bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chemical grafted 4‐vinylpyridine onto polycarbonate membranes for pervaporation
Authors: Chen Shih‐Hsiung , Lai Juin‐Yih 
Published: April 2003

Abstract4‐Vinylpyridine‐homografted‐polycarbonate (PC‐g‐4VP) membrane was prepared for water perselective pervaporation. The conditions of the chemical grafting reaction for synthesis PC‐g‐4VP were studied in terms of the reaction time, reaction temperature, monomer concentration, and the concentration of initiator in the reaction. The effect of feed composition, degree of swelling, and operation on temperature on the pervaporation performances were investigated. It was found that water permeated through the PC‐g‐4VP membrane perferential in all range of feed compositions. The permeation rate and separation factor increased with increasing 4‐vinylpyridine content in the membrane. PC‐g‐4VP membrane effectively improved both the water permeation rate and water–ethanol separation factor of the unmodified polycarbonate membrane. The total permeation rate of PC‐4‐VP membrane with 26.7% degree of grafting was 153 g/m2 h, and the separation factor was above 6300 for a 90 wt % aqueous ethanol feed solution. © 1995 John Wiley & Sons, Inc.
Structure and properties of self‐reinforced polyethylene prepared by oscillating packing injection molding under low pressure
Authors: Guan Qing , Shen Kaizhi , Ji Jiliang , Zhu Jumu 
Published: April 2003

AbstractThis article reports the influence of oscillating pressure on the mechanical performance of general‐grade high‐density polyethylene (HDPE). The tensile strength of 93 MPa and the Young's modulus of 5 GPa were obtained by an oscillating packing technique. The great improvement of the mechanical properties of HDPE specimens is due to the existence of the shish‐kebab crystalline structure, the orientation of the molecular chains along the flow direction, and the more perfect crystallites. © 1995 John Wiley & Sons, Inc.
Reactivity of glycidyl‐methacrylate‐grafted cellulose prepared by means of photografting
Authors: Kubota Hitoshi , Ujita Shuji 
Published: April 2003

AbstractPhotografting was applied to functionalize cellulose, that is, epoxy groups were introduced into the cellulose substrate by photografting of glycidyl methacrylate (GMA) using hydrogen peroxide as a photoinitiator. Dissolving pulp from softwoods was used as the cellulose sample. The GMA‐grafted cellulose (G‐Cell) was subjected to the following examinations in comparision with epoxy‐activated cellulose (E‐Cell) prepared by reaction with epichlorohydrin: (1) reactivity of G‐Cell towards amines such as ethylenediamine, tetramethylenediamine, hexamethylenediamine, diethylenetriamine, and triethylenetetramine; (2) ability of the aminated celluloses obtained by examination (1) to adsorb cupric ion; and (3) catalytic activity of the aminated cellulose–cupric ion complexes prepared by examination (2) for decomposition of hydrogen peroxide. The amount of amine residue introduced into the substrate was higher for E‐Cell than G‐Cell, showing the existence of epoxy groups in G‐Cell which cannot contribute to the reaction. The ability of the aminated celluloses to adsorb cupric ion was nearly equal for G‐Cell and E‐Cell though tetramethylenediamine and hexamethylenediamine‐introduced samples did not show the ability. It was found that all complexes prepared by reaction of the aminated cellulose with cupric ion exhibited catalytic activity for decomposition of hydrogen peroxide. © 1995 John Wiley & Sons, Inc.
Modification of industrial polypropylene film by grafting of poly(acrylic acid)
Authors: Dogué Louis Joseph , Mermilliod N. , Gandini A. 
Published: April 2003

AbstractGrafting of poly(acrylic acid) onto commercial polypropylene films following irradiation by γ‐rays was carried out in order to improve their surface properties. The amount of grafting with the irradiation dose was found not to follow the expected linear dependence as it is normally observed for polypropylene films prepared in laboratory amounts. We therefore analyzed the influence of the industrial manufacture process in terms of orientation of the film and addition of antioxidants by determining the peroxide surface density and the extent of grafting therefrom. The unoriented polypropylene film presented the highest peroxide concentration and was thus the most adapated material for successful grafting. Whereas phenol antioxidants limit the peroxide formation and thus must be removed from the film for grafting, the thickness of the chemical modification and can be controlled by means of phosphites. Atomicforce microscopy and wettability measurements showed that the grafted poly(acrylic acid) was heterogeneously distributed on the surface of the film, explaining the observed low reproducibility of the grafting reaction. However, we observed that the polarity of the surface was increased by the grafting. © 1995 John Wiley & Sons, Inc.
Study of the chemical polymerization of pyrrole onto printed circuit boards for electroplating applications
Authors: Saurin M. , Armes S. P. 
Published: April 2003

AbstractWe have studied the deposition of thin films of a conducting polymer, polypyrrole, onto printed circuit boards (PCBs). Film formation occurs as a result of the in situ polymerization of pyrrole monomer using a 1 : 1 FeCl3/5‐sulfosalicylic acid oxidant complex in aqueous solution. We have optimized the polymerization conditions in order to coat a large number of PCBs with a single polymerization bath, while at the same time maintaining the quality of the conducting polymer coating (i.e., keeping its surface resistance below 104 Ω per square). These improvements were achieved simply by controlling the initial oxidant–monomer mole ratio such that the oxidant is always present in significant excess. We have also examined the formation of thick polypyrrole layers obtained from the progressive buildup of thin layers. The morphology and film thickness of these polypyrrole coatings have been studied by scanning electron microscopy. Some preliminary electroplating experiments using these polypyrrole–PCB composites are also described. © 1995 John Wiley & Sons, Inc.
A study on blends of liquid crystalline copolyesters with polycarbonate. I. Compatibility by transesterification
Authors: Su Koe‐Fu , Wei Kung‐Hwa 
Published: April 2003

AbstractBlends of poly(bisphenol‐A carbonate) (PC) and synthesized liquid crystalline poly(oxybenzoate‐co‐ethylene terephthalate 40/60) (P46) were prepared through meltmixing in a Brabender mixer. The miscibility of the blends at different compositions and blending time was investigated with differential scanning calorimetry. The corresponding morphology of the blends was analyzed with scanning electron microscopy. It was found that for blends containing more than 20% P46 and mixed at 250°C or above the transesterification between PC and P46 took place. This transesterification was confirmed at a blend containing 40% P46 by nuclear magnetic resonance spectroscopy. The transesterification happened first between PC and the ester in the poly(ethylene terephthalate) (PET) block and then between PC and the ester in the polyoxybenzoate (POB) block. At 260°C and after 60 min' blending, the blend containing 30% P46 became an almost compatible system for appearing of a single glass transition temperature. This is also verified by the disappearing of P46 droplets in the PC matrix in the micrographs' observation. After 60 min' of blending, the compatibility of the system can be greatly improved even for the blend containing 40% P46 mixed at 260°C by the micrograph's observation. © 1995 John Wiley & Sons, Inc.
Stress–strain effects of mechanically degraded natural rubber latex
Authors: Nwanorh K. O. , Enyiegbulam M. E. 
Published: April 2003

AbstractA well‐characterized fresh natural rubber latex with total solids content of 42.1% was subjected to high‐speed mechanical stirring for over 6 h. Mechanical and solution studies on samples withdrawn at intervals showed clearly that rubber degradation occurred within 4–5 h of continuous stirring. Such degradation in the liquid phase is considered to be of industrial importance in the rubber industry. © 1995 John Wiley & Sons, Inc.
Influence of disproportionated rosin acid soap on the emulsion polymerization kinetics of styrene
Authors: Mayer M. J. J. , Meuldijk J. , Thoenes D. 
Published: April 2003

AbstractThe effect of disproportionated rosin acid soap (DRAS) on the emulsion polymerization kinetics of styrene has been studied. Batch experiments reveal a significant influence of chain transfer and limited particle coagulation on the polymerization process. For the recipes studied, the number of growing chains in the emulsion and consequently the polymerization rate were found to be independent of the particle number during the interval of coagulation. However, for relatively large particles (dp ≈ 100 nm), the polymerization rate was proportional to the particle number, indicating Smith–Ewart case II kinetics. These effects have been shown to be well predicted by model calculations using a radical population balance over the particles. Since DRAS is derived from naturally occurring constituents found in pine trees, its performance, and with that the properties of the product latex, may vary significantly. However, if the performance of DRAS is known, the recipe and process conditions can be optimized. For this reason a procedure has been developed to quantify the performance of DRAS from the simple batch experiments discussed in this paper, the polymerization kinetics, and the information obtained about the coagulation process. © 1995 John Wiley & Sons, Inc.
Morphological and mechanical properties of PET‐LCP blend fibers
Authors: Mehta Sanjay , Deopura B. L. 
Published: April 2003

AbstractBlends of poly(ethylene terephthalate‐co‐p‐oxybenzoate) (PET–PHB) with poly(ethylene terephthalate) (PET) have been studied in the form of as‐spun and drawn fibers. Mechanical properties of drawn blend fibers (DR‐6.0) up to 10 wt % liquid crystalline polymer (LCP) component exhibit significant improvement in modulus and strength. With the addition of 10 wt % LCP content in PET matrix, the modulus increases from 11.78 to 17.72 GPa, and the strength increases from 0.76 to 1.0 GPa in comparison to the PET homopolymer. With further addition of LCP content, the properties drop down. Scanning electron microscopy studies of drawn blend fibers show that up to 10 wt % LCP content the blends contain the LCP domains in the size range of 0.07–0.2 μm and are well distributed in the PET matrix. © 1995 John Wiley & Sons, Inc.
Miscibility studies of poly(ethylene oxide)–poly(vinyl acetate) blends by viscometry methods
Authors: Chen Xue , Hu Huizhen , Yin Jinghua , Zheng Changren 
Published: April 2003

AbstractThe intrinsic viscosities of poly(ethylene oxide)–poly(vinyl acetate) blends (PEO–PVA) have been measured in chloroform as a function of molecular weights of blend components and compositions. The interaction parameters Δb obtained from the modified Krigbaum and Wall theory and the differences between the intrinsic viscosities of polymer mixtures and the weight‐average intrinsic viscosities of the two blend components were both used to characterize the extent of miscibility of the blend mixtures. © 1995 John Wiley & Sons, Inc.
Evaluation of the amount of defects in the comonomer alternation included in the crystal phase for ethylene–tetrafluoroethylene and ethylene–chlorotrifluoroethylene alternating copolymers
Authors: De Rosa C. , Guerra G. , D'Aniello C. , Petraccone V. , Corradini P. , Ajroldi G. 
Published: April 2003

AbstractA method for the evaluation of the amount of defects in the comonomer alternation included in the crystalline phase of alternating ethylene–tetrafluoroethylene (ETFE) and ethylene–chlorotrifluoroethylene (ECTFE) copolymers, is proposed. The method is based on a comparison between X‐ray fiber diffraction profiles and calculated Fourier transforms for isolated chain models. The proposed method is not affected by the regioirregularities and stereoirregularities possible for ECTFE. For the considered ECTFE sample, the chains in the crystalline phase present an amount of defects in the comonomer alternation much lower than those evaluated for all the considered ETFE samples. Substantial differences in the melting temperatures between ETFE samples are accounted for by the different amounts of defects in the comonomer alternation included in the crystalline phase. © 1995 John Wiley & Sons, Inc.
Surface modification of ultrafiltration membranes by low temperature plasma. I. Treatment of polyacrylonitrile
Authors: Ulbricht Mathias , Belfort Georges 
Published: April 2003

AbstractExcitation with low temperature helium or helium/water plasma and subsequent exposure to air of polyacrylonitrile (PAN) ultrafiltration membranes was used to hydrophilize the surface of these materials. We analyzed the effectiveness of this approach as a function of plasma operating variables including gas phase composition, plasma power, treatment time, and system pressure. Following the changes in physical and chemical composition of the PAN surface resulting from these modifications was a major aspect of this work. Techniques such as the captive bubble contact angle method, ellipsometry, ESCA, and FTIR‐ATR were all used. In addition, the formation and lifetime of peroxides during these processes were determined. At low powers (≤ 25 W) and short treatment periods (≤ 30 s), the main chemical conversion of PAN surfaces was simultaneous hydrophilization and stabilization via PAN cyclization. Relatively small water permeability changes were observed as a result of such treatment. © 1995 John Wiley & Sons, Inc.
Surface and interfacial FTIR spectroscopic studies of latexes. X. The effect of coalescence on surfactant exudation in polystyrene and poly(n‐butyl acrylate) latex films
Authors: Tebelius Lara K. , Urban Marek W. 
Published: April 2003

AbstractIn an effort to establish to what extent transient effects prior to coalescence may influence mobility, distribution, and orientation of surfactant molecules after coalescence, poly(n‐butyl acrylate) (n‐BA) and polystyrene (Sty) were polymerized independently and mixed in a 5 : 1 ratio. It appears that if a mixture of the n‐BA and Sty latex particles is allowed to stabilize prior to coalescence, the time of stabilization may have a significant effect not only on the distribution of SDOSS surfactant molecules across the coalesced film, but also on their orientation changes depending upon the stage of coalescence and the water front moving toward the surface. The coalescence of latex films was conducted under gaseous nitrogen and at 60% relative humidity. While the water front moves from the film‐substrate upward, during this process, various segments of the surfactant molecule change their orientation. Near the F–A interface, hydrophobic segments are being reoriented from parallel to perpendicular, whereas preferentially parallel orientation exhibit hydrophylic SO−3 Na+ segments. When water molecules, however, diffuse out of the film, the surfactant molecules have no preferred orientation. © 1995 John Wiley & Sons, Inc.
Solid‐state polycondensation of poly(ethylene terephthalate) recycled from postconsumer soft‐drink bottles. II
Authors: Karayannidis George P. , Kokkalas Demetris E. , Bikiaris Demetris N. 
Published: April 2003

AbstractPoly(ethylene terephthalate) (PET) taken from postconsumer soft‐drink bottles was subjected to solid‐state polycondensation after cutting into small pieces or after dissolution in trifluoracetic acid, trifluoracetic acid/dichloromethane mixture (50/50%, v/v), or nitrobenzene, and coagulation in methanol. The effect of various reaction parameters such as time and temperature of reaction (180, 200, 220, and 230°C) on intrinsic viscosity [η] and carboxyl and hydroxyl end‐group content have been investigated. The highest number average molecular weight, M̄n = 61,400 was obtained from PET (M̄n = 20,300) dissolved in nitrobenzene and solid‐state polycondensated by heating under vacuum at 230°C for 8 h. The thermal behavior of solid‐state samples was studied by differential scanning calorimetry (DSC); all samples showed a characteristic double endothermal melting peak and no glass‐transition temperature. The PET samples taken from the bottles without dissolution were also studied by thermomechanical analysis. The heat distorsion temperatures obtained by this analysis were in very good agreement with the two endothermal melting peaks taken by DSC. This finding indicates that in these samples the crystallites form a coherent matrix and the amorphous phase is dispersed in the voids. © 1995 John Wiley & Sons, Inc.
Nonlinear stress properties of poly(styrene‐block‐butadiene‐block‐styrene) melt under elongational and shear deformation
Authors: Takahashi Tatsuhiro , Toda Hideyuki , Minagawa Keiji , Takimoto Jun‐Ichi , Iwakura Kenji , Koyama Kiyohito 
Published: April 2003

AbstractEffects of block copolymerized structure on nonlinear stress properties under elongational and shear deformation were investigated. Samples used in this study were poly(styrene‐block‐butadiene‐block‐styrene) (SBS, weight rate of S/B = 40/60) and polystyrene (PS) as a reference. Tensile stress–strain and shear stress relaxation properties were measured at the molten state. SBS showed high elasticity after reaching the yield point under elongational deformation at room temperature. PS melt showed substantial tensile stress increase after the yield point as strain rates increased. However, SBS melt did not exhibit noticeable tensile stress rise at higher elongation, and this property was almost independent of strain rates. Stress relaxation experiments revealed that the damping function of SBS melt was more strain‐softening than that of PS melt. The results suggested that the block copolymerized structure decreases melt elasticity under elongational and shear deformation. A transmission electron micrograph indicated that the lack of melt elasticity in SBS melt is caused by orientation of the lamellar structure toward the stretched direction during deformation. © 1995 John Wiley & Sons, Inc.
Tensile and compressive behavior of poly(p‐phenylene benzobisthiazole) fibers
Authors: Sahafeyan Mohsen , Kumar Satish 
Published: April 2003

AbstractHeat treated poly(p‐phenylene benzobisthiazole) (PBZT) fibers tested in tension result in two types of failure modes. In failure mode I, the fiber exhibits a relatively sharp break; mode II is characterized by significant axial fiber splitting. Approximately 20% of the fibers failed in mode II when tested at 2.54, 7.62, and 12.7 cm gage lengths. At 1.25 cm gage length all the fibers failed in mode I. Tensile strength decreased from the 1.25 to 7.62 cm gage length, but tensile strength of the fibers tested at 7.62 and 12.7 cm gage lengths were similar. The two failure mode observation is supported by the Weibull statistical distribution. Fiber tensile properties were also measured at 150°C. Axial compressive strength of the PBZT fibers as determined from the recoil test is also reported and is found to be independent of fiber tensile modulus and fiber diameter. As‐received heat‐treated fibers were post heat treated between 700 and 775°C. Structural changes in the fiber were studied using infrared spectroscopy, small and wide angle x‐ray scattering, and swelling studies. © 1995 John Wiley & Sons, Inc.
Fluorinated copolyimides prepared by one‐shot and stepwise monomer addition method
Authors: Chun Byong‐Wa 
Published: April 2003

AbstractCopolyimides containing a hexafluoropropylidene group are prepared by the stepwise monomer addition method as well as the conventional one shot method. The stepwise addition method goes through an oligomeric imide prepolymer. The molecular weight distribution of the prepolymers approximately follows the Flory's statistical distribution in the fluorinated imide prepolymer. Except for the final molecular weight, the conventional one‐shot method does not give a significant difference in the copolymer character from the stepwise method, indicating that the segmental distribution in the copolyimides is practically statistical in the present monomer combination. The observed difference in the molecular weight by the preparation method may be related to the reactivity difference of the two monomer pairs. © 1995 John Wiley & Sons, Inc.
Quantification of the functional groups present at the surface of plasma polymers deposited from propylamine, allylamine, and propargylamine
Authors: Fally F. , Doneux C. , Riga J. , Verbist J. J. 
Published: April 2003

AbstractThe surface chemistry of plasma‐deposited films created from amine‐functionalized saturated (propylamine) and unsaturated (allylamine and propargylamine) precursors has been investigated by high‐energy resolution XPS, chemical derivatization, elemental analysis, and HREELS.XPS results show that nitrogen‐rich deposits are obtained from unsaturated precursors at low power or at high power in the postdischarge region. Quantitative information on the chemical groups in the polymers is obtained by simulating the XPS C1s and N1s core levels and by performing derivatization reactions. The proportion of primary amine functions deduced from tagging reactions with pentafluorobenzaldehyde in the liquid phase and with 4‐trifluoromethylbenzaldehyde in the vapor phase varies between 10 and 33%. These groups are converted into imine (more than 50%) in polypropylamine and polyallylamine, while imine and nitrile functions were found in polypropargylamine. HREELS has allowed us to distinguish between different nitrogen‐containing functionalities present at the extreme surface of the polymers. The comparison of the HREELS and TIR spectra shows that the chemical composition at the extreme surface of the samples is representative of that of the bulk. To explain the conversion of the chemical groups in the plasma, polymerization mechanisms are proposed for each of the monomers. © 1995 John Wiley & Sons, Inc.
Effect of MAA/MAM pregrafting on DMEU finishing of cotton fabrics
Authors: Min Rong‐Rong , Hwang Kuo‐Shien 
Published: April 2003

AbstractCotton fabrics were pregrafted with mixed monomer of methacrylic acid (MAA) and N‐methylolacrylamide (MAM) before undergoing finishing with 1,3‐dimethylolethylene urea. Experiments show that when the molar ratio of MAA and MAM is 4 : 6 the finished fabric has the maximum nitrogen content (N%) and crosslinking density. The pregrafting can improve the wet crease recovery angle and the moisture regain, can reduce the tensile strength retention, and has little effect on the dry crease recovery angle. In addition, at a pregrafting ratio of 4 : 6, the finished fabric has the highest crease recovery angle and moisture regain. © 1995 John Wiley & Sons, Inc.
Pervaporation separation of alcohol–water mixture through 4‐vinylpyridine chemical modified poly(4‐methyl‐1‐pentene) membrane
Authors: Lai J. Y. , Yin Yih‐Lang , Lee Kueir‐Rarn 
Published: April 2003

AbstractFor dehydrating separation aqueous alcohol solution by the pervaporation technique, a chemical modified poly(4‐methyl‐1‐pentene) (TPX) membrane was synthesized with 4‐vinylpyridine (4‐VP). The morphology, crystallinity, and thermodegradation properties were investigated by scanning electron microscopy, X‐ray, and thermogravimetric analysis, respectively. The modified TPX membrane possessed higher stability than that of the unmodified TPX membrane. The effects of feed temperature and poly(4‐VP) (P4‐VP) content of the modified TPX membranes on the performances of pervaporation were studied. A separation factor of 133 and a permeation rate of 115 g/mh can be obtained for the TPX/P4‐VP membrane with 3.0 wt % P4‐VP content. © 1995 John Wiley & Sons, Inc.