bluuebunny/crossref_metadata_2025_split huggingface dataset:
Composite membranes of poly(1‐trimethylsilyl‐1‐propyne) and poly(dimethyl siloxane) and their pervaporation properties for ethanol–water mixture
Authors: Kang Yong Soo , Shin Eun Mi , Jung Bumsuk , Kim Jae‐Jin 
Published: April 2003

AbstractA poly(1‐trimethylsilyl‐1‐propyne) (PTMSP) membrane was systematically modified to prevent flux decline over time by incorporating poly(dimethyl siloxane) (PDMS) in three different ways: (1) semi‐interpenetrating polymer network (I series), (2) PDMS sorption (S series), and (3) PDMS sorption and crosslinking (X series). The PTMSP and PDMS phases were partially mixed in the I series, which was confirmed by the measurement of density and glass transition temperature. The flux and separation factor in pervaporation of an ethanol–water mixture decrease with time for the I series, analogous to the behavior of pure PTMSP. However, the flux and separation factor remained steady with time in the case of the S and X series. The sorption method appears to be a good means for maintaining a time‐unvarying flux and separation factor at a minimum expense. © 1994 John Wiley & Sons, Inc.
Relaxations in thermosets. XXIX. Calorimetric studies of the curing kinetics of nonstoichiometric diamine–epoxy mixtures
Authors: Wasserman S. , Johari G. P. 
Published: April 2003

AbstractThe curing kinetics of nonstoichiometric mixtures of diglycidyl ether of bisphenol A, with ethylene diamine, propylene diamine, and hexamethylene diamine have been measured under both isothermal and ramp‐curing condition. Their kinetics are faster than for stoichiometric compositions and the reactions reach completion. The total heat evolved for the amine‐rich composition is greater than for the amine‐deficient. None of the available formalisms is consistent with the results. This and the variation in the heat of reaction indicate that steric effects are important for both the reaction rate and the heat evolved. It is argued that the standard heat of reaction of primary amine with the epoxide group differs from that of secondary amine. © 1994 John Wiley & Sons, Inc.
Self‐crosslinkable blend of zinc‐sulfonated EPDM and epoxidized natural rubber
Authors: Manoj N. R. , De P. P. , De S. K. , Peiffer D. G. 
Published: April 2003

AbstractThe zinc‐sulfonated EPDM (SEPDM)–epoxidized natural rubber (ENR) blend is selfcrosslinkable in the sense that it undergoes crosslinking on molding at high temperatures without the aid of any external curing agents. This is evident from Monsanto rheometric, solvent swelling, and infrared spectroscopic studies. The sulfonate anion is believed to react with an epoxide ring, leading to the formation of sulfonate ester and ether crosslinks. The extent of crosslinking depends on the degree of sulfonation of SEPDM and epoxidation level of ENR, the blend ratio, molding time, and temperature. Dynamic mechanical analyses of the blends show the immiscibility of the blend components. The chemical interaction is also manifested in the shift of the glass transition temperature of ENR to the hightemperature region. © 1994 John Wiley & Sons, Inc.
Pervaporation of ethanol–organic solvent mixtures through poly(2,6‐dimethyl‐1,4‐phenylene oxide) membrane
Authors: Schauer J. 
Published: April 2003

AbstractHomogeneous dense membranes of poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) were used to separate mixtures of ethanol—organic liquid by pervaporation. If the organic liquid had a strong affinity to PPO (e.g., toluene) and its concentration in the feed was low, smaller molecules of ethanol permeate preferentially through the membrane. When the concentration of this liquid in the feed was increased up to a certain value, the membrane was, on the contrary, permeated by it preferentially. When its concentration in the feed was further increased, flux through the membrane is dramatically increased and the membrane lost its selectivity. If the liquid in a binary mixture with ethanol in the feed had a low affinity to PPO (e.g., 1‐propanol), the selectivity of the PPO membrane virtually did not depend on the feed composition, and the membrane was preferentially permeated by smaller molecules. © 1994 John Wiley & Sons, Inc.
Development of in situ blends of poly(p‐oxybenzoate‐co‐p‐phenyleneisophthalate) with other thermotropic liquid crystalline polymers
Authors: Gupta Balaram , Calundann Gordon , Charbonneau Larry F. , Linstid H. Clay , Shepherd James P. , Sawyer Linda C. 
Published: April 2003

AbstractA new in situ polymerization method is discussed wherein monomers of the major component are polymerized in the presence of a preformed thermotropic liquid crystalline polymer (LCP). Poly(p‐oxybenzoate‐co‐p‐phenyleneisophthalate) (HIQ) was chosen for this study. HIQ is well known to have a narrow process window and to be difficult to process reproducibly, both drawbacks for a commercial product. An in situ polymerization of the HIQ monomers in the presence of a fully polymerized LCP, such as poly(4‐oxybenzoate‐co‐6‐oxy‐2‐naphthoate) (CO) results in the “CO–HIQ” in situ blend. The in situ blend exhibited reduced biphasic morphology and was more homogeneous than was HIQ. The glass fiber‐filled CO–HIQ resin also featured improved melt flow and more reproducible mechanical properties than those of HIQ. The in situ blends were characterized by optical microscopy, 1H‐NMR, and melt rheology. The effect of the LCP level on the morphology of the in situ blend is discussed. © 1994 John Wiley & Sons, Inc.
Self‐assembled structures of azobenzene amphiphiles: A new photorecording medium
Authors: Gillberg G. , Leube H. , Mckenzie L. , Pruksarnukul L. , Reeder L. 
Published: April 2003

AbstractThe self‐assembly of azobenzene amphiphiles by themselves and in the presence of a nonionic polymer has been studied. The conditions that yield homeotropic and uniaxial films, i.e., the optical properties of a single crystal, by spin‐coating were identified. It is shown that these films constitute a very sensitive write and erase recording medium. © 1994 John Wiley & Sons, Inc.
Monoepoxy polymerization initiated by BF3‐amine complexes in bulk. III. Influence of γ‐butyrolactone on polymer formation
Authors: Chabanne Philippe , Tighzert Lan , Pascault Jean‐Pierre 
Published: April 2003

AbstractThe influence of γ‐butyrolactone (γ‐BL), used as solvent of BF3‐amine complexes, on the polymerization of monoepoxides was studied. Different intermediate reaction products of PGE initiated by BF3‐4‐methoxyaniline (BF3‐4MA) previously solubilized in γ‐BL (55% by weight), were separated and analyzed by 1H‐NMR. It is shown that there is the opening of both epoxy and γ‐BL. The latter does not homopolymerize, but copolymerizes well with epoxy groups. The use of a large quantity of γ‐BL leads to a decreasing molar mass of the formed polymer. The kinetic study allowed to propose the mechanism of the cationic polymerization of epoxy initiated by BF3‐amine complex in the presence of γ‐BL. © 1994 John Wiley & Sons, Inc.
Terminal attachment of perfluorinated polymers to solid surfaces
Authors: Rühe J. , Blackman G. , Novotny V. J. , Clarke T. , Street G. B. , Kuan S. 
Published: April 2003

AbstractPhysisorption and chemisorption of perfluoropolyethers on solid surfaces is investigated using infrared spectroscopy, microcalorimetry, ellipsometry, X‐ray photoelectron spectroscopy, and atomic force microscopy. Physisorbed polymers show shifts of vibrational modes to lower frequencies in a few nanometers thick films, indicating interactions with the solid surfaces. Hydroxyl‐terminated polymers are thermally attached to solid surfaces, and their thicknesses increase to saturated values with increasing heating time. The thermally attached thin polymer film consists of strongly physisorbed material as well as chemisorbed material. Strongly physisorbed polymer is slowly displaced from the surface by polar, low‐molecular‐weight compounds such as water or alcohols. This is to be expected on the basis of microcalorimetric results, which yield higher heats of immersion with water than with reactive perfluoropolyethers. Atomic force microscopy experiments show that the mobility of the polymer remaining on the surface decreases substantially as the amount of the physisorbed material decreases. © 1994 John Wiley & Sons, Inc.
Static and dynamic strain‐dependent viscoelastic behavior of black‐filled EPDM vulcanizates
Authors: Namboodiri C. S. S. , Tripathy D. K. 
Published: April 2003

AbstractThe strain dependence of the dynamic mechanical properties of HAF‐N330‐filled EPDM vulcanizate was studied using a Rheovibron DDV III EP. It is shown that when a dynamic strain is superposed on a static strain, the viscoelastic response of filled rubbers becomes more complex. Under these conditions, dynamic mechanical properties do not correlate with the double strain amplitude. A strain called the “total strain” has been defined in order to interpret the experimental results. It is also shown that the dynamic mechanical properties are displacement velocity dependent, while the comparison is made under identical conditions of strain and frequency. Separability of time and strain effects is observed for the storage modulus, whereas the loss modulus is shown to be a nonseparable function. The elastic and the relaxation components, constituting the mixed function representing the storage modulus are shown to have similar deformation dependence. © 1994 John Wiley & Sons, Inc.
Novel dielectrics from IPNs derived from castor oil based polyurethanes
Authors: Suthar Bhikhu , Klempner Daniel , Frisch Kurt C. , Petrovic Zoran , Jelcic Zelimir 
Published: April 2003

AbstractThree series of interpenetrating polymer networks (IPNs) based on a polyurethane (castor oil + toluene diisocyanate) with polystyrene, poly(methyl methacrylate), and poly(n‐butyl methacrylate) were synthesized and characterized. Dielectric relaxation studies of these IPNs were carried out from −150 to 100°C in the 100 Hz to 100 kHz range. The effects of structural variables such as composition, type of vinyl monomer, as well as the effect of interaction of the phases on the dielectric properties were studied. A certain degree of phase mixing was observed to exist in all series as detected by the variation of the glass‐transition temperatures of the IPNs. Maxwell–Wagner–Sillars polarization at the interface of the two phases was observed. © 1994 John Wiley & Sons, Inc.
Synthesis and antibacterial activity of immobilized quaternary ammonium salts
Authors: Augusta S. , Gruber H. F. , Streichsbier F. 
Published: April 2003

AbstractQuaternary ammonium salts were immobilized on hydrophilic gels based on sucrose methacrylates (SM) and tested for their antibacterial properties. The cross‐linked polymers were prepared by copolymerization of monomer–SM mixtures with 4‐vinylpyridine and subsequent quaternization with 1‐bromoctane and 1‐bromoctadecan and by esterification of SM gels with 3‐pyridine carboxylic acid chloride and quaternization. In addition, immobilized quaternary salts bonded by hydrophobic as well as by hydrophilic spacers were synthesized by esterification of SM gels with 11‐bromundecanoic acid chloride and the tetraethylene glycol‐based acid chloride 13c, respectively, and subsequent reaction of the halogen‐substituted gels with tertiary amines. Suspension tests for antibacterial properties of the immobilized bactericides against Escherichia coli, Staphylococcus aureus, and Micrococcus luteus demonstrated high activity of the quaternary salts bonded by the hydrophobic spacer. Advantageously, these insoluble bactericides can be applicated without contamination of the substrate; they can be removed easily and used repeatedly. © 1994 John Wiley & Sons, Inc.
Investigation of polyamine quinones as hydrophobic curatives for epoxy resins
Authors: Rushing Rock A. , Thompson Corley , Cassidy Patrick E. 
Published: April 2003

AbstractPolyamine quinones (PAQs), which have been used previously to produce solvent‐based coatings with exceptional durability in corrosive environments, were synthesized and blended with an aliphatic diamine (diethylenetriamine, DETA) to provide a liquid, epoxy curing agent. The PAQ–amine mixture was evaluated as a curing agent for an epoxy matrix resin system for glass‐reinforced composites. After elevated temperature water exposure, short‐beam shear and dynamic mechanical analyses were performed on the composites. The ability of PAQs to enhance fiber–resin bonding was evaluated. Dynamic mechanical analysis (DMA), which is a sensitive measurement of fiber‐resin interactions, showed that the PAQ curative enhances strength retention of composites exposed to aggressive environments. © 1994 John Wiley & Sons, Inc.
Use of neural networks for modeling of olefin polymerization in high pressure tubular reactors
Authors: Chan Wai‐Man , Nascimento Cláudio A. O. 
Published: April 2003

AbstractNeural network computing is one of the fastest growing fields of artificial intelligence due to its ability to “learn” nonlinear relationships. This article presents the approach of back propagation neural networks for modeling of free radical polymerization in high pressure tubular reactors. Industrial data were used to train the network for prediction of the temperature profile along the reactor, as well as polymer properties such as density, melt flow index, and molecular weight averages. Comparisons were made between the neural network and mechanistic model predictions published in the literature. Results showed the promising capability of a neural network as an alternative approach to model polymeric systems. © 1994 John Wiley & Sons, Inc.
GPC and HPLC characterization of unsaturated polyester resins
Authors: Podzimek S̆. , Hyrs̆l J. 
Published: April 2003

AbstractThis article is concerned with the characterization of unsaturated polyester (UP) resins by conventional gel permeation chromatography (GPC), GPC connected with multiangle laser light scattering detector (GPC‐MALLS), and reversed‐phase high performance liquid chromatography (HPLC). The ability of particular methods to analyze UP resins is demonstrated in several examples. © 1994 John Wiley & Sons, Inc.
High‐performance semi‐interpenetrating polymer networks based on acetylene‐terminated sulfone. II. Phase separation and morphology
Authors: Mai Kancheng , Zeng Hanmin 
Published: April 2003

AbstractThe dynamic mechanical behavior, phase separation, and morphology of high‐performance semi‐interpenetrating polymer network (semi‐IPN) obtained from acetylene‐terminated sulfone (ATS‐C) and high‐performance thermoplastics have been studied by torsional braid analysis (TBA) and scanning electron microscopy (SEM). All the ATS‐C/thermoplastic blends studied are compatible before curing. The addition of ATS‐C results in a dramatic reduction in the glass transition temperature (Tg) of the thermoplastic. As the reaction of cure proceeds, the initially compatible blend passes through a stage of partial compatibility to achieve a fully incompatible semi‐IPN. SEM observation of the fracturedetched surface reveals the formation of a co‐continuous two‐phase structure in the semi‐IPNs. The connected globule and network morphology of the cured ATS‐C phase are dispersed in a matrix of the thermoplastic phase. The size of dispersed particles decreases with increasing Tg of the thermoplastic. The mechanism of phase separation is discussed. © 1994 John Wiley & Sons, Inc.
Synthesis and mesomorphic behavior of terminal oligo(ethylene glycol)monomethyl ether‐substituted low molecular weight thermotropic liquid crystals
Authors: Liaur Wen‐Bong , Ma Sun , Chang‐Chieh Guo‐Ping , Kuo Jen‐Feng 
Published: April 2003

AbstractA number of alkenyl monomers containing biphenyl benzoate‐based on a mesogenic core with various lengths of oligo(ethylene glycol) monomethyl ether as the terminal group were synthesized. The purity, the thermotropic transition temperature, and the mesomorphic texture were investigated with 1H‐nuclear magnetic resonance spectroscopy, differential scanning calorimetry, and optical polarized microscopy with a hot stage. The monomers studied in this project showed predominately nematic phases, whereas those with esterlinked derivatives studied in our previous work were able to present both nematic and smectic phases. They also exhibited higher isotropic transition temperatures than those of the ester‐linked derivatives. The factors governing mesophase texture and transition temperature are discussed thoroughly. © 1994 John Wiley & Sons, Inc.
Time‐resolved, pulsed laser sensitized acoustic technology: Application to on‐line sorting of waste plastics
Authors: Wan J. K. S. , Vepsäläinen K. P. , Ioffe M. S. 
Published: April 2003

AbstractIn industrial recycling of waste plastics the on‐line sorting of different kinds of consumer plastics often represents the key to the successful commercial operation. The principle and a limited feasibility study of a novel wavelength independent photoacoustic sensor applied to this problem are presented. This wavelength independent sensor offers the advantages of low cost, portability, and is not limited by the surface modifications such a color, printed labels, etc. in the commercial products. © 1994 John Wiley & Sons, Inc.
Polymer drying. IX. Effect of history on the kinetics of evaporation from poly(styrene‐co‐divinylbenzene)–liquid systems in the rubbery and glassy states
Authors: Errede L. A. , Henrich P. J. , Schroepfer J. N. 
Published: April 2003

AbstractIn these time studies of evaporation from liquid‐saturated microporous composite film samples, comprised of poly(styrene‐co‐divinylbenezene) particles enmeshed in poly(tetrafluoroethylene) microfibers, the samples were preswelled to saturation in a good solvent, such as toluene, which was then replaced via solvent exchange in excess test liquid before the start of the time study that monitored the residual weight (Wt) of sorbed liquid to virtual dryness. The patterns of change with time (i.e., Wt. vs. t and Log Wt vs. t) obtained thereby were compared with the corresponding time studies already reported for evaporation from equivalent polystyrene–liquid (PS–L) systems that did not have a history of preswelling in a better solvent. These comparisons show that the history of the samples in its liquid‐saturated gel state can affect markedly the kinetics of desorption from the PS–L system in its glassy state, and also during the interval of transition from the rubbery state to the glassy state, as discussed in the text. © 1994 John Wiley & Sons, Inc.
Studies on VOCl3/MgCl2/NaY/Al2Et3Cl3 complex support catalysts for the copolymerization of ethylene and propylene
Authors: Wang L. , Feng L. X. , Xu J. T. , Yang S. L. 
Published: April 2003

AbstractUsing VO2+ as a spin probe, a new method to obtain microenvironmental information on supports was developed which can be used in the choice of supports for coordination catalysts. Utilizing the above method, NaY was chosen as second support component. A complex support catalyst VOCl3/MgCl2/NaY/Al2Et3Cl3 was prepared and used in ethylene–propylene copolymerization. Higher polymerization activity was obtained with this catalytic system. Alternating the ratio of two kinds of supports, the composition and sequence structure of copolymers could be controlled, which showed that NaY participated in the active species, affected the insertion of monomer, and changed the composition and sequence structure of copolymers. © 1994 John Wiley & Sons, Inc.
Aqueous polymerization of methyl methacrylate initiated by redox pair: Ce(IV)–Azo compounds with methylol functional groups and synthesis of copolymers
Authors: Tunca U. 
Published: April 2003

AbstractHydroxyl functional azo compounds have been used as reducing agents in redox polymerization of methyl methacrylate (MMA) in conjuction with ceric ammonium nitrate (which acts as an oxidizing agent in aqueous nitric acid at 20°C). Kinetic measurements were followed by gravimetric method, at lower conversions, not exceeding 10% conversion. The dependence of rate of polymerization and average molecular weight, which was determined by gel permeation chromatography (GPC), on azo, Ce(IV), and MMA concentrations, respectively, were investigated. The homopolymers, which contain thermo‐and photolabile azo groups, were utilized with different comonomers to give block or graft copolymers depending on termination mechanism of homopolymerization. © 1994 John Wiley & Sons, Inc.
The effect of viscosity ratio on the phase inversion of polyamide 66/polypropylene blends
Authors: Hietaoja Pirjo T. , Holsti‐Miettinen Riitta M. , Seppälä Jukka V. , Ikkala Olli T. 
Published: April 2003

AbstractThe rheological properties of the blend components are an important parameter in the formation of a blend morphology. The effect of viscosity ratio on the morphology of polyamide 66/polypropylene blends was studied, with primary attention to the phase‐inversion behavior and the average particle size of the dispersed phase. The relationship between the mechanical properties and the phase‐inversion composition was investigated as well. Noncompatibilized and compatibilized blends having five different viscosity ratios were prepared by twin‐screw extrusion. Maleic anhydride‐grafted polypropylene was used as the compatibilizer to increase the adhesion between the two polymers and to stabilize the blend morphology. Investigation of the morphology of the blends by microscopy (SEM and TEM) showed that the smaller the viscosity ration (ηPA/ηPP) the smaller was the polyamide 66 concentration at which the phase inversion took place and that polyamide 66 became the continuous phase. The results are in accord with the model of Jordhamo. The compatibilizer induced a sharp reduction of particle size, but did not have a major effect on the phaseinversion point. The tensile and impact properties of the compatibilized blends were found to correlate with the phase inversion. An improvement in the mechanical properties was observed when polyamide 66 provided the matrix phase. © 1994 John Wiley & Sons, Inc.
Deformation behavior of polytetrafluoroethylene films under tensile stress at various temperatures
Authors: Yamaguchi Ken , Takachi Masayuki , Hirakawa Susumu 
Published: April 2003

AbstractDeformation behavior of polytetrafluoroethylene (PTFE) films was investigated by thermomechanical analysis (TMA) under various tensile stresses (σ) up to 1.15 MPa in the temperature range from room temperature to 360°C. In the heating process above σ ≈ 0.25 MPa, a contraction of the PTFE film occurs in the melting temperature region. In the cooling process above σ ≈ 0.05 MPa, an elongation occurs in the crystallization temperature region, and above σ ≈ 0.5 MPa, it reaches 20–30% of the original length of the film. The PTFE films in the melt state above σ ≈ 0.5 MPa contract with increasing temperature up to 360°C and elongate with decreasing temperature. For the films that underwent deformation in the TMA, the crystalline orientation and the surface morphology were investigated by wide‐angle X‐ray diffraction and scanning electron microscopy, respectively. The degree of crystalline orientation in the deformed films increases with increasing σ and approaches a plateau at σ ≈ 0.4 MPa. On the surface of the deformed films, alignment of the bands and deformation of granules, which are formed by heat treatment above the melting point, are observed. © 1994 John Wiley & Sons, Inc.