bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of morphology on brittle‐ductile transition of HPDE/CaCO3 blends
Authors: Fu Qiang , Wang Guiheng 
Published: April 2003

AbstractIn this paper, the results of a series of investigations of the effect of morphology on the brittle‐ductile transition for HDPE/CaCO3 blends are summarized: (1) It seems the critical ligament thickness increases with increasing matrix toughness; (2) the interphase adhesion is very important for the toughness of HDPE/CaCO3 blends; (3) small particles are more effective than large ones; (4) CaCO3 particle aggregation will reduce toughening efficiency; (5) uniform CaCO3 particle size is more effective than heterogeneous size for the toughening of HDPE. It is expected that a polymer with higher modulus as well as higher toughness will be obtained by appropriately controlling the morphology of HDPE/CaCO3 blends. © 1993 John Wiley & Sons, Inc.
Synthesis and characterization of homopolymers and copolymers of various acrylates and acrylonitrile
Authors: Joseph Roychen , Devi Surekha , Rakshit Animesh Kumar 
Published: April 2003

AbstractVarious homopolymers and copolymers of methyl acrylate, ethyl acrylate, butyl acrylate, and acrylonitrile in different feed ratios were synthesized. These were characterized by IR, 13C‐NMR, DSC, DTA, and TGA. Spectroscopic characterization helped in differentiating copolymers of different mol ratios. Thermal analysis revealed different degradation patterns for homopolymers and copolymers. The temperature and energy changes associated with various phase transitions were dependent on the chemical composition of homo‐ and copolymers, as expected. © 1993 John Wiley & Sons, Inc.
Preparation of magnetic latex particles by emulsion polymerization of styrene in the presence of a ferrofluid
Authors: Yanase Noriko , Noguchi Hiromichi , Asakura Hideki , Suzuta Tatsuo 
Published: April 2003

AbstractMagnetic latex particles were prepared by the emulsion polymerization of styrene at 70°C in the presence of a commercial ferrofluid containing surfactant‐stabilized magnetite particles in the aqueous phase or its modification by ultrafiltration, using potassium persulfate as an initiator. The effects of diversified variables such as the amounts of initiator, monomer, and additive (calcium chloride and fluorescent dyes) on the polymerization reaction and particle characteristics were investigated. The general polymerization features were analogous to those of ordinary emulsion polymerizations. Transmission electron microscopy revealed that when the commercial ferrofluid was used the magnetite particles localized in the latex particles and the magnetite content varied from particle to particle and that when the ferrofluid was used after ultrafiltration the magnetite particles were dispersed well in the latex particles. © 1993 John Wiley & Sons, Inc.
Physical properties and structure of unreacted PC/PBT blends
Authors: Sánchez P. , Remiro P. M. , Nazábal J. 
Published: April 2003

AbstractUnreacted PC/PBT blends have been obtained by melt blending in all the composition ranges. The followed processing method produced partially miscibilized and crystalline blends. The plot of the density of the amorphous part of the blends against its composition indicates that this parameter is more important than the crystallinity level in determining the mechanical properties of the blends. The blends exhibited an overall improvement of mechanical properties with a combination of behaviors that are close to linearity and are synergistic. © 1993 John Wiley & Sons, Inc.
Glucose oxidase immobilization onto a plasma‐induced graft copolymerized polymeric membrane modified by poly(ethylene oxide) as a spacer
Authors: Wang Chee‐Chan , Hsiue Ging Ho 
Published: April 2003

AbstractPlasma‐induced graft copolymerization of acrylic acid, which was incorporated onto polyethylene (PE) film, was prepared. A bisamino poly(ethylene oxide) (PEO) was immobilized onto the poly(acrylic acid) (PAAc)‐grafted PE membrane to modify the surface properties. The samples were characterized by ESCA. A respective chemical shift of Ar plasma‐treated and control polymeric film was revealed by ESCA. The presence of the grafted PAAc and PEO was also verified. Glucose oxidase (GOD) was immobilized onto this novel grafted polymeric film with and without PEO being used as a spacer. The Michaelis constant, Km, and the maximum reaction velocity, Vmax, were estimated for the free and the immobilized GOD. GOD immobilized onto the polymeric films with and without a spacer obeyed Michaelis kinetics. The Michaelis constant, Km, was larger for the immobilized GOD than for the free one whereas Vmax was smaller for the immobilized GOD. The bioactivity of PEO‐modified PAAc‐grafted PE membrane (PAAc–PEO–GOD) was higher than that of PAAc‐grafted PE membrane (PAAc–GOD). The pH and thermal stabilities of the immobilized GOD without a spacer (PAAc–GOD) were higher than those of the immobilized GOD with a spacer (PAAc–PEO–GOD) and the free form. © 1993 John Wiley & Sons, Inc.
Structure and properties of compatibilized blends of polyamide‐6 and ABS
Authors: Misra A. , Sawhney G. , Kumar R. Ananda 
Published: April 2003

AbstractMechanical and Morphological properties of polyamide‐6/ABS blend systems, compatibilized by styrene‐maleic anhydride (SMA) copolymer, have been studied. The strength, modulus, and impact properties improved upon the addition of SMA. Morphological studies, using small angle light scattering, polarizing microscopy, and scanning electron microscopy, showed that SMA acts as a compatibilizer for the above system. © 1993 John Wiley & Sons, Inc.
Structures and mechanisms of formation of poly(acrylic acid)‐iron (II and III) chloride gels in water and hydrogen peroxide
Authors: Lindén Lars‐åke , Rabek Jan F. 
Published: April 2003

AbstractPoly(acrylic acid) (PAA) can form stable and insoluble gels with FeCl3 in water or in H2O2 (30 wt %). Two carboxylic groups are complexed by the FeCl2+ ion. PAA‐FeCl3 (2 : 1) gels have found practical application in the blocking of microscopic channels in tooth dentin and thereby decrease the fluid permeability and protect against tooth decay. © 1993 John Wiley & Sons, Inc.
Structural analysis and degradation behavior in polyethylene glycol/poly(L‐lactide) copolymers
Authors: Hu David Shiaw‐Guang , Liu Hsin‐Jiant 
Published: April 2003

AbstractThe objective of this research is to investigate the molecular weight, degradation mechanism, and crystalline morphology of polyethylene glycol/poly(L‐lactide) (PEG/PLLA) copolymers during hydrolytic degradation. PEG/PLLA copolymers were prepared from cyclic L‐lactide and polyethylene glycol with molecular weights ranging from 1000 to 6000 Da. The structural analysis was carried out by GPC, DSC, FTIR, 13C‐NMR, and 1H‐NMR. Gel permeation chromatograms also indicate that the hydrolysis causes the change of mass distribution from a unimodal to a bimodal from. An exothermic recrystallization peak and its shoulder portion at the lower temperature range during melting appears immediately following the hydrolytic degradation. This indicates the heterogeneity of the crystals. The data of NMR and FTIR shows that during the initial period (0–200 h) of hydrolysis, there appears to be a formation of hydroxyl end groups connected to PEG blocks and carboxyl end groups connected to polylactide blocks. Due to the hydrophilic ethylene oxide segment in PEG/PLLA copolymers, the rate of hydrolysis is much faster during the first 200 h relative to longer hydrolysis time. It is therefore concluded that the chain scission during the initial period occurs at the ester linkage connecting PEG and PLLA blocks, in addition to ester groups within the PLLA blocks. © 1994 John Wiley & Sons, Inc.
Miscibility studies of polymer blends by viscometry methods
Authors: Lizymol P. P. , Thomas Sabu 
Published: April 2003

AbstractThe intrinsic viscosities of blends of poly(vinyl chloride)/poly(ethylene‐co‐vinyl acetate) (PVC/EVA), poly(vinyl chloride)/poly(styrene‐co‐acrylonitrile) (PVC/SAN), and poly(ethylene‐co‐vinyl acetate)/poly(styrene‐co‐acrylonitrile) (EVA/SAN) have been studied in cyclohexanone as a function of blend composition. In order to predict the compatibility of polymer pairs in solution, the interaction parameter term, Δb, obtained from the modified Krigbaum and Wall theory, and the difference in the intrinsic viscosities of the polymer mixtures and the weight average intrinsic viscosities of the two polymer solutions taken separately are used. © 1994 John Wiley & Sons, Inc.
Physical properties of model graft copolymers and their use as blend compatibilizers
Authors: Peiffer Dennis G. , Rabeony M. 
Published: April 2003

AbstractThe present investigation pertains to the structure–property relationships of highly structured graft copolymers. The specific model graft copolymers are based on an elastomeric backbone, i.e., poly(ethyl acrylate), and monodisperse thermoplastic grafts, i.e., polystyrene. The synthesis of these graft copolymers is based on the free‐radical polymerization of ethyl acrylate and an anionically polymerized polystyrene macromonomer. It is clearly demonstrated that grafts significantly enhance tensile properties. The level of improvement is directly related to the graft level, i.e., number of grafts/chain, and graft molecular weight. In addition, blending these graft copolymers into their respective homopolymer mixture results in a mechanical performance strikingly dependent on the molecular characteristics of the graft copolymer. For example, tensile strength is maximized at a level between one and two grafts per chain. This result parallels observations noted in blend compatibilization using diblock and triblock copolymers. It is also demonstrated that using mutually grafted copolymers produces an interesting variety of compatibilized ternary (or higher) component blends. © 1994 John Wiley & Sons, Inc.
Miscibility and interaction studies on some aqueous polymer blend solutions by ultrasonic and rheological techniques
Authors: Paladhi R. , Singh R. P. 
Published: April 2003

AbstractThe aqueous solutions of poly(ethylene oxide)–polyacrylic acid, poly(vinyl pyrrolidone)–poly(vinyl alcohol), and poly(ethylene oxide)–poly(vinyl alcohol) blends have been studied by ultrasonic, rheological, and viscometric techniques. Extensive investigation over a wide range of concentrations, temperatures, compositions, pH, and shear rates indicate the degree of miscibility, extent of interaction between the polymers, and stoichiometry of the polymer complexes formed by the strong interaction between the polymers in solutions. These investigations indicate the miscibility of poly(ethylene oxide)–polyacrylic acid and poly(ethylene oxide)–poly(vinyl pyrrolidone) blends and the immiscibility of poly(ethylene oxide)–poly(vinyl alcohol) blends in conformity with other reported investigations. © 1994 John Wiley & Sons, Inc.
Studies related to in‐plane flow behavior of elastomer matrix in nonwoven fibrous structures
Authors: Epstein M. , Shishoo R. L. 
Published: April 2003

AbstractThe purpose of the present work has been to produce knowledge as regards the rheological behavior of polymer matrix in nonwoven fibrous reinforcing structures for composites. The results are expected to contribute toward a better understanding of flow mechanisms in fibrous systems in order to develop better techniques for fabricating elastomer‐based composites. Theoretical and experimental analyses have been made of interactions between the structural parameters of the fibrous mats and the flow characteristics of the matrix with systematically varied material and process parameters. In nonwoven mats with fibers laid lengthwise, the flow rate along the fiber direction was found to be significantly higher than the flow rate crosswise to the fiber direction. Nonwoven mats with multidirectionally laid fibers exhibited a practically radial flow front pattern. Nonwoven mats made of coarser fibers showed greater matrix polymer flow rate as compared with finer fibers. The matrix flow distance was proportional to the logarithm of injection time. The decrease of pressure in the mold cavity was linearly proportional to the matrix flow distance. The dependence of permeability on the level of compression of the fibrous structure is in agreement with the results published by other workers. © 1994 John Wiley & Sons, Inc.
Gelation of poly(vinyl alcohol) solutions at low temperatures (20 to −78°C) and properties of gels
Authors: Yamaura Kazuo , Karasawa Koh‐Ichi , Tanigami Tetsuya , Matsuzawa Shuji 
Published: April 2003

AbstractThe flow points of atactic poly(vinyl alcohol) (a‐PVA) gels with H2O/dimethyl sulfoxide (DMSO) = 90/10 (v/v) chilled at 20 to −78°C for 24 h depended on the chilling temperature and were 0–30°C for gels with the initial polymer concentrations (Ci) of 2–5 g/dL, whereas those for H2O/DMSO = 50/50 chilled at 0 to −78°C were independent of the chilling temperature and were 70–75°C. Syneresis occurred after eight cycles of freezing (−24°C) and thawing (20°C) for a‐PVA hydrogels at concentrations above Ci = 4 g/dL and two such cycles for syndiotacticity‐rich PVA (s‐PVA) hydrogels at concentrations above Ci = 1 g/dL. The extent of syneresis per one cycle for s‐PVA hydrogels was higher than that for a‐PVA hydrogels at the initial cycles. In the a‐PVA hydrogels with an initial polymer concentration of ca. 30 g/dL, syneresis was expected not to occur even after 20 cycles. If all the free water in the gels is assumed to have transuded by syneresis after 20 cycles, the residual water is bound water and is estimated to be six water molecules per one vinyl alcohol monomer unit. © 1994 John Wiley & Sons, Inc.
A 13C NMR study of polyflavonoid tannin adhesive intermediates. II. Colloidal state reactions
Authors: Pizzi A. , Stephanou A. 
Published: April 2003

AbstractWater solutions of 40–50% polyflavonoid tannin extracts appear to be in a colloidal state. This is caused by both the presence of noticeable amounts of hydrocolloid gums as well as the presence of higher molecular mass tannins. 13C NMR analysis appears to confirm that during chemical treatment, reactions occur in these colloidal solutions that would not be likely to occur in noncolloidal solutions as used in model compound experiments. These reactions centre on the role of the organic anhydride used during treatment, and lead to intramicellar direct α‐set attack or to acetylation of the tannin followed by a rapid rearrangement again to an α‐set attack, which is similar to both a Kolbe reaction and a Fries rearrangement. This eventually leads to accelerated cross‐linking of the tannin‐formal‐dehyde adhesive prepared from the chemically modified tannin extract. It appears that such reactions and rearrangements are performance determining in the case of the two lower‐reactivity tannins examined, mimosa and quebracho; have some noticeably positive effects on the higher reactivity pine tannin, and appear instead to have a deleterious effect on the other higher reactivity tannin, namely pecan nut tannin. The reasons for such behaviour are briefly discussed. © 1994 John Wiley & Sons, Inc.
Surface chlorination of polypropylene film by CHCI3 plasma
Authors: Inagaki N. , Tasaka S. , Suzuki Y. 
Published: April 2003

AbstractPolypropylene films were treated with the CHCI3 plasma, and their chemical composition was analyzed with XPS and ART IR spectroscopy. The CHCI3 plasma irradiation made polypropylene films hydrophilic. The advancing contact angle decreases from 95° for the untreated to about 73° for the CHCI3 plasma‐treated films. In the CHCI3 plasma irradiation, the chlorination occurs, and CCl, CCl2, and CCl3 units are formed in the polypropylene films. Simultaneously with the chlorination, unsaturated units (CC and conjugated CC units) are formed from dehydrogen chlorination of the chlorinated products, but the oxygen incorporation into the films is low. The CHCI3 plasma is preferred in chlorination of polypropylene films to the CCl4 plasma. © 1994 John Wiley & Sons, Inc.
Synthesis and evaluation of acrylate polymers for improving flow properties of waxy crudes
Authors: El‐Gamal I. M. , Ghuiba F. M. , El‐Batanoney M. H. , Gobiel S. 
Published: April 2003

AbstractN‐Alkyl acrylates and n‐alkyl methacrylates were prepared by esterification of acrylic and methacrylic acids with two long‐chain alcohol blends NAFOL 2022 and NAFOL 1822. The prepared monomers were characterized and polymerized individually. In addition, copolymers of n‐alkyl acrylate‐n‐alkyl methacrylate, and n‐alkyl methacrylate–vinyl acetate and a terpolymer of n‐alkyl acrylate–acrylic acid–vinyl acetate were also synthesized. These polymers were also characterized and then evaluated as flow improvers in Khalda mixtureand Salam Egyptian waxy crudes. The majority of the prepared additives showed good performance in improving the flow properties of the tested crudes. © 1994 John Wiley & Sons, Inc.
LDPE/PP blends modified by peroxide and radiation induced reactions
Authors: Yu D. W. , Xanthos M. , Gogos C. G. 
Published: April 2003

AbstractLDPE/PP polyblends, modified through either peroxide initiated reactions or irradiation, were characterized in terms of rheological and mechanical properties and microstructure. In the presence of peroxide, or through irradiation LDPE crosslinks, PP degrades. Data were obtained at two peroxide concentration levels (0.1 and 1% by weight) and two radiation doses (30 and 100 kGy). The results show that in peroxide modification, the degradation of PP prevails over the crosslinking of LDPE. However, the effect of irradiation of LDPE (crosslinking) is predominant over that of PP (degradation). The irradiation process tends to yield improved mechanical properties vs. peroxide modification for the PP‐rich blends. In addition, the melt viscosity and elasticity of the irradiated PP‐rich blends are higher than those of the peroxide‐reacted blends at a given level of PP content and frequencies between 10 and 100 rad/s. Attempts were made to relate the shape of the rheological curves and the mechanical properties of the blends to the observed changes in their microstructure. © 1994 John Wiley & Sons, Inc.
Mechanisms of interactive crazing in PC/SAN microlayer composites
Authors: Sung K. , Haderski D. , Hiltner A. , Baer E. 
Published: April 2003

AbstractMechanisms are proposed for the two types of interactive crazing that have been observed in PC/SAN microlayer composites when the PC layer thickness is on the micron‐size scale. It is demonstrated that when the PC layer is thin enough the deformation zone that forms at a craze tip can interact with the next‐neighboring SAN layer. By measuring the dimensions of the craze tip in scanning electron micrographs, it was found that the craze‐tip opening does not depend on the SAN layer thickness, i.e., the length of the SAN craze. Consequently, the size and shape of the resulting plastic zone in the PC layer are also independent of layer thickness. The zone that forms in the PC layer consists of a colinear plastic zone together with a pair of micro‐shearbands that grow at an angle of about 45°. When the PC layer is less than 6 μm, the elastic stress concentration from the colinear plastic zone increases the probability of crazing in the neighboring SAN layer with the formation of craze doublets that consist of two aligned crazes in neighboring SAN layers. By taking into consideration the Weibull distribution of crazing, a craze doublet fraction comparable to the 30% observed experimentally was predicted with a stress intensification factor in the range of 1.03–1.05. When the PC layer thickness is less than 1.3 μm, the length of the colinear plastic zone is comparable to the PC layer thickness. Formation of a craze at the point of impingement of the plastic zone on the neighboring SAN layer leads to craze arrays with many aligned crazes in neighboring SAN layers. At higher strains, the micro‐shearbands grow through the PC layers and extend into several adjacent SAN and PC layers. This produces a change in deformation mechanism in the SAN layers at the yield instability, from craze opening to shear yielding. © 1994 John Wiley & Sons, Inc.
Ductility of filled polymers
Authors: Bazhenov S. , Li J. X. , Hiltner A. , Baer E. 
Published: April 2003

AbstractThe ductility of a calcium carbonate‐filled amorphous copolyester PETG in a uniaxial tensite test was examined as a fiction other filler volume fraction. A ductile‐to‐quasibrittle transition occurred as the volume fraction of filler increased. This transition was from propragation of a stable neck through the entire gauge length of the specimen to fracture in the neck without propagation. The draw stress (lower yield stress) did not depend on the filler content and was equal to the draw stress of the unfilled polymer. It was therefore possible to use a simply model to predict the dependence of the fracture strain on the filler volume fraction. It was proposed that when the fracture strain decreases to the draw strain of the polymer the fracture mechanism changes and the fracture strain drops sharply. The critical filler content at which the fracture mode changes is determined primarily by the degree of strain‐hardening of the polymer. © 1994 John Wiley & Sons, Inc.
Studies on cure synergism. I. Effect of safe zinc dithiocarbamates on NR vulcanization accelerated by thiazole‐based accelerators
Authors: Debnath S. C. , Basu D. K. 
Published: April 2003

AbstractInvestigations have been carried out on the effect of several zinc dithiocarbamates in the presence of thiazole‐based accelerators in the vulcanization of natural rubber (NR), keeping in mind the possibility of introducing safe dithiocarbamates derived from safe amines. Mutual activity is observed in all the binary systems studied, the highest being observed in the zinc dibenzyldithiocarbamate‐dibenzothiazyldisulfide (ZBEC–MBTS)‐accelerated system. The effect of zinc diisopropyl dithiophosphate, reportedly a safe rubber additive, which is recognized as an age‐resistant agent for NR, on cure has also been studied. The study reveals that thiuram disulfide and MBT are always formed from the reaction either between zinc dithiocarbamate (ZDC) and MBTS or between ZDC and N‐cyclohexyl‐2‐benzothiazole sulfenamide (CBS). It has been conclusively proved that 2‐mercaptobenzothiazole (MBT) generated from MBTS or CBS reacts with ZDC and produces tetramethyl thinram disulfide (TMTD). The observed mutual activity has been discussed based on the cure and physical data and explained through the results based on HPLC and a reaction mechanism. © 1994 John Wiley & Sons, Inc.
Equilibrium swelling properties of weakly lonizable 2‐hydroxyethyl methacrylate (HEMA)‐based hydrogels
Authors: Baker John P. , Blanch Harvey W. , Prausnitz John M. 
Published: April 2003

AbstractHydrogles, sensitive to pH, were prepared by copolymerizing 2‐hydroxyethyl methacrylate (HEMA) with 2‐dimethylaminoethyl methacrylate (DMA). The mole fraction of the DMA monomer present during synthesis was fixed at 0.3, while the volume fraction of total monomer varied from 0.29 (I) to 1.0 (II). Swelling equilibria were measured in citrate of phosphate buffer for pH from 3.0 to 7.6 Swelling of the hydrogels depends on the volume fraction monomer present during synthesis, solution, pH, and identity of the buffer, Hydrogel I reached a four‐fold larger swelling ratio (g swollen hydrogel/g dry hydrogel) in pH 3.0 citrate buffer, as compared to hydrogel II. Experimental results are interpreted on the basis of ideal Donnan equilibria. © 1994 John Wiley & Sons, Inc.