bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies of the effect of fiber surface and matrix rheological properties on nonwoven reinforced elastomer composites
Authors: Epstein Mikael , Shishoo R. L. 
Published: April 2003

AbstractThe influence of fiber type and fiber‐surface properties on matrix flow behavior was investigated using structural reaction injection‐molding (SRIM). The influence of fiber type, fiber‐surface properties, and matrix type on strength properties in elastomeric composites reinforced with nonwoven fibrous structures was investigated using tensile tests on elastomer composite samples from SRIM and latex coagulation (LC) fabrication methods and the microbond strength method on individual fibers. The fibers used were PET, LLDPE, and p‐aramid. Fibers were treated with epoxy, styrene, and isocyanate derivatives, which make the surface chemically reactive. Treatments were also made with NaOH and a copolymer of polyester and polyol ether, causing a change in the fiber surface energy. The matrix types were polyurethane elastomer and natural rubber. The results show that the surface treatments which produced a change in the surface energy influenced the flow rate of the matrix polymer during the composite fabrication process. The treatments resulted in chemically reactive fiber surfaces which improved the fiber‐matrix bond strength without affecting the Young's modulus of the composite material. Good correlation was found between bond strength and surface energy including the dispersive component of surface energy in the case of polyurethane elastomer and surface‐modified PET fibers. The age of the polyurethane matrix has a marked influence on the bond strength. The fiber volume fraction in composites has a strong influence on the Young's modulus of the elastomer composite. © 1995 John Wiley & Sons, Inc.
Physicomechanical properties of poly(methyl methacrylate‐co‐N‐arylmaleimides)
Authors: Bharel Renu , Choudhary Veena , Varma I. K. 
Published: April 2003

AbstractThe article describes the effect of incorporating low mol fractions of N‐o‐tolymaleimide (MO)/N‐p‐tolymaleimide (MP) in poly(methyl methacrylate) (PMMA) on Tg, thermal behavior, mechanical, and optical properties. The glass transition temperature (Tg) of PMMA increased by 10–12°C upon incorporation of an ∼ 0.026 mol fraction of N‐arylmaleimides. A further increase of N‐arylmaleimide content up to 0.1 mol fraction in the copolymers resulted in a further ∼ 10°C increase in Tg. The tensile strength and % elongation decreased, whereas modulus increased with increasing maieimide content. The solar transmittance and % transmittance at higher wavelengths of the copolymer sheets having a low mol fraction of N‐arylmalemides (i.e., 0.026–0.05) were comparable to PMMA. © 1995 John Wiley & Sons, Inc.
Preparation of macroporous carbons from phase‐inversion membranes
Authors: Hatori H. , Yamada Y. , Shiraishi M. 
Published: April 2003

AbstractPreparation of porous carbons from phase‐inversion membranes was investigated as a control method of pore structure in carbon materials. The structure in carbon films was estimated by means of electron microscopy, mercury porosimetry, and gas‐adsorption methods. When phase‐inversion membranes of Kapton‐type polyimide were carbonized, they maintained the film form and gave macroporous carbon films having high porosity. However, micro‐ and mesopore structures in the carbon films were not influenced by phase inversion in the polymer stage, and, thus, the macroporous carbons had a molecular sieve property similar to that of carbons prepared from nonporous polyimide films. A macroporous structure in cellulose membranes was similarly maintained through the carbonization step, but some of these were fractured or deformed owing to the large shrinkage. Polymer membranes have a capability as porous carbon precursors if they satisfy two requirements: solid‐state carbonization and relatively high carbon yield. A composite membrane of a macroporous carbon with a dense carbon having an impervious ability was readily produced by shaping at the precursor stage. © 1995 John Wiley & Sons, Inc.
Transition points of polymers
Authors: Furukawa Junju 
Published: April 2003

AbstractAs a model for polymers, the pseudocrosslink of various sizes is proposed. The size of links, lengths of connected chains, and the times τ's for their translation or relaxation are derived. According to the size, four transition temperatures (T's) are proposed such as the linking for the smallest size A (TA), that for the largest one B (TB), the melting point (Tm), and the glass transition point (Tg). The equation for Tg is derived with an assumption that the cooling time t is equal to the relaxation time of the segment at Tg and Tg is found to be about 50°C higher than TA. Tg decreases with t. TB is twice as much as TA. Tg/TB is 2/3 in the general case and 1/2 for hindered polymers. Tm is very close to TB, but somewhat lower than it when the cohesion heat is large. Related problems are discussed: The thermal expansion coefficient above Tg is about 1/10 Tg. The rebound resilience of rubber at temperature T is given by a ratio of (T – Tg)/(T – TA). The sound velocities in glassy plastics and rubber are 2000 and 50–100 m/s, respectively, depending on the elasticity. The temperature‐shift factor for the stress‐relaxation spectrum is derived directly from the equation for the relaxation time without use of the thermal expansion coefficient. © 1995 John Wiley & Sons, Inc.
Surface modification of polypropylene by a combination of photooxidation and photosubstitution reactions
Authors: Pasternak Mordechai 
Published: April 2003

AbstractAn efficient photoprocess has been developed to increase polypropylene surface wettability by insertion of acid, ester, and amide functionalities. A systematic study of polypropylene surface irradiations indicates that photoxidations always precede the photosubstitution reactions that occur at the carbonyl site to form carboxyl, ester, and amide groups. Irradiations with amines to form amide groups always achieved the highest level of wettability improvement without changing bulk morphology. This process may be very beneficial in facilitating the fabrication of composite membranes with hydrophilic barriers on top of a hydrophobic polymeric support such as polypropylene. The high chemical resistance of polypropylene matrix to various solvents makes the partially hydrophilized polypropylene an ideal membrane support when hydrophilic membrane barriers made by interfacial polymerization/crosslinking are needed for a variety of separation application. © 1995 John Wiley & Sons, Inc.
Water‐soluble sulfonated phenolic resins. I. Synthesis
Authors: Hsu K. C. , Lee Y. F. 
Published: April 2003

AbstractA new water‐soluble sulfonated phenolic resin as a water reducer in concrete was prepared in this study. It was synthesized from formaldehyde, phenol, and NaHSO3through a four step reaction procedure. The structure of resin was determined through analyses of IR and NMR spectra. The influence of reaction conditions on the properties of synthesized products was also examined and discussed. © 1995 John Wiley & Sons, Inc.
Biocidal polymers active by contact. IV. Polyurethanes based on polysiloxanes with pendant primary alcohols and quaternary ammonium groups
Authors: Hazziza‐Laskar J. , Helary G. , Sauvet G. 
Published: April 2003

AbstractFunctional polysiloxanes bearing both primary alcohols and quaternary ammonium salts (QAS) as lateral substituents were prepared. The synthesis involves a cohydrosilylation of allylic derivatives (N,N‐dimethylallylamine and allyloxytrimethylsilane) with various poly(dimethylsiloxane‐co‐hydrogenomethylsiloxane)s. During the quaternization of the tertiary amino groups the alcohol functions are also deprotected. The hydroxyl groups allow the polysiloxane to be incorporated in polyurethane films whereas the QAS impart biocidal properties to the coating. In the case of a QAS bearing a hexadecy substituent, a very high activity was found against Escherichia coli without any observable diffusion. The mode of action by contact between the solid polymer and the microorganisms was confirmed by the excellent durability of the biocidal power after 1 month of immersion in water. © 1995 John Wiley & Sons, Inc.
Use of EVA‐containing mercapto groups in natural rubber–EVA blends. I. Mechanical, thermal, and morphological properties
Authors: Jansen P. , Amorim M. , Gomes A. S. , Soares B. G. 
Published: April 2003

AbstractThe effect of ethylene–vinyl acetate (EVA) modified with mercaptoacetic acid on mechanical, thermal, and morphological properties of blends of natural rubber (NR) and EVA copolymers has been investigated. The introduction of EVASH promotes a crosslinking of natural rubber phase as indicated by extraction experiments and microscopy analysis. This crosslinking may be attributed to bonding between sulfhydryl groups along the EVASH backbone and double bonds in rubber phase and may be responsible for the hardness improvement of most of the studied blends. Better results on hardness and ultimate tensile strength with EVASH addition were achieved for NR–EVA (60 : 40) ratio, probably due to cocontinuous morphology of this composition. The influence of EVASH on crystallinity degree of NR–EVA blends was also studied by differential scanning calorimetry. The morphology of the blends was studied through scanning electronic microscopy. © 1995 John Wiley & Sons, Inc.
Degradability and antigen‐release characteristics of polyester microspheres prepared from polymer blends
Authors: Sah Hongkee , Chien Yie W. 
Published: April 2003

AbstractBiodegradable microspheres were prepared to function as a depot system for the controlled release of a model protein antigen bovine serum albumin (BSA). As an approach to achieve its controlled release, microspheres were fabricated blending a high‐molecular‐weight poly‐d,l‐lactide‐co‐glycolide (Mw = 61,000) with a low‐molecular‐weight poly‐d,l‐lactic acid (Mw = 2000, PLA2000). The effects of PLA2000 on microsphere degradability and release characteristics of BSA from microspheres were investigated. On the basis of the pH change in microsphere suspensions and water uptake of microspheres, the kinetics of microsphere degradation was derived to describe the rate of formation of hydrogen ions due to hydrolysis of ester linkages of polymers. It substantiated that PLA2000‐containing microspheres were subject to controlled degradation that was necessary to achieve continuous release profiles of the antigen. Immunization of rabbits by subcutaneous injection of BSA‐containing microspheres enhanced the antigenicity of BSA, and significantly increased the duration of humoral immune responses. © 1995 John Wiley & Sons, Inc.
Determination of the interfacial mass transfer coefficient of vinyl acetate monomer diffusion into poly(vinyl acetate) and polystyrene latex particles stabilized with different stabilization mechanisms using a vapor phase addition method
Authors: Kim Joong‐In , Vanderhoff John W. , Klein Andrew 
Published: April 2003

AbstractA vapor phase monomer addition method was used to measure the monomer transfer rate into latex particles. The classical mathematical model for the diffusion process was used to calculate the overall mass transfer coefficients of monomer between the vapor and the water phases, and between the water and the polymer particle phases. At the initial stage of the monomer transfer into the glassy polystyrene latex particles at 60°C, the rate‐determining step was the monomer transfer inside the polymer. As more monomer transferred into the latex particles and the glass transition temperature of the swollen latex particles decreased below the experimental temperature, the rate‐determining step became the monomer transfer across the interfacial surfactant layer. This transition was not observed with poly(vinyl acetate) latex, which was rubbery at the experimental temperature. The diffusion coefficients calculated were in the order of 10−13 to 10‐14 cm2/s. These low values correspond to molecular diffusion of small molecules through a solid or glassy membrane. This was attributed to the resistance of the adsorbed surfactant layer. The mass transfer rates into latex particles stabilized with ionic, nonionic surfactants, and a water‐soluble polymer were compared. In the case of the ionic surfactant, sodium dodecyl sulfate, when a large amount of electrolyte was added, the mass transfer rate decreased compared to the electrolyte addition free case. This was attributed to the formation of a “condensed” layer of adsorbed surfactant. Adsorbed nonionic surfactant or water‐soluble polymer showed larger resistance to monomer transport compared to the ionic surfactant layer. © 1995 John Wiley & Sons, Inc.
The molecular basis of fracture in polystyrene films: Role of molecular weight
Authors: Sambasivam M. , Klein A. , Sperling L. H. 
Published: April 2003

AbstractThe molecular basis for fracture was examined using a custom‐built Dental Burr Grinding Instrument, which cuts at a depth of 500 nm per pass. A direct miniemulsification method was used to form uniform‐sized latex particles from narrow molecular weight distribution, anionically synthesized polystyrenes. Several polystyrenes were examined as a function of molecular weight, and blends were made of high and low molecular weight polystyrenes. In addition, a broad molecular weight polystyrene was included for comparison. These latexes were dried and cleaned, and molded under mild conditions, followed by annealing for various lengths of time at 144°C. The Dental Burr Grinding Instrument measures the total energy required to fracture the sample. The total number of chains undergoing scission per unit volume was determined via GPC before and after the fracture process. Using an energy balance approach, the total number of chains undergoing pullout (from either side of the fracture surfaces) was estimated. In order to obtain a broader picture of the process, data collected by Mohammadi et al., and by Sambasivam et al., were integrated into the analysis. Basically, at very low molecular weights, ca. 32,000 g/mol, substantially 100% pullout occurs. At the midmolecular weight range, about 150,000 to 180,000 g/mol, chain scission and chain pullout contributions to the total energy are approximately equal. For very high molecular weights, the chain scission contribution is about 90%. A scaling relationship is proposed between the molecular weight of the polymer and the fraction of chains undergoing scission. © 1995 John Wiley & Sons, Inc.
Core‐shell structured latex particles. I. Copolymerization of styrene/benzyl methacrylate as a choice for shell material and characterization of poly(n‐butyl acrylate) core latex particles
Authors: Segall I. , Dimonie V. L. , El‐Aasser M. S. , Soskey P. R. , Mylonakis S. G. 
Published: April 2003

AbstractComposition, molecular weight, and microstructure of the “shell” polymer in core‐shell structured latex particles, designed for toughening polycarbonate matrix, should be controlled for enhanced miscibility between the shell polymer and the matrix. Various “shell polymer” systems based on styrene (St) and benzyl methacrylate (BM) were synthesized. Reactivity ratios were determined for (St) and (BM). Chain transfer efficiency studies revealed the susceptibility of styrene to transfer to a chain transfer agent. Benzyl methacrylate was found to have steric and stability factors hindering its tendency to chain transfer with various chain transfer agent. Miscibility tests between P(St/BM) and polycarbonate (PC) indicated different degrees of miscibility, depending upon polymerization conditions. Factors other than molecular weight, such as branching and crosslinking, were found to play a role in the miscibility. Monodisperse poly(n‐butyl acrylate) (PBA) seed latex particles of variable degree of crosslinking and particle size were successfully synthesized by batch emulsion polymerization. © 1995 John Wiley & Sons, Inc.
Rheo‐optical FTIR spectroscopy of epoxy resins
Authors: Scherzer Tom 
Published: April 2003

AbstractThis article presents the results of the first application of rheooptical Fourier transform infrared (FTIR) spectroscopy to monitor orientation phenomena in highly crosslinked epoxy/amine networks during the uniaxial deformation above their glass transition temperature. The resins were prepared from the diglycidyl ether of bisphenol‐A (DGEBA) and various polyether di‐and triamines in order to influence the structure of the network formed. The molecular orientation is discussea with respect to network density and structure. The orientation behavior is mainly determined by the flexibility of the polyether chain and the homogeneity of the network structure. Additionally, the epoxy resins were subjected to successive loading‐unloading cycles. The investigations show that the orientation of epoxy networks in their rubbery state is completely reversible, and that no significant fatigue due to gradual chain rupture occurs until sample failure. © 1995 John Wiley & Sons, Inc.
Effect of ethylene‐propylene copolymer with residual PE crystallinity on mechanical properties and morphology of PP/HDPE blends
Authors: Zhu Wei , Zhang Xuequan , Feng Zhiliu , Huang Baotong 
Published: April 2003

AbstractMorphology and mechanical properties of polypropylene (PP)/high density polyethylene (HDPE) blends modified by ethylene‐propylene copolymers (EPC) with residual PE crystallinity were investigated. The EPC showed different interfacial behavior in PP/HDPE blends of different compositions. A 25/75 blend of PP/HDPE (weight ratio) showed improved tensile strength and elongation at break at low EPC content (5 wt %). For the PP/HDPE = 50/50 blend, the presence of the EPC component tended to make the PP dispresed phase structure transform into a cocontinuous one, probably caused by improved viscosity matching of the two components. Both tensile strength and elongation at break were improved at EPC content of 5 wt %. For PP/HDPE 75/25 blends, the much smaller dispersed HDPE phase and significantly improved elongation at break resulted from compatibilization by EPC copolymers. © 1995 John Wiley & Sons, Inc.
1H‐NMR study of reaction of melamine with oxiranes
Authors: Lubczak Jacek 
Published: April 2003

AbstractThis work describes results of investigations relative to composition and structure of the initial products of the addition of oxiranes to melamine analyzed by1H‐NMR spectrometry. The work Algebraic equations are shown that describe changes of contents in the functional groups of intermediate products in the function of the number of moles of oxirane that were attached. Reactivity of individual function groups of intermediate products are also discussed. The structure of polyetherols with ans‐triazine ring that forms in the reaction of melamine with oxiranes is proposed on the basis of these investigations. © 1995 John Wiley & Sons, Inc.
Acoustic absorption performance of polyacrylic composite latex
Authors: Yao Kangde , Cheng Guoxiang , Lu Tao , Zhu Wengsheng , Shun Qingchi , Wang Tiyong , Zhang Dawei 
Published: April 2003

AbstractIn this work, copolymers and a multilayer core/shell P(BA/BA‐MMA/MMA) composite latex of methyl methacrylate (MMA), butyl acrylate (BA), and ethyl acrylate (EA) were prepared by emulsion polymerization. The thermal and the mechanical properties of their films were characterized by differential scanning calorimeter (DSC) and dynamic mechanical analysis (DMA), while the acoustic absorption performance of dried films were estimated using the standing wave pipe method. The results show that a multilayer core/shell polymer of P(BA/BA‐MMA/MMA) has many glass transitions in a broad temperature region, and in the frequency range of sound, this core/shell polymer has better acoustic absorption properties than the random copolymer of P(BA‐MMA). © 1995 John Wiley & Sons, Inc.
Swelling of hydrophilic polymers. IV
Authors: Ogawa Ikuko , Yamano Hideki , Miyagawa Kinjiro 
Published: April 2003

AbstractThe swelling of five types of spherical crosslinked dextrans (Sephadex) that are either nonionic (G) or ionic [carboxymethyl (CM), sulphopropyl (SP), diethylaminoethyl (DEAE), and diethyl‐(2‐hydroxypropyl)aminoethyl (QAE)] in the same skeleton has been studied in water at different dissolved oxygen concentrations by microscopic observation and by dilatometry. The maximum specific volume, Vmax/V0 obtained by microscopic observation increased with the lowered dissolved oxygen concentration for each Sephadex. The change of the maximum specific volume was closely related to the changes of the dissolved oxygen concentrations. The maximum changes of the total volume took the larger negative values at the lower dissolved oxygen concentration. The effect of the difference in the dissolved oxygen on the change of the total volume with swelling was closely related to the viscosity B coefficient of the Jones‐Dole equation. From these results, we conclude that the structure of water on the inside of the gel differs from that on the outside of the gel. © 1995 John Wiley & Sons, Inc.
Plasma surface modification of propylene‐based polymers by silicon and tin‐containing compounds
Authors: Akovali Güneri , Rzaev Zakir M. O. , Mamedov D. H. 
Published: April 2003

AbstractPlasma surface modifications of homo‐, co‐, and terpolymers of propylene films in the presence of selected organosilicon and organotin compounds were investigated. For this, organosilan(stannan)e type compounds (such as vinyltriethoxysilane, 3‐aminopropyltriethoxysilane, and tetraethylstannane) as well as organosiloxan (stannoxan)e type compounds (such as hexamethyldisiloxane and hexabutyldistannoxane) were exployed in plasma. Plasma surface modification of polyolefin films with organosilicon plasma has led to increase of the hydrophobicity, while the presence of organotin compounds in plasma produced less hydrophobic surfaces. Reaction of plasma‐activated polyolefin films further with vinyltriethoxysilane‐maleic anhydride oligomer also led to an increase in the hydrophobicity of polypropylene surfaces. It is observed that the degrees of swelling of (virgin, plasma‐treated, and plasma‐modified) polypropylene films in cyclohexanone strongly depend on the nature of the organoelement compounds used, organosilicon plasma causing lower degrees of swelling. The changes of surface properties observed are explained by different surface structures produced in plasma: in the case of organosilicon compounds, it is believed that poly(organosiloxane) and for organotin compounds poly(organotincarboxylate) fragments are formed primarily. © 1995 John Wiley & Sons, Inc.
Photooxidative degradation of polyethylene containing flame retardants by monochromatic light
Authors: Torikai Ayako , Chigita Ko‐Ichi , Okisaki Fumio , Nagata Masatoshi 
Published: April 2003

AbstractPhotodegradation of incombustible polymer materials [high‐density (HD) and low‐density (LD) polyethylene (PE) containing 0.5 to 2.0 phr of decabromodiphenyl ether (DBDE) or tetrabromobisphenol A (TBA) as a flame retardant] were studied using an Okazaki Large Spectrograph (OLS). Samples were irradiated in air at 23°C with monochromatic light of wavelengths at 260, 280, 300, 320, 340, and 360 nm. Ultraviolet and Fourier transform infrared (FTIR) spectra were taken to estimate the chemical changes caused by photoirradiation. Molecular weight change was followed by gel permeation chromatography (GPC) measurements. It was found that the photostability of PE samples was reduced by the addition of flame retardants. The threshold wavelengths of photodegradation are 320 nm and 360 nm for PE–TBA samples and PE–DBDE samples, respectively. Main‐chain scission is favored when the irradiation was carried out with the light of wavelength 300 nm for HDPE–DBDE and HDPE–TBA samples. The most effective irradiation wavelengths for crosslinking are found to be 300 nm and 280 nm for LDPE–DBDE and LDPE–TBA samples, respectively. 1995 John Wiley & Sons, Inc.