for two shear rates (in terms of rotational speed). Rheological data were related to the resistivity of blends. Results show that the CB structure (porosity, surface area, apparent bulk density, and particle size) largely determine the resulting equilibrium torque and electrical properties. Furthermore, since CB is preferentially located in the HDPE phase, higher conductivity is observed as the PET content decreases, since the relative CB content in this phase increases. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 562–569, 2001
Curing of epoxy–urethane copolymers in a heated mold: Effect of the curing conditions on the phase‐separation process
Authors: Stefani P. M. , Moschiar S. M. , Aranguren M. I. , Marieta C. , Mondragon I. 
Published: August 2002

AbstractThe curing process of an epoxy–urethane copolymer in a heated mold was studied. The epoxy resin (DGEBA, Araldyt GY9527; Ciba Geigy), was coreacted with a urethane prepolymer (PU, Desmocap 12; Bayer) through an amine that acted as crosslinking agent (mixture of cycloaliphatic amines; Distraltec). The study focused on the effect of the curing condition and PU concentration on time–temperature profiles measured in the mold and the consequent final morphologies obtained. As the PU concentration increases, the maximum temperature reached in the mold decreases as a result of the dilution effect of the elastomer on reaction heat, whereas the Tg of the piece also decreases. Phase separation is a function of conversion and temperature reached in the curing part and was analyzed using experimental data and a mathematical model that predicts temperature and conversion throughout the thickness of the mold. Scanning electron microscopy and atomic force microscopy were used to determine the characteristics of the dispersed phase for the different formulations and conditions of curing. It was shown that the size of the dispersed phase increased with the initial PU concentration, whereas there were practically no differences in the separated phase as a function of position or temperature of curing (in the range of 70 to 100°C studied). The superposition of the phase diagrams with the conversion–temperature trajectories during cure provided an explanation of the morphologies generated. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 889–900, 2001
Antimicrobial treatment of nylon
Authors: Lin Jian , Winkelman Catherine , Worley S. D. , Broughton R. M. , Williams J. F. 
Published: August 2002

AbstractThe preparation of an antimicrobial nylon material and its properties are discussed. Biocidal cyclic N‐chloramine moieties were covalently bonded to Nylon 66. These moieties, which included hydantoins, oxazolidinones, and imidazolidinones, were stable during at least 3 months of dry storage, and their antimicrobial activities, once lost by reaction with reducing sodium thiosulfate, could be regenerated by exposure to free chlorine. Biocidal swatch tests showed that the nylon fabrics containing N‐chlorinated hydantoin functional groups provided a 7.2 log reduction of Staphylococcus aureus and a 7.1 log reduction of Escherichia coli at a contact time of only 10 min. Antimicrobial nylon should find a variety of important uses such as in clothing, carpets, sutures, brushes, and so forth. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 943–947, 2001
Copolymerization of polypropylene and functionalized linear α‐olefin onto glass fibers
Authors: Barbosa Silvia E. , Ferreira María L. , Damiani Daniel E. , Capiati Numa J. 
Published: August 2002

AbstractThis work deals with a novel glass fiber surface modification and subsequent metallocenic propylene polymerization onto it. Experimental results are presented on methylaluminoxane (MAO) fixation at the fiber surface, followed by propylene–α‐olefin graft copolymerization catalyzed by EtInd2ZrCl2/MAO. First results indicate that part of the produced polymer is chemically bonded to the glass fiber. Scanning electron microscopy, Fourier transform infrared spectroscopy, and X‐ray disperse energy microanalysis characterization confirm the permanence of a thin polymer layer as well as aluminum and oxygen (from the MAO) on the glass surface, even after a severe solvent extraction treatment. From these results, the copolymerization of hydroxy‐α‐olefin, grafted on MAO pretreated glass fiber, is foreseen as a possible way to improve fiber–matrix adhesion in glass fiber thermoplastic composites. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1266–1276, 2001
Analysis of annealed thin polymer films prepared from dichloro(methyl)phenylsilane by plasma polymerization
Authors: Cech V. , Horvath P. , Trchova M. , Zemek J. , Matejkova J. 
Published: August 2002

AbstractThin plasma polymer films were deposited from a mixture of dichloro(methyl)phenylsilane (DCMPS) vapor and gaseous hydrogen in an rf (13.56 MHz) capacitive coupling deposition system on pieces of silicon wafers. Some of samples were annealed in a vacuum to temperatures ranging from 450 to 700°C. The chemical composition, structure, and surface morphology of the annealed samples and those stored in air at room temperature were studied by FTIR, XPS, SEM, and optical microscopy. The thermal stability and decomposition of the plasma polymer with increasing temperature were characterized using thermogravimetry together with mass spectrometry. The plasma polymer was stable to a temperature of 300°C. Above that temperature, the material started to decompose together with additional crosslinking due to the incorporation of extra oxygen atoms forming new siloxane bonds. The plasma polymer was tough at room temperature but much more brittle after annealing. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2106–2112, 2001
Accelerating effect of NaNO2 on the polymer plating of 6‐substituted‐1,3,5‐triazine‐2,4‐dithiol mono sodium salts
Authors: Mori Kunio , Sasaki Yaeko , Hirahara Hidetoshi , Oishi Yoshiyuki 
Published: August 2002

AbstractOrganic polymer plating properties of 6‐substituted‐1,3,5‐triazine‐2,4‐dithiol mono sodium salts were investigated in the presence of various supporting electrolytes. Among these, the NaNO2 supporting electrolyte greatly accelerated the film formation rate in polymer plating. The accelerating effect of NaNO2 was further confirmed by comparing plating potentials in the presence of NaNO2 and Na2CO3. The potentiostatic polymer plating of DAN in the presence of the NaNO2 supporting electrolyte took place in the potential range of 1.65–1.8 V (compared against saturated calomel electrode reference). Film formation was influenced by such factors as the pH of solution and both the chemical structure and the concentration of triazine dithiol. In polymer platings, NO anions are thought to be electrochemically oxidized to yield NO radicals and these radicals react with DAN to yield new thiyl radicals. The thiyl radicals in the DAN molecules couple with each other by means of disulfide bonds, resulting in the growth of polymer film. Organic polymer plating films are shown to contain disulfide bonds, monosulfide bonds obtained by the reaction between allyl groups and thiyl radicals, and network chains. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2300–2309, 2001
Piezo‐ and pyroelectric photothermal characterization of polymers as a function of temperature
Authors: Mura J. , Miranda L. C. M. , Baesso M. L. , Bento A. C. , Rubira A. F. 
Published: August 2002

AbstractIn this article, piezo‐ and pyroelectric signals are used for the photothermal characterization of the thermomechanical properties of polymers as a function of temperature. The potentialities of the proposed technique are explored using poly(ethylene terephthalate) as the test sample. The influence of the sample thermal aging on the polymer physical properties is also discussed. The sensitivity of the proposed photothermal technique is tested by comparing its results with complementary dielectric response measurements and X‐ray diffraction. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2669–2678, 2001