bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and mesomorphic behavior of terminally carboxyl oligo(ethylene oxide) monomethyl ethers‐substituted side chain liquid crystalline polysiloxanes. I
Authors: Jeng Gow‐Pyng Cheng , Kuo Jen‐Feng , Chen Chuh‐Yung 
Published: April 2003

AbstractA series of alkene monomers containing carboxyl biphenyl benzoate ester or carboxyl p,p′‐phenyl benzoate ester based on mesogenic core with a carboxyl (±)‐2‐methyl ethylene glycol monomethyl ether group or various lengths of carboxyl oligo (ethylene oxide) monomethyl ethers as the terminal group were synthesized. And they were grafted onto the poly(methylhydrosiloxanes) (PMHS) by the platinum catalyzed hydrosilylation process. Their molecular structure, the thermal transitions temperature, and mesophase texture of monomers and of polymers were characterized using 1H nuclear magnetic resonance, differential scanning calorimetry, and polarizing optical microscopy with hot stage. The polymers obtained all show smectic phase while their precursor monomers show both smectic and/or nematic phase, or in some cases, no mesophase. The factors governing mesophase texture and transition temperature are discussed. © 1993 John Wiley & Sons, Inc.
Effect of filler on rheologic and thermodynamic characteristics of binary polymeric mixture melts
Authors: Lipatov Yu. S. , Shumsky V. F. , Rosovitsky V. F. , Getmanchuk I. P. , Kvitka N. A. 
Published: April 2003

AbstractRheologic, thermodynamic, and mechanical loss tangent properties of a binary polymeric mixture were studied. The system was a mixture of poly(vinyl acetate) (PVA) with ethylenevinyl acetate copolymer (EVC) with varying concentrations of the polymer components and filler. A correlation between the above characteristics of the PVA/EVC two‐phase mixture was found. This mixture was thermodynamically unstable (positive values of the interaction parameter, χ) practically over the entire range of compositions at temperatures of rehologic studies. The presence of a disperse filler raised the thermodynamic stability, that is, parameter χ decreased. Reversal of the sign of the temperature dependence of χ of a mixture with increasing concentration of filler was found. The variations of viscosity with the composition, temperature, and shear for the PVA/EVC mixture are ascribed to different levels of heterogeneity occurring in the process of the shear straining in the working unit of the rheometer. © 1993 John Wiley & Sons, Inc.
Determination of optimum blending conditions for poly(vinyl chloride)/epoxidized natural rubber blends
Authors: Nasir Zainal A. , Ishiaku Umaru S. , Ishak Zainal A. Mohd 
Published: April 2003

AbstractAn attempt to resolve the difficulties normally faced in preparing PVC‐dominant PVC/ENR blends with the Brabender plasticorder is discussed. As expected, it was found that the mechanical properties of PVC/ENR blends are greatly influenced by the mixing parameters, which are further reinforced with evidence from both dynamic mechanical analysis (DMA) and morphological studies. Both techniques showed the attainment of compatible 50/50/PVC/ENR blends, the former a single glass transition temperature (Tg) and the latter a single‐phase system, albeit their inherent properties are dependent on the blending parameters. By utilizing the correlation between mixing temperature and rotor speed derived, good PVC/ENR blends can be easily procured. © 1993 John Wiley & Sons, Inc.
Study of the acid hydrolysis of the starch graft copolymers with hydroxylic methacrylates
Authors: Gurruchaga M. , Goñi I. , Valero M. , Guzman G. M. 
Published: April 2003

AbstractThe acid hydrolysis method is usually utilized to separate acrylic polymer chains grafted onto amylopectin (AMP). The hydrolysis with the HCl acid has been found to be appropriate when we grafted hydroxyethyl methacrylate (HEMA) and hydroxypropyl methacrylate (HPMA). Using the perchloric acid method, various secondary reactions appear falsifying the grafting yields. © 1993 John Wiley & Sons, Inc.
Permeation of several gases through elastomers, with emphasis on the deuterium/hydrogen pair
Authors: Fitch M. W. , Koros W. J. , Nolen R. L. , Carnes J. R. 
Published: April 2003

AbstractThe diffusion and permeation coefficients for He, H2, D2, O2, and N2 in a variety of elastomers were measured by simple manometric methods. The elastomers studied were butyl rubber; Hypalon® 40 and 45; Viton® E60 and GF; Hydrin® 100 and filled Hydrin® 100; Kraton® G, FG, and KG VTEOS; EPDM; epoxidized natural rubber; and neoprene. Consistent with earlier studies, elastomers with higher glass transition temperatures exhibited lower diffusion coefficients. The ratio of diffusion coefficients of the hydrogen isotope pair differed from the purely molecular‐weight‐based prediction. Deuterium's slightly smaller size relative to hydrogen is consistent with observed deviations from the molecular‐weight‐based diffusion coefficient ratio. © 1993 John Wiley & Sons, Inc.
Improvement of wood properties by impregnation with macromonomeric initiators (macroinimers)
Authors: Hazer Baki , Örs Yalçin , Alma M. Hakki 
Published: April 2003

AbstractScotch pine, eastern spruce, and eastern beech samples sawed longitudinally were impregnated with a new type of polymerization mixture (macroinimer and styrene), leading to crosslinked block copolymers of styrene and poly(ethylene glycol). Weight gains of 36.37–91.13% were obtained after polymerization for 2 h. Water uptake of the polymerized wood was found to be 35.13–72.07% after a water soak test of 144 h. While spruce gave the highest uptake (72.07%), beech showed the lowest value (35.13%). The specimens impregnated with the mixture of macroinimer and styrene showed a water‐repellent effectiveness of 35.14–58.15% after a water soaking test of 144 h. The highest values of water‐repellent effectiveness were found for spruce, while the lowest values were obtained for pine. A maximum antiswell efficiency (ASE) of 42.43% was obtained for spruce, followed in order by beech and pine, respectively. The ASE value increases with an increase in wt % gain. Improvements of 19.12% in longitudinal compression and 25% in bending strength were also achieved for spruce samples with low weight percent gain. IR spectroscopy was used for chemical characterization of the wood–polymer composite. © 1993 John Wiley & Sons, Inc.
Surface and interfacial FTIR spectroscopic studies of latexes. V. The effects of copolymer composition on surfactant exudation
Authors: Thorstenson Timothy A. , Urban Marek W. 
Published: April 2003

AbstractThe influence of copolymer structure on the magnitude of surfactant enrichment to the film—air and film—substrate interfaces of latex films prepared on a polytetrafluoroethylene (PTFE) substrate is investigated. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR FTIR) is used to elucidate the surfactant enrichment by the comparison of butyl acrylate/methyl methacrylate/methacrylic acid (BA/MMA/MAA) and ethyl acrylate/methacrylic acid (EA/MAA) latex systems prepared with various anionic surfactants. It is found that, in all cases, the magnitude of exudation of the sulfonate‐containing surfactants manifested by the presence of S—O bending and scissors modes is reduced in the case of the BA/MMA/MAA latex. Similar behavior is observed when the spectra of films prepared on a liquid mercury substrate are compared. It is believed that this behavior results from the longer aliphatic n‐butyl groups present in this copolymer that enhances compatibility by providing a greater opportunity for hydrophobic surfactant—copolymer interactions. The butyl groups may also reduce excess interfacial free energy by orienting themselves toward the film interfaces, which, in turn, will reduce the surface tension‐induced driving force for surfactant exudation. © 1993 John Wiley & Sons, Inc.
Miscible and immiscible blends of ABS with PMMA. II. Mechanical and surface properties
Authors: Kim Byung Kyu , Shin Gui Sook , Kim Young Jin , Park Tae Sung 
Published: April 2003

AbstractMechanical and surface properties of injection‐molded specimens for miscible and immiscible blends of ABS with PMMA were investigated. Regardless of miscibility, hardness, modulus, and strength of the blends generally showed a smooth variation with composition, with the possible exception of impact strength. In miscible blends, impact strength decreased smoothly with PMMA; however, in immiscible blends, a drastic drop to less than the half that of ABS was obtained at 10 wt % PMMA. Compounding at higher temperature gave decreased modulus and strength and increased impact strength. Surface gloss decreased with PMMA addition in the miscible system and increased in the immiscible system up to 50 wt % PMMA. From contact‐angle and FTIR measurements, it is suggested that the surface properties are governed by miscibility and the viscosity ratio of the components. © 1993 John Wiley & Sons, Inc.
Characterization of the surface layer of integrally skinned polyimide membranes: Relationship with their mechanism of formation
Authors: Perez S. , Merlen E. , Robert E. , Addad J. P. Cohen , Viallat A. 
Published: April 2003

AbstractA series of dense films and membranes was prepared using different processes; their surface morphology was investigated by transmission electron microscopy using the replication technique. On the basis of TEM results, SEM observations of cross sections of membranes and gas‐separation properties of membranes, two kinds of membrane morphology are evidenced in relation to their preparation conditions and final properties. The first one gives an ultrafiltration‐type membrane. Large nodules are observed on the surface of the membranes. It is suggested that these are formed by liquid–liquid separation that occurs by nucleation and growth of the polymer‐rich phase. The second one yields gas‐separation‐type membranes. No nodules are evident at the surface of these membranes. The skin is formed by a step that concentrates the initial solution. It is followed by the transformation of the solution in the glassy state. Liquid—liquid separation takes place below the first skin layers by nucleation and growth of the polymer‐poor phase. © 1993 John Wiley & Sons, Inc.
Fractionation of low molecular weight polyethylene by high‐pressure soxhlet extraction
Authors: Scholsky Kevin M. 
Published: April 2003

AbstractThe use of quantitative, high‐pressure Soxhlet extraction for the fractionation of low molecular weight polyethylene samples is described. Liquid carbon dioxide was found to be a suitable solvent for the lowest molecular weight hydrocarbons but failed to solubilize hydrocarbons with molecular weights greater than C‐40—C‐50. Liquid pentane was found to be an effective solvent for hydrocarbons that were insoluble in liquid CO2. Careful, stepwise adjustment of the extraction solvent temperature produced polymer fractions with molecular weight distributions substantially narrower than those of the parent materials. Polymer fractions with molecular weights up to C‐90 were analyzed by high‐temperature gas chromatography. These analyses demonstrated the effectiveness of the technique in fractionating polymers according to molecular weight. Further evidence was provided by thermal analysis of the fractions that indicated melting‐point transitions that were much sharper than those of the parent materials. High‐pressure Soxhlet extraction offers considerable potential as a general method for purification and fractionation of synthetic and natural polymers. © 1993 John Wiley & Sons, Inc.
SEC–viscometer detector systems. I. Calibration and determination of mark–houwink constants
Authors: Lew R. , Cheung P. , Balke S. T. , Mourey T. H. 
Published: April 2003

AbstractFive different types of calibration curve currently used in size exclusion chromatography‐differential viscometer (SEC–DV) systems were identified and their use summarized. A simple method of deriving weighting factors for fitting local intrinsic viscosity calibration curves was shown to greatly improve the precision of calculated molecular weight distributions. The problem of reliably extrapolating the fitted curves to allow for differences in sensitivity among detectors has yet to be examined. With regard to Mark—Houwink constants, a method of fitting data from the SEC–DV system to obtain more statistically sound values was derived. For the data used here, the new method involves fitting a plot of logarithm of the local intrinsic viscosity of the sample vs. logarithm of the universal calibration curve parameter, Ji. Results for the data obtained appeared only slightly more precise than those for the traditional method. However, the new method promises improved reliability. © 1993 John Wiley & Sons, Inc.
Curie transition and piezoelectricity of the blends of a ferroelectric VDF/TrFE copolymer and PMMA
Authors: Kim Kap Jin , Kim Gwan Bum 
Published: April 2003

AbstractThe Curie transition, even though the conformational change at the Curie transition primarily arises from intermolecular interaction, is highly dependent on the crystallization conditions. A slower cooling rate from the melt during paraelectric crystallization lowers Tc, increases the portion of Fβ at the expense of Fα reduction, and produces a more unstable ferroelectric phase. T is rarely dependent upon the amount of PMMA, but T is increased with the PMMA content. PMMA has a favorable action in forming a more stable ferroelectric phase in the P(VDF/TrFE)/PMMA blend and elevating the Curie transition point because of the all‐trans sequence conformation of PMMA and a specific intermolecular interaction with P(VDF/TrFE) in the melt state. However, PMMA reduces the total amount of the crystalline phase, the electric response, and the piezoelectricity. © 1993 John Wiley & Sons, Inc.
Novel phthalocyanine/polyol high‐solids coatings: Structure—property relationships
Authors: Exsted Bert J. , Urban Marek W. 
Published: April 2003

AbstractA convenient synthetic procedure for preparing nickel carboxylated phthalocyanine is reported. Upon further hydroxylation, such metal phthalocyanine moieties are incorporated into several melamine‐based polyester high‐solids systems and the structure—property correlations are examined. Molecular level spectroscopic FTIR analysis and mechanical testing are correlated in an effort to establish structure—property relations in these coatings. It is found that the presence of metal phthalocyanine macrocycle as a cross‐linking agent enhances such properties as adhesion, hardness, and impact resistance. © 1993 John Wiley & Sons, Inc.
Nonaqueous diagnostic polymers and coatings
Authors: Azhar A. , Burke A. , Dubois J. , Usmani A. 
Published: April 2003

AbstractWater‐borne enzymatic coating‐based dry chemistries have been used for more than 20 years, especially by diabetics, for self‐monitoring of blood glucose. Until now, it has been believed that enzymes work only in water and not in organic solvents. Synthesis of a hydroxylated acrylic polymer and the novel concept of dispersing enzymes have enabled us to design nonaqueous diagnostic coatings. These coating films gave excellent dose response and dynamic range. Additionally, these coatings can easily be ranged by a wide variety of antioxidants. In contrast, water‐borne coatings are extremely difficult to range. Furthermore, nonaqueous coating films produce color signals that are independent of the reaction time with excellent thermal stability. Molecular forces and thermodynamical considerations have been used to explain the performance of the new dry chemistries. An organic reaction mechanism of ranging has also been proposed for the nonaqueous system. © 1993 John Wiley & Sons, Inc.
A differential scanning calorimetric study of the interaction of zinc benzothiazole‐2‐thiolate, sulfur, stearic acid, and zinc stearate in the absence and presence of polyisoprene
Authors: Luyt Adriaan S. 
Published: April 2003

AbstractThe interactions between mixtures of zinc benzothiazole‐2‐thiolate (ZMBT), sulfur, stearic acid, and zinc stearate were studied by DSC in the absence and presence of polyisoprene (IR). It was established that ZMBT reacts with stearic acid to form zinc stearate and 2‐mercaptobenzothiazole (MBT). In the presence of stearate compounds, MBT is readily available from the start of vulcanization, whereas it becomes only slowly available in the absence of these compounds. The effectiveness of the vulcanization process increases for the systems IR/ZMBT/sulfur < IR/ZMBT/sulfur/stearic acid < IR/ZMBT/sulfur/zinc stearate. In view of the above results, interaction mechanisms are proposed for the different systems. © 1993 John Wiley & Sons, Inc.
Precrack hysteresis energy of elastomer‐modified polycarbonates in determining its ductile–brittle transition
Authors: Chang Feng‐Chin , Hsu Hon‐Chun 
Published: April 2003

AbstractFor ductile fracture, the precrack plastic zone has to exceed a critical value, and precrack hysteresis energy has been employed to characterize the plastic zone. The presence of elastomer in polycarbonate is able to enhance precrack hysteresis and, therefore, toughens the polycarbonate matrix. Higher precrack hysteresis means that a greater fraction of the input energy converts into plasticity and leaves less storage energy available to strain the crack tip for crack Initiation. If the precrack plastic zone is above the critical value before onset of initiation, the crack growth developed thereafter will be effectively contained within the domain of the plastic zone and results in mass shear, yielding ductile fracture. In this paper, the elastomer toughening is classified as promotion of ductile failure through mass shear yielding and the localized energy dissipation processes. The localized energy dissipations are further divided into the activities occurring on and underneath the fracture surface. A different approach in interpreting the elastomer‐toughening mechanism is discussed in detail. © 1993 John Wiley & Sons, Inc.
Chromatographic separation of azeotropic and low‐conversion poly(styrene‐stat‐2‐methoxyethyl methacrylate) according to chemical composition
Authors: Konáš M. , Kubín M. 
Published: April 2003

AbstractDistribution of the chemical composition of statistical copolymers was studied by HPLC using azeotropic and low‐conversion copolymers of styrene and 2‐methoxyethyl methacrylate that are expected to exhibit only statistical chemical heterogeneity. Adsorption behavior of the copolymers was studied dynamically with a specially designed apparatus, using flow through a column packed with a macroporous silica and a mixed mobile phase 1,2‐dichloroethane (DCE)–heptane (50 : 50 v/v) and tetrahydrofuran (THF). The shape of displacement isotherms indicates the existence of a region lying near the displacement critical composition, where the total amount of adsorbed copolymer is independent of the mobilephase composition. Fractionation was achieved by step‐by‐step desorption of a copolymer sample previously adsorbed on silica packed into a chromatographic column, by means of a stepwise gradient of mobile‐phase composition. The styrene content of isolated fractions decreased with increasing content of THF in the mobile phase. The experimentally determined integral weight distribution of chemical composition shows good agreement with theoretical curves. © 1993 John Wiley & Sons, Inc.
Network structure and properties of platinum‐catalyzed addition cure release coatings
Authors: Stein J. , Grade H. , Williams E. A. , Codella P. J. , Smith J. F. 
Published: April 2003

AbstractSilicone‐release coatings are used by the pressure‐sensitive adhesive industry for labeling applications. Typical release coatings are prepared by the platinum‐catalyzed addition reaction of a silicone hydride fluid with a silicone vinyl polymer. Methodology has been developed to determine the network structure of cured release coatings, which involves degradation of the network with trifluoromethane sulfonic acid in excess hexamethyldisiloxane. Gas chromatography–mass spectrometry (GC–MS) and gas chromatography (GC) were employed to identify and quantify residual functionality and cross‐links. Residual hydride functionality was also determined by attenuated total reflectance–Fourier transform infrared spectroscopy (ATRFTIR). The observation of network structure by solid‐state 29Si‐NMR using cross polarization (CP) and magic angle spinning (MAS) is also discussed. The networks underwent a postcure as evidenced by a decrease in residual hydride functionality and an increase in silane content and/or cross‐links. © 1993 John Wiley & Sons, Inc.
The use of latex rubber‐modified polystyrene as a model system for HIPS: Effect of particle size
Authors: Cook D. G. , Rudin A. , Plumtree A. 
Published: April 2003

AbstractThe effect of particle size in high‐impact polystyrene (HIPS) is difficult to determine because of a size polydispersity and changes in particle morphology during the HIPS synthesis process. In this study, poly(n‐butyl acrylate) rubber core/polystyrene shell particles were made by emulsion polymerization methods such that the only difference was in particle diameter, which ranged from 0.4 to 6.2 μm. The latexes were subsequently incorporated into a polystyrene matrix to form a toughened composite that acted as a simple model for HIPS. Charpy impact energies (notched and unnotched) of the composites showed that there was no toughening for particle sizes less than 2μm in diameter. The optimal impact energy was obtained with particle diameters in the region of 2–3 μm at 8 wt % rubber loading. The results imply that craze stabilization is the most important aspect of the toughening process. A simple toughening model based on the crack opening displacement of craze breakdown between adjacent rubber particles is suggested, with interparticle distance as the most important variable. © 1993 John Wiley & Sons, Inc.
Preparation and characterization of electropolymerized poly(N‐substituted methacrylamide) matrices on graphite fibers
Authors: Liang Jeng‐Li , Bell James P. , Scola Daniel A. 
Published: April 2003

Abstract2‐ or 4‐carboxyphenyl methacrylamide (2‐ or 4‐CPM) was successfully electrocopolymerized with either methylmethacrylate (MMA) or N‐phenylmaleimide (NPMI) to form a thick thermoplastic matrix with high glass‐transition temperature (200–300°C), on Hercules AS‐4 graphite fibers. The dependence of the diffusion of active species through the coating upon the solvent/water ratio in the cell was estimated from the electrochemical diffusion behavior of hexacyanoferrate (III) ions. A higher solvent/water ratio helped to increase polymer weight gain by increasing the solvent swelling and increasing the diffusion coefficient of active species. A highly solvent‐swollen polymer layer promoted the rate of polymer weight gain. The copolymer composition of 4‐CPM/MMA and 4‐CPM/NPMI polymers was random, and the effects of variables were consistent with free‐radical polymerization kinetics. The electropolymerization rates of 4‐CPM/MMA and 4‐CPM/NPMI were increased by increasing current density and monomer concentration. For a slight temperature increase (from 28–45°), electropolymerization rate and polymer weight gain increased dramatically for the 4‐CPM/NPMI system. © 1993 John Wiley & Sons, Inc.
A relationship between NMR cross‐polarization rates and dynamic storage modulae of polymers
Authors: Parker A. A. , Marcinko J. J. , Rinaldi P. , Hedrick D. P. , Ritchey W. M. 
Published: April 2003

AbstractA relationship between dynamic storage modulus (E′) and the mean cross‐polarization time constants 〈TCH〉 for 16 polymer data sets has been established by using a standard linear solid model. This model is used in an attempt to equate the process of cross‐polarization with mechanical rigidity by virtue of the implicit dependence of each phenomenon on molecular motion. The apparent validity of the relationship between these parameters indicates that cross‐polarization in polymers can be a function of molecular motion in addition to microscopic spin dynamics. The limitations as well as practical applications of this relationship are discussed. © 1993 John Wiley & Sons, Inc.