bluuebunny/crossref_metadata_2025_split huggingface dataset:
A qualitative model for the mechanical behavior of pretreated asbestos‐epoxy composites
Authors: Papaspyrides C. D. , Papanicolaou G. C. 
Published: April 2003

AbstractThe aim of the present work was to investigate the effect of fiber pretreatment, fiber content, coating concentration, and also pretreatment procedure on the tensile properties of asbestos‐epoxy composites. These composites comprise materials of considerable industrial importance. Asbestos exhibits unique properties. Occasionally it is difficult to disperse asbestos properly because the individual fibrils are very small and tend to agglomerate, but there is no evidence that asbestos is not easily wetted out by all systems. However, the higher potential aspect ratio of asbestos fibers compared with glass is not always realized in practice because the fibers break in length to fine diameters. Accordingly, the very considerable new surface created makes successful wetting difficult or impossible. For this reason, asbestos was precoated with a well adhered film of poly(hexamethylene adipamide), a polymer especially compatible with the epoxy phase. The pretreatment procedure followed was based on the principles of the interfacial polymerization involving the serial application to the asbestos of two immiscible solutions of hexamethylenediamine and adipoyl chloride. Accordingly, epoxy‐nylon‐chrysotile composites were made while varying pretreated fiber volume fraction, concentration of the polyamide coating, and reactants application order. Results obtained from tensile measurements proved quite interesting: Relative modulus of elasticity and relative ultimate strength exhibited a similar behavior when correlated with the ratio of polyamide to asbestos concentration. The corresponding curves pass through distinct maxima at which severe improvement of the material performance is effected. A thorough interpretation of these results is also included.
Polyethers. I. Polyethers from 2,4‐dichloroquinolines and alkylene diols
Authors: Patel M. G. , Patel K. C. , Patel S. R. 
Published: April 2003

AbstractPolyethers are prepared by condensing, respectively, 2,4‐dichloroquinoline and its 6‐methyl and 6‐methoxy derivatives separately with ethylene, propylene, butylene, diethylene and triethylene glycols. These polyethers are characterized and the electrical conductivity of polyethers is measured at various temperatures up to 150°C.
Viscoelastic properties and coating performance of acrylic copolymers crosslinked with melamine resin
Authors: Takahashi Seiichi , Okoshi Noboru , Matsumoto Takanori , Ikeda Takenori 
Published: April 2003

AbstractFor 8 carboxy and hydroxy functional acrylic copolymers crosslinked with melamine resin, glass transition temperature (Tg), molecular weight of chain segments between crosslinked point (Mc), and polymer‐solvent interaction parameters (χg ) were determined by dynamic mechanical measurements and swelling measurements. Tg increases and Mc decreases with the increase of hydroxyl value and the molecular weight of acrylic copolymers. Tg decreases and Mc increases with the increase of alkyl chain length of acrylate in acrylic copolymers. The film hardness, Tg and polarity of methyl methacrylate (MMA) containing acrylic‐melamine‐cured films are higher than those of styrene‐containing acrylic‐melamine‐cured films, but both films are almost the same in the degree of crosslinking (maximum loss tangent, tan δmax, and Mc). Tg increases and Mc decreases with the increase of melamine resin content for acrylic‐melamine coatings. The cured film consists of the acrylic‐melamine segments and the melamine‐melamine segments at crosslinking points. The carboxy group enhances the crosslinking reactions at low temperatures. All films crosslinked have single glass transition temperatures and broad damping peaks, which show good compatibility. The values of χg of acrylic copolymer‐melamine films in polar and nonpolar solvents depend on the polarity of acrylic composition and the degree of crosslinking. χg values of carboxy functional acrylic‐melamine film in any solvents are smaller than that of carboxy and hydroxy functional acrylic‐melamine film. χg values of MMA‐containing acrylic‐melamine film in polar solvents are smaller than those of styrene‐containing acrylic‐melamine film, but χg values of MMA‐containing acrylic‐melamine film in nonpolar solvents are larger than those of styrene‐containing acrylic‐melamine film. χg values of acrylic‐melamine film in polar and nonpolar solvents increase with the increase of alkyl chain length of acrylate. The χg values of acrylic‐melamine coatings in toluene are less than 0.3 and smaller than those of alkyd coatings.
Behavior of azo dyes dispersed in fluid polymeric matrices with different rheological properties. A kinetic study of the cis‐trans isomerization of 3′‐nitro‐4‐diethylamino azobenzene in polyethylenoxides
Authors: Dubini‐Paglia Ernestina , Beltrame Pier Luigi , Marcandalli Bruno , Seves Alberto , Vicini Loredana 
Published: April 2003

AbstractThe thermal cis‐trans isomerization of 3′‐nitro‐4‐diethylaminoazobenzene in seven polyethyleneoxides at different molecular weight has been studied kinetically in the temperature range 35–70°C. The dependence of the reaction rate on the polymer polarity and viscosity is discussed. The kinetics of the isomerization of the dye dispersed in the fluid polymeric matrix was found to be a useful probe of the structural features of the polymer.
Heat distortion of phenolic fiber reinforced thermoplastics
Authors: Jinen Eiichi 
Published: April 2003

AbstractHeat distortion temperature of phenolic short fiber‐reinforced thermoplastics (FRTP) (polystyrene, polypropylene, nylon 66), which are molded by injection, have been estimated by an ASTM standard and the reinforced effect is examined from the standpoint of the dependence on the fiber content and maximum fiber stress (bending stress). For polystyrene (PS), the temperature dependence on the fiber content and the maximum fiber stress dependence on the gradient (increase in heat distortion temperature with an increase in 1% of fiber) of these lines show a fine relation, and in regard to the heat distortion temperature, also indicates a nearly linear relation on a log–log scale. However, for the other two polymers, a good relation cannot be recognized but shows a nonlinear one. For polypropylene (PP), a decrease in the phenomenon in the heat distortion temperature dependence on fiber content is found and an interpretative explanation of the results is given.
Thermotropic polyester carbonates. II. Polyester carbonates as high performance fibers
Authors: Lai Y. C. , Debona B. T. , Prevorsek D. C. 
Published: April 2003

AbstractThe fiber spinning and heat treatments of spun fibers from thermotropic polyester carbonates are described. Thermotropic polyester carbonates derived from t‐butylhydroquinone, methylhy‐droquinone, diphenyl terephthalate, and diphenyl carbonate in the molar ratios of 50 : 50 : 55 : 45; 50 : 50 : 57.5 : 42.5; can be spun successfully, and after proper heat treatment, yield fibers with tenacity as high as 20 g/denier. Normally the best spinning temperature is 10–20°C above melting.
Drag reduction by polymer–polymer mixtures
Authors: Malhotra J. P. , Chaturvedi P. N. , Singh R. P. 
Published: April 2003

AbstractAn extensive study on the turbulent drag reduction caused by the various mixtures of polyacrylamide, purified guargum, xanthangum, and their graft copolymers has been conducted at low concentrations and Re = 14,000 using a turbulent flow rheometer. It has been found in most of the cases that the drag reduction caused by mixtures shows a positive deviation from the linearly additive straight line. This effect is more prominent when the drag reduction caused by both the constituents differ appreciably. In most of the cases, the drag reduction caused by the mixtures is higher than the DR caused by either of the constituent polymers; however, the drag reduction caused by the mixture is less than the sum of the drag reduction caused by both the constituents at their respective concentration in the mixture. It has also been noticed that there is no evidence of synergism in these mixtures at low concentrations.
Processing–property interactions in poly(vinylidene fluoride). II. Morphology and property characterization of extruded films
Authors: Khomami B. , McHugh A. J. 
Published: April 2003

AbstractThe effects of flow history, processing temperature, and exit draw ratio have been studied for a poly(vinylidene fluoride) resin. Quantification of the stress fields and flow kinematics were described in Part I while, in this publication, attention has been addressed to the evaluation of film properties. Hot‐stage and differential scanning colorimetry (DSC) analyses were used to characterize the thermal behavior; polarized light optical microscopy and electron microscopy were used to characterize the morphology; Fourier transform infrared (FTIR) and wide‐angle x‐ray scattering (WAXS) were used to evaluate crystal structure; and mechanical testing was used to evaluate tensile properties. Extensional melt stresses on the order of 1.4 × 106 dyne/cm2 were necessary to induce row‐nucleated crystallization in undrawn samples, and in all cases, preorientation of the melt by extensional flow enhanced the efficiency of the α → β transformation with drawing. The various transformations on drawing were as follows: unoriented α to oriented superheatable α phase for draw ratio (DR) < 5; transformation from α to β phase for 5 < DR ≤ 25; transformation to more highly oriented α and β phases, DR > 25.
Hot nip drawing: A rapid method of producing high modulus polypropylene films
Authors: Laughner M. P. , Harrison I. R. 
Published: April 2003

AbstractThere are many methods currently producing high modulus and high strength films and fibers in industry. This publication examines the results of a hot nip drawing process to produce high modulus PP films at a relatively rapid production rate. The effects of both temperature and rate of draw on the drawn material will also be examined.
Effects of brominated flame retardants and crosslinking agents on the flame retardancy of rubbers
Authors: Yang Chin‐Ping , Chen Wen‐Tung 
Published: April 2003

AbstractTetrabromo‐p‐cresol (TBPC), pentabromophenol (PBP), and their allyl ether derivatives—tetrabromo‐p‐cresol allyl ether (TBPC–AE) and pentabromophenol allyl ether (PBP–AE)—were used in the study of flame retardancy of ethylene–vinyl acetate (EVA) copolymer and styrene–butadiene rubber (SBR), which were cured by dicumyl peroxide (DCP) and sulfur, respectively. The dependence of the flammability of crosslinking polymers on the polymer matrix, its additives, and the degree of crosslinking was investigated. The empirical equations of flame retardancy were established for these rubbers and compared with the measured values. It was found that the oxygen index of SBR–S system was in accordance with the empirical equations, while the EVA–DCP system, affected by the decomposed residue of DCP, showed a slight deviation. The brominated phenolic compounds of allyl ether (BPs–AE) showed a greater deviation than their precursors. This may be due to the fact that allyl group could react with DCP and lose its excellent flame resistance characteristic, which may be caused by the modified Claisen rearrangement produced in the thermal processing or burning. The phenolic brominated compounds containing the allyl group and a higher bromine content showed better flammability.
Characterization of water‐soluble cellulose derivatives produced by alkali treatment of ozonized allylated celluloses
Authors: Kondo Tetsuo , Ishizu Atsushi , Nakano Junzo 
Published: April 2003

AbstractOzonization products of allylated celluloses such as completely allylated methylcellulose and tri‐O‐allylcellulose, which are insoluble in both organic solvents and water, gave water‐soluble derivatives by alkaline treatment. Infrared (IR) and 13C‐NMR (nuclear magnetic resonance) spectrometries revealed that the products have many carboxyl as well as carbonyl groups. Allyl ethers in allylated celluloses were found to be cleaved by 30–35% during ozonization, whereas alkyl ethers such as methyl and ethyl ethers in cellulose derivatives were completely stable.
Flameproofed polyesters prepared by direct polycondensation of aromatic dicarboxylic acids and brominated bisphenols with tosyl chloride and N,N′‐dimethylformamide in pyridine
Authors: Yang Chin‐Ping , Hsiao Sheng‐Huei 
Published: April 2003

AbstractBrominated aromatic polyesters were successfully prepared by reacting isophthalic acid and terephthalic acid with p‐toluenesulfonyl chloride in pyridine in the presence of N,N′‐dimethylformamide, followed by treating with a pyridine solution of tetrabromobisphenols. The tetrabromobisphenols were synthesized by a facile bromination of their corresponding bisphenols in aqueous acetic acid solution under mild conditions. The polycondensation was significantly affected by the reactivity of bisphenols and the solubility of the resulting polymers in the reaction media. Tetrabromobisphenols with positive linking groups between the aromatic rings and better solubility of the resulting polymers give a more favorable result. The products were nonflammable having limiting oxygen index 59–62 (ASTM D2863‐77) without much sacrifice in thermal stability.
The dyeability and properties of some structurally modified poly(ethylene terephthalate) filaments
Authors: Ugbolue S. C. O. , Ekpenyon O. E. 
Published: April 2003

AbstractThe effect of solvent treatment on the dyeability and mechanical properties of drawn poly(ethylene terephthalate) (PET) filaments has been studied. It is observed that strongly interacting solvents such as N,N‐dimethyl formamide (DMF) improved the dyeability of PET which has been treated with these solvents at 74°C for 15 min before dyeing with disperse dyes at 100°C. Pretreatment in N,N‐dimethyl formamide and acetonitrile also resulted in a lowering of tensile strength and initial modulus, whereas subsequent dyeing caused further reduction in extensibility but initial modulus results are less consistent.
Polyester formation: Aminolytic degradation and proposed mechanisms of the reaction
Authors: Popoola V. A. 
Published: April 2003

AbstractThe acid‐catalyzed chemical degradation of polyesters is discussed, with emphasis on the chemistry of the reactions involved. Using primary amines as degrading agents in presence of water as the acid‐ionizing medium, mechanisms consistent with the chemistry of the reaction and those of realted esters are proposed.
Properties of copolymer‐type polyacetal/polyurethane blends
Authors: Chiang Wen‐Yen , Lo Ming‐Song 
Published: April 2003

AbstractMechanical and physical properties of the blends of copolymer‐type polyacetals (POM) with polyurethane (PU) were investigated. The properties relationships of POM/PU blends are established by studying their morphology and compatibility. For the blends rich in POM, the morphology of the blends observed with a scanning electron microscopy (SEM) indicates that the blends containing lower than 50 wt % (46 vol %) PU are almost completely filled with spherical particles of the dispersed PU. As the concentration of PU increases, the spherulites of the POM observed by SEM become less perfect with coarse fine structure. Furthermore, when the concentration of PU was increased up to 50 wt %, the spherulties of POM in the blends are smaller than those of unblended POM. X‐ray diffraction studies reveal that the degree of crystallinity of POM decreases with increasing PU content, which is nonmonotonic. This conclusion agrees with the observations made by differential scanning calorimetry (DSC) and density measurements. For the blends rich in POM, mechanical properties show that the impact strength of POM/PU blends increased with decreasing spherical size of the dispersed PU.
Preparation and properties of UV‐curable poly(dimethylsiloxane) urethane acrylate. II. Property‐structure/molecular weight relationships
Authors: Chiang Wen‐Yen , Shu Wey‐Jye 
Published: April 2003

AbstractA series of UV‐curable polyurethane acrylate resins based on hydroxy‐terminated polydimethylsiloxane (PDMS) soft segments with different molecular weights and various diisocyanate hard segments were synthesized. The products were obtained by employing direct‐addition polymerization techniques in a nonsolvent system. The structures of the final products were elucidated by IR and 1H‐NMR. The fundamental and physical properties of this type of UV‐curable material, the effects on properties by varying the molecular weight of PDMS or the type of diisocyanates, and the effect of using various reactive diluents were widely studied. This resin possessed good optical, electrical insulating, and adhesive properties. The mechanical strength of UV‐cured films corresponds approximately to the ratio of hard segments within these material and the dielectric insulating properties correspond to the chain length of PDMS.
Aging and performance of structural film adhesives. III. Effect of humidity on a modern aerospace adhesive
Authors: Ennis B. C. , Pearce P. J. , Morris C. E. M. 
Published: April 2003

AbstractThe aging of an uncured, DGEBA‐based commercial film adhesive exposed to high humidity at 40°C was monitored by high performance liquid chromatography (HPLC), thermal analysis, solubility, flow, and mechanical testing of joints. DGEBA and brominated DGEBA resins, and representative mixes of these were hydrolyzed in vitro. It is suggested that the major reaction at 40°C is polymerization, which is accelerated by moisture and leads to a crosslinked structure different to that resulting from normal cure. The poorer adhesive performance after aging is mainly the result of reduced resin flow during joint formation, although there is some contribution from the hydrolysis of epoxide groups which leads to lower crosslink density in the cured adhesive. The softening point of the uncured material and Tg of the cured material are useful indicators of the quality of this adhesive which, compared to some earlier formulations, has improved resistance to these conditions.
The radiation‐induced graft copolymerization of methacrylic acid with polyethylene. Ion‐exchange properties of the copolymeric composites
Authors: Guthrie J. T. , Kotov S. 
Published: April 2003

AbstractThe study involves the preparation and characterization of a series of polyethylene‐g‐comethacrylic acid polymers in which the comonomer provides a degree of hydrophilicity to the backbone polymer. Such copolymers have been shown to possess efficient ion‐exchange properties with respect to Fe(III) ions, used as a model for general exchange. As such, we have a useful extension to our work on enzyme immobilization and protein separations using this type of support. Grafting was carried out in air and under vacuum. A correlation between the carboxylic acid group content and the extent of grafting was found. Under the conditions employed in our experiments, a maximum in grafting levels was observed when water was used as a continuous medium but not when methanol was included in the solvent assembly. No significant difference was observed between grafting carried out in air and that carried out under vacuum, when aqueous solutions of methacrylic acid were used. The graft copolymers have been shown to be effective in isolating Fe(III) ions and to be amenable to recycling procedures.
Structural features of poly(alkylene ether carbonate) diol oligomers by capillary gas chromatography
Authors: Harris Robert F. 
Published: April 2003

AbstractA series of poly(ethylene ether carbonate) diol oligomers were synthesized from ethylene carbonate (EC) using various catalysts and low EC:initiator molar ratios. The structures of these oligomers have been studied by alkaline degradation to the poly(ethylene glycol)s, which make up their backbone, followed by capillary gas chromatographic (CGC) analysis. Comparisons of CGC traces before and after hydrolysis indicate which volatile components contain carbonate moieties. Some poly(ethylene glycol)s were not chemically bound into the polymer backbone and were analyzed directly by CGC. Based on the combination of analytical techniques developed in this study, it is possible for the first time to establish the approximate composition of a given poly(ethylene ether carbonate) diol. A typical composition made using a sodium stannate trihydrate catalyst consists of (1) an oligomeric portion which is a copolymer of carbon dioxide and poly(ethylene glycol)s and (2) a monomeric portion which consists mostly of diethylene glycol with lesser quantities of monoethylene glycol, triethylene glycol, 1,4‐dioxane and unreacted ethylene carbonate.
Photochemical surface modification of poly(ethylene terephthalate)
Authors: Goldblatt Ronald D. , Park Jae M. , White Robert C. , Matienzo Luis J. , Huang Samuel J. , Johnson Julian F. 
Published: April 2003

AbstractTo elucidate the role of chemical interactions in the promotion of metal–polymer adhesion, a poly(ethylene terephalate)/copper system was studied. Surface photografting of unsaturated monomers containing different chemical functional groups onto a three‐mil poly(ethylene terephthalate) film provided a means of examining a variety of copper‐polymer interfaces. Initial graft verification was accomplished via contact angle measurements. Adhesion strengths to vacuum‐deposited copper were determined using 90° peel tests. Graft analysis, as well as investigation of the interfacial interaction between copper and the grafted moieties, was accomplished using X‐ray photoelectron spectroscopy.
Anionic polymerization of styrene: The search for an industrial process
Authors: Priddy Duane B. , Pirc Michael 
Published: April 2003

AbstractAnionic polymerizations were carried out in the laboratory using a CSTR reactor design and conditions typical of current commercial mass polystyrene plants. Polystyrene having excellent color and polydispersity was produced. Polymer quality, styrene conversion, and molecular weight control were all linked to use of polymerization feed of consistently high purity and polymerization in the 90–110°C temperature range. The results of this study clearly show that high quality polystyrene can be made utilizing anionic polymerization chemistry in existing well mixed mass polystyrene reactors of the CSTR design. The key to the successful practice of this technology is the ability to produce consistently high purity polymerization feed.
Blends of imidized acrylic polymers with SAN copolymers and with PVC
Authors: Fowler M. E. , Paul D. R. , Cohen L. A. , Freed W. T. 
Published: April 2003

AbstractA series of imidized acrylic polymers of varying structural composition generated by reaction of methylamine with poly(methyl methacrylate) were blended with a range of styrene/acrylonitrile or SAN copolymers (0–33% AN) and with poly(vinyl chloride). On the basis of glass transition behavior determined by differential scanning calorimetry, some but not all imidized acrylic structures were found to be miscible with PVC and with SAN copolymers within a limited window of AN levels. Acid functionality in the imidized acrylics appears to hinder their miscibility with SAN rather significantly and with PVC to a lesser extent. Miscible SAN blends showed lower critical solution temperature behavior whereas miscible blends with PVC did not up to the highest attainable temperatures. The composition factors that influence the phase behavior are described and interpreted in terms of possible mechanisms.