bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transport of ethylene oxide through polymer films
Authors: Phatak A. , Burns C. M. , Huang R. Y. M. 
Published: April 2003

AbstractThe transport of gaseous ethylene oxide (EtO) in several polymer films is studied using the carrier gas method of measurement. Permeability, solubility, and diffusion coefficients describing ethylene oxide (EtO) transport in polypropylene, polyvinylchloride, Teflon‐FEP copolymer, and polyethylene films have been obtained over a 30 Celsius degree range at a low concentration of EtO using the carrier gas method of measurement. The results indicate that the diffusion of EtO in polyethylene is independent of penetrant concentration over the range of concentrations used. However, concentration‐independent diffusion could not be verified directly for the other films studied. Two different techniques of determining diffusion coefficients were used, and within the precision of the data both yield the same result. An excess enthalpy of solution for the solubility of EtO in Teflon‐FEP copolymer was calculated, an observation that suggests that dual‐mode sorption may be taking place.
Dynamic mechanical behavior and structure of polyurethaneimides
Authors: Masiulanis B. , Hrouz J. , Baldrian J. , Ilavský M. , Dušek K. 
Published: April 2003

AbstractDynamic mechanical behavior and X‐ray diffraction of two series of segmented polyurethaneimides (PUI) prepared either from poly(ethylene adipate) glycol (PEA), pyromellitic dianhydride (PMDA) and 4,4′‐diphenylmethane diisocyanate (MDI), or from PEA, PMDA, and a mixture of 2,4‐ and 2,6‐tolylene diisocyanate (TDI) were studied. All samples have a two‐phase structure of the soft polyester (PE) phase and hard polyimide (PI) phase. PI microdomains containing MDI units are semicrystalline, whereas those with TDI are crystalline only at highest contents of TDI. The storage modulus E′ increases with increasing fraction of the hard phase. The MDI‐containing hard phase has a stronger effect on E′ and also makes the plateau on the dependence of E′ on temperature more pronounced.
New aspects in cationization of lignocellulose materials. VIII. Modification of immitted spruce wood with quarternary ammonium groups
Authors: Šimkovic Ivan , Alföldi Juraj , Antal Miroslav 
Published: April 2003

AbstractImmitted spruce wood meal (ISWM) was modified with 3‐chlor‐2‐hydroxypropyltrimethyl‐ammoniuchloride (CHMAC) or 1,3‐bis(3‐chlor‐2‐hydroxypropyl)imidazoliumhydrogensulphate (BCHIHS) in alkaline medium. The obtained material was gradually extracted with water and 5% NaOH. The yields of water‐soluble hemicelluloses modified with quarternary ammonium groups were lower in comparison to healthy spruce material obtained under the same conditions but even more material could be obtained from ISWM‐holocellulose. The quantity of alkali‐soluble polysaccharides from ISWM was the same as obtained from undamaged spruce. The residues after alkali extractions are suitable ion exchangers with low solubility in dilute alkali solutions. The yields of extracts from material modified with BCHIHS were lower than yields of extracts from material modified with CHMAC because ISWM was crosslinked when alkylated with bifunctional chemicals.
Release routes of incorporated desmetryn from EVA‐films. An example for the behavior of low volatility additives in polymers under outdoor conditions
Authors: Kraxenberger M. , Pfister G. , Bahadir M. 
Published: April 2003

AbstractRelease of desmetryn into the gas phase from films of ethylene‐vinyl acetate copolymer, in which the herbicide was incorporated for special agricultural applications, was investigated for comparison with release into water and under outdoor conditions. It could be shown that the rate of release of the active chemical into the gas phase was negligible compared with that into water and only slightly dependent on temperature in the range 0–75°C.
Model for prediction of the elastic response of reinforced materials over wide ranges of concentration
Authors: Farber Jorge N. , Farris Richard J. 
Published: April 2003

AbstractA model for the prediction of the elastic response of reinforced materials over wide ranges of concentration is presented. The method is based on the mathematical analogy between the motion of particles suspended in viscous media and the elastic deformation of solids. The system is locally described by linearized forms of the elastic moduli. The validity of these relations is then extended to all concetrations under the assumption that any new portion of filler “sees” the existing structure as a noniteracting homogeneous matrix. The method predicts the behavior of reinforced materials with solid spherical inclusions and foams over wide ranges of concentration. The model, free from adjustable parameters, shows excellent agreement with existing experimental data. The extension of the method to other inclusion geometries is straightforward.
Electro‐copolymerization of acrylonitrile and methyl acrylate onto graphite fibers
Authors: Chang J. , Bell J. P. , Shkolnik S. 
Published: April 2003

AbstractElectro‐copolymerization of methyl acrylate, acrylic acid, methacrylic acid, acrylamide, and methyl methacrylate with acrylonitrile onto graphite fibers has been successfully done in our laboratory. The coatings are relatively uniform and their properties, especially their modulus, can be systematically varied by controlling the monomer ratio in the eletrolyte solution. This technique is being used to introduce a ductile interlayer of contrlled composition and thickness between the composite fibers and matrix. Copolymers of methyl acrylate and acrylonitrile formed by this technique are random copolymers, with Tg′s varying from 10 to 90°C. These copolymers have fairly high molecular weight, in the range of 100,000 g/mol. Monomer reactivity ratios were determined, based upon free radical polymerization kinetics, from cyclic voltammetry. An indirect initiation mechanism is suggested. Bonding between interlayer and matrix can be improved by introducing vinyl monomers with proper functional groups, capable of reacting with the epoxy resin, at the last stage of the electropolymerization process.
The effect of stretching conditions on properties of amorphous polyethylene terephthalate film
Authors: Sharma S. K. , Misra A. 
Published: April 2003

AbstractThe effect of stretching condition on stress‐induced crystallization of amorphous polyethylene terephthalate (PET) film has been studied. Cast PET film was stretched at 85°C with stretching rates ranging from 100% per minute to 600% per minute for various stretching ratios. The stretched film samples were annealed at 140°C both under tension as well as under relaxed conditions. Tensile properties were determined using Instron Tensile Tester and results were compared. Tenacity, yield stress, and initial modulus were found to increase while elongation at break decreased with the increase in stretching rate. The degree of crystallinity was measured by x‐ray diffraction as well as density methods. Birefringence and crystalline orientation factor values were determined experimentally and using these, amorphous orientation factor values were calculated. Birefringence, crystalline orientation and amorphous orientation values were found to increase with the increase in stretching rate. These studies showed that at low stretching rates a significant amount of relaxation takes place, resulting in lower orientation and strength. On the other hand, at higher stretching rates relaxation is minimized thus providing high orientation and strength. Upon annealing the crystallinity values increased as expected, however the trend of orientation and mechanical properties with respect to stretching rate was similar to those of unannealed films.
Mechanical properties of grafted casein films
Authors: Somanathan N. , Arumugam V. , Sanjeevi R. , Narasimhan V. 
Published: April 2003

AbstractCasein was grafted with mixtures of acrylonitrile (AN) and n‐butyl methacrylate (n‐BMA). The mole ratios of AN: n‐BMA were 0.9:0.1 and 0.8:0.2. The mechanical properties of the grafted casein films were studied under uniaxial and biaxial stress conditions. A reduction in longitudinal stress and elongation at break was observed with the simultaneous application of lateral stress. Scanning electron micrographs of the stretched films (uniaxial and biaxial stress) are also presented.
Synthesis, characterization, and polymerization of bismaleimides and bisnadimides chain‐extended by N,N′‐substituted ureas
Authors: Melissaris Anastasios P. , Mikroyannidis John A. 
Published: April 2003

AbstractA series of new polymer precursors such as bismaleimides, bisnadimides, and bismethylnadimides chain‐extended by N,N′‐substituted ureas was synthesized and characterized. They were prepared by reacting a diamine containing ureylene linkages with maleic/nadic/methylnadic anhydride. Another alternative method for preparing these monomers included reaction of a diamine (1 mol) with an equimolar amount of maleic/nadic/methylnadic anhydride, subsequent reaction with a diisocyanate (0.5 mol) followed by cyclodehydration of the itermediate diamic acid. The monomers were characterized by infrared (IR) and proton nuclear magnetic resonance (1H‐NMR) spectroscopy. Their thermal polymerization was investigated by differential thermal analysis (DTA). The thermal stability of the polymers was evaluated by dynamic thermogravimetric analysis (TGA) and isothermal gravimetric analysis (IGA). No weight loss was observed when the polymers containing arylureas in their backbone were heated up to 324–334°C in nitrogen or air atmospheres. Their anaerobic char yield at 800°C fluctuated between 41 and 61%.
Formation of primary particles in vinyl chloride polymerization
Authors: Törnell Bertil , Uustalu Jaan 
Published: April 2003

AbstractThe formation of primary particles in agitated bulk polymerizations of vinyl chloride was found to proceed in two stages. The first stage occurred at the very beginning of the polymerization; the second stage started as the initially nucleated particles began to agglomerate, and continued up to at least 7% conversion. Upon formation, the primary particles were stable and did not agglomerate until reaching a limiting size, which was found to be lower at higher stirring speeds. The number of particles formed in the first stage was independent of agitation and other polymerization parameters. The rate of particle formation during the second stage was equal to the rate of particle agglomeration. Thus the total number of primary particles formed was determined almost exclusively by the rate of particle agglomeration. Addition of the surfactant Span 20 caused an increase in the total number of primary particles. Also, this addition increased the tendency of the particles to fuse together after agglomeration. These effects can be understood to be a consequence of particle destabilization by the surfactant. When a small amount of a high molecular weight PMMA was dissolved in the monomer, the polymerization behaved quite differently. In this case, the primary particles were prevented from agglomeration, reaching a limiting size independent of stirring speed.
Synthesis of polymer materials by low energy electron beam. III. Effects of polymerization temperature in EB solid‐state polymerization of semicrystalline urethane‐acrylate film
Authors: Ando Masayuki , Uryu Toshiyuki 
Published: April 2003

AbstractIn an electron beam (EB) polymerization of a urethane‐acrylate prepolymer, the polymerization temperature greatly affected the structure and properties of the resulting gel film. Urethaneacrylate, which was synthesized by the reaction of poly(butylene adipate)diol, 4,4′‐diphenylmethane diisocyanate, and 2‐hydroxyethyl acrylate, was used as a prepolymer. The prepolymer was semicrystalline and showed a melting point in the region of 50–60°C. The maximum polymerization rate of the prepolymer was obtained when the prepolymer film was irradiated in the temperature range of 25–40°C. EB polymerization below the melting point (Tm) of the prepolymer produced semicrystalline polyurethane‐acrylate gel films with a spherulitic texture. On the other hand, EB polymerization above the Tm destroyed the crystalline phase of the prepolymer to give transparent gel films. The gel film cured below the Tm had higher stress at yield, Young's modulus, and tensile strength than those cured above the Tm. Such temperature effects are attributed to whether or not the EB polymerization proceeds with retention of crystalline structure of the prepolymer.
Rheological properties of liquid crystalline solutions of ethyl celluloses with different molecular weight in m‐cresol
Authors: Suto Shinichi , Ohshiro Masahiko , Nishibori Wataru , Tomita Hisashi , Karasawa Mikio 
Published: April 2003

AbstractSteady‐state shear rheological properties of liquid crystalline solutions of four ethyl celluloses (ECs) were determined at a low shear rate (1 s−1) and at relatively high shear rates by using two rheometers (cone‐plate and capillary types), and were compared with those of liquid crystalline hydroxypropyl cellulose (HPC). The effect of molecular weight (MW) on the viscoelastic behavior was also determined. The viscoelastic behavior was also determined. The viscometric behavior of EC solutions was similar to that of HPC solutions: (1) with respect to temperature, the shear viscosity (η) at shear rate of 1 s−1 exhibited a minimum (ηmin) and a maximum (ηmax), and the concentration–temperature superposition for η could be applied; (2) the behavior of η at relatively high shear rates as a function of shear rate or polymer concentration was typical of lyotropic liquid crystals. The MW dependence of ηmin was greater than that of ηmax for EC solutions. The behavior of the elastic parameters such as Bagley correction factor (v), entrance pressure drop (ΔPent), and die swell (B) at relatively high shear rates for EC solutions was essentially similar to that for HPC solutions: (1) the shear rate or stress dependence of the elastic parameters was greatly dependent on whether the polymer solution was in a single phase or biphase; (2) with respect to concentration the elastic parameters showed a maximum and a minimum and the maximum or minimum point for each parameter was not always identical to each other. η for the isotropic or fully anisotropic solutions at a given concentration (C) increased, whereas η for the solutions in the vicinity of the biphasic region showed a minimum, with respect to MW. The slope of η at a given shear rate vs. CMw depended on shear rate, and this slope for the isotropic solutions appeared to be greater than that for fully anisotropic solutions. ΔPent and v at a given concentration showed either a monotonical increase or a maximum or minimum with MW, and this behavior was not fully consistent with that of η. B for the isotropic solutions increased and B's for both biphasic and fully anisotropic solutions were almost constant, with MW.
Infrared spectral study on the heat curing reaction of glycerin‐terminated urethane prepolymers
Authors: Yang Chin‐Ping , Lee Lung‐Ta 
Published: April 2003

AbstractGlycerin, toluene diisocyanate (TDI), and polyglycol (PG) were reacted at various molar ratios to produce glycerin‐terminated urethane prepolymers of different molecular weights. The prepolymers were mixed with equivalent phenol‐blocked trimethylol propane–TDI–urethane triisocyanate in m‐cresol to give a coating solution. The solution was coated and baked to give polyurethane crosslinked films. The changes of the functional groups during the crosslinking reaction and the mechanical properties of the polyurethane crosslinked films were studies. Experimental results show that the phenol‐blocked urethane triisocyanate will deblock phenol to regenerate free isocyanate groups above 120°C and then react with the hydroxyl groups of urethane prepolymers. At 220°C, the rate of deblocking phenol to regenerate isocyanate groups is faster than that of the reaction of urethane prepolymers with isocyanate groups. The deblocking reaction is contemporaneous with the reaction of isocyanate groups with hydroxyl groups, so that the characteristic absorption peaks of isocyanate groups can be observed from IR spectra during the crosslinking reaction. The absorption peak of isocyanate groups gradually decreased with the crosslinking reaction, but the absorption peak increased after curing for about 50–60 min. This feature is caused by the reactivity of the secondary hydroxyl groups of glycerin which is slower than that of the primary hydroxyl groups of glycerin.
Flame‐retardation studies of poly(ethylene terephthalate) fabrics treated with tris dibromo alkyl phosphates
Authors: Day M. , Suprunchuk T. , Omichinski J. G. , Nelson S. D. 
Published: April 2003

AbstractThe flammability characteristics of tris(2,3‐dibromopropyl) phosphate (TRIS‐BP), a known carcinogen, has been compared with other tris dibromo alkyl phosphates which show reduced mutagenic responses in experimental studies. The effectiveness of these alternative chemicals in releasing hydrogen bromide (HBr), a recognized combustion inhibitor, has been measured and the results compared with flammability evaluation of polyester fabrics treated with these chemicals. Results indicate that tris(2,3‐dibromo‐3,3‐dimethyl propyl) phosphate, while having reduced mutagenicity and nephrotoxicity in comparison to TRIS‐BP, exhibits excellent flame‐retardant characteristics when applied to polyester fabrics. Meanwhile, other chemicals studied show comparable flame retardation to TRIS‐BP, but with substantial reduced mutagenicity.
Composite materials of radiation‐treated coconut fiber and thermoplastics
Authors: Owolabi O. , Czvikovszky T. 
Published: April 2003

AbstractFollowing our previous work using fibrous biomass byproducts for radiation‐treated composite materials, polypropylene and two different kinds of PVC have been compounded with chopped coconut fiber (coir). Preirradiation of coir has been applied together with some crosslinking additive to achieve chemical bond between thermoplastics and fibrous biopolymer. Effect of addition of 10–50% coir to PVC and PP on the processability was monitored by Brabender plastograph. Dynamical mechanical analysis (DMA) data as well as tensile and impact strength of these coir composites have not been found superior to that of the starting thermoplastics. Considering, however, coconut fiber as a cheap filler, composites with acceptable tensile and impact strength could be produced with coir content as high as 30%.
Morphology of water‐blown flexible polyurethane foams
Authors: Armistead James Paul , Wilkes Garth L. , Turner Robert B. 
Published: April 2003

AbstractA series of four TDI–polypropylene oxide (PO) water‐blown flexible polyurethane foams was produced in which the water content was varied from 2 to 5 pph at a constant isocyanate index of 110. A portion of each foam was thermally compression molded into a plaque. The morphology of both the foams and plaques was investigated using dynamic mechanical spectroscopy (DMS), differential scanning calorimetry (DSC), transmission electron microscopy (TEM), scanning electron microscopy (SEM), swelling, wide angle X‐ray scattering (WAXS), and small angle X‐ray scattering (SAXS). A high degree of microphase separation occurs in these foams, and its degree is nearly independent of water (hard segment) content. In the foam with the lowest water content the morphology possesses many similarities to that of typical linear segmented urethane elastomers. Small hard segment domains are present with a correlation distance of about 7.0 nm. When the water content is increased a binodal distribution of hard segment material appears. There are the small hard segment domains typical of segmented urethane elastomers as well as larger “hard aggregates” greater than 100 nm in size. The larger domains are thought to be aggregates of rich polyurea that develop by precipitation during the foaming reaction. WAXS patterns of the foams suggest urea and possibly hard segment ordering that may be of a paracrystalline nature but certainly lacking in true 3‐dimensional crystallinity.
Deformation behavior of HDPE/(PEC/PS)/SEBS blends
Authors: Schwarz M. C. , Keskkula H. , Barlow J. W. , Paul D. R. 
Published: April 2003

AbstractImmiscible blends of high density polyethylene (HDPE) and an amorphous glassy phase consisting of either pure polystyrene (PS) or a miscible blend of PS and a polyether copolymer (PEC) were compatibilized with various amounts of a styrene‐hydrogenated butadiene block copolymer (SEBS). PEC is structurally similar to poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO). Using a liquid displacement stress dilatometer, the volume change of samples during uniaxial mechanical straining was determined and related to the various modes of deformation. Blends were fabricated by both injection and compression molding. Miscible PEC and PS blends were found to undergo a craze to shear yielding transition between 40 and 60% PS, which occurred at higher PS concentrations as SEBS was added. Blends with a HDPE matrix and a dispersed glassy phase showed reduced volume dilatation on adding SEBS, indicating better interfacial adhesion between the incompatible blend components. Increases in the sample volume were substantially less in blends with a PEC/PS glassy phase instead of pure PS, suggesting more effective compatibilization by the SEBS copolymer in blends with PEC. This trend is presumed to stem from an exothermic heat of mixing between the PS endblocks of SEBS and the PEC‐rich phases in the blend. Microscopic evidence of the improved adhesion and modes of deformation agrees with the results obtained by dilatometry. The volume dilatation of compression‐molded materials do not seem to be similarly affected by the composition of the glassy phase which may reflect morphological differences between injection‐and compression‐molded blends.
Polypropylene composites. I. Studies of the effect of grafting of acrylic acid and silane coupling agent on the performance of polypropylene mica composites
Authors: Chiang Wen‐Yen , Yang Wen‐Der 
Published: April 2003

AbstractTo improve adhesion between polypropylene (PP) and mica in PP composites, acrylic acid (AA) is graft‐copolymerized onto PP by a melt‐mixing method. At the same time, applying a silane coupling agent to treat the surface of inorganic filler enhances the mechanical, thermal, and electrical properties, as well as decreases mold shrinkage and color difference of the composites.
Studies on the cure characteristics and vulcanizate properties of 50/50 NR/SBR blend
Authors: Joseph Rani , George K. E. , Francis D. Joseph 
Published: April 2003

AbstractBlends of 50/50 natural rubber (NR) and styrene‐butadiene rubber (SBR) are vulcanized using several conventional and semi‐EV systems. The cure characteristics and vulcanizate properties are compared. The quantity and quality of crosslinks in each case are deciphered by chemical probes to correlated them with the vulcanizate properties.
Toughening bismaleimide resins by reactive liquid rubbers
Authors: Takeda Shinji , Kakiuchi Hiroshi 
Published: April 2003

AbstractThe modification of bismaleimide resins with carboxyl‐terminated butadiene–acrylonitrile rubbers (CTBN) was studied. The effects of the rubbers on mechanical and thermal properties such as flexural strength, tensile strength, fracture toughness, glass transition temperature, and decomposition temperature of the rubber‐modified bismaleimide resins are discussed. The morphology of these resins were investigated by means of scanning electron microscopy and dynamic mechanical analysis. Addition of the rubbers improved the toughness of the bismaleimide resins without significant reductions in heat resistance of the resins.