bluuebunny/crossref_metadata_2025_split huggingface dataset:
Composition control in emulsion copolymerization. II. Application to binary and ternary systems
Authors: Canegallo Stefano , Canu Paolo , Morbidelli Massimo , Storti Giuseppe 
Published: April 2003

AbstractThe optimal monomer feed policy for producing in a semibatch reactor a given amount of polymer with constant instantaneous composition, in the minimum reaction time and complete monomer depletion, as developed in Part I of this work, has been implemented experimentally. Conversion has been monitored on‐line using a densitometer suitably connected to the laboratory reactor. The procedure has been applied to two binary and one ternary systems. The composition of the polymer produced has been characterized through various experimental techniques. The composition control procedure is insensitive to most types of irreproducibilities that arise in batch reactions performed in industrial appli‐fjcations. © 1994 John Wiley & Sons, Inc.
Crosslinking by etherification of bisepoxide with divalent metal salts of p‐aminobenzoic acid
Authors: Takechi Shicetoshi , Matsuda Hideaki 
Published: April 2003

AbstractCrosslinking by etherification of a large excess of bisepoxide with divalent metal salts of p‐aminobenzoic acid was investigated. Mg and Ca were selected as the divalent metal salts, and bisphenol A diglycidyl ether was the bisepoxide used. In the crosslinking reactions, the metal salts exhibited catalytic activity for the etherification, with the Ca salt showing higher catalytic activity than the Mg salt. Hence, the etherification proceeded via an ionic mechanism in which carboxylate anion is concerned. The orders of reaction with respect to carboxylate anion concentration were one order for the both systems. The overall ac‐tivation energies of the crosslinking reaction were 13.4 kcal/mol for the system containing Mg and 23.0 kcal/mol for the system containing Ca. The metal‐containing cured resins obtained showed higher flexural strength, Rockwell hardness, and compressive strength than the resins without metal. Heat distortion temperature and glass transition temperature determined by dynamic mechanical properties increased with an increase in the metal salt content in the feed. Thermal decomposition was accelerated by the incorporated metal. In addition, the metal‐containing cured resins have high boiling water and water resistances.
Characterization of crosslinking of random polymer network by rheological and equilibrium swelling data
Authors: Espinasse I. , Cassagnau P. , Bert M. , Michel A. 
Published: April 2003

AbstractThe transesterification reaction in the molten state of ester groups of ethylene vinyl acetate (EVA) copolymers and ethylene acrylic ester (EMA) copolymers has been used to crosslink the chains of this polymeric system. The relative EVA copolymers (or EMA copolymers) concentration dependence of the network formation by co‐crosslinking of EVA/EMA miscible blends has been assessed. EVA/EMA networks were characterized by swelling experiments, rheological measurements, and determination of the extent of the reaction through a chromatographic technique. All results can be compared in a master curve. The influence of the polydispersity and the microstructure of EVA and EMA samples was put in evidence. On the other hand, a scaling law (v2∼Mc−3/5) was observed in agreement with predictions of the Flory‐Rhener expression. © 1994 John Wiley & Sons, Inc.
Fluorinated poly(butylene terephthalate): Preparation and properties
Authors: Toselli M. , Pilati F. , Fusari M. , Tonelli C. , Castiglioni C. 
Published: April 2003

AbstractFluorinated poly(butylene terephthalate) (PBT) can be easily prepared using a telechelic perfluoropolyether (PFPE) as a comonomer. The functional groups of the PFPE react completely with other monomers, but the distribution of the PFPE blocks is not homogeneous and in the final polymeric material there is a significant fraction of PFPE bonded to very short segments of polyester. Due to the very poor miscibility of PFPE and PBT, the PFPE is present as a separate phase dispersed in an almost pure PBT matrix. Accordingly, both thermal and mechanical properties of PBT are little affected by the PFPE. The presence of PFPE induces a slight improvement on the fracture resistance and on surface properties such as wear resistance and coefficient of friction. © 1994 John Wiley & Sons, Inc.
Single‐step dyeing and finishing treatment of cotton with 1,2,3,4‐butanetetracarboxylic acid
Authors: Choi Hyuang‐Min , Srinivasan Magesh , Morris Nancy M. 
Published: April 2003

AbstractA single‐step dyeing and finishing (SDF) process was developed to eliminate dyeing problems associated with cotton crosslinked by polycarboxylic acid such as 1,2,3,4‐butanetetracarboxylic acid (BTCA). This process consisted of several steps: (a) impregnation of the fabric by the bath containing BTCA, dye, and catalyst; (b) drying; and (c) curing at high temperature. Color strength (K/S) and dye fixation of cotton treated by the SDF process were excellent, especially with reactive dyes containing mono‐ or dichlorotriazinyl compounds and, in some cases, were higher than those of the sample dyed by a conventional batch process without finishing treatment. The presence of dye in the SDF process did not interfere with crosslinking of cotton. We believed that the reaction occurred between carboxyl groups of BTCA and s‐triazinyl groups in reactive dyes in the presence of imidazole and other catalyst. FTIR, Raman, and X‐ray fluorescence spectroscopies were used to confirm the mechanism of dye fixation. Elemental analysis also supported this mechanism. The SDF process can be an excellent way to dye fabric that also requires crosslinking treatment for smooth drying appearance. © 1994 John Wiley & Sons, Inc.
Slow crack growth in polyethylene: A novel predictive model based on the creep of craze fibrils
Authors: Rose L. J. , Channell A. D. , Frye C. J. , Capaccio G. 
Published: April 2003

AbstractAn extensive series of homopolymers and copolymers has been investigated to test earlier indications of a possible link between resistance to slow crack growth and creep of macroscopic oriented samples. It was found that in the majority of cases a good correlation exists between a single creep parameter and slow crack growth. The existence of such a correlation supports the model presented, in which crack growth is primarily controlled by the creep of fibrils spanning the craze zone. The limit of improvement achievable by increasing molecular weight and the greater effectiveness of short‐chain branching to improve fibril creep have been highlighted. © 1994 John Wiley & Sons, Inc.
Water absorption effects on the thermal transition and stiffness of ethylene ionomers
Authors: Tachino Hitoshi , Hara Hisaaki , Hirasawa Eisaku , Kutsumizu Shoichi , Yano Shinichi 
Published: April 2003

AbstractChanges in the thermal transition and stiffness of ionomers occuring during aging or water absorption were investigated. Ionomers used in this study are Na, K, Mg, and Zn salts of poly(ethylene‐co‐methacrylic acid) (EMAA), whose methacrylic acid unit is 5.4 mol %. It was found that ionomer stiffness is subject to water absorption and the effect differs with the neutralizing cations. Water absorption effects on the thermal transition, measured by differential scanning calorimetry (DSC), indicate that there are no significant changes in the higher‐temperature endotherm assigned to a melting of polyethylene (PE) crystallities. However, the lower‐temperature endotherm, which we attribute to an order‐disorder transition of ionic aggregates (Ti), exhibits significant changes upon water absorption. The mechanism of the water absorption effects on the thermal transition and stiffness is described. © 1995 John Wiley & Sons, Inc.
Recognition of amino acids by membrane potential of immobilized globulin membranes
Authors: Yun K.‐S. , Tak T.‐M. , Shimada S. , Nakagawa T. , Hara M. , Higuchi A. 
Published: April 2003

AbstractThe shifts in membrane potential, caused by the injection of some amino acids into a permeation cell, were measured using immoblized γ‐globulin membranes. The shifts in membrane potential were observed to be positive or negative when the isoelectric point of each amino acid injected into the cell was less or higher than 6.0. The potential response caused by the injection of each amino acid shows an individual and characteristic curve depending on the amino acid, and the difference in potential curves between D‐aspartic acid and L‐aspartic acid is significantly observed in the immobilized γ‐globulin membranes. The t3/4 value was found to increase in the following order: lysine = glutamic acid <arginine < D‐aspartic acid = asparagine < L‐aspartic acid < histidine < alanine, where t3/4 indicates the time at which 75% of the shifts in membrane potential has been observed. The modified membrane potential theory provides satisfactory explanations for the membrane potential obtained experimentally before and after the injection of L‐alanine, and the theoretical shifts can explain the experimental shifts in membrane potential due to the injection of L‐alanine into the cell. © 1995 John Wiley & Sons, Inc.
Structure and physical properties of grafted jute fiber
Authors: Kundu S. K. , Ray P. K. , Sen S. K. , Bhaduri S. K. 
Published: April 2003

AbstractJute fiber was grafted by acrylonitrile and methylmethacrylate monomers in raw and bleached condition. It was also noted that optimum grafting takes place after about 4 h of grafting. It was also noted that in bleached jute fiber, the grafting percentage is higher at all stages of grafting but the tenacity value at the highest add‐on is practically the same as that of raw fiber with much less add‐on. The crystalline orientation of the grafted jute fiber was correlated with the fiber tenacity. The moisture regain (%) of the fiber after grafting showed a decreasing trend with an increase in grafting percentage. No structural change of the fiber occurred due to grafting. © 1995 John Wiley & Sons, Inc.
Size‐exclusion chromatography of cross‐linked superabsorbent polymers
Authors: Cutié Sergio S. , Martin Steven J. 
Published: April 2003

AbstractSuperabsorbent polymers are cross‐linked poly(acrylic acid) with some degree of neutralization. These polymers have found extensive use as constituents in personal care products such as sanitary napkins, incontinent devices, and disposable baby diapers that absorb body fluids. Polymer networks are formed, which makes the chromatography of these materials impossible. In this study, hydrolysis under heat and high pH was used to break the cross‐links, which allows for traditional size‐exclusion chromatography to determine molecular weight and molecular weight distribution of the primary chains. For the chromatography, TSK‐GEL®†PWXL columns and TSK‐GEL PW columns were used. The mobile phase was buffered with sodium chloride and sodium phosphate salts to eliminate ionic interactions. Detection was by refractive index. © 1995 John Wiley & Sons, Inc.
Preparation and characterization of pH‐sensitive, interpenetrating networks of poly(vinyl alcohol) and poly(acrylic acid)
Authors: Gudeman Linda F. , Peppas Nikolaos A. 
Published: April 2003

AbstractHydrogels with varying cross‐linking ratio and ionic content were prepared from interpenetrating networks of poly(vinyl alcohol) and poly(acrylic acid). Equilibrium swelling studies were conducted and the average molecular weight between cross‐links, Mc, and mesh size were determined. Hydrogels with large Mc, values were found to swell to a greater extent than those with small Mc values. It was also observed that an increase in Mc yielded faster swelling and deswelling rates, as the rates for membranes with Mc = 18,000 were about twice as fast as were the rates for membranes with Mc = 34,000. Oscillatory swelling behavior was investigated in response to changes in the pH and ionic strength of the swelling medium. A change in pH from 3 to 6 caused an ionization of the hydrogels and an increase in the weight swelling ratio, with a greater increase exhibited by IPNs with a higher ionic content. Increase in pH also caused an increase in the average mesh size. © 1995 John Wiley & Sons, Inc.
A 13C‐NMR analysis method for phenol–formaldehyde resin strength and formaldehyde emission
Authors: Panamgama L. A. , Pizzi A. 
Published: April 2003

AbstractA method based on the use of 13C‐NMR relative peak intensity ratios for different characteristic chemical groups, known or supposed to contribute to phenol–formaldehyde (PF) resin strength and formaldehyde emission is presented. The method relates results obtained by 13C‐NMR analysis of liquid PF resins with the strength and formaldehyde emission in the resin‐hardened state. Correlation of differnt peak ratio with experimental results allows the proposal of equations relating the sum of different 13C‐NMR peak ratios with the two mentioned physical properties of the same resins in their hardened state. The equations presented appear to have some applied value in predicting physical properties of hardened industrial‐type PF resins from a single 13C‐NMR spectrum of the original liquid resin, as well as to render easier comparison between different PF resin formulations. © 1995 John Wiley & Sons, Inc.
Blends of a PPO–PS alloy with a liquid crystalline polymer
Authors: Viswanathan R. , Isayev A. I. 
Published: April 2003

AbstractBlends of a PPO–PS alloy with a liquid crystalline polymer have been studied for their dynamic properties, rheology, mechanical properties, and morphology. This work is an extension of our previous work on PPO/LCP blends. The addition of the LCP to the PPO–PS alloy resulted in a marked reduction in the viscosity of the blends and increased processibility. The dynamic studies showed that the alloy is immiscible and incompatible with the LCP at all concentrations. The tensile properties of the blends showed a drastic increase with the increase in LCP concentration, thus indicating that the LCP acted as a reinforcing agent. The tensile strength, secant modulus, and impact strength of the PPO–PS/LCP blends were significantly higher than that of PPO/LCP blends. Morphology of the injection molded samples of the PPO–PS/LCP blends showed that the in situ formed fibrous LCP phase was preserved in the solidified form. A distinct skin–core morphology was also seen for the blends, particularly with low LCP concentrations. The improvement of the mechanical properties of the blends is attributed to these in situ fibers of LCP embedded in the PPO–PS matrix. The improvement in the properties of PPO–PS/LCP over PPO/LCP is also attributed to the addition of the PS which consolidates the matrix. © 1995 John Wiley & Sons, Inc.
Surface modification of poly(vinyl chloride) with poly(methyl methacrylate)/poly(dimethyl siloxane) graft copolymers
Authors: Gorelova M. M. , Pertsin A. J. , Muzafarov A. M. , Gritsenok O. T. , Vasilenko N. G. 
Published: April 2003

AbstractX‐ray photoelectron spectroscopy is used to study the surface segregation of siloxane in dilute blends of poly(methyl methacrylate)/poly(dimethyl siloxane) graft copolymers in poly(vinyl chloride)(PVC). The graft copolymers are found to be extremely efficient surface modifiers, which form, when added in amounts of 0.5% or more, a continuous siloxane overlayer on the surface of PVC. © 1995 John Wiley & Sons, Inc.
The effect of a liquid isothermal bath in the threadline on the structure and properties of poly(ethylene terephthalate) fibers
Authors: Wu Gang , Zhou Qiang , Chen Jiunn‐Yow , Hotter Joseph F. , Tucker Paul A. , Cuculo John A. 
Published: April 2003

AbstractThe process of melt‐spinning poly(ethylene terephthalate) (PET) filament at high speeds was modified through the inclusion of a liquid isothermal bath (LIB) in the spinline. A wide range of positions, temperatures, and depths associated with the operation of the LIB were utilized in this study. The structural characteristics and mechanical properties of the as‐spun fibers were characterized by birefringence, wide‐angle X‐ray diffraction (WAXD), infrared spectroscopy, and tensile testing. Experimental results showed that the structure and mechanical properties of the as‐spun fibers were significantly influenced by the LIB operating conditions. The as‐spun fibers prepared under optimum LIB conditions exhibit high birefringence and excellent mechanical properties. Results suggest the development of a critical value of threadline stress that is determined primarily by LIB depth and take‐up velocity. Below this critical value, raising of LIB temperature, LIB depth, and take‐up velocity resulted in increases of the apparent crystallite size, sample crystallinity, and both the crystalline and amorphous orientation. As would be expected, the mechanical properties of the fiber samples were improved in a corresponding manner. Above this critical stress value, molecular chains in the amorphous phase are stretched tautly, but the crystal growth process is restricted, resulting in a decrease in crystallite size and crystallinity, as well as a continued increase in mechanical properties. The fiber properties were also found to be very responsive to the relative location of the LIB. A unique structure, believed never before obtained in a one‐step high‐speed PET melt‐spinning process, has been achieved that combines high amorphous orientation, low crystallinity, and high tenacity. © 1995 John Wiley & Sons, Inc.
Plasma polymerization of copper phthalocyanines and application of the plasma polymer films to NO2 gas sensor device
Authors: Inagaki N. , Tasaka S. , Ikeda Y. 
Published: April 2003

AbstractFour copper phthalocyanines without substituent (CuPc) and with chlorine (CuPc‐Cl), hydroxymethyl (CuPc‐CH2OH), and phthalimidomethyl substituents (CuPc‐CH2N‐[C(O)]2Ph) were plasma‐polymerized to obtain amorphous and thin films having the extended π‐electron system. The chemical composition of the plasma polymer films was discussed from the data of the electronic spectra, IR spectra, and XPS spectra. The application of the plasma polymer films was discussed with regard to the NO2 sensitivity, the NO2 selectivity, the response time, and the reversibility. Plasma polymerization of CuPc, CuPc‐Cl, CuPc‐CH2OH, and CuPc‐CH2OH gives amorphous films having the extended π‐electron system. In the plasma polymerization process, a part of the extended π‐electron system is broken down. The CH2OH and CuPc‐CH2N[C(O)]2Ph substituents contribute to minimizing the degradation. The Cu atoms liberated from the chelation in the plasma polymerization process exist as CuO in the deposited films. The plasma polymer films of CuPc‐CH2OH and CuPc‐CH2N[C(O)]2Ph show good sensitivity to NO2 molecules. With regard to the sensitivity, the selectivity, the response time and the reversibility, the plasma polymer films are applicable materials to the NO2 sensor device. © 1995 John Wiley & Sons, Inc.
Copolymeric systems with pendant thioxanthone and α‐morpholinoacetophenone moieties as photosensitizing and photoinitiating agents for UV‐curable pigmented coatings
Authors: Angiolini Luigi , Caretti Daniele , Corelli Elena , Carlini Carlo 
Published: April 2003

AbstractThe synthesis and structural characterization of copolymers of 1‐[(2‐acryloyloxy) ethoxycarbonyl]thioxanthone (ATX) with 1‐[4‐(2‐acryloyloxyethylthio)phenyl]‐2‐methyl‐2‐morpholino‐propan‐1‐one (AMMP), as well as ATX, AMMP and n‐butyl acrylate (BA) terpolymers, is reported. These copolymeric systems have been checked in the photoinitiated polymerization in film matrix of the 1,6‐hexanediol diacrylate (HDDA)–BA equimolar mixture under UV irradiation over 380 nm, i.e., under conditions simulating a TiO2‐pigmented acrylic coating formulation, and compared with the corresponding mixture of low‐molecular‐weight structural models 1‐[(2‐isobutyroyloxy)ethoxycarbonyl]thioxanthone (ITX) and 1‐[4‐(2‐isobutyroyloxyethylthio)phenyl]‐2‐methyl‐2‐morpholino‐propan‐1‐one (IMMP). The much higher photoinitiation activity shown by the copolymers is discussed in terms of close vicinity of thioxanthone and α‐morpholinoacetophenone moieties along the backbone, which favors the excitation energy transfer from the former to the latter photosensitive group. © 1995 John Wiley & Sons, Inc.
Crystallization and compatibility of poly(vinyl alcohol)/poly(3‐hydroxybutyrate) blends: Influence of blend composition and tacticity of poly(vinyl alcohol)
Authors: Yoshie Naoko , Azuma Yoichiro , Sakurai Minoru , Inoue Yoshio 
Published: April 2003

AbstractCompatibility of a crystalline/crystalline polymer blend, poly(vinyl alcohol) (PVA)/poly(3‐hydroxybutyrate) (PHB), was studied by high‐resolution solid‐state 13C‐NMR spectroscopy. The 1H T1 measurement demonstrated that both the compatibility and the domain size depend on the composition of the blend. The PVA/PHB blend is compatible only when the blend contains a large amount of PVA. The domain sizes of the compatible blend are less than 200 Å. In the pulse saturation transfer (PST) MAS NMR spectra, the carbonyl carbon resonance from PHB showed a downfield shift, which indicates that the compatibility of the PVA/PHB blends is due to the hydrogen‐bonding interaction in the amorphous phase. The DSC measurement showed that the compatible blends adopt low crystallinity for both PHB and PVA. The crystallization in these blends is likely to be distributed by the hydrogen‐bonding interaction in the amorphous phase. The compatibility of PVA/PHB is also affected by the tacticity of PVA. The compatible composition range of the syndiotacticrich PVA/PHB blend is wider than that of the atactic‐PVA/PHB blend. It is likely that the capacity to form the hydrogen bond depends on the tacticity of PVA. © 1995 John Wiley & Sons, Inc.
Morphology and tensile properties of styrene–butadiene copolymer reinforced asphalt
Authors: Blanco R. , Rodríguez R. , García‐Garduño M. , Castaño V. M. 
Published: April 2003

AbstractMorphology and tensile properties of several styrene‐butadiene copolymer reinforced asphalts have been investigated. In all cases, the raw materials were commercial samples; for the styrene‐butadiene copolymer, a branching (nonlinear) block polymeric chain of high molecular weight was used. On the other hand, the asphalt was a nonoxydized commercial sample. The raw materials were characterized prior to making the composite. The morphology and mechanical properties of composites obtained at different chemical compositions were determined, and a comparison of these experimental results to different models, according to the composite morphology, is shown. © 1995 John Wiley & Sons, Inc.
Phenomenology of surface failure of poly(methylmethacrylate) resulting from rolling contact fatigue
Authors: Hosseini S. M. , Stolarski T. A. 
Published: April 2003

AbstractResults of phenomenological study into the forms of surface failure of poly(methylmethacrylate) (PMMA) are presented. Surface failure of the polymer resulted from rolling contact fatigue produced in a model configuration consisting of a PMMA disc with nominally flat surface loaded against three steel balls able to roll free over the surface of the disc. It was found that the performance of the polymer under the test conditions used is influenced by lubricating medium and the main form of failure is of surface fatigue type. © 1995 John Wiley & Sons, Inc.
Emulsion copolymerization of vinyl esters in continuous reactors: Comparison between loop and continuous stirred tank reactors
Authors: Abad Carlos , De La Cal José C. , Asua José M. 
Published: April 2003

AbstractThe high solids emulsion copolymerization of vinyl acetate and veova 10 was studied in a continuous loop reactor and in a continuous stirred tank reactor (CSTR) in an attempt to elucidate the similarities and differences between these reactors. Reactions were carried out under comparable conditions, namely, similar macromixing and the same feed composition and space time. The behavior of both reactors was almost the same when the heat generation rate was low; otherwise, thermal runaway occurred in the CSTR whereas the loop reactor temperature was easily controlled. © 1995 John Wiley & Sons, Inc.