bluuebunny/crossref_metadata_2025_split huggingface dataset:
Miscible blends of poly(aryl ether ketone)s and polyetherimides
Authors: Harris J. E. , Robeson L. M. 
Published: April 2003

AbstractA new class of high performance engineering resins, poly(aryl ether ketone)s, has emerged with a property balance not offered by existing polymeric materials. Blends of poly(aryl ether ketone)s with other polymers have not been described in the open literature, although several patents have revealed interesting and important properties of certain blend combinations. Ultem polyetherimide has been found to be miscible over the entire composition range and as a consequence is a very effective heat distortion temperature builder, particularly if the poly(aryl ether ketone) is allowed to crystallize. Crystallization kinetics and mechanical properties were studied as a function of blend composition and poly(aryl ether ketone) melting point. The blends exhibited a maximum in toughness at intermediate compositions along with an accompanying maximum in poly(aryl ether ketone) crystallinity. The chemical resistance of the polyetherimide is significantly improved with the addition of a poly(aryl ether ketone). In organic chemicals, the improvement was expected when tensile stress was plotted vs. log time to rupture. However, in aqueous bases, the resistance of the blends was much greater than anticipated. This property profile suggests that these blends will be useful as thermoplastic composite matrix resins.
Synthesis and properties of elastomeric ionenes I. Polybutadiene ionenes
Authors: Yamashita Shinzo , Itoi Masaaki , Kohjiya Shinzo , Kidera Akinori 
Published: April 2003

AbstractPolybutadiene ionene (PBI) carrying quaternary ammonium ions in the main chain was synthesized from dimethylamino‐terminated polybutadiene and 1,4‐dibromobutane. Dimethylamino‐terminated polybutadiene was prepared by the reaction of isocyanate‐terminated polybutadiene with 2‐dimethylaminoethanol. The swelling property and the mechanical properties of PBI were compared with those of polybutadiene urethane (PBU), which was prepared by the reaction of hydroxy‐terminated polybutadiene with a diisocyanate. The following points were found: (1) PBI shows almost the same solubility parameter δp as that of PBU; (2) PBI attains a four time greater tensile strength at break than PBU at room temperature; (3) PBI shows a thermoplastic behavior.
Rheological properties and crystalline structure of the dynamically cured EPDM and PP/HDPE ternary blends
Authors: Ha Chang Sik , Kim Sung Chul 
Published: April 2003

AbstractThe rheological properties and crystalline structure of the polyolefin ternary blends of EPDM/polypropylene/high density polyethylene were studied. Blends were prepared in a laboratory internal mixer by two different methods. In blend–cure process, blending and curing were performed simultaneously and EPDM was cured by dicumyl peroxide (DCP) in the presence of PP/HDPE under shear. The cure–blend was to cure EPDM alone first under shear (dynamic curing) and then mix the cured EPDM with PP and HDPE. The effect of DCP concentration, intensity of the shear mixing, and the rubber/plastic composition were studied using capillary rheometer and X‐ray diffractometer. The PP‐rich ternary blends showed the effect of the mechanooxidative degradation of PP by shear and peroxide. The melt viscosity increased with increasing DCP concentration in blends of EPDM‐rich compositions. X‐ray diffraction studies revealed that the inclusion of 25 wt % of linear EPDM in the PP/HDPE mixture for the PP‐rich ternary blends changed the crystal structure of polypropylene component in the ternary blends. However, the dynamic curing did not alter the crystal structure of PP or HDPE in the blends.
The use of infrared spectroscopy for determination of polypropylene stereoregularity
Authors: Burfield David R. , Loi Patrick S. T. 
Published: April 2003

AbstractThis study examines the application of infrared (IR) spectrometry to the determination of polypropylene (PP) stereoregularity. The use of the absorption bands at 998 cm−1 and 841 cm−1 as indices of isotacticity and bands at 1167 cm−1 and 973 cm−1 as internal references have been explored. Calibration curves relating various absorption ratios to isotacticity as measured by 13C nuclear magnetic resonance are reported. The ratios A998/A973 and A841/A973 are the most useful and provide linear correlations with isotacticity. The effect of instrument type on the calibration has been investigated for both dispersive and Fourier transform type IR spectrometers. For samples annealed at room temperature the average of measurements on the same set of PP films by five instruments provide the calibrations: A998/A973 = 1.08 ± 0.02 (mm)−0.15 ± 0.03; and A841/A973 = 0.84 ± 0.06 (mm)−0.04 ± 0.02. High temperature annealing increases the crystallinity of the samples and the corresponding value of the absorption ratio but is not necessary for obtaining reproducible calibration curves.
Stress relaxation studies of model silicone RTV networks
Authors: Stein Judith , Prutzman Lori C. 
Published: April 2003

AbstractThe stress relaxation behavior of model silicone room temperature vulcanizing (RTV) elastomers has been used to examine the chemistry of the cured silicone network. It has been shown that the tin crosslinking catalyst, together with water, produces siloxane bond rearrangement which results in chemical stress relaxation. The measurement of the rate of stress relaxation of unfilled model elastomers at various temperatures gave an apparent activation energy of 10.3 kcal/mole−1 for the relaxation process. In addition, the effects of some of the constituents of the RTV on relaxation behavior have been examined.
Study on rough‐surface biaxially oriented polypropylene film. II. Influence of stretching conditions
Authors: Fujiyama Mitsuyoshi , Kawamura Yoshimasa , Wakino Tetsuo , Okamoto Tomomi 
Published: April 2003

AbstractThe production of rough‐surface biaxially oriented polypropylene film (BOP) has been studied by means of casting a polypropylene which contained γ‐quinacridone, a β‐crystal nucleator, with a T‐die extruder into a sheet which has subsequently been stretched successively in the machine direction (MD) and the transverse direction (TD) with a roll‐type stretching machine and a pantograph‐type stretching machine, respectively. For roughening of BOP using β‐form crystals in a successively stretching tenter method, it is preferable to roughen in the MD‐stretching process, with suppression of the recrystallization into the α crystals after melting of the β crystals being the most important objective. By rapid heating of a cast sheet in the MD‐stretching process, a rough‐surface BOP with a crater‐like roughness was obtained. Theoretical proof for the effectiveness of the rapid heating in the MD‐stretching process was obtained from experiments on the melt‐transformation of the β crystals by differential scanning calorimetry (DSC) measurements.
Irradiation of solvent‐treated cotton fibers
Authors: Rabie S. M. , Abd‐El‐Nour K. N. , Moharram M. A. 
Published: April 2003

AbstractThe infrared spectra and dielectric properties of cotton fibers pretreated for one day with toluene, methanol, and mixtures of the two have been investigated after drying the samples for 1 and 4 days. The effect of γ‐radiation on the crystallinity and dielectric properties of the solvent‐treated was examined. The samples were irradiated in air and also in the presence of the solvents. The data obtained indicate that the addition of toluene to methanol increases the rate of uptake of methanol by cotton. Moreover, it is found that irradiation of cotton fibers in the presence of toluene assists the oxidation of the cotton while irradiation in the presence of methanol reduces the oxidation effects of γ‐radiation.
Ductile transition in nylon‐rubber blends: Influence of water
Authors: Gaymans R. J. , Borggreve R. J. M. , Spoelstra A. B. 
Published: April 2003

AbstractOn nylon 6 and nylon 6/EPDM blends the influence of water on the glass transition temperature, mechanical properties, and the ductile transition temperature was studied. Blends of 10% and 20% were prepared with a particle size of 0.3 μm and the tensile properties, flexural moduli, torsion moduli, and notched izod impact strength were studied as functions of water concentration. The ductile transition temperature in polyamides can be lowered by plasticizing the nylon and by a rubber particle‐induced process; both processes show some synergistic effects.
The effect of modification on structure and dynamic mechanical behavior during the processing of acrylic fiber to stabilized fiber
Authors: Ko Tse‐Hao , Chiranairadul Phaichit , Ting Hsing‐Yie , Lin Chung‐Hua 
Published: April 2003

AbstractPolyacrylonitrile (PAN) fibers pretreated with potassium permanganate have reduced the time required for stabilization, and also improved mechanical properties of the resultant carbon fibers. In this study, the effect of modification on the stabilization process and the dynamic mechanical properties of PAN fibers have been examined. The beta peak appeared at about 125°C on the loss tangent curves caused by molecular motion in the PAN fiber. Appearing at about 254°C, the alpha peak is attributed to chemical reactions and molecular motion in the formation of the crystalline phase of stabilized fibers. The alpha peak of the modified PAN fiber had lower absorption and had a smaller peak in the temperature range of 212–239°C. This indicated that potassium permanganate acts as a catalyst to lower the reaction temperature by about 20°C of the initial cyclization reaction. The dynamic storage modulus analysis indicated that modified PAN fibers have a lower initial transition temperature and that formation of the ladder polymer is gradual and steady.
Studies on composites from wood and polypropylenes. II
Authors: Takase Setsuko , Shiraishi Nobuo 
Published: April 2003

AbstractComposites of polypropylene (PP) or maleic‐anhydride‐modified polypropylene (MPP) with refiner ground pulp (RGP) were prepared under various kneading conditions (mixing temperature, rate of rotation, and mixing time) and evaluated for their tensile strength (σmax), break elongation (ϵmax), and Young's modulus (E). Particularly, for the rate of rotation, fiber length distribution and its fibrillation were investigated in connection with mechanical properties of the composites. Also evaluated in this study was the effect of modifiers of PP on the properties. Modified PP that can be grafted or can have affinity to RGP was proved to improve the tensile strength of the molded composites as the RGP content increases, while the strength was decreased for PP–RGP composite without a modifier. MPP was also evaluated as a compatibilizer for the PP–RGP composites, and a tremendous improvement of tensile strength was achieved with MPP addition of only 2.5%, indicating that MPP can act as a compatibilizer in its system. These lines of evidence is interpreted to be caused from the improvement of the adhesion between RGP and PP through localizing MPP at the interface of these two components.
Use of wood fibers in thermoplastics. VII. The effect of coupling agents in polyethylene–wood fiber composites
Authors: Raj R. G. , Kokta B. V. , Maldas D. , Daneault C. 
Published: April 2003

AbstractLinear low density polyethylene (LLDPE) was reinforced with different wood fibers, aspen chemithermomechanical pulp (bleached and unbleached), and other commerical wood pulps. Silane coupling agents A‐172, A‐174, A‐1100, and polymethylene polyphenyl isocyanate were used to improve the bonding between the fiber and matrix. LLDPE filled with pretreated wood fiber produced a significant improvement in tensile strength and modulus. Comparison of tensile and impact properties of wood fiber composites with mica and glass fiber composites shows the potential advantage (in terms of material cost and specific properties) of wood fiber as a reinforcement.
The boron trifluoride monoethyl amine complex cured epoxy resins
Authors: Chen C. S. , Pearce Eli M. 
Published: April 2003

AbstractThe curing exotherm pattern is affected by the equivalent ratio of curing agent, boron trifluoride monoethylamine complex (BF3 · MEA), to epoxy resin. The diglycidyl ether of 9,9‐bis(4‐hydroxyphenyl) fluorene (DGEBF) cures more slowly than the diglycidyl ether of bisphenol A (Epon 828). The glass transition temperatures (Tg's) of BF3 · MEA cured Epon 828 are increased with inceasing concentration of curing agent (0.0450–0.1350 eq.) cured DGEBF. The activation energies for the thermal decomposition for BF3 · MEA (0.0450–0.1350 eq.) cured DGEBF. The activation energies for the thermal decomposition for BF3 · MEA (0.0450 eq./epoxy eq.) cured Epon 828 and DGEBF are almost equivalent 43 and 44 kcal/mol, respectively. DGEBF when added to DGEBA improves the Tg and char yield with the BF3 · MEA curing system. The Tg of both resin systems can be increased by longer post cure, whereas the char yield does not appear to change significantly. No ester group formation is found for the BF3 · MEA‐cured DGEBF, although this has been previously reported for the DGEBA system. The BF3 · MEA cure at 120°C is better than at 140°C because of vaporization and degradation of the curing agent at the higher temperature. The rapid gelation of the epoxy resin may be another reason for the lower degree of cure at high temperature.
A solid state NMR study on crystalline forms of nylon 6
Authors: Okada Akane , Kawasumi Masaya , Tajima Ichiro , Kurauchi Toshio , Kamigaito Osami 
Published: April 2003

AbstractHigh‐resolution 13C‐NMR spectra were studied for two different crystalline structures of nylon 6 in the solid state by the cross polarization/magic angle spinning (CP/MAS) method. Two crystalline structures, α‐form and γ‐form, gave different chemical shifts for methylene carbons. The results showed that the hydrogen bonds between intermolecular chains are stronger in the γ‐form than in the α‐form. This strongly supports the results of the X‐ray study of nylon 6 by Malta et al. Our results also showed that interamolecular delocalization of positive charges occurs in the γ‐form through hyperconjugation in which the dihedral angle between the π bond and neighboring σ bonds is 30° while no such effect can be expected in the α‐form in which the angle is 0°.
Studies on swelling of cotton fibers in alkali metal hydroxides. II. Influence of morphology and fine structure on tensile behavior
Authors: Iyer P. Bhama , Sreenivasan S. , Patel G. S. , Chidambareswaran P. K. , Patil N. B. 
Published: April 2003

AbstractCotton fibers varying widely in gravimetric fineness but having nearly same percentage mature fibers have been subjected to swelling in 4.5N LiOH, NaOH, and KOH at room temperature and 0°C. The resultant changes in fine structure are analyzed by X‐ray diffraction and infrared absorption methods while variations in surface morphology are followed by scanning electron microscopy. Extent of swelling measured by changes in gravimetric fineness follows the order LiOH ≥ NaOH ≥ KOH, the exact gradation being dependent on the variety. Analysis of tensile data shows that whereas moderate swelling leads to an increase in tenacity at 3.2 mm gauge length, excessive swelling leads to a decrease of the same, the extent of decrease being a function of swelling. KOH treatment produced uniform swelling and gave better retention of T0 and T3 for all varieties. Tensile behavior after slack swelling in the various reagents could be interpreted on the basis of fine structural variations produced by them. However, the differential response of cottons to a swelling agent is explained by postulating variations in the packing of structural elements along the radii.
The effect of chemical treatment of wood and polymer characteristics on the properties of wood–polymer composites
Authors: Manrich Sati , Agnelli José Augusto Marcondes 
Published: April 2003

AbstractThe physical‐mechanical properties and the microscopic structure of caixeta (Chrysophyllum viride) and slash pine (Pinus elliottii) impregnated with polystyrene (PS) were investigated. The influences of a pretreatment with hydrogen peroxide (H2O2) solutions utilized in the production of the wood–polymer composites (WPC) and the characteristics of polystyrene formed in situ on the properties of WPC were analyzed. The incorporation of polystyrene improved the compression and static bending properties of slash pine and caixeta. The micrographies confirmed that there were distinct but continuous phases of polymer and wood cell wall which granted the composites a better physical‐mechanical behavior. The sensibilizing treatment with dilute hydrogen peroxide solution led to an increase in the viscosity average molecular weight (Mv) of polystyrene, and to the graft polymerization of the monomer, which, in turn, enhanced the stress properties of caixeta–polystyrene composites. Concentrated H2O2 solutions degraded caixeta wood, decreasing its tensile properties. Lower initiator concentration favoured higher molecular weight of polystyrene formed in pine wood. A fivefold increase in Mv of PS, however, had little effect on the compression properties of pine–polystyrene composites.
Preparation and swelling of polymeric hydrogels
Authors: Andreopoulos A. G. 
Published: April 2003

AbstractHydrogel polymers find extensive biomedical applications combining the properties of hydrophilic and crosslinked materials. In this work, poly(methacrylic acid) hydrogels were prepared by the copolymerization of methacrylic acid with varying amounts of 1,4‐butanediol dimethacrylate. The polymerization reaction was followed by viscometric measurements and the swelling properties of the samples prepared were also investigated. Alkaline treatment of the hydrogels was performed, to define the changes induced. Finally, a correlation between swelling data, derived from loosely crosslinked samples, led to the determination of the interaction parameter of the system poly(methacrylic acid)–water.
Study on the drawing behavior of poly(L‐lactide) to obtain high‐strength fibers
Authors: Postema A. R. , Pennings A. J. 
Published: April 2003

AbstractThe tensile drawing behavior of poly(L‐lactide) has been studied in order to obtain high strength fibers. Elongational viscosity measurements indicated that the hot drawing can take place in two temperature regions with different activation energies. Up to 180°C, the deformation proceeds in the semicrystalline state of the polymer having an activation energy of 15–28 kJ/mol, presumably by shear deformation. In the range of 180–190°C, the deformation proceeds in the liquid state of the polymer having an activation energy of 145–165 kJ/mol, leading to a semicrystalline state by strain hardening after displacement of topological defects. By using high deformation rates during drawing in a temperature gradient (tube drawing), the deformation will principally proceed in the semicrystalline region and inhomogeneous draw will take place leading to inferior fiber properties, unless the deformation rate and drawing temperature are strictly adjusted. Homogeneous drawing can be achieved by applying low deformation rates so that the deformation may take place in the liquid state of the polymer in which individual chains can be easily aligned and topological defects can be removed. Poly(L‐lactide) fibers with tensile strengths of 2.3 GPa have been produced in this way.
Chemical and property modification of silk with dibasic acid anhydrides
Authors: Tsukada Masuhiro , Shiozaki Hideki 
Published: April 2003

AbstractIn an attempt to provide information for improving silk fiber and fabric properties including crease recovery and yellowing, silk modification has been studied by using succinic and glutaric anhydrides. Glutarylation has been found to protect silk fibers from yellowing caused by the high energy radiation and to be more effective on increasing the crease proofing. The silk fabrics did not reduce the tensile properties such as strength and elongation at break even after the chemical modification with dibasic acid anhydrides. Thermal properties of the fibers remained unchanged in spite of the succinylation or glutarylation. From all the considerations of the survey of dye uptake, it would seem that the ester crosslinks are easily formed much more by the glutarylation than by the succinylation. The recovery values and yellowness indices of the modified silk fabrics and the measuring results of thermal and thermomechanical properties are explicable, taking into account of the different reactivity of the functional groups induced by the chemical modification with the dibasic acid anhydrides.
Coconut‐fiber‐reinforced rubber composites
Authors: Arumugam N. , Selvy K. Tamare , Rao K. Venkata , Rajalingam P. 
Published: April 2003

AbstractDifferent formulations of rubber with chopped coconut fiber (treated and untreated) as reinforcing agent were prepared. These reinforced systems were vulcanized at 153°C and the properties of the vulcanizates were studied by stress–strain, shore A hardness, and abrasion loss measurements. The bonding between the rubber and fillers were improved by the addition of bonding agents. The bonding effect of different bonding agents were compared. The reinforcing property of the treated fiber was compared with the untreated one. Aging resistance of the composites were studied. The fracture surfaces have been studied by scanning electronmicroscopy (SEM) and the failure mechanism has been explained.
Nonisothermal orientation‐induced crystallization in melt spinning of polypropylene
Authors: Jinan Cao , Kikutani Takeshi , Takaku Akira , Shimizu Jiro 
Published: April 2003

AbstractTwo kinds of polypropylene with different molecular weight (MI = 15 and 30) were melt‐spun at the spinning temperatures of 210–290°C and take‐up velocities of 0.15–3 km/min. In the cases of the spinning temperatures of 270 and 290°C for MI15 and 250 and 290°C for MI30, the density showed a minimum with increasing take‐up velocity at around 0.5–1 km/min. This result suggests that crystallization behavior is influenced by two competitive effects, i.e., cooling rate and crystallization rate both of which are enhanced by the increase in take‐up velocity. Crystal structures of slightly oriented monoclinic, slightly oriented pseudohexagonal, highly oriented pseudohexagonal, and highly oriented monoclinic were successively observed with increasing take‐up velocity. The change of crystallization temperature may result in the different kinds of crystal modifications. Numerical calculations on nonisothermal orientation‐induced crystallization in the melt spinning process and experimental results showed qualitative agreement in the change of crystallinity with take‐up velocity, spinning temperature, and molecular weight.
Synthesis and antibacterial activity of copolymers having a quaternary ammonium salt side group
Authors: Senuma Masao , Tashiro Tatsuo , Iwakura Masahiro , Kaeriyama Kyoji , Shimura Yukio 
Published: April 2003

AbstractCopolymers with a quaternary ammonium salt side group have been prepared from vinylbenzyl–cetyldimethylammonium chloride and acrylonitrile and their antibacterial activity has been examined with Bacillus subtilis, Staphylococcus aureus, and Escherichia coli. Growth inhibitory effect has been found to increase with the increase in the quaternary ammonium salt concentration in the copolymer. The effect is small on gram‐negative bacteria and large on gram‐positive bacteria.