bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamic viscoelasticities for short fiber‐thermoplastic elastomer composites
Authors: Guo Wuyun , Ashida Michio 
Published: April 2003

AbstractDynamic moduli, E′ and E″, and loss tangent tan δ were investigated for thermoplastic elastomers (TPEs), styrene‐isoprene‐styrene copolymers (SISs), styrene‐butadiene‐styrene copolymer (SBS), and Hytrel and composites reinforced by poly(ethylene terephthalate) (PET) short fibers. The styrenic TPEs have a typical rubbery behavior and the Hytrel TPE has medial characteristics between rubber and plastic. Both E′ and E″ of the composites depended on the matrix as well as the fiber loading and fiber length. Based on the viewpoint of different extensibility between the fiber and the matrix elastomer, a triblock model was considered for estimating the storage modulus of the short fiber‐TPE composites as follows: Ec = αVfEf + β (1 − Vf) Em, where α and β are the effective deformation coefficients for the fiber and the matrix elastomer, respectively. They can be quantitatively represented by modulus ratio M (= Em/Ef) and fiber length L: α = ( Ln + k) M/ ( LnM + k), β = (1 − α Vf)/ (1 − Vf), where the constants n and k are obtained experimentally. When k = 0.022 and n = 0.45, Ec of the TPE composites agreed well with the prediction of the proposed model. The relaxation spectrum of the composites showed a distinct main peak ascribed to the matrix elastomer, but no peak to the PET fiber. The relative damping of main relaxation, (tan δmax)c/(tan δmax)m, decreased monotonously with increasing fiber loading and fiber length and with decreasing modulus of matrix elastomer. Thus, the relative damping may be attributed not only to the volume effect of matrix, but also to the unevenness of the strain distribution in the matrix phase, which depends on the fiber length and the matrix's modulus. The findings prove that the different extensibility between fiber and matrix and the uneven distribution of strain in matrix were important for the short‐fiber reinforcement of the TPE composites. © 1993 John Wiley & Sons, Inc.
Oxidation induction time correlations with radiation dose and antioxidant concentration in EPR and XLPE polymers
Authors: Mason L. R. , Doyle T. E. , Reynolds A. B. 
Published: April 2003

AbstractOxidation induction time (OIT), as measured by differential scanning calorimetry, is useful in assessing the extent of degradation in polymeric materials. Values of OIT for typical EPR and XLPE polymer insulation materials used for electric cable insulation in nuclear power plants were measured as a function of both radiation dose and antioxidant concentration after accelerated aging. Irradiations were performed at the University of Virginia Cobalt Irradiation Facility. OIT was found to decrease exponentially with increasing radiation dose and with decreasing antioxidant concentration for both ethylene‐propylene rubber (EPR) and cross‐linked polyethylene (XLPE) insulations. It was determined experimentally that, when polymers are subjected to a constant radiation dose rate, antioxidant concentration decreases linearly with time, and it was shown that this variation is consistent with theoretical autoxidation kinetics. © 1993 John Wiley & Sons, Inc.
Time–temperature viscoelastic behavior of an interlaminar‐toughened epoxy composite
Authors: Woo E. M. 
Published: April 2003

AbstractViscoelastic deformation of an interlaminar‐toughened laminated composite was investigated, and effects of the interlaminar heterogeneity were examined. Dynamic mechanical experiments were performed on the laminates and neat matrix resins of the laminated composite in the temperature range of 82–210°C to probe linear time‐temperature behavior. The reason for using torsional shear deformation for probing was that it usually is more dominated by the matrix. In the relatively low‐temperature regime, time‐temperature superposition was applicable, and the effect of the interlaminar heterogeneity was found to be not pronounced. A methodology based on the Arrhenius activation energy approach was proposed for predictions of long‐term viscoelasticity of the heterogeneous‐phase composite. The effects of the interlaminar toughening phase became more significant at temperatures greater than the Tg of the toughening phase and presented some limitations for accurate predictions of time‐dependent behavior. © 1993 John Wiley & Sons, Inc.
Phase separation phenomena of polysulfone/solvent/organic nonsolvent and polyethersulfone/solvent/organic nonsolvent systems
Authors: Wang Dongliang , Li K. , Sourirajan S. , Teo W. K. 
Published: April 2003

AbstractThe precipitation values (PVs) of several organic nonsolvents in polysulfone (PSf)/solvent and polyethersulfone (PESf)/solvent systems were measured in temperatures ranging from 10 to 80°C by the direct titration method and compared with those of water in the same systems. The solvents used were N‐methyl‐2‐pyrrolidone (NMP) and N,N‐dimethylacetamide (DMAC); the organic nonsolvents employed were methanol, ethanol, 1‐propanol, 1‐butanol, 1‐pentanol, ethylene glycol, and diethylene glycol as well as acetic acid and propionic acid. The compositions of nonsolvent, polymer, and solvent at the precipitation points for different polymer concentrations up to 10 wt % were also determined at 30°C with respect to both the polymers and six nonsolvents presented. These results were used to obtain the polymer precipitation curves in the polymer‐solvent‐nonsolvent triangular phase diagrams and to determine the theta composition of solvent‐nonsolvent for a polymer. The results show that the precipitation value of nonsolvent in polymer/solvent systems depends on both the nature of polymer, solvent, and nonsolvent used and the temperature. The effect of temperature on the precipitation value was observed to be dramatically different for different polymer/solvent/nonsolvent systems. These results were explained on the basis of polar and nonpolar interactions of the polymer, solvent, and nonsolvent system. The results indicate that the precipitation values of the type presented in this paper not only give a relative measure of the nonsolvent tolerance of the polymer/solvent system involved and the strength of solvent and nonsolvent for the polymer, but also determine the relative location of the polymer precipitation curve in the triangular phase diagram. © 1993 John Wiley & Sons, Inc.
Novel UV absorbers prepared from 2,4‐dihydroxybenzophenone and hexachlorocyclotriphosphazene
Authors: Inoue Kenzo , Takahata Hiroaki , Tanigaki Teiichi 
Published: April 2003

AbstractThe UV‐stabilizing ability and thermal loss from the polystyrene film of novel UV absorbers, 2‐[(3‐hydroxy‐4‐benzoyl) phenoxy] pentachlorocyclotriphosphazene (HBPC) and hexakis[ (2‐hydroxy‐4‐benzoyl) phenoxy] cyclotriphosphazene (HBPP), were investigated. The UV‐stabilizing ability of HBPC estimated by the formation of carbonyl groups in polystyrene was comparable to that of 2,4‐dihydroxybenzophenone (DHB), suggesting that the phosphazene moiety does not affect the efficiency of the stabilizing ability of DHB units. No significant difference of efficiency per stabilizing units between HBPC and HBPP was observed. HBPC and HBPP are noteworthy for their low thermal losses from the polystyrene film, i.e., the thermal loss of HBPP was completely suppressed and the diffusion coefficient of HBPC at 160°C was two orders of magnitude smaller than that of DHB. The thermogravimetric analysis and differential scanning calorimetry measurement showed that HBPC and HBPP are nonvolatile and stable up to 230 and 300°C, respectively. © 1993 John Wiley & Sons, Inc.
Melt viscosity increase during rheological testing of poly(phenylene sulfide)
Authors: Fagerburg D. R. , Watkins J. J. , Lawrence P. B. 
Published: April 2003

AbstractPoly(phenylene sulfide) (PPS) made via the melt polymerization of p‐diiodobenzene and sulfur has previously been reported to increase in melt viscosity with time during rheological testing. Analysis of the oligomer from cleavage of PPS chains at the disulfide bonds via solution in 1‐chloronaphthalene demonstrated that the disulfide content of the polymer decreased with rheological testing time. DSC of the polymer before and after rheological testing in combination with the Tcc and Tm of the chain fragments after the dissolution/cleavage in 1‐chloronaphthalene showed that many samples exhibited primarily chain extension rather than chain branching, whereas for many others, some degree of chain branching occurred. This is currently only qualitatively understood. Chain branching as the exclusive mechanism of melt viscosity increase during rheological testing appears untenable in light of the Tm, in particular, of the chain fragments and also the polymer prior to chain cleavage. © 1993 John Wiley & Sons, Inc.
Optimal operations of semibatch solution polymerization of acrylamide with molecular distribution as constraints
Authors: Jang Shi‐Shang , Tan Di‐Ming , Wei I‐Jen 
Published: April 2003

AbstractIn this work, optimal control profiles of a semibatch solution polymerization of an acrylamide system are investigated for the first time. The control variables are the monomer and initiator feed rates. The objective function is the operating time of each batch. One of the operating constraints is the maximum of the polymerization rate of the reaction, which is important due to the limitation of the heat‐removal equipment. The expected number‐average molecular weight and molecular weight distribution are also included as constraints in order to guarantee the quality of the products. A nonlinear programming approach developed by Jang and Yang is used for solving the equations. Several simulation and experimental runs show that the operation of this semibatch system is very smooth and conversions are fitted well by the model. The molecular weights and molecular weight distributions of the polymer products are also well controlled. © 1993 John Wiley & Sons, Inc.
Pressure–volume–temperature relationships for poly(vinylidene fluoride) and polyamide‐11
Authors: Rodgers Patrick A. 
Published: April 2003

AbstractExperimental specific volume data as a function of temperature (30–269°C) and pressure (0–2000 bar) are presented for two semicrystalline polymers, namely, poly(vinylidene fluoride) and polyamide‐11. Data for the melt state were used to determine the characteristic parameters for six theoretical equations of state as well as the empirical Tait equation. The theories employed were the cell models of Flory–Orwoll–Vrij, of Prigogine et al., and of Dee and Walsh, the latticefluid theory of Sanchez and Lacombe, the hole theory of Simha and Somcynsky, and the semiempirical model of Hartmann and Haque. Solid‐state data were also fit using the Hartmann–Haque and Tait equations. © 1993 John Wiley & Sons, Inc.
Pentavalent vanadium ion–cellulose thiocarbonate redox‐system induced grafting of methyl methacrylate and other vinyl monomers onto cotton fabric
Authors: Hebeish A. , El‐Rafie M. H. , Zahran M. K. 
Published: April 2003

AbstractCellulose thiocarbonate was prepared by reacting cotton cellulose fabric with carbon disulphide in the presence of sodium hydroxide. The treated fabric formed, with pentavalent vanadium ion, an effective redox system capable of initiating grafting of methyl methacrylate (MMA) and other monomers no+o the cotton fabric. The dependence of grafting on vanadium concentration, pH of the polymerization medium, temperature and duration of grafting, nature and concentration of monomer, and solvent/water ratio was studied. The results indicated that increasing the pentavalent vanadium (Vv) concentration up to 60 mmol/L was accompanied by enhancement in the rate of grafting; the latter was not affected by further increase in Vv concentration. Maximum grafting yield was achieved at pH 2; grafting fell greatly at higher pH. The rate of grafting followed the order: 70° > 60° > 50°C. The graft yield increased significantly by increasing the MMA concentration from 0.5 to 5%. Of the solvents studied, n‐propanol and isopropanol enhanced the grafting rate provided that a solvent/water ratio of 5 : 95 was used; a higher solvent ratio decreased the magnitude of grafting. Other solvents, namely, methanol, ethanol, n‐butanol, and acetone, in any proportion, decreased the rate of grafting. With the monomer used, the graft yield followed the order: methyl methacrylate > methyl acrylate > methacrylic acid > ethyl methacrylate > acrylic acid. Also reported was a tentative mechanism for vinyl‐graft copolymerization onto cotton fabric using cellulose thiocarbonate‐Vv. © 1993 John Wiley & Sons, Inc.
Infrared spectroscopy study of powder celluloses modified by Lewis acids
Authors: Sultankulova A. S. , Sarybaeva R. I. , Afanasev V. A. 
Published: April 2003

AbstractIt is shown that modified powder celluloses distinguish from microcrystal cellulose produced by a hydrolytic method by the presence of the modification of cellulose II and by a low index of crystallinity. © 1994 John Wiley & Sons, Inc.
Branching measurement by analytical TREF: A fully quantitative technique
Authors: Pigeon Michael G. , Rudin Alfred 
Published: April 2003

AbstractConversion of analytical TREF data to accurate branching distributions of polyethylene requires a calibration of branching frequency as a function of elution temperature. It has been found that the elution temperature of a semicrystalline polymer such as polyethylene depends on molecular weight, branch content, branch length, and branch clustering. It stands to reason that every polymer will have its own unique relation of branch frequency and elution temperature. Ideally, the polymer would be fractionated by a preparative TREF technique and the fractions analyzed by NMR or IR to determine branch frequency with respect to elution temperature. This method is tedious and time‐consuming. An alternative method is described here to determine the relation between branch frequency and TREF elution temperature and to generate a calibration from analytical TREF data only. A twodetector system is used to simultaneously measure both concentration and branching frequency as a function of elution temperature. Each polymer is analyzed using analytical TREF data alone, eliminating the need for preparative TREF fractionation and NMR analysis of the fractions. © 1994 John Wiley & Sons, Inc.
Preparation and characterization of amidoxime resins based on poly(acrylonitrile‐co‐vinylidene chloride‐co‐divinylbenzene)
Authors: Kabay Nalan , Egawa Hiroaki 
Published: April 2003

AbstractThe poly(acrylonitrile‐co‐vinylidene chloride‐co‐divinylbenzene) beads with macroporous morphology were synthesized by suspension polymerization. The use of dichloroethane as a solvating diluent resulted in copolymer beads having highly porous structures. These have been reacted with hydroxylamine in methanol, which generates amidoxime groups. The precursory resins were readily functionalized within 0.5–1 h. A detailed analysis is made of the pore structure of resins in the anhydrous state including pore size distribution and specific surface area. © 1994 John Wiley & Sons, Inc.
Crystallization kinetics of pure and fiber‐reinforced poly(phenylene sulfide)
Authors: Auer C. , Kalinka G. , Krause Th. , Hinrichsen G. 
Published: April 2003

AbstractIsothermal DSC investigations on pure as well as glass, carbon, and aramid fibre‐reinforced poly(phenylene sulfide) (PPS) were carried out in order to obtain informations on the crystallization kinetics, that is, the Avrami exponent, constant, half‐time of crystallization, and (final) degree of crystallinity. PPS is a typical representative of semicrystalline polymers with a maximum degree of crystallinity of about 60%. The Avrami exponent reaches values from n = 2.1–2.7 depending on fibre type but independent of crystallization temperature. The system aramid fibre/PPS has a much shorter half‐time of crystallization than the other three systems that could be attributed to the high nucleation effect of the aramid fibre surface to PPS. As a consequence of the high nuclei density a transcrystalline zone is built up around the aramid fibre. The relatively low value of the Avrami constant was discussed and a computer simulation attempt was made to understand the measured value quantitatively. © 1994 John Wiley & Sons, Inc.
Evidence for chemical bond formation between surface treated carbon fibres and high temperature thermoplastics
Authors: Hüttinger K. J. , Krekel G. , Zielke U. 
Published: April 2003

AbstractThe interaction between surface‐treated carbon fibres and high temperature thermoplastics (polyethersulfone and polycarbonate) was studied by measuring the interlaminar shear strength of unidirectionally reinforced composites with a fibre volume content of 60%. The ILSS‐values were correlated with the surface concentration of the acidic functional groups of the carbon fibres, as analysed by temperature programmed desorption and contact angle measurements using basic aqueous solutions (pH ≥ 12). Linear relationships were found with both the amount of carbon dioxide desorbed by decomposition of carboxylic surface groups and the work of adhesion calculated from the measured contact angles. This result could be interpreted as a consequence of acid–base interactions with the basic polymers. However, strongly acidic carboxylic groups are decomposed during processing of the composites. Therefore, the high ILSS‐values can only be explained by chemical bonds being formed with the functional groups of the polymers during decomposition of the carboxylic surface groups. © 1994 John Wiley & Sons, Inc.
Reaction condition effects in the melt preparation of poly(phenylene sulfide) from p‐lodophenyl disulfide
Authors: Fagerburg D. R. , Van Sickle D. E. 
Published: April 2003

AbstractHigh melt viscosity poly(phenylene sulfide) (PPS) can be prepared via melt condensation of p‐iodophenyl disulfide analogous to the solution condensation previously reported by other investigators. Depending upon reaction conditions, the material contained varying amounts of gels, whereas under all conditions, anywhere from 1 to 3 mol % disulfide linkages were present. Solution in 1‐chloronaphthalene allowed separation of soluble and gel fractions and also cleaved the disulfide linkages, which allowed better quantitation of the disulfide content than did elemental analysis. Cleavage of the disulfides with 1‐chloronaphthalene was verified via a model reaction. Branching in the preparations was related to the level of iodine in the melt reaction and also the reaction temperature. A branching mechanism is proposed based on model experiments that showed a complex reaction order and an initial rate of branching that was dependent on iodine concentration. © 1994 John Wiley & Sons, Inc.
Design of an extrusion die with a variable choker bar
Authors: Wu Ping‐Yao , Liu Ta‐Jo , Chang Hsu‐Ming 
Published: April 2003

AbstractA novel approach is proposed to adjust flow nonuniformities caused by production variations from an extrusion die. A mathematical model that is based on the lubrication approximation was developed, and the effect of four types of production variations was examined separately. To each production variation, a specially designed choker bar was constructed and inserted into the extrusion die to correct flow nonuniformities. © 1994 John Wiley & Sons, Inc.
Hydrophilic foams containing corn products for horticultural use
Authors: Cunningham R. L. , Carr M. E. , Bagley E. B. , Gordon S. H. , Greene R. V. 
Published: April 2003

AbstractPolyurethane foams containing equal amounts of commercial unmodified cornstarch and a polyisocyanate‐terminated polyether exhibit properties suitable for horticultural applications. The use of cornstarch in the foam formulation increased the volume by one‐fourth as compared to the foam without cornstarch. This volume increase represents an economic advantage of 20% savings based on material cost. When cornstarch or corn flour is added to the foam formulation, the foams are more resistant to compressive force. Upon wetting and draining, the foams prepared with no auxiliary blowing agent and containing corn products exhibit higher volumes than do the unfilled foams. Radish seeds planted inside 25 mm cubes of foams began to sprout after 1 day. Early developmental growth for the plants was similar in the control and cornstarch‐filled foams. Spectroscopic analyses of the starch‐containing foams revealed that 60–70% of the cornstarch was metabolized within 4–5 weeks by a microbial consortium. Control polyurethane foams were not affected by the microorganisms tested. © 1994 John Wiley & Sons, Inc.This article is a U.S. Government work and, as such, is in the public domain in the United States of America.
Natural rubber–HDPE blends with liquid natural rubber as a compatibilizer. I. Thermal and mechanical properties
Authors: Ahmad Sahrim , Abdullah Ibrahim , Sulaiman Che Som , Kohjiya S. , Yoon J. R. 
Published: April 2003

AbstractThe measurement of physical properties of thermoplastic natural rubber (TPNR) of NR–HDPE blends have been made at various compositions of high‐density polyethylene (HDPE). The tensile properties and hardness of TPNR improve significantly with the addition of liquid natural rubber (LNR) to the blend. The degree of cross‐linking also increases with increasing amount of LNR added. The LNR with molecular weight (Mw) of 50,000 and reactive terminals promotes cross‐linking within the rubber phase and grafting of the polyethylene chains onto the rubber matrix system. The maximum stress and strain of the blends measured are about 7.5 MPa and 1000%, respectively. Dynamic mechanical analysis results indicate a single Tg on a tan δ trace at about −50 and −55°C for the two types of blends, respectively. © 1994 John Wiley & Sons, Inc.
Hemolglobin encapsulation in chitosan/calcium alginate beads
Authors: Huguet M. L. , Groboillot A. , Neufeld R. J. , Poncelet D. , Dellacherie E. 
Published: April 2003

AbstractA mild chitosan/calcium alginate encapsulation process, as applied to encapsulation of hemoglobin, was investigated. The first procedure consisted of adding dropwise a hemoglobin‐containing sodium alginate mixture in a chitosan solution, then hardening the interior of capsules thus formed, in the presence of CaCl2. In the second method, the droplets were directly pulled off in a chitosan–CaCl2 mixture. Both procedures led to beads containing a high concentration in entrapped hemoglobin as more than 90% of the initial concentration (150 g/L) were retained inside the beads provided that the chitosan concentration was great enough. The molecular weight of chitosan (M̄u 245,000 or 390,000) and the pH of its solution (2, 4, or 5.4) had only a slight effect, the best retention being obtained with beads prepared at pH 5.4. The hemoglobin release during the bead storage in water was found to depend on the conditions of their formation and especially on the chitosan molecular weight. The best retention during storage in water was obtained with beads prepared with the high M̄u chitosan solution at pH 2. Considering the total loss in hemoglobin during the bead formation and after 1 month of storage in water, the best results were obtained by preparing the beads in an 8 g/L solution of a 390,000 chitosan at pH 4 (less than 7% of loss with regard to the 150 mg/L initial concentration). © 1994 John Wiley & Sons, Inc.
Interfacial tension of poly(p‐phenylene sulfide) with other polymer melts
Authors: Yoon Pil Joong , White James L. 
Published: April 2003

AbstractThe interfacial tension of poly(p‐phenylene sulfide) (PPS) with various thermoplastics of different compostion and polarity has been carried out using the breaking thread and pendent drop methods. The value of the polyethylene (PE)/PPS interfacial tension is found to be intermediate between PE/polysulfone and PE/polycarbonate. The highest interfacial tension for PPS found in the systems studied was with polyamide‐6 followed by PE. The lowest values were with polysulfone followed by polystyrene. The effects of small additions of polysulfone and polystyrene in PPS on interfacial tension is studied with various thermoplastics. © 1994 John Wiley & Sons, Inc.