bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spectroscopic studies on the effect of doping with iodine on metal chloride‐treated poly(vinyl alcohol)
Authors: Moharram M. A. , Rabie S. M. , El‐Hamouly W. S. 
Published: April 2003

AbstractThe ultraviolet and infrared spectra of films of PVA treated with Co(11), Ni(11), and Cu(11) and then doped with iodine were studied. The spectra of the films preheated in air at temperatures from 25 to 180°C for 2 h were investigated. The obtained data revealed that treatment of PVA with different concentrations of each of the mentioned metal salts causes profound spectral changes. The analysis of UV spectra showed that the intensity of the band at 280 nm decreases with increasing metal concentration. It was also found that doping with iodine results in an appearance of an additional peak at about 360 nm. Careful examination of the infrared spectra indicated that the crystallinity of the samples depends on the concentration of metals and is affected by temperature treatment.
Mechanical properties of i‐PP/CaCO3 composites
Authors: Maiti S. N. , Mahapatro P. K. 
Published: April 2003

AbstractTensile and impact behavior of CaCO3‐filled polypropylene was studied in the composition range 0–60 wt % filler. Tensile modulus increased while tensile strength and breaking elongation decreased with increase in CaCO3 content. The modulus increase and elongation decrease were attributed to increased filler–polymer interaction resulting in reduction in molecular mobility, while increased amorphization and obstruction to stress transfer accounted for the tensile strength decrease. Analysis of tensile strength data showed introduction of stress concentration in the composites. Izod impact strength at first increased up to a critical CaCO3 content, beyond which the value decreased. Surface treatment of CaCO3 with a titanate coupling agent LICA 12 enhances the adhesion of the filler and polymer, which further modifies the strength properties. Scanning electron microscopic studies indicated better dispersion of CaCO3 particles upon surface treatment, which effected the changes in the strength properties of the composites.
Parametric study of EAA polymer thin film deposition on carbon substrates in a fluidized electrode bed reactor
Authors: Desai V. M. , Mahalingam R. , Subramanian R. V. 
Published: April 2003

AbstractElectrodeposition of ethylene‐co‐acrylic acid (EAA) polymer, as thin films on carbon particle substrates, was carried out in a fluidized electrode bed reactor. Feeder current, time of deposition, and flow rate of anolyte (i.e., bed expansion or bed porosity) were the key parameters investigated. The film characteristics were evaluated through SEM and FTIR analyses and the amounts determined by weighing. The effect of these parameters on the electrodeposition process is discussed, and optimum conditions for deposition are proposed. Also, a possible mechanism for electrodeposition, particularly for the EAA–carbon system, is discussed.
Estimation of diffusion coefficient for solute–polymer systems
Authors: Vahdat Nader 
Published: April 2003

AbstractDiffusion coefficients are needed for the analysis of many mass transfer problems involving polymers. Since the diffusivity for such systems are strong functions of temperature and concentration, the analysis of these problems is greatly facilitated if predictive methods are available for the determination of the required diffusion coefficient. Because of the limitations of the theoretical approaches for estimating diffusivity, empirical correlation of solute–polymer diffusion coefficient data with physical properties of the solute were investigated. Chemical permeation measurements were made for several organic liquids through three elastomers (polychoroprene, butyl and nitrile rubber) at five different temperatures, ranging from 25 to 65°C. The collected diffusivities were correlated with liquid kinematic viscosity. Diffusivities (at different temperatures) depend mainly on the kinematic viscosity of solutes. The results also indicate a close relation between the variation of diffusivity and viscosity with temperature.
Distribution of higher‐order structures in injection‐molded polypropylenes
Authors: Fujiyama Mitsuyoshi , Wakino Tetsuo 
Published: April 2003

AbstractFlexural test specimens were injection‐molded from six homoisotactic polypropylenes with MFI = 0.49‐25.1 dg/min under cylinder temperatures of 200‐320°C. Distributions in the flow direction of higher‐order structures such as crystallinity Xc, thickness of skin layer, a*‐axis‐oriented component fraction [A*], and crystalline orientation functions and distributions in the thickness direction of higher‐order structures such as Xc, β‐crystal contents, [A*], and crystalline orientation functions were studied. These higher‐order structures are inhomogeneous in the flow and thickness directions, which strongly influences the product properties such as mechanical and thermal properties. Molecular orientation process in injection molding was theoretically analyzed from a viewpoint of growth of recoverable shear strain at the gate and its relaxation in the cavity, which could considerably well explain the variations in the flow and thickness directions of the quantities such as thickness of the skin layer and crystalline orientation functions which express the degree of molecular orientation.
Surface characterization of plasma‐derivatized polyurethanes
Authors: Giroux Thomas A. , Cooper Stuart L. 
Published: April 2003

AbstractThe use of plasma deposition to introduce sulfonate groups to the surface of a polyurethane was attempted. In previous work, the bulk incorporation of sulfonate groups was found to improve the blood contacting properties of the base polyurethane but physical properties in the hydrated state were adversely affected. Plasma deposition schemes involving ammonia and sulfur dioxide were utilized in an attempt to incorporate sulfonate groups. Surface characterization by X‐ray photoelectron spectroscopy (XPS) and contact angle measurements was used to follow polymer surface rearrangement dynamics and to address the issue of plasma chemistry specificity. Concerns of reaction specificity were alleviated by using the plasma as a pretreatment which is followed by a chemical surface derivatization.
Modification of nylon‐6 with wholly rigid poly(m‐phenylene isophthalamide)
Authors: Wang Huei‐Hsiung , Lin Ming‐Fung 
Published: April 2003

AbstractIn this study, the flexible nylon‐6 was reinforced by the wholly rigid aromatic polyamide poly(m‐phenylene isophthalamide) (PmIA) (Nomex) by physical polyblending and chemical copolymerization using p‐aminophenylacetic acid (P‐APA) as a coupling agent. From DSC measurements, it was shown that Tg of the polyblends increased with the increase of Nomex content. The Tg and Tm of multiblock copolyamides were found to be higher than those of polyblends and triblock copolyamides. Scanning electron microscopy revealed that the polyblends were a dispersed phase structure, although the multiblock copolyamides exhibited a homogeneous texture rather than an aggregated one. From the wide‐angle X‐ray diffraction pattern, it was found that the triblock copolyamides and polyblends had two diffraction peaks, i.e., 2 θ = 20.5 and 24°. However, the multiblock had only one at 2 θ = 20°, indicating a different crystal structure for multiblock copolyamides. For the mechanical properties, it was found that the multiblock copolyamides had a more significant reinforcing effect than those of polyblends and triblock copolyamides.
Rubber‐Modified epoxies. IV. Influence of morphology on mechanical properties
Authors: Verchere D. , Pascault J. P. , Sautereau H. , Moschiar S. M. , Riccardi C. C. , Williams R. J. J. 
Published: April 2003

AbstractThe mechanical properties of a system consisting of a bisphenol A diglycidylether (DGEBA) expoxy, cured with a cycloaliphatic diamine (4,4′‐diamino‐3,3 dimethyldicyclohexyl‐methane, 3DCM), in the presence of an epoxy‐terminated butadiene‐acrylonitrile random copolymer (ETBN), was studied as a function of the cure schedule and the initial rubber concentration. Fracture toughness (KIc) and fracture energy (GIc) were increased, while Young's modulus and yield strength decreased slightly with increasing volume fraction of the dispersed phase. We show that there is no significant influence of the precure schedule and of the various observed particle diameters on the mechanical properties for a constant rubber volume fraction. In our case, the main deformation process in the rubber‐modified epoxy networks is shear yielding while cavitation is negligible.
Polybutylene terephthalate/high‐density polyethylene alloys. I. Morphological studies
Authors: Joshi M. , Misra A. , Maiti S. N. 
Published: April 2003

AbstractPolybutylene terephthalate (PBT) is a commercially successful thermoplastic polyester but has certain drawbacks such as low impact strength and low melt strength. An attempt has been made to modify the properties of PBT by blending it with polyolefin such as highdensity polyethylene (HDPE). Since PBT and HDPE are incompatible, an ionomer has been used as a compatibilizer to form an alloy. Alloys of PBT and HDPE with varying amounts (2‐8%) of ionomer were prepared by melt blending. The ultimate mechanical properties improved significantly on the addition of the ionomer due to an increase in interfacial adhesion between PBT and HDPE. DSC studies show that the presence of ionomer facilitated the crystallization of PBT in the alloy. DMTA studies show that more of PBT (amorphous) is going in to the HDPE‐rich phase in the presence of ionomer. The morphology of the alloys was studied using scanning electron microscopy (SEM), polarizing microscopy (PM), and small‐angle light scattering (SALS). They showed improved dispersion of HDPE domains in PBT matrix with increasing ionomer content and change in the type of superstructure on adding the ionomer. It has been shown that an alloy of PBT and HDPE with improved mechanical properties and homogeneous morphology can be made with use of ionomer as a compatibilizer. Such alloys are cost effective and can find use in several engineering applications.
The effect of blending temperature, composition, and shear rate on PET/Vectra A900 LCP blend viscosity and morphology
Authors: Perkins W. G. , Marcelli A. M. , Frerking H. W. 
Published: April 2003

AbstractThe rheological and morphological properties of several melt‐blended compositions of poly(ethylene terephthalate) (PET) and Vectra A900 liquid crystalline polyester were investigated, using blending temperature, composition, and shear rate as variables. Rheological behavior was determined at several shear rates on an Instron capillary rheometer at 300°C, and three‐dimensional surface plots of the results were prepared, detailing the effect on melt viscosity of changes in the variables. Scanning electron microscopy was used to examine the internal morphology of selected samples. In the preparation of melt blends containing an isotropic and anisotropic polymer, blending temperature and composition both influence the resulting morphology. These effects are accentuated during extrusion of the blends at low shear rates and diminished at high shear rates.
A self‐vulcanizable and miscible blend system based on hypalon and carboxylated nitrile rubber
Authors: Mukhopadhyay Sujata , De P. P. , De S. K. 
Published: April 2003

AbstractBlends of hypalon and carboxylated nitrile rubber can be vulcanized during molding at high temperatures without addition of any curing agent. This is supported by studies on a Monsanto rheometer, solvent swelling, and FTIR spectroscopy. We designate such a blend system as “self‐vulcanizable rubber blend.” Dynamic mechanical analyses and differential scanning calorimeter studies show that hypalon and carboxylated nitrile rubber form a completely miscible blend. Physical properties of the blends are comparable to that of control single‐rubber vulcanizates. The blend can be reinforced by carbon black filler.
Reactive melt blends of nylon with poly(styrene‐co‐maleic anhydride)
Authors: Kim Byung Kyu , Park Sang Jin 
Published: April 2003

AbstractMelt blends of nylon with poly(styrene‐co‐maleic anhydride) (SMA) were prepared in a twin‐screw extruder. Viscoelastic properties of the melt and morphological, thermal, and mechanical properties of the blends were determined. Fourier‐transform infrared (FTIR) spectroscopy measurement indicated reactions between nylon and SMA. Melting peak temperature (Tm) of nylon was not changed in blends. This, together with the FTIR results, assured that the reactions occur mainly with the free amide end groups of nylon. Melt viscosity, elasticity, and the heat‐distortion temperature (HDT) of nylon was significantly increased with the addition of SMA. Tensile strength and impact strength of nylon were, respectively, in general, increased and decreased with SMA.
Analysis of oxidized moiety of partially periodate‐oxidized cellulose by NMR spectroscopy
Authors: Maekawa Eiichi 
Published: April 2003

AbstractPeriodate‐oxidized celluloses (S‐100, S‐70, S‐50) with different degrees of oxidation were prepared. It is presented in this article that oxidized moieties of partially periodate‐oxidized cellulose are determined from analyses of 1H and 13C nuclear magnetic resonance (NMR) spectra of those reduction products and the corresponding polytriacetates.
Miscibility of poly(tetrahydrofurfuryl methacrylate) and poly(tetrahydropyranyl‐2‐methacrylate) with some chlorine‐containing polymers
Authors: Chong Y. F. , Goh S. H. 
Published: April 2003

AbstractThe miscibility of poly(tetrahydrofurfuryl methacrylate) (PTHFMA) and poly(tetrahydropyranyl‐2‐methacrylate) (PTHPMA) with some chlorine‐containing polymers was studied by differential scanning calorimetry (DSC). PTHPMA was found to be miscible with poly(vinyl chloride) (PVC), polyepichlorohydrin (PECH), and a vinylidene chloride/vinyl chloride copolymer [P (VDC/VC)] and only partially miscible with an epichlorohydrin/ethylene oxide copolymer [P (ECH/EO)]. PTHFMA was shown to be miscible with PECH and P(VDC/VC), but its miscibility with P(ECH/EO) is composition‐dependent. Information about interactions between components in PTHFMA/P (VDC/VC) and PTHPMA/P(VDC/VC) blends was estimated from melting‐point depression. The interaction parameters B were found to be −1.7 and −3.6 J/cm3 for PTHFMA/P(VDC/VC) and PTHPMA/P(VDC/VC) blend systems, respectively. The miscibility behavior of PTHFMA and PTHPMA is compared to that of poly(cyclohexyl methacrylate).
Glass fiber reinforced polypropylene/EPDM blends. II. Mechanical properties and morphology
Authors: Gupta A. K. , Srinivasan K. R. , Kumar P. Krishna 
Published: April 2003

AbstractTensile and impact properties of the ternary system polypropylene (PP)/ethylene propylene diene elastomer (EPDM)/glass fiber (GF) and the corresponding binary systems PP/EPDM blend and PP/GF composite are studied. Results are presented and analyzed as functions of compositional variables, viz., (i) matrix PP/EPDM blending ratio at constant GF loadings and (ii) GF loading at constant matrix blending ratios for the ternary system and (iii) EPDM content for PP/EPDM binary system and (iv) GF content for the binary system PP/GF, respectively. The role of individual components EPDM and GF in these mechanical properties is discussed and their combined effects are inspected at certain composition ranges. Theoretical analysis of tensile data is presented which reveals the effect of EPDM on the reinforcing effect of GF. Unlike the conventional role of an elastomer, increase of EPDM content in the presence of GF increases the modulus of the ternary system. Impact strength of the ternary system increases with increasing GF content both in the presence and absence of EPDM, showing a distinct minimum at matrix blending ratio PP/EPDM 90/10. Scanning electron micrographs of impact‐fractured surfaces are presented to illustrate the dispersion of the two phases of the polyblend matrix, fiber alignment, and the fiber interface.
Interpenetrating polymer networks from polyurethanes and poly(methyl acrylate)
Authors: Frisch Harry L. , Wang Linfu , Huang Weiyu , Hua Yao He , Xiao Han X. , Frisch Kurt C. 
Published: April 2003

AbstractSimultaneous two‐component interpenetrating polymer networks (IPNs) of polyurethane (PU)–poly(methyl acrylate) (PMA) were prepared, as well as the corresponding pseudo‐IPNs. A comparison was made between the full IPNs, pseudo‐IPNs, and the respective homopolymers. Their ultimate mechanical properties were obtained and the dynamic glass transition temperatures (Tg's) were found using a thermomechanical analyzer. At all compositions, a single Tg(except 50–50 wt %) was found.
Polyurethane–polystyrene interpenetrating polymer networks synthesized at low temperature: Effect of crosslinking level
Authors: Lee Doo Sung , Park Tae Sung 
Published: April 2003

AbstractInterpenetrating polymer networks (IPNs) of polyurethane (PU)–polystyrene (PS) containing 50 wt % PU were synthesized at low temperature with varying crosslink density of each component. PU was polymerized first, followed by the photopolymerization of PS at low temperature (0 and 40°C). The theoretical molecular weight between crosslink (M̄c) of PU ranged from 8200 to 2050, and the M̄c of PS varied from linear to 2000. The degree of mixing of the components in these IPNs was investigated using dynamic mechanical analysis, electron microscopy, and density measurement. The degree of mixing increased with decreasing M̄c and/or synthesis temperature. The crosslink density variation at low synthesis temperature is more effective in enhancing the miscibility of IPN than at high synthesis temperature, because both the temperature and crosslink density can affect the polymer chain mobility during the synthesis. The variation of PU network crosslink density shows the better effect in increasing the miscibility of IPN than that of the PS network. The morphology and the density behavior agree well with the dynamic mechanical result.
Polysulfones and their derivatives: Materials for membranes for different separation operations
Authors: Staude Eberhard , Breitbach Ludger 
Published: April 2003

AbstractPolysulfones, as well as their derivatives obtained by chemical reactions, are versatile materials for membrane preparation. The selection of an optimum material clearly depends on the separation process for which the membranes will be used. Membranes made from these materials may serve diverse functions, ranging from an actual permselective separation barrier to a support for a thin membrane layer in a composite structure. Illustrative examples of polysulfone membranes useful in these various applications are given and compared with respect to their cross‐sectional and/or their surface morphology as well as in their surface charge and chemical composition.
Effect of comonomer composition on the properties of polyacrylonitrile precursor and resulting carbon fiber
Authors: Tsai Jin‐Shy , Lin Chung‐Hua 
Published: April 2003

AbstractSince the itaconic acid (IA) comonomer is the potential initiator of cyclization, therefore the introduction of IA comonomer into polyacrylonitrile (PAN) precursor can depress the onset of exotherm (or cyclized temperature) and peak temperature. However, the more the IA content, the lower the conversion of acrylonitrile (AN) in the polymerization reaction. Although 2‐ethylhexyl acrylate (2‐EHA) comonomer in PAN precursor may prevent the cyclization propagation of nitrile groups during oxidation, PAN precursor with a few percent of 2‐EHA comonomer has a more preferred orientation. As the content of 2‐EHA comonomer further increases, the orientation of the resulting carbon fiber decreases correspondingly.In this study, PAN precursor, with the composition of 98 mol % AN, 1.5 mol % 2‐EHA, and 0.5 mol % IA, and its resulting carbon fiber have the best mechanical properties. From the results, it is shown that there is a good relationship between the tenacity and modulus of PAN precursor and those of its resulting carbon fiber.
Simple model for swelling‐induced stresses in a supported polymer thin film
Authors: Fu T. Z. , Durning C. J. , Tong H. M. 
Published: April 2003

AbstractSolvent transport in multilayer thin film structures can induce damaging stresses. It is important to understand these quantitatively for the design of processing methods for microelectronics manufacture. As a model for such systems, this article focuses on the connection between solvent transport in a thin, supported film and the induced bending curvature of the film/substrate combination. We develop a simple mechanical model to calculate the bending curvature based on the transport‐induced stresses. A phenomenological moving boundary description of non‐Fickian solvent transport often found in glassy polymers has been used. The evaluation of dimensionless bending curvature for a number of generic cases is presented. As an application of the model, experimental data for a polymide (PI)/quartz‐n‐methyl‐2‐pyrrolidinone (NMP) system involving significant swelling (15–20%) of the PI film is analyzed. The analysis shows that the measured bending during the transport of NMP in the PI film compares well with that predicted based on an “intermediate,” non‐Fickian diffusion mechanism of NMP, consistent with the finding obtained from a laser interferometric study. Estimation of the swelling‐induced stress shows that it is large and as significant as that due to thermal “curing.”
Morphological deformities in cotton
Authors: Patel G. S. , Iyer K. R. Krishna 
Published: April 2003

AbstractEight types of structural deformities have been identified in cotton fibers by using the SEM, and their incidence has been quantified in four varieties grown in India. Although the total number of deformities per cm was found to be nearly equal in these four varieties, their number showed a wide spread when structural reversals (which constitute one class of deformity) were excluded. The correspondence found between the number of defects other than reversals and the drop in bundle tenacity with increase in gauge length seems to suggest that weak links other than reversals might strongly influence fiber strength.
Curing of diepoxides with tertiary amines: Influence of temperature and initiator concentration on polymerization rate and glass transition temperature
Authors: Vazquez A. , Bentaleb D. , Williams R. J. J. 
Published: April 2003

AbstractThe cure of an epoxy resin based on diglycidyl ether of bisphenol A (DGEBA), with benzyldimethylamine (BDMA), was investigated using differential scanning calorimetry. The kinetics showed a first‐order behavior with respect to both epoxy and tertiary amine concentrations and a non‐Arrhenius dependence on temperature. An activation energy could be defined only in the low‐temperature range, i.e., from 80 to 120°C. Its value (E = 24.2 kJ/mol = 5.8 kcal/mol) indicates a very slight dependence on temperature. The glass transition temperature of epoxy networks decreased with an increase in both the tertiary amine concentration and the cure temperature. These effects are attributed to plastification by the free amine and to the decrease in the average length of polyether chains, which, in turn, increases the number of network defects.