bluuebunny/crossref_metadata_2025 huggingface dataset:
Curie transition and piezoelectricity of the blends of a ferroelectric VDF/TrFE copolymer and PMMA
Authors: Kim Kap Jin , Kim Gwan Bum
Published: April 2003

The Curie transition, even though the conformational change at the Curie transition primarily arises from intermolecular interaction, is highly dependent on the crystallization conditions. A slower cooling rate from the melt during paraelectric crystallization lowers Tc, increases the portion of Fβ at the expense of Fα reduction, and produces a more unstable ferroelectric phase. T is rarely dependent upon the amount of PMMA, but T is increased with the PMMA content. PMMA has a favorable action in forming a more stable ferroelectric phase in the P(VDF/TrFE)/PMMA blend and elevating the Curie transition point because of the all‐trans sequence conformation of PMMA and a specific intermolecular interaction with P(VDF/TrFE) in the melt state. However, PMMA reduces the total amount of the crystalline phase, the electric response, and the piezoelectricity. © 1993 John Wiley & Sons, Inc.
Novel phthalocyanine/polyol high‐solids coatings: Structure—property relationships
Authors: Exsted Bert J. , Urban Marek W.
Published: April 2003

A convenient synthetic procedure for preparing nickel carboxylated phthalocyanine is reported. Upon further hydroxylation, such metal phthalocyanine moieties are incorporated into several melamine‐based polyester high‐solids systems and the structure—property correlations are examined. Molecular level spectroscopic FTIR analysis and mechanical testing are correlated in an effort to establish structure—property relations in these coatings. It is found that the presence of metal phthalocyanine macrocycle as a cross‐linking agent enhances such properties as adhesion, hardness, and impact resistance. © 1993 John Wiley & Sons, Inc.
Nonaqueous diagnostic polymers and coatings
Authors: Azhar A. , Burke A. , Dubois J. , Usmani A.
Published: April 2003

Water‐borne enzymatic coating‐based dry chemistries have been used for more than 20 years, especially by diabetics, for self‐monitoring of blood glucose. Until now, it has been believed that enzymes work only in water and not in organic solvents. Synthesis of a hydroxylated acrylic polymer and the novel concept of dispersing enzymes have enabled us to design nonaqueous diagnostic coatings. These coating films gave excellent dose response and dynamic range. Additionally, these coatings can easily be ranged by a wide variety of antioxidants. In contrast, water‐borne coatings are extremely difficult to range. Furthermore, nonaqueous coating films produce color signals that are independent of the reaction time with excellent thermal stability. Molecular forces and thermodynamical considerations have been used to explain the performance of the new dry chemistries. An organic reaction mechanism of ranging has also been proposed for the nonaqueous system. © 1993 John Wiley & Sons, Inc.
A differential scanning calorimetric study of the interaction of zinc benzothiazole‐2‐thiolate, sulfur, stearic acid, and zinc stearate in the absence and presence of polyisoprene
Authors: Luyt Adriaan S.
Published: April 2003

The interactions between mixtures of zinc benzothiazole‐2‐thiolate (ZMBT), sulfur, stearic acid, and zinc stearate were studied by DSC in the absence and presence of polyisoprene (IR). It was established that ZMBT reacts with stearic acid to form zinc stearate and 2‐mercaptobenzothiazole (MBT). In the presence of stearate compounds, MBT is readily available from the start of vulcanization, whereas it becomes only slowly available in the absence of these compounds. The effectiveness of the vulcanization process increases for the systems IR/ZMBT/sulfur < IR/ZMBT/sulfur/stearic acid < IR/ZMBT/sulfur/zinc stearate. In view of the above results, interaction mechanisms are proposed for the different systems. © 1993 John Wiley & Sons, Inc.
Precrack hysteresis energy of elastomer‐modified polycarbonates in determining its ductile–brittle transition
Authors: Chang Feng‐Chin , Hsu Hon‐Chun
Published: April 2003

For ductile fracture, the precrack plastic zone has to exceed a critical value, and precrack hysteresis energy has been employed to characterize the plastic zone. The presence of elastomer in polycarbonate is able to enhance precrack hysteresis and, therefore, toughens the polycarbonate matrix. Higher precrack hysteresis means that a greater fraction of the input energy converts into plasticity and leaves less storage energy available to strain the crack tip for crack Initiation. If the precrack plastic zone is above the critical value before onset of initiation, the crack growth developed thereafter will be effectively contained within the domain of the plastic zone and results in mass shear, yielding ductile fracture. In this paper, the elastomer toughening is classified as promotion of ductile failure through mass shear yielding and the localized energy dissipation processes. The localized energy dissipations are further divided into the activities occurring on and underneath the fracture surface. A different approach in interpreting the elastomer‐toughening mechanism is discussed in detail. © 1993 John Wiley & Sons, Inc.
Chromatographic separation of azeotropic and low‐conversion poly(styrene‐stat‐2‐methoxyethyl methacrylate) according to chemical composition
Authors: Konáš M. , Kubín M.
Published: April 2003

Distribution of the chemical composition of statistical copolymers was studied by HPLC using azeotropic and low‐conversion copolymers of styrene and 2‐methoxyethyl methacrylate that are expected to exhibit only statistical chemical heterogeneity. Adsorption behavior of the copolymers was studied dynamically with a specially designed apparatus, using flow through a column packed with a macroporous silica and a mixed mobile phase 1,2‐dichloroethane (DCE)–heptane (50 : 50 v/v) and tetrahydrofuran (THF). The shape of displacement isotherms indicates the existence of a region lying near the displacement critical composition, where the total amount of adsorbed copolymer is independent of the mobilephase composition. Fractionation was achieved by step‐by‐step desorption of a copolymer sample previously adsorbed on silica packed into a chromatographic column, by means of a stepwise gradient of mobile‐phase composition. The styrene content of isolated fractions decreased with increasing content of THF in the mobile phase. The experimentally determined integral weight distribution of chemical composition shows good agreement with theoretical curves. © 1993 John Wiley & Sons, Inc.
Network structure and properties of platinum‐catalyzed addition cure release coatings
Authors: Stein J. , Grade H. , Williams E. A. , Codella P. J. , Smith J. F.
Published: April 2003

Silicone‐release coatings are used by the pressure‐sensitive adhesive industry for labeling applications. Typical release coatings are prepared by the platinum‐catalyzed addition reaction of a silicone hydride fluid with a silicone vinyl polymer. Methodology has been developed to determine the network structure of cured release coatings, which involves degradation of the network with trifluoromethane sulfonic acid in excess hexamethyldisiloxane. Gas chromatography–mass spectrometry (GC–MS) and gas chromatography (GC) were employed to identify and quantify residual functionality and cross‐links. Residual hydride functionality was also determined by attenuated total reflectance–Fourier transform infrared spectroscopy (ATRFTIR). The observation of network structure by solid‐state 29Si‐NMR using cross polarization (CP) and magic angle spinning (MAS) is also discussed. The networks underwent a postcure as evidenced by a decrease in residual hydride functionality and an increase in silane content and/or cross‐links. © 1993 John Wiley & Sons, Inc.
The use of latex rubber‐modified polystyrene as a model system for HIPS: Effect of particle size
Authors: Cook D. G. , Rudin A. , Plumtree A.
Published: April 2003

The effect of particle size in high‐impact polystyrene (HIPS) is difficult to determine because of a size polydispersity and changes in particle morphology during the HIPS synthesis process. In this study, poly(n‐butyl acrylate) rubber core/polystyrene shell particles were made by emulsion polymerization methods such that the only difference was in particle diameter, which ranged from 0.4 to 6.2 μm. The latexes were subsequently incorporated into a polystyrene matrix to form a toughened composite that acted as a simple model for HIPS. Charpy impact energies (notched and unnotched) of the composites showed that there was no toughening for particle sizes less than 2μm in diameter. The optimal impact energy was obtained with particle diameters in the region of 2–3 μm at 8 wt % rubber loading. The results imply that craze stabilization is the most important aspect of the toughening process. A simple toughening model based on the crack opening displacement of craze breakdown between adjacent rubber particles is suggested, with interparticle distance as the most important variable. © 1993 John Wiley & Sons, Inc.
Preparation and characterization of electropolymerized poly(N‐substituted methacrylamide) matrices on graphite fibers
Authors: Liang Jeng‐Li , Bell James P. , Scola Daniel A.
Published: April 2003

2‐ or 4‐carboxyphenyl methacrylamide (2‐ or 4‐CPM) was successfully electrocopolymerized with either methylmethacrylate (MMA) or N‐phenylmaleimide (NPMI) to form a thick thermoplastic matrix with high glass‐transition temperature (200–300°C), on Hercules AS‐4 graphite fibers. The dependence of the diffusion of active species through the coating upon the solvent/water ratio in the cell was estimated from the electrochemical diffusion behavior of hexacyanoferrate (III) ions. A higher solvent/water ratio helped to increase polymer weight gain by increasing the solvent swelling and increasing the diffusion coefficient of active species. A highly solvent‐swollen polymer layer promoted the rate of polymer weight gain. The copolymer composition of 4‐CPM/MMA and 4‐CPM/NPMI polymers was random, and the effects of variables were consistent with free‐radical polymerization kinetics. The electropolymerization rates of 4‐CPM/MMA and 4‐CPM/NPMI were increased by increasing current density and monomer concentration. For a slight temperature increase (from 28–45°), electropolymerization rate and polymer weight gain increased dramatically for the 4‐CPM/NPMI system. © 1993 John Wiley & Sons, Inc.
A relationship between NMR cross‐polarization rates and dynamic storage modulae of polymers
Authors: Parker A. A. , Marcinko J. J. , Rinaldi P. , Hedrick D. P. , Ritchey W. M.
Published: April 2003

A relationship between dynamic storage modulus (E′) and the mean cross‐polarization time constants 〈TCH〉 for 16 polymer data sets has been established by using a standard linear solid model. This model is used in an attempt to equate the process of cross‐polarization with mechanical rigidity by virtue of the implicit dependence of each phenomenon on molecular motion. The apparent validity of the relationship between these parameters indicates that cross‐polarization in polymers can be a function of molecular motion in addition to microscopic spin dynamics. The limitations as well as practical applications of this relationship are discussed. © 1993 John Wiley & Sons, Inc.
Cellulose‐based fibers from liquid crystalline solutions. III. Processing and morphology of cellulose and cellulose hexanoate esters
Authors: Davé Vipul , Glasser Wolfgang G.
Published: April 2003

Cellulose and a cellulose hexanoate ester (DS 0.69) exhibited liquid crystalline behavior in dimethylacetamide/lithium chloride and dimethylacetamide, respectively. The experimentally observed critical volume fraction (Vcp) of cellulose was lower than that predicted by Flory's theory, whereas the experimental and theoretical values of Vcp were within 70% of prediction for cellulose hexanoate. The Vcp value obtained for cellulose hexanoate was lower than that previously reported for cellulose acetate butyrate with a maximum degree of butyration (CAB‐3). This indicates that bulky substituents may lower Vcp values. Fibers were spun from isotropic and anisotropic solutions of cellulose and cellulose hexanoate by a dry jet/wet spinning method. There was an increase in mechanical properties through the isotropic to anisotropic transition with moduli reaching 152 g/d (20.8 GPa) for cellulose fibers. The formation of cellulose fibers with high modulus at large extrusion rates and large takeup speeds (draw ratio) is explained with molecular organization prior to coagulation. This unexpected enhancement is attributed to the air gap that exists in the dry jet/wet spinning process. Similar improvements were not observed for cellulose hexanoate fibers. This is explained with incomplete development of liquid crystalline structure at the solution concentrations from which the fibers were spun. © 1993 John Wiley & Sons, Inc.
Photocross‐linking of low‐density polyethylene. I. Kinetics and reaction parameters
Authors: Qu Bao Jun , Rånby Bengt
Published: April 2003

The kinetic characteristics and the reaction conditions of photocross‐linking of low‐density polyethylene (LDPE) in the melt have been studied using benzophenone (BP) and its derivatives such as 4‐chlorobenzophenone (4‐CBP) as photoinitiator and triallyl cyanurate (TAC) as cross‐linker. The efficiency of the photoinitiated cross‐linking system LDPEBP‐TAC and various factors affecting the cross‐linking process, such as photoinitiator and cross‐linker and their concentrations, irradiation time, temperature, and atmosphere, and UV light intensity were examined extensively by determining gel content, IR, and UV spectra. It has been found (i) that LDPE samples of 2–3 mm thickness are easily cross‐linked to a gel content of about 70% with a UV‐irradiation time of about 15 s under optimum conditions; (ii) that the photoinitiating system of a suitable initiator combined with a multifunctional cross‐linker such as 4‐CBP–TAC can enhance the efficiency of photocross‐linking reactions, especially by increasing the initial rate of cross‐linking; (iii) that photocross‐linking of LDPE should be carried out in the melt, which increases the penetration of UV light by decreasing the scattering by crystallites, and (iv) that the rate of cross‐linking is proportional to the square of the light intensity. An increase in light intensity can decrease the concentration of photoinitiator required to reach a certain rate of cross‐linking. The photocross‐linking of polyethylene is promising for industrial applications. © 1993 John Wiley & Sons, Inc.
The elastic and plastic mechanical responses of microcellular foams
Authors: Ozkul M. H. , Mark J. E. , Aubert J. H.
Published: April 2003

Microcellular foams were prepared by the thermally induced phase‐separation technique, which yields materials having very small cell dimensions (0.1–20μm). The polymers employed were isotactic polystyrene, polyacrylonitrile, poly(4‐methyl‐1‐pentene), polyurethane, and Lycra® and the resulting foams all had densities in the range 0.04–0.27 g cm−3. Values of Young's modulus and the collapse stress for these foams were measured and compared with predictions for conventional foams containing defects. Also investigated were plastic deformations, some time‐dependent behavior, and Poisson's ratio. © 1993 John Wiley & Sons, Inc.
Sorption and diffusion of organic esters into fluoropolymer membranes
Authors: Aminabhavi Tejraj M. , Munnolli Ravindra S. , Stahl William M. , Gangal Subhas V.
Published: April 2003

A sorption gravimetric technique has been used to estimate the diffusion and thermodynamic parameters of four different VITON fluoropolymers in the presence of five ester molecules. Diffusion parameters have been obtained by assuming the Fickian transport and their concentration dependencies are studied. Fluorine contents of the fluoropolymers have significant effects on the membrane transport characteristics. © 1993 John Wiley & Sons, Inc.
Water‐soluble polymers. I. Synthesis of N‐succinimido (N) thiocarbonyl acrylamide and its polymerization: Grafting of this monomer and acrylamide onto poly(vinyl alcohol)
Authors: Devarajan R. , Arunachalam V. , Jayakumar E. , Selvi P.
Published: April 2003

A new monomer, N‐succinimido (N) thiocarbonyl acrylamide is formed when succinic anhydride, thiourea, and acryloyl chloride are condensed in mole proportions at low temperatures. The monomer is polymerized and graft copolymerized onto poly(vinyl alcohol) using a potassium bromate‐thiourea redox system. Acrylamide is also similarly grafted to poly(vinyl alcohol) using the same initiator system. Grafting efficiencies of the monomers are determined from the elemental analyses data of the graft copolymers. Thermal behavior of the polymers are derived from the DSC thermograms of the polymers. © 1993 John Wiley & Sons, Inc.
Microhardness as a thermally activated process: Indentation time dependence for an amorphous copolyester
Authors: Lorenzo V. , Benavente R. , Pérez E. , Bello A. , Pereña J. M.
Published: April 2003

Vickers microharness, MH, measurements have been performed on samples of a plasticized amorphous copolyterephthalate with different diluent contents. The dependence of MH on contact time is explained in terms of the Eyring equation and it has been found that the activation volume increases abruptly in the vicinity of the glass transition. © 1993 John Wiley & Sons, Inc.
HPLC and 13C‐NMR study of carboxymethyl‐β‐(1 → 6)‐D‐gluco‐β‐(1 → 3)‐D‐glucan derived from saccharomyces cerevisiae
Authors: S̆oltés Ladislav , Alföldi Juraj , S̆andula Jozef
Published: April 2003

Sodium salt of carboxymethyl‐β‐(1 → 6)‐D‐gluco‐β‐(1 → 3)‐D‐glucan (CMG‐Na) was prepared from β‐D‐glucan isolated from baker's yeast (Saccharomyces cerevisiae). Three samples, Fractions I, II, and III, were further separated from the crude CMG‐Na derivative. For the physicochemical characterization of the separated fractions, the methods of high‐performance liquid chromatography (HPLC) in the size‐exclusion mode and carbon−13 nuclear magnetic resonance (13C‐NMR) spectroscopy were applied. The HPLC method revealed that the molecular weights, Mn, Mw, and Mz averages, of Fraction II were 9.71 × 104, 2.27 × 105, and 3.59 × 105 Da, respectively, whereas those of Fraction III were 1.52 × 104, 2.13 × 104, and 3.57 × 104 Da, respectively. The 13C‐NMR spectra of Fraction II showed a ratio of 3 : 1 for β−(1 → 3) / β−(1 → 6), whereas for Fraction III, the content of β‐(1 → 3) units was smaller. © 1993 John Wiley & Sons, Inc.
Separability of SO2 from SO2/N2 mixture through sulfoxide‐modified poly(vinyl alcohol) and cellulose membranes
Authors: Imai Kiyokazu , Shiomi Tomoo , Tezuka Yasuyuki , Itamochi Hiroko , Miya Masamitsu
Published: April 2003

Separability of SO2 from mixtures of SO2 and N2 gases was studied for membranes of poly(vinyl alcohol) (PVA) and cellulose modified with methyl, ethyl, t‐butyl, and phenyl vinyl sulfoxides. Of these sulfoxide‐modified polymers, the phenyl vinyl sulfoxide‐modified PVA membranes were found to give the best separation of SO2. In the phenyl vinyl sulfoxide modified PVA membranes, the permeability coefficient of SO2 increased with sulfoxide content while separability of SO2 was maximum at a sulfoxide content of 23.5 mol %; the separation factor of SO2 was about 170 at this sulfoxide content. © 1993 John Wiley & Sons, Inc.
Rate and extent of supercritical fluid extraction of additives from polypropylene: Diffusion, solubility, and matrix effects
Authors: Cotton N. J. , Bartle K. D. , Clifford A. A. , Dowle C. J.
Published: April 2003

Analytical extraction of additives from polymers using a supercritical fluid (SFE) is a promising alternative to liquid extraction. Factors affecting SFE with carbon dioxide of Irgafos 168 and Irganox 1010 from commercial polypropylene have been studied, with analysis of extracts by capillary supercritical fluid chromatography (SFC). A diffusion limited extraction model was investigated by measuring the rate of SFE as a function of pressure, particle size, flow rate, and temperature. The rate of extraction was found to fit the sum of exponential decays; results were also consistent with an extrapolation procedure to obtain the total mass of additive without exhaustive extraction. Derived diffusion coefficients for the additive in polypropylene differed from literature values by approximately two orders of magnitude apparently because of swelling of the polymer by sorbed carbon dioxide. The variation of extraction rate with pressure and flow rate confirmed the solubility limitation of proposed model. The rate of extraction increased between 20 and 140°C, then fell away at higher temperatures with the onset of melting. © 1993 John Wiley & Sons, Inc.
Study on the kinetics of lignin methylolation
Authors: Peng W. , Riedl B. , Barry A. O.
Published: April 2003

The kinetics of lignin (ammonium‐based lignosulfonate and sodium‐based lignosulfonate) methylolation were studied in solution by monitoring the rate of disappearance of form‐aldehyde and by using differential scanning calorimetry (DSC) techniques under an iso‐thermal program, at 20, 40, 50, and 60°C, respectively. The kinetic parameters obtained from these two methods agree with each other. The results show that the degree of lignin methylolation depends on the number and availability of reactive sites per C9 unit of lignin. Lignin methylolation has a lower activation energy and a lower preexponential factor than that of phenol methylolation. Lignins took a shorter time to reach complete methylolation than did phenol at the low temperatures used here. © 1993 John Wiley & Sons, Inc.
Solid‐State NMR characterization of a superactive supported ziegler–natta catalyst
Authors: Vizzini James C. , Shi J.‐F. , Chien James C. W.
Published: April 2003

The formation of CH‐type catalysts has been investigated by high‐resolution and solid‐state NMR. These catalysts are prepared from a soluble MgCl2 and 2‐ethyl‐1‐hexanol adduct (MgCl2·3EH) by reaction with phthalic anhydride (PA) to form dioctylphthalate (DOP) and then with TiCl4 in the presence of di‐i‐butylphthalate (BP). In the model systems MgCl2·3EH/PA, MgCl2/BP, and MgCl2/TiCl4/BP, the ester is complexed with MgCl2 and /or TiCl4 in two or more states. Only single‐ester CO and OCH2 resonances are seen in TiCl4/BP, probably due to exchange of ester coordinations. CH‐catalysts prepared by three different procedures exhibit a single mode of bonding for the ester. The chemical shift values are consistent for ester complexed with MgCl2. The most active and stereoselective catalyst has the most shielded chemical shift values for the CO and —OCH2— carbons, shortest TH1 and TH1p, and longest TCH relaxation times. These parameters change monotonically with the decrease of activity and stereoselectivity of the catalyst preparation. © 1993 John Wiley & Sons, Inc.
Transport and dielectric properties of poly(ethylene terephthalate) as determined via electrochemical techniques
Authors: Kloppers M. J. , Bellucci F. , Latanision R. M. , Brennan J. E.
Published: April 2003

The electrochemical impedance spectroscopy (EIS) technique was used to evaluate the water transport (diffusion and equilibrium water uptake) and the dielectric properties of free‐standing poly(ethylene terephthalate) (PET) membranes at 40°C. Permeability and diffusion coefficients were also obtained using the Payne cup method and the MacBain quartz spring balance to assess the reliability of the EIS method when compared to other techniques. In addition, an electromigration (dc) technique was used to estimate the NaCl diffusion coefficient across PET films. Results obtained indicate that PET is highly permeable to water and much less permeable to salt. The water diffusion coefficient, D, varies from 2.11× 10−9 to 9.97× 10−9 cm2s−1 for thicknesses between 22 and 205μm, whereas the equilibrium water uptake, W, varies from 0.54 to 0.95 wt % for the same given range of thicknesses. The average calculated dielectric constant of the free‐standing PET films is 3.6. An estimate of the NaCl diffusion coefficient, Ds, is 9.34× 10−14 cm2s−1. Transport properties results obtained via the electrochemical technique are in reasonable agreement with those obtained with the classical gravimetric method. © 1993 John Wiley & Sons, Inc.
Modification of polythioesters from bis (4‐mercaptophenyl) ether with adipoly, sebacoyl, and isophthaloyl chlorides with the use of 2,2‐bis (4‐hydroxyphenyl) propane
Authors: Podkościelny Wawrzyniec , Wdowicka Danuta
Published: April 2003

Modification of polythioesters obtained by interfacial polycondensation bis (4‐mercapto‐phenyl) ether and adipoyl, sebacoyl, or isophthaloyl chlorides with the use of 2,2‐bis (4‐hydroxyphenyl) propane (bisphenol A) has been described. Polycondensates with 10, 50, or 90% molar of bisphenol A in relation to dithiol were obtained under the same conditions as those established earlier as optimal for synthesis of polythioesters from dithiol and adipoyl, sebacoyl, or isophthaloyl chlorides. The structure of all the polycocondensates was determined by infrared spectra and X‐ray analysis. Thermal and some mechanical and electrical properties for polycocondensates containing 50% molar bisphenol A in relation to dithiol were defined. © 1993 John Wiley & Sons, Inc.
Effects of mean stress and frequency on fatigue crack propagation in rubber‐toughened polycarbonate/copolyester blends
Authors: Moskala Eric J.
Published: April 2003

The effects of an impact modifier, mean stress level, and test frequency on the fatigue crack propagation rate in a miscible amorphous blend of polycarbonate and a copolyester were investigated. Experiments were performed on a servohydraulic testing machine, in load control, using a sinusoidal waveform. The addition of a small amount of impact modifier improved the fatigue resistance of the blend. Fatigue crack propagation rate, da/dN, at any value of crack tip stress intensity factor range, ΔK, in the impact modified blend, was more than a factor of 20 lower than that in the untoughened blend. Significantly more plastic deformation occurred on the fracture surface of the toughened blend than on that of the untoughened blend. The effect of mean stress level on da/dN was determined by varying the minimum‐to‐maximum stress ration, R, from 0.1 to 0.5. Plots of log (da/dN) vs. δK showed that the fatigue crack propagation rate was unaffected by R and, consequently, the mean stress level. The effect of frequency on da/dN was determined by varying the frequency from 0.25 to 25 Hz. The fatigue resistance of the untoughened blend was not affected by test frequency, whereas the fatigue resistance of the toughened blend increased with increasing frequency. Hysteretic heating at the crack tip was minimal at the highest frequency. The frequency sensitivity of the toughened blend was explained in terms of creep‐assisted crack growth. © 1993 John Wiley & Sons, Inc.
Viscosities of ethylene–propylene–diene terpolymer blends in oil
Authors: Rubin Isaac D. , Kapuscinski Maria M.
Published: April 2003

Viscosities were obtained on oil solutions of two ethylene–propylene–diene terpolymers (EPDMs) and their blends. For the amorphous terpolymer with 59 mol% ethylene, intrinsic viscosities were constant between–10 and 40°C. The viscosities decreased rapidly at low temperature for blends of this material with as little as 20 wt % of a slightly crystalline EPDM with 79 mol% ethylene. Dynamic viscosity measurements on 1.0% solutions of blends likewise gave considerably smaller values at low temperature than measurements on an amorphous EPDM of similar molecular weight. The data are in agreement with the view that longer ethylene sequences that crystallize in the bulk polymer can organize in oil into ordered domains that interfere less with flow than the disordered amorphous polymer regions. © 1993 John Wiley & Sons, Inc.
Characterization and radical polymerization of (E‐CE)C/AA mesomorphic solutions
Authors: Jiang S. H. , Huang Y.
Published: April 2003

Ethyl–cyanoethyl cellulose (E–CE)C/poly (acrylic acid) (PAA) composites were prepared by polymerizing acrylic acid (AA) in (E–CE) C/AA cholesteric liquid crystalline solutions. The morphology and structure and the compatibility of composites prepared in different conditions were studied by small‐angle light scattering (SALS), differential scanning calorimetry (DSC), X‐ray spectrometry, polarizing microscopy, and electron microscopy. Ho‐mogeneous composites with the cholesteric structure could be obtained by photopolymerization. During the photopolymerization, however, the morphology of the liquid crystalline domains became crylindric and the axial direction of the cylindric domain was at an angle of about 45° to the layers of the ordered molecular chains. The polymerization initiated by azobisisobutyronitrile (AIBN) resulted in the phase separation. The morphology of the liquid crystalline domains was maintained although the cholesteric structure of the composite was partly destroyed. © 1993 John Wiley & Sons, Inc.
Flame‐retardant EPM compositions for cable insulation, containing Br‐N‐S fire retardants
Authors: Karaivanova M. S. , Gjurova K. M.
Published: April 2003

The influence of ammomnium salts of oligomeric Br‐N‐containing sulphonic acids and some inorganic fire retardants on the physico‐mechanical properties, flammability characteristics, and thermooxidative degradation of EPM compositions for insulation of ship cables has been studied. The ternary system consisting of bromosulphaminic acid bromonitrosulphonic acid and antimony trioxide in 6.6 : 3.4 : 4–5 mass ratio has been found to exhibit an addictive effect on the fire retardancy. A correlation between the flammability characteristics and some thermal properties of EPM compositions has also been established. The organic fire retardants of certain concentrations in EPM compositions have been found to exhibit a positive plasticizing performance. © 1993 John Wiley & Sons, Inc.
Thermal shock test of IC packages sealed with epoxy molding compounds filled with irregular‐shaped silica particles
Authors: Nakamura Yoshinobu , Yamaguchi Miho , Tanaka Atsushi , Okubo Masayoshi
Published: April 2003

The effect of the filler silica particle size on the properties of integrated circuits (IC) packages sealed with an epoxy molding compound was studied. For this purpose, two kinds of epoxy molding compounds filled with irregular‐shaped silica particles having mean sizes of (A) 16 μm and (B) 5 μm were prepared. The fracture toughness (Kc) of cured A was higher than that of cured B, but the flexural strength of cured A was lower than that of cured B, i.e., cured A and B had opposite physical properties. The thermal shock test was carried out in which IC packages were repeatedly dipped alternately in −65 and 150°C liquids and package cracking was observed. The thermal shock property of the IC package sealed with A was superior to that sealed with B. There was a good relationship between the thermal shock test property and Kc value. © 1993 John Wiley & Sons, Inc.
Exudation processes in hydrogenated bisphenol‐a‐based epoxy coatings: Spectroscopic study
Authors: He Mingbo , Urban Marek W. , Bauer Ronald S.
Published: April 2003

Surfaces of hydrogenated bisphenol‐A (DGEHBPA)‐based epoxy resins cross‐linked with polyamide based on dimer fatty acid and triethylenetetramine coatings were studied using ATR FTIR spectroscopy. These studies illustrate that for nonpigmented coatings the surface species resulting from the coatings' exposure to ambient conditions generate noncross‐linked epoxies, whereas for pigmented coatings, polyamide is the primary surface component. The presence of these species is attributed to the adsorption on pigment particles and small, yet significant amounts in nonstoichiometry changes introduced into the system during formulation. © 1993 John Wiley & Sons, Inc.
The role of crystallization kinetics in the development of the structure and properties of polypropylene filaments
Authors: Lu F. M. , Spruiell J. E.
Published: April 2003

The processing, structure, and properties of filaments melt spun from three polypropylenes with similar rheology but substantially different crystallization kinetics were studied. The crystallization kinetics of the homopolymer was increased by the addition of a nucleating agent, whereas slower crystallization kinetics was obtained through a small amount of random copolymerization with ethylene. The relative crystallization kinetics of these three polymers was examined under quiescent conditions using differential scanning calorimetry. The technique of on‐line diameter and birefringence measurement was used to show the characteristics of the on‐line crystallization of the different resins. It was found that changing the quiescent crystallization kinetics by either the addition of a nucleating agent or through copolymerization with ethylene can produce profound effects on the structure and properties of polypropylene as‐spun filaments when they are spun under relatively low stress and low takeup velocity conditions. Higher takeup velocities and spinline stresses reduce the effect of differences in quiescent crystallization due to the influence of on‐line stress‐induced (molecular orientation‐enhanced) crystallization. © 1993 John Wiley & Sons, Inc.
Distribution of onium salt photoinitiators in a two‐phase epoxy system
Authors: Covert Kathleen L. , Russell David J.
Published: April 2003

A phase‐separated epoxy blend containing a sulfonium salt cationic photoinitiator was studied. The onium salt was found to be preferentially soluble in one of the resins of the system. Scanning electron microscopy and microprobe analyses were done to determine the concentration distribution in the phases and the results compared to a model based on liquid extraction distribution coefficient behavior. Finally, the photolithographic behavior of various blends of the epoxy resins is discussed and the results compared to the behavior predicted by the photoinitiator distribution. © 1993 John Wiley & Sons, Inc.
Epoxy polymerization initiated by BF3–amine complexes. I. Synthesis and characterization of BF3–amine complexes and BF3–amine complexes dissolved in γ–butyrolactone
Authors: Chabanne Philippe , Tighzert Lan , Pascault Jean‐Pierre , Bonnetot Bernard
Published: April 2003

With the aim of identifying the species responsible for initiating epoxy homopolymerization, several BF3–amine complexes were synthesized. Their characterization was accomplished by several spectroscopic techniques, notably by 11B‐NMR. In these polymerizations, the active species appears to be the R–NHBF salt and not the BF3–amine complex. The interactions between BF3–amine complexes and the γ–butyrolactone were also studied by FTIR. © 1993 John Wiley & Sons, Inc.
Poly(N5‐benzyl‐l‐glutamine)‐coated silica gels as chiral stationary phase for direct resolution of hydantoins
Authors: Chen Yun , Yu Duu‐Haur
Published: April 2003

Poly(N5‐benzyl‐L‐glutamine) (PNLG), Poly[N5‐(+)‐1‐phenylethyl‐L‐glutamine] [P(+)NLG], and poly[N5‐(±)‐1 phenylethyl‐L‐glutamine) [P(±)NLG] were synthesized from poly [γ‐(β‐chloroethyl)‐L‐glutamate], which, in turn, was obtained by ester exchange of poly(γ‐methyl‐L‐glutamate) with 2‐chlorethanol. The PNLG was found to exist mainly in an α‐helical conformation in the film state by using circular dichroic and infrared spectra. Moreover, the PNLG, P (+) NLG, and P (±) NLG have been coated on macroporous silica gels (10μm) and packed as chiral stationary phases for direct chromatographic resolution of 10 hydantoins. The column bearing PNLG resolved satisfactorily four hydantoins (α = 1.34–1.73), and the enantioselectivity (α) increased with the bulkiness of 5‐substituent in hydantoins. On the other hand, an increase in 2‐propanol concentration of the eluent (2‐propanol/hexane) resulted in a smooth decrease of the capacity factor. However, the selectivity (α) increased slightly, indicating that the α‐helix of PNLG plays an important role in chiral resolution. From these results, it is concluded that the main chiral recognition force is the steric hindrance between the 5‐substituents of hydantoin and the side chains of PNLG. The temperature effect on the resolution of the hydantoins by PNLG was also investigated. © 1993 John Wiley & Sons, Inc.
Graft copolymers of wood pulp and 1‐phenylethene. I. Generality of synthesis and proof of copolymerization
Authors: Meister John J. , Chen Meng‐Jiu
Published: April 2003

A method of grafting lignin‐containing materials is now known that allows 1‐phenylethylene (styrene, [100‐42‐5]) graft copolymers of a lignin source to be quantitatively made. The grafting reaction is a solution polymerization often run in aprotic, polar, organic solvents. Grafting changes solubility and surface properties of the lignin‐containing material. The lignin‐containing materials grafted are unbleached wood pulps produced by chemical, thermal, and mechanical pulping. Grafting wood pulp produces a wood‐reinforced, thermoplastic composite. © 1993 John Wiley & Sons, Inc.
Supercritical fluid fractionation of copolymers based on chemical composition and molecular weight
Authors: Pratt J. Alan , Lee Sang‐Ho , McHugh Mark A.
Published: April 2003

Poly(ethylene‐co‐methyl acrylate) copolymers of 30, 40, 60, and 70 wt % acrylate in the backbone have been fractionated with supercritical (SCF) propane, propylene, butane, 1‐butene, and chlorodifluoromethane. The fractionations were performed isothermally using an increasing pressure profile that provided gram‐sized fractions with molecular weight distributions of ∼ 1.2 to 2.2 as compared to those of the parent copolymers, which were ∼ 2.6 to 3.5. If the chemical composition distribution of the copolymer is greater than ±2%, it is possible to fractionate with respect to chemical composition by chosing solvents that preferentially dissolve the nonpolar ethylene‐rich or the polar acylate‐rich oligomers. Cloud‐point curves were determined for each copolymer in the SCF solvents to provide an indication of whether the solvent would dissolve the copolymer at temperatures and pressures within the range of the fractionation apparatus. © 1993 John Wiley & Sons, Inc.
Removal of color from effluents using polyamide–epichlorohydrin‐cellulose polymer. II. Use in acid dye removal
Authors: Hwang M. C. , Chen K. M.
Published: April 2003

The ability of polyamide–epichlorohydrin‐cellulose (PAE‐cell) to remove various acid dyes from aqueous solutions was investigated. The classes of acid dyes included the milling type, levelling type, and metal‐complex type. Operational conditions such as PAE‐cell type, dye type, PAE‐cell particle size, dye bath flow rate, filling density in the column, initial dye concentration, pH of solution, and adsorbent mass were studied. The results show that these PAE‐cell polymers exhibit better capacity for acid dye removal than some commercial activated carbons. © 1993 John Wiley & Sons, Inc.
Dangling polymer networks: Glass transition of PU elastomers
Authors: Lee Yng‐Long , Sung Po‐Hou , Liu Hsin‐Tzu , Chou Lain‐Ching , Ku Wen‐Hsiung
Published: April 2003

Polyurethane elastomers possessing dangling chains were prepared by partial substitution of the multifunctional polyol with a monohydroxyl alcohol in the reaction with an isocyanate terminated prepolymer. The dynamic mechanical spectroscopy showed that created dangling segements resulted in a broader glass‐transition region. This indicated material with potentially good energy absorbing properties might be prepared from a ‘dangling polymer’ system. © 1993 John Wiley & Sons, Inc.
Studies on co[poly(ethylene terephthalate‐p‐oxybenzoate)] thermotropic copolyester (III): Morphological observation by polarizing microscopy
Authors: Shinn Ted‐Hong , Lin Chen‐Chong
Published: April 2003

A series of co[poly(ethylene terephthalate‐p‐oxybenzoate)] thermotropic copolyesters with various compositions were prepared by the copolymerization of either poly(ethylene terephthalate) (PET) polymer or its oligomer as moiety (I) and p‐acetoxybenzoic acid as moiety (II). A detailed description of the crystalline morphology of copolyesters with different compositions as well as under different preparation temperatures is discussed by using a polarized optical micrograph. It is found that the p‐oxybenzoate (POB)/PET copolyesters with the POB moiety content above 60 mol % were shown to be highly anisotropic. It is also believed that the copolyester made from the PET oligomer (OET) as moiety (II) has shorter repeating units than that of the copolyester made from PET polymer (PET) in the main‐chain structure. The solid‐state polymerization may cause the randomization of two units due to a transesterification reaction that is examined by NMR spectroscopy analysis. Using the micrographs with different compositions, parallels between before and after the solid‐state polymerization are contrasted. © 1993 John Wiley & Sons, Inc.
Size exclusion chromatographic measurement of PVC molecular weight distributions
Authors: Pang Simon , Rudin Alfred
Published: April 2003

Aggregates that may exist in poly(vinyl chloride) (PVC) solutions at ambient temperatures compromise the accuracy of SEC measurements of molecular weight distributions. Aggregate‐free solutions can be produced in 1,2,4‐trichlorobenzene (TCB) by controlling the dissolution time and temperature. SEC measurements were made in trichlorobenzene at 110°C after dissolution for 12 h at 120°C. An on‐line continuous viscometer can be used to determine when aggregate‐free solutions have been produced. The Mark‐Houwink parameters (K = 0.161 mL/g, α = 0.762) can be used for universal calibration procedures in TCB at 110°C. Complete dissolution of the PVC affects the high molecular weight end of the molecular weight distribution. Measured M̄n values are not affected, but Mz's are much higher than those estimated, for example, from room‐temperature SEC analyses in tetrahydrofuran. Molecular weight distributions are also seen to be broader, especially for higher molecular weight PVCs. © 1993 John Wiley & Sons, Inc.
Acrylic acid γ‐ray irradiation‐grafted nylon 4 membranes
Authors: Lai J. Y. , Chen M. H. , Shih C. Y. , Hsu K. Y.
Published: April 2003

This study was to improve the performances of nylon 4 membranes for washing waste‐water treatment of nuclear power plants, e.g., removal of detergent and salt by membranes. The effects of the degree of grafting and ionization on the reverse osmosis performances of acrylic acid (AA)‐grafted nylon 4 membranes by γ‐ray irradiation modification were investigated. The relationships of operating conditions, such as feed concentrations of salt and detergent, operating temperature, and pressure, and the performances of water flux and solute rejection of the prepared membranes were obtained. Water flux of the prepared membranes was highly sensitive with the operating temperature. It was found that an increase in the operating pressure could increase the water flux and the impaction effect directly. Water flux and salt rejection were significantly improved by both ionized and nonionized AA‐grafted nylon 4 membranes compared to ungrafted nylon 4 membranes. Water flux increased rapidly and solute rejection dropped off slightly as the grafted membranes were ionized. The 100% detergent rejection could be obtained by the nonionized AA‐grafted nylon 4 membranes with 38.6 and 69.6% degrees of grafting under various operating conditions. Results obtained showed that these modified nylon 4 membranes were usable for washing waste‐water treatment of nuclear power plants. © 1993 John Wiley & Sons, Inc.
Fractionation of a diblock copolymer in a demixing‐solvent system
Authors: Podes̆va Jir̆í , Stejskal Jaroslav , Kratochvíl Pavel
Published: April 2003

Phase behavior of a hydrogenated styrene/isoprene diblock copolymer in a dimethylformamide/methylcyclohexane demixing‐solvent pair has been studied. At a fixed copolymer concentration (1% w/v), the scheme of phase behavior (temperature vs. mixed‐solvent composition) of the system has been found to be complex, with several areas where various supramolecular structures are spontaneously formed. In a particular area of the scheme, a multistep demixing‐solvent fractionation of the copolymer has been performed. The resulting fractions have been characterized and the data used to construct integral distribution functions of copolymer molar mass and copolymer composition. These functions have been compared with those obtained by a previously reported light‐scattering characterization of the whole, unfractionated, nonhydrogenated precursor of the copolymer © 1993 John Wiley & Sons, Inc.
Ultrasonic and thermal properties of γ‐irradiated low‐density polyethylene
Authors: Zahran A. R. R. , Kandeil A. Y. , Higazy A. A. , Kassem M. E.
Published: April 2003

The ultrasonic pulse‐echo technique and differential thermal analysis were utilized to characterize and to monitor the effect of γ‐irradiation on the sonic modulus and the heat effect of low‐density polyethylene. The sonic wave velocity, sonic modulus, and specific gravity exhibit a minimum for samples irradiated at 10 Mrad. A minimum in the heat capacity was observed at 1 Mrad. The estimated relative change of the activation energy of ordering exhibits a minimum at 100 Mrad. Below 10 Mrad, the perturbation and the loss of the crystalline phase override the effect of radiation cross‐linking. From 10 to 100 Mrad, the effect of cross‐linking as well as that of crystallinity are prevailing. Oxidative degradation is dominating above 100 Mrad. © 1993 John Wiley & Sons, Inc.
A stepwise scheme for the calculation of molecular weight distribution in condensation polymers. I. Scheme for monomolecular condensation polymers
Authors: Tung L. H.
Published: April 2003

A stepwise scheme has been devised for the calculation of molecular weight distribution in condensation polymers prepared under the condition of unequal reactivity. In the scheme, a condensation polymerization is arbitrarily subdivided into a number of steps. The polymer obtained in one step is treated as the monomer for the next step. In each of the steps, Flory's distribution for the condensation polymer under equal reactivity is used as the molecular weight distribution for that step. Reactivity variances are incorporated into the calculation through the application of weighing factors on the concentrations of the reacting molecules in each of the steps. The distributions of polymers prepared under other unusual conditions, such as monomers with only limited solubility or endcapping at late stages of the condensation reaction, can also be conveniently calculated by this scheme. The treatment presented in this paper is devoted only to polymers prepared by monomolecular condensation. Extension to bimolecular condensation will not be trivial and will be the subject of another paper. © 1993 John Wiley & Sons, Inc.
Characterization of spinel and hydrated spinel‐filled ABS: Antioxidant effect and strength properties
Authors: Cousin P. , Magdzinski L.
Published: April 2003

Differential thermal analyses (DTA) were conducted on spinel‐filled and hydrated spinel‐filled acrylonitrile–butadiene–styrene (ABS) terpolymer. Spinel and hydrated spinel displayed antioxidizing properties in the ABS composite. The enthalpies of oxidation for ABS, spinel‐filled ABS, and hydrated spinel‐filled ABS were 130, 15, and 0 J/g, respectively. Mechanical property measurements show that hydrated spinel reinforcing properties equal that of precipitated calcium carbonate treated with zinc stearate. © 1993 John Wiley & Sons, Inc.
Die extrusion behavior of carbon black‐filled block copolymer thermoplastic elastomers
Authors: Kim Jin Kuk , Han Min Hyeon , Go Jin Hwan , Oh Se Chul
Published: April 2003

The properties of carbon black‐filled thermoplastic elastomers were studied. We compared the extrudate swell behavior and the rheological properties of carbon black‐filled polymers with those of raw polymers. The shear viscosity increases with increasing amount of carbon black. The extrudate swell becomes smaller with increasing carbon black amount, indicated by the decreased elasticity of the material when adding carbon black. © 1993 John Wiley & Sons, Inc.