bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of phthalic anhydride as a coupling agent on the mechanical behavior of wood fiber–polystyrene composites
Authors: Maldas D. , Kokta B. V. 
Published: April 2003

AbstractThe performance of phthalic anhydride used as a coupling agent in wood fiber‐filled polystyrene composites have been verified by evaluating the mechanical properties of the composites materials. Generally, mechanical properties improved along with the increase in concentrations of the coupling agent as well as wood fiber in the composites up to a certain limit and then decreased at the higher concentrations. The concentrations of phthalic anhydride and fibers which produce maximum improvements in mechanical properties differ with the change in wood species and pulping techniques. Compared to other efficient coupling agents (e.g., isocyanate), phathlic anhydride's performance seemed inferior.
Temperature dependence of the reaction between some metal oxides and polyacrylic acid
Authors: Rabie S. M. , Sawaby A. , Moharam M. A. , Nassar A. M. , Tahon K. H. 
Published: April 2003

AbstractThe temperature dependence of the reaction between some metal oxides and an aqueous solution of polyacrylic acid was investigated using the infrared measurements. The obtained data indicated that the divalent metal oxides MgO, ZnO, and PbO react rapidly with the polyacrylic acid forming carboxylate salts. The bonding between the acid groups and these metals is purely ionic in character. The reactivity between these metals and the carboxylic acid is inversely proportional to the radius of metal ions. The reaction of Bi2O3, Cr2O3, and TL2O3 is far from complete. However, SiO2 reacts slowly with polyacrylic acid at 0°C only. The results provided strong evidences that the rate of reaction between some metal oxides and polyacrylic acid depends on the temperature of reaction, This rate of reaction is enhanced as the temperature is lowered.
Polyurethane elastomers based on molecular weight advanced poly(ethylene ether carbonate) diols. I. Comparison to commercial diols
Authors: Harris Robert F. , Joseph Michael D. , Davidson Carla , Deporter Craig D. , Dais Virginia A. 
Published: April 2003

AbstractPoly(ethylene ether carbonate)diols (2025 mol wt) have been made by the molecular weight advancement of lower molecular weight oligomers and have been fabricated into polyurethane elastomers by reaction with 4,4′‐MDI and 1,4‐butanediol using the prepolymer method. Polymer structure has been delineated by carbon‐13 NMR. Comparisons have been made to a series of elastomers based on other polyester and polyether polyols (2000 mol wt) under conditions where the only variable was the soft segment structure. The poly(ethylene ether carbonate) diol gives a polymer with a partially phase mixed morphology, a higher ambient temperature modulus, and a lower ΔHm than the other polyester polyols. This lower ΔHm leads to a significantly lower rubbery plateau modulus than the other polyester polyols. Phase mixing is increased by post‐curing at 150°C. Organic solvent resistance is the most outstanding property. The poly(ethylene ether carbonate) diol produces a polymer with predominantly polyester polyol features.
Study of polymer latex coalescence by dielectric measurements in the microwave domain: Influence of latex characteristics
Authors: Cansell F. , Henry F. , Pichot C. 
Published: April 2003

AbstractThe coalescence process of polymer latex particles has been investigated by following simultaneously weight losses and dielectric constants variations during water evaporation in a latex deposited as a film in a resonant cavity at microwave frequency (5 GHz) and under controlled humidity and temperature. Different styrene (S) n‐butyl acrylate (BuA) emulsion copolymer latexes were examined so as to differentiate the behaviors of film forming or non‐film‐forming latexes. In the latter ones, both flocculation and maximum packing points were clearly evidenced, whereas only the first point was shown in the former ones. The effect of other colloidal variables (particle size distribution, surface charge density, particle diameter, ionic strength) have also been studied. It is found that the influence of the last three parameters is reflective of the latex stability and can be well detected by dielectric measurement. Such a method appears to be quite reliable for studying the film‐forming process of latexes having different colloidal characteristics.
The surface migration of extender oil in EPDM vulcanizates
Authors: Zinbo M. , Skewes L. M. , Theodore A. N. 
Published: April 2003

AbstractExtender oil bloomed on the surface of ethylene–propylene–diene rubber (EPDM) vulcanizates has been analyzed by a dissolution/size exclusion chromatographic (SEC) method. Dissolution is here defined as the quantitative and selective removal of bloomed extender oil from the vulcanizates. The rate of migration of three potentially useful extender oils for windshield‐wiper materials has been determined by the method. In this work a bloomed oil includes both an excluded oil surfaced during the process of vulcanization and a migrated oil surfaced during the course of aging or weathering. Typical initial rates of oil migration in the presence and absence of an excluded oil on the surface of compression‐set EPDM vulcanizates were ca. 0.8 and 2.2 μg/cm2/h at 25°C, respectively. The rate of migration at an attained uniform oil concentration was found to be ca. 0.5 μg/cm2/h for the three extender oils.
The optimization of the smoke suppressant and flame retardant properties of flexible PVC
Authors: Carty P. , Metcalfe E. , Annison W. N. 
Published: April 2003

AbstractThe combination of mixture diagrams and quality functions can be a straightforward and rapid method of simultaneously optimizing polymer formulations for both flame retardancy and smoke suppression. For a semirigid PVC formulation using a three‐component additive mixture it was found possible to raise the limiting oxygen index by over 7 units, while simultaneously reducing smoke production by more than 20%.
Fibers from flexible liquid crystal main‐chain polymers. II. Functional copolymers based on the 4,4′‐dihydroxy‐2,2′‐dimethylazoxybenzene mesogen and spacers based on 2‐dodecenedioic and nonanedioic acids
Authors: Lin C. H. , Maeda M. , Blumstein A. 
Published: April 2003

AbstractFibers spun from liquid crystalline solutions or melts are characterized by a high degree of chain alignment which promotes high values of tenacity and tensile modulus in the direction of fiber axis but lower values in the transversal direction. Structural modifications are introduced into the flexible moiety and the mesogenic group to alleviate this shortcoming. The incorporation of a spacer based on 2‐dodecenedioic acids into a thermotropic liquid crystalline polyester was studied. A phase diagram was established to optimize the composition of such copolyesters. A significant increase in mechanical properties on crosslinking through UV irradiation was observed. A remarkable property of such systems is the retention of molecular chain order in spite of temperatures in excess of Tg. This is valid for both crosslinked and uncrosslinked systems. Remarkable also is the crystallization on annealing of a number of copolymer compositions in spite of a structural difference between the comonomer units.
DSC studies of tactic polypropylenes: The correlation of polymer stereochemistry with thermal properties
Authors: Burfield David R. , Loi Patrick S. T. , Doi Yoshiharu , Mejzík Jir̆í 
Published: April 2003

AbstractA large number of polypropylene samples, of isotacticities spanning the range 0.35 to 1.00 mm, have been examined by differential scanning calorimetry (DSC) in order to establish a calorimetric index for determining stereostructure. Crystallization studies show that the crystallization onset temperature decreases in step with reduced isotacticity. However, samples prepared with supported catalysts show significantly lower crystallization onset temperatures than those from conventional catalysts which is believed to be due to differences in the inter‐ or intramolecular distribution of stereodefects. Furthermore, whole and fractionated samples cannot be fitted by one calibration curve. However, the enthalpy of crystallization is found to be related to the isotacticity by an equation of the form: log ΔH = m log (isotacticity) + c. This relationship is found to be applicable to samples from all types of catalysts examined and to both whole and fractionated samples. Fusion curves have been determined for “as received” as well as conditioned and annealed samples but the melting temperatures are not found to be a reliable guide to isotacticity. The respective enthalpies of fusion are found to follow the same logarithmic relationship stated above and thus can also be used as a basis for a calorimetric isotactic index. Examination of glass transition and related heat capacity data does not provide any clear‐cut alternative index.
Epoxy resins based on aromatic glycidylamines. II. Preparation ofN,N,N′,N′‐tetraglycidyl‐4,4′‐diaminodiphenylmethane from 4,4′‐diaminodiphenylmethane: Analysis of product by GPC and HPLC
Authors: Podzimek S̆. , Dobás̆ I. , S̆vestka S̆. , Horálek J. , Tkaczyk M. , Kubín M. 
Published: April 2003

AbstractN,N,N′,N′‐tetrakis(2,3‐epoxypropyl)‐4,4′‐diaminodiphenylmethane (N,N,N′,N′‐tetraglycidyl‐4,4′‐diaminodiphenylmethane, TGDDM) and an intermediate of its synthesis,N,N,N′,N′‐tetrakis(2‐hydroxy‐3‐chloropropyl)‐4,4′‐diaminodiphenylmethane (N,N,N′,N′‐tetrachlorohydrin of 4,4′‐diaminodiphenylmethane, TCHDDM), were analyzed by GPC and HPLC. The main impurities were identified by analogy withN,N‐diglycidylaniline (DGA) andN,N‐dichlorohydrin of aniline (DCHA) that had been analyzed in our previous work,1and by IR, NMR, and mass spectroscopy after their isolation by semipreparative HPLC. Attention was also paid to quantitative determination of the TGDDM content and to GPC elution behavior of TGDDM and TCHDDM‐based oligomers.
Surface modification by continuous graft copolymerization. IV. Photoinitiated graft copolymerization onto polypropylene fiber surface
Authors: Yao Zhang Pei , Rånby Bengt 
Published: April 2003

AbstractPhotochemically induced graft copolymerization (with UV light) of acrylamide (AM) and acrylic acid (AA) on polypropylene (PP) fiber surface by the presoaking method under nitrogen atmosphere in a continuous process has been developed. The results are measured by means of ESCA spectra. In grafting AM and AA, the relative intensity N1s/C1s and O1s/C1s of the fiber increase from 3–5 and 20% (background) to 8–13 and 23–39% in 9–10 s irradiation time, respectively. Titration results show that 1.75 3.58 mg/m2 poly(acrylic acid) has been grafted on the surface of PP fiber at various monomer concentrations of the presoaking solution. Commercial additives, such as antioxidant and UV stabilizer, affect the grafting yield of the fiber. As solvent in the presoaking solution, acetone is better than MEK and MPK. Various monomer and initiator concentrations in the presoaking solution have been studied. In the process developed 0.5–0.8 M acrylamide or 1.5–2.0 M acrylic acid and 0.2 M benzophenone (BP) in the presoaking solution are approapriate.
Cyanoacetamide accelerators for the epoxide/isocyanate reaction
Authors: Eldin Sameer H. , Renner Alfred 
Published: April 2003

AbstractThe cyanoacetamides NCCH2CONHR1N (R2) (R3) are a new family of accelerators for the epoxy/isocyanate (EP/IC) reaction. Results obtained from systematic structure variations indicate that they belong to the “deactivated tertiary amine” type of catalyst with the cyanoacetamide group as the deactivating moiety. Reactivity can be controlled via the R1 substituent (cyanoacetamide) and/or by R2/R3. A reaction mechanism is proposed. The results of a factorial design experiment and IR determination of the oxazolidinone (OX)/isocyanurate (ICR) extinction maxima ratios were used to develope an optimized EP/IC system. A trial formulation (filled) is given in which rapid gelation, a high Tg value, and excellent mechanical properties were achieved with an accelerator concentration of less than 0.2%.
The electrical and physical properties of CuS– and CdS–polyacrylonitrile composite films prepared by using the organosol method
Authors: Im Sung Soon , Im Hee Suk , Kang Eun Young 
Published: April 2003

AbstractElectrical and physical properties of the CuS‐ and CdS‐introduced polyacrylonitrile (PAN) films were studied. Electrically conducting PAN film was prepared by introducing CuS and CdS by the organosol method. Electrical surface conductivity of CuS‐ and CdS—PAN composite film prepared by the organosol method was 10−1 and 10−5 S/cm, respectively. Temperature dependence of surface conductivity for CuS—PAN composite film was investigated. The IV characteristics and time dependence of conductivity of samples were observed. The conduction mechanism of CuS– and CdS–PAN composite film was mainly electronic. Electrical properties of the CuS– and CdS—PAN composite film were mainly governed by the CuS and CdS crvstal formed in the PAN film. Temperature dependence of surface conductivity of the heat‐treated CuS—PAN composite film was also investigated. Results show that the electrical properties of the sample were varied slightly according to annealing temperature. Tensile strength and modulus of CuS– and CdS—PAN composite film were slightly decreased than original PAN film, but this decrease was not prevented utilization in electronic devices.
Evaluation of alkylated diphenyl ether disulfonate surfactants in 60 : 40 styrene—butadiene emulsion copolymerization
Authors: Vanderhoff J. W. , Dimonie V. L. , El‐Aasser M. S. , Settlemeyer L. A. 
Published: April 2003

AbstractDowfax* 2A1 is a branched C12‐alkylated diphenyl ether disulfonate surfactant widely used in industrial emulsion polymerization because of its electrolyte tolerance, stability in concentrated acids and alkalis, oxidation resistance, temperature stability, efficiency in solubilization, and moderate foaming. This surfactant and other similar surfactants were evaluated as emulsifiers in 60 : 40 styrene‐butadiene emulsion copolymerizations carried out at 70°C using persulfate ion initiator, and their solution properties were determined. The similar surfactants were Dowfax 3B2 (linear C10‐alkylated), XD‐8390 (linear C16), XD‐8292 (linear C6), XD‐8174 (linear C12), and various laboratory monoalkylated and dialkylated variations. Sodium lauryl sulfate, Aerosol MA, and Aerosol OT were used as standards for comparison. The emulsifier concentration required to give a 200‐nm particle diameter varied strongly with the degree of alkylation of the emulsifier; the linear C16‐monoalkylated diphenyl ether disulfonate emulsifier gave the desired diameter with the lowest concentration. The adsorption isotherms of these emulsifiers on the 60 : 40 styrene—butadiene copolymer particles were determined and correlated with the emulsifier structure. The interfacial tensions between styrene and the aqueous emulsifier solutions were measured and used to calculate the free energies of micellization and adsorption.
Immobilization of α‐chymotrypsin onto hydrolyzed poly(ethylene)‐g‐co‐hydroxyethyl methacrylate
Authors: Da Silva M. Alves , Gil M. H. , Guiomar A. J. , Martins C. , Guthrie J. T. 
Published: April 2003

Abstractα‐Chymotrypsin has been immobilized onto partially hydrolyzed poly(ethylene)‐g‐co‐hydroxyethyl methacrylate (120% graft), using 1‐cyclohexyl‐3‐(2‐morpholinoethyl)‐carbodiimide‐p‐toluene‐sulphonate (CMC) as the activating agent. The influence of the enzyme concentration, the carbodiimide concentration, and the coupling medium on the immobilization reaction was studied. A system with 160 mg of coupled enzyme per gram copolymer, providing 126 mg of active enzyme per gram of copolymer was obtained. The KM, Vmax, and the optimum temperature profile and optimum pH value for the free and immobilized α‐chymotrypsin were determined.
The preparation and properties of polyarylate block copolymers by interfacial polycondensation
Authors: Tseng Teng‐Yuan , Chu Ning‐Jo , Lee Yu‐Der 
Published: April 2003

AbstractBlock copolymers of bisphenol A isophthalate and sebacate were prepared by a two‐step interfacial polycondensation. The copolymers had sebacate contents of 1 : 5 and 1 : 3 molar with block lengths (DP) of 4,9, and 19. Thermal analysis of the copolymers by DSC showed the Tm of PBI. The crystallizability of PBI chain segments in the block copolymers was confirmed by X‐ray diffraction. The Tm of the copolymers was primarily influenced by the DP of the chain segments rather than the sebacate content. The Tg of the copolymers was mainly affected by the sebacate content rather than the DP of chain segments. The independent Tg of sebacate in the copolymers was not detected by DSC, i.e., the two polymer chains were compatible without phase separation. Phase separation was only observed in the rheometric spectrum of a 1 : 1 blend of the two homopolymers. The sebacate, being compatible with the isophthalate, had a plasticizing effect upon the polyarylate, which resulted in an improvement in toughness of the copolymers.
Fracture of irradiated polystyrene
Authors: Birkinshaw C. , Buggy M. , O'Neill M. 
Published: April 2003

AbstractSamples of polystyrene and high impact polystyrene of the butadiene copolymer type, have been subjected to irradiation in air to give received doses of up to 50 Mrad. Tensile and impact properties of the materials were measured using standard techniques. Whilst polystyrene showed little change in mechanical properties with received dose, the two phase high impact material showed significant effects with elongation at break and impact strength being reduced by an order of magnitude over the dose range examined. This behavior is thought to be associated with radiation induced crosslinking in the polybutadiene phase reducing the ability of the rubber to dissipate fracture energy. Micrographs of the tensile fracture surfaces of irradiated high impact polystyrene show evidence consistent with this mechanism.
Catalysis of isocyanate—alcohol and blocked‐isocyanate—alcohol reactions by amidines
Authors: Katsamberis Dimitris , Pappas S. Peter 
Published: April 2003

AbstractThe catalytic activity of completely substituted amidines in the reactions of isocyanates and blocked isocyanates with polyols was investigated. A bicyclic amidine was an effective catalyst for these reactions, whereas the monocyclic caprolactam type amidines were found to be ineffective.
Poly‐1,2,4‐triazoles containing arylene sulfone ether linkages
Authors: Idage Susheela B. , Idage Bhaskar B. , Vernekar Subhash P. 
Published: April 2003

AbstractPoly‐1,2,4‐triazoles containing arylene sulfone ether linkages have been synthesized by the reaction of polyhydrazide precursors and aniline in polyphosphoric acid at 260°C. The polyhydrazide intermediates were prepared from arylene sulfone ether containing dihydrazides and aromatic diacidchlorides via solution and interfacial polycondensation. These polymers and their intermediates were characterized by infrared, solubility, solution viscosity, elemental analysis, thermogravimetric analysis, differential scanning calorimetry, and X‐ray diffraction.
Grafting of vinyl acetate–methyl acrylate mixture onto cellulose. Effect of ceric ion and nitric acid concentrations
Authors: Fernandez M. J. , Casinos I. , Guzman G. M. 
Published: April 2003

AbstractThe effect of ceric ion and nitric acid concentrations on the graft copolymerization of a mixture of vinyl acetate and methyl acrylate onto cellulose was studied. Two procedures for the reactants addition were employed. Several grafting parameters were determined. Both ceric ion and nitric acid concentrations have a strong effect on the graft copolymerization and they affect similarly some of the polymerization parameters. A variety in the nature of the graft copolymers obtained has been reached. The general behavior of reaction parameters is discussed.
Bulk polymerization of diallyl benzene‐dicarboxylates. II. Effect of temperature on the gel point
Authors: Kostanski Leopold K. 
Published: April 2003

AbstractThe effect of bulk polymerization temperature on the gelation of diallyl phthalate (DAP), diallyl isophthalate (DAI), and diallyl terephthalate (DAT) has been investigated in the temperature range 353–568 K (80–295°C). The critical double‐bond conversion at the gel point increases significantly with temperature in a different manner for each of the monomers: for DAP, from ca. 17% at 353 K up to 46% at 568 K, whereas for DAI and DAT, from 15% and 13.5% up to 32 and 33%, respectively. These values are, on average, four to six times higher than those predicted according to Stockmayer's equation. Surprisingly, the yield of prepolymer precipitated just before the gel point is almost the same for DAP, DAI, and DAT at every polymerization temperature despite different tendencies to cyclization for each of the monomers. The yield increases significantly with the temperature: from ca. 24% at 353 K up to above 60% at 568 K. These yields are four to six times higher than are critical prepolymer contents predicted according to Gordon's theory. Empirical relationships between the gel point parameters and temperature have been developed.
Permeabilities of water, several alcohols, and water/alcohol mixtures through thin films of syndiotactic‐rich poly(vinyl alcohol)
Authors: Yamaura Kazuo , Kirikawa Shuichi , Sakuma Nobuhiro , Tanigami Tetsuya , Matsuzawa Shuji 
Published: April 2003

AbstractThe permeabilities of liquids through syndiotactic‐rich poly(vinyl alcohol) (s‐PVA) very thin films (about 0.3 μm) scooped up from the interface of air/aqueous solution were compared with that of casting s‐PVA films (about 15 μm). The permeability of water decreased with time and the volume of permeate leveled off after 4 or 5 days in both films. In the case of the very thin films, the permeabilities of alcohols decreased with the increase in the molecular weight of alcohol, whereas, in the case of casting films, the permeability of methanol was lower than that of ethanol. In the case of the very thin films, the permeabilities of any water/alcohol (=50/50) mixtures were lower than those of pure water and alcohols. These results were correlated to rearrangement of s‐PVA molecules, formation of bound water, hydrophobic interaction, and clusterization of small molecules.
The transport and sorption of water in polyethersulphone, polysulphone, and polyethersulphone/phenoxy blends
Authors: Swinyard B. T. , Sagoo P. S. , Barrie J. A. , Ash R. 
Published: April 2003

AbstractSorption isotherms and steady state permeabilities for water have been measured at 40°C for polyethersulphone, polysulphone, phenoxy polymer, and polyethersulphone–phenoxy blends. The pressure dependence of the permeability in all cases was weak and the permeability of phenoxy polymer is an order of magnitude smaller than that of polyethersulphone and polysulphone. The dependence of the permeability on blend composition is compared with an empirical expression often used to describe transport in miscible blends. The effect of phase separation on the permeability is studied briefly.
Improvement of the processability of advanced polymers
Authors: Nobile M. R. , Acierno D. , Incarnato L. , Amendola E. , Nicolais L. , Carfagna C. 
Published: April 2003

AbstractThe possibility of improving processability of engineering polymers was studied in this work. Low percentages of a thermotropic liquid crystalline polymer supplied by Bayer Co. were added to the polyetherimide Ultem. The thermal and morphological analysis revealed a two phase system. Rheological measurements in shear flow were carried out in the temperature range of the existence of the mesophase. A significant drop of ∼ 30% in the Ultem viscosity occurs even with 5% w/w TLCP. The influence of the addition of the thermotropic polymer on the mechanical properties of Ultem was also investigated. Moreover, the morphological analysis of the unfilled polymers and of the blends was performed and related to their rheological and mechanical behavior.