bluuebunny/crossref_metadata_2025_split huggingface dataset:
Crystallization kinetics of polyaryl ether ketones
Authors: Jog J. P. , Nadkarnit V. M. 
Published: April 2003

AbstractThe crystallization kinetics of a grade of polyaryl ether ketone has been investigated over a temperature range of 295–315°c by differential scanning calorimetry.The results of the present investigation are compared with other members of the polyaryl ether ketone family in the context of the effect of chemical structure on the crystallizability of the polymers. It is concluded that the crystallizability is reduced with increasing amount of ketone linkages in the chain, and therefore the optimum molding conditions for different grades of polyaryl ether ketones will be different.
Sorption and permeation behavior of water vapor and carbon dioxide gas through ethylene ionomer membranes
Authors: Itoh Ken‐Ichiro , Tsujita Yoshiharu , Takizawa Akira , Kinoshita Takatoshi 
Published: April 2003

AbstractSorption and permeation of water vapor and carbon dioxide gas through ethylene ionomer membranes were studied as a function of pressure. Water sorption increased with an increase of the acid content and especially degree of neutralization of ethylene ionomers. The sodium salt ionomer enhanced water sorption compared to the zinc salt ionomer. However, there was no remarkable difference of permeability coefficient of water vapor through the sodium and zinc ionomer membranes. Diffusion coefficient of the sodium salt ionomer is one order smaller than that of zinc salt ionomer, corresponding to an immobilized water structure in the sodium salt ionomer. Differential scanning calorimetry studies on water sorbed to membrane manifested that water sorbed was almost nonfreezable. Sorption of carbon dioxide gas in ethylene ionomers was a dual‐mode type. The pressure dependence of permeability coefficient of carbon dioxide gas was interpreted in terms of a partial immobilization model, independent of the kind of the metal salt in ethylene ionomer.
Factors affecting improvement in the flexural modulus of polyacrylic acid‐modified crystalline films
Authors: Sugama T. , Kukacka L. E. , Carciello N. , Warren J. B. 
Published: April 2003

AbstractWhen high‐molecular weight polyacrylic acid (PAA) macromolecules are incorporated into phosphating solutions, they significantly increase the stiffness and ductility of zinc phosphate conversion crystal films deposited on metal substrate surfaces. The degree of improvement in these mechanical properties depends primarily on the thickness and fineness of the highly dense PAA‐complexed zinc phosphate crystals that are formed. The presence of this complexed PAA polymer at the outermost surface sites on the crystal layer plays an essential role in promoting adhesion with polymeric topcoats by the formation of polymer—polymer chemical bonds. The use of low‐molecular weight PAA results in a poor interfacial adhesion because of a high degree of alternation in chain conformation caused by charge‐transfer reactions between the proton‐donating COOH groups and the nucleophilic Zn2+ ions in the acidic aqueous medium. In addition, the protective polymer topcoat overlayed on the complex precoat surfaces increases the flexibility of the crystalline precoat itself. The most important factors controlling the flexibility of the precoat were low elastic modulus, high tensile strength, and elongation of the topcoat systems. These characteristics are more important than the magnitude of interfacial adhesive bonds at topcoat/precoat joints.
Effect of ionizing radiation on styrene/acrylonitrile copolymer hollow fiber membranes
Authors: Fritzsche A. Keith 
Published: April 2003

AbstractA thin layer of highly permeable, nonselective polymer is applied to the surface of an asymmetric membrane to reduce permeability through the membrane pores and defects and to render permeation through the matrix predominant. In environments which contain active moieties, the coating may be swollen and dissolved causing it to lose its effectiveness. The effects of irradiation to induce crosslinking between the hollow fiber membrane and the coating were studied. Fibers were irradiated both before and after coating with polydimethylsiloxane. Radiation dosages at 10, 25, and 50 Mrads were used. The increased stabilities of the crosslinked coating and substrate were reflected by the higher retention of H2/CH4 separation factor after exposure to a solvent (i.e., isopentane) which dissolves the coating. The results also suggest that ionizing radiation also alters the structure and morphology of the dense selective layer on the surface of the styrene/acrylonitrile copolymer hollow fiber.
Degradation of polymers during aerosol formation from antimisting polymer solutions
Authors: Ilano Arron L. , Williams Michael C. , Grens Edward A. 
Published: April 2003

AbstractDegradation of polyisobutylenes as a consequence of spraying jet‐fuel solutions of these polymers was studied as a function of polymer molecular weight and concentration and the spray conditions. Assessment of the degradation was made by measuring the maximum ductless siphon height h* for sprayed samples and comparing this with prespray values. Two polymers, L‐160 from Exxon and B‐288 from BASF (Mv = 4.1× 106 and 11.9 × 106), were studied to concentrations of 3000 and 2000 ppm, respectively. Degradation was found to be extremely sensitive to the air speed used in wind‐shear spraying, above a critical value of approximately 30–40 m/s. At the highest air speed employed, 135 m/s, degradation was so severe that h* values were reduced nearly to Newtonian (solvent) values, for all concentrations of both polymer additives. The implications of these results are important for designing effective antimisting fluids.
Cross‐linking of amidated polybutadiene with resole. II.
Authors: Hara Hajime , Araki Yoshihiko , Orii Shingo 
Published: April 2003

AbstractTo prove the main cross‐linking reaction between amidated polybutadiene and resole, cross‐condensation reactions involving simple amide compounds and resole were examined. Amide compounds having both an amide group and a carboxylic acid group inhibited the self‐condensation of resole itself. The cross‐condensation products obtained from succinamic acid and 2‐methylolphenol were separated using a preparative chromatography method to identify the cross‐condensed products in which the main products were cross‐condensed oligomers having an imide linkage. A cross‐condensation scheme was proposed, and it was concluded that the main cross‐linking reaction between amidated polybutadiene and resole also followed the same scheme.
Determination of the molecular weight between cross‐links of elastomeric stocks by tensile retraction measurements. II. Polyurethanes
Authors: Hergenrother W. L. 
Published: April 2003

AbstractTensile retraction measurements of Mc were made on a variety of polyurethanes or polyurethane‐ureas. These samples were prepared using a number of prepolymer MW and functionalities. In addition, the stoichiometry of the cure was allowed to range widely. In all cases, excellent linear correlation coefficients were obtained between the Mc and the Amax of the test. The slope and Mr (the value of Mc extrapolated to Amax = 1) determined from this was used to characterize the polymer. These data allowed the determination of χ for each of the different systems such that comparable values of Mc could be measured by swelling. Identical formulations cured at different temperatures were shown to have measurable differences in Mc, slope, and percentage set. These variations appear to relate to the perfection of the network and morphology of the hard domains.
The effects of a synergistic molybdenum–copper smoke retarder additive during the pyrolysis and combustion of rigid poly(vinyl chloride) compounds
Authors: Kroenke William J. , Lattimer Robert P. 
Published: April 2003

AbstractThe addition of an effective transition metal‐based smoke retarder to rigid poly(vinyl chloride) (PVC) has three general effects during combustion and inert atmosphere pyrolysis: (1) smoke formation is reduced; (2) char formation is enhanced; and (3) volatile aromatic pyrolyzate formation is reduced while aliphatic pyrolyzate formation is enhanced. A very efficient molybdenum—copper smoke retarder additive has been developed for PVC. It consists of an equal weight mixture of melaminium beta‐octamolybdate and copper(II) oxalate. This combination is synergistic in reducing smoke during the combustion of PVC, i.e., the mixture is more effective than either of the two ingredients used individually at the same concentration as the mixture. The molybdenum—copper system reduced smoke effectively in three rigid PVC compounds, two of which resemble commercial formulations. The combustibility and pyrolysis effects of this molybdenum—copper additive can be interpreted in terms of an “early cross‐linking” mechanism of smoke retardation in PVC. In this mechanism the metal smoke retarder works primarily by catalytically promoting early crosslinking of decomposing PVC chains to yield char as a residue.
The influence of annealing on the thermal properties of poly(ethylene terephthalate) fibers I. The heat capacity of annealed PET fibers
Authors: Urbanczyk G. W. , Michalak G. 
Published: April 2003

AbstractThe influence of annealing of PET fibers on their specific heat capacity has been examined. The annealing has been performed in air in the loose state of the fibers within the temperature range 130–210°C for 2,5,10, and 30 min. The obtained results give evidence that three temperature intervals of annealing may be distinguished. The ascertained variation of cp has been discussed on the basis of established morphological and fine structure changes in the fibers caused by the applied annealing.
Photocrosslinking of chlorinated polydimethylsiloxanes
Authors: Inoue Hiroshi , Kohama Shigemi 
Published: April 2003

AbstractPhotocrosslinking behavior of chlorinated polydimethylsiloxanes (C‐PDMS) has been studied. It was found that the viscous C‐PDMS were readily crosslinking to form the rubberlike materials on irradiation from a high pressure mercury lamp. The crosslinking mechanism was proposed on the basis of infrared spectroscopy. It was suggested that the photolysis of the carbon—chlorine bond induced by the ultraviolet irradiation is a primary step for crosslinking, and is followed by mutual combination of SiCH2· radicals, eventually, to form the crosslinked C‐PDMS. The effect of halogens and atmosphere on the crosslinking was also discussed.
Effect of types of carbon black and cure conditions on dynamic mechanical properties of elastomers
Authors: Trexler Harold E. , Lee Michael C. H. 
Published: April 2003

AbstractThe dynamic mechanical properties of natural rubber and bromobutyl rubber (used in automotive suspension parts) were investigated to determine the effect of particle size of carbon black filler and state of cure of the rubber matrix. The results indicate that state of cure has little effect on storage modulus (hardness and stiffness). However, elastomers with a desirable storage modulus, with low sensitivity to temperature change, can be developed using a filler with a small particle size.
The adhesive properties of hydantoin vinyl ether polymers
Authors: Eldin Sameer H. 
Published: April 2003

AbstractThe hydantion vinyl ether polymers are alternating copolymers of 3‐vinyloxyethyl‐5,5‐dimethylhydantion (HVE) and maleic anhydride (MA). The adhesive properties of HVE/MA and structurally related polyvinyl pyrrolidone (PVP) and methylvinylether/maleic anhydride (MVE/MA) polymers were compared on an approximately 1:1 specific viscosity basis. Lap shear strength measurements showed approximately 10:1 and 4:1 ratios in favor of the HVE/MA polymers as compared to PVP and MVE/MA, respectively. These differences are possibly due to the higher cohesive strength of the HVE/MA repeating unit and to the fact that this polymer would appear to contain more structural elements liable to make physical and chemical contributions to the interfacial attachment strength. Based on these preliminary results, HVE/MA and MVE/MA polymers with identical specific viscosities were applied to carbon pitch fiber via electrodeposition. Using the standard MY 720/DDS epoxy laminating system for advanced composite applications 36% and 13% improvements in interlaminar shear strength were observed for an add‐on of 2%.
Effect of metal halides on thermal, mechanical, and electrical properties of polypyromellitimide films
Authors: Varma Indra K. , Saxena Sneh , Tripathi Anita , Goel T. C. , Varma D. S. 
Published: April 2003

AbstractThis paper describes the effect of metal halides (Co2+, Sn2+, and Hg2+) on the properties of polyimides. Low temperature, solution polycondensation reaction of pyromellitic dianhydride and 4,4′‐diaminodiphenyl ether was used for preparation of a poly(amide‐acid) solution in dimethylformamide ([η] = 2.0 dL/g). Films containing 1% (w/w) of cobalt (II) chloride, tin (II) chloride, and mercury (II) chloride were prepared by solution casting of poly(amide‐acid) from the DMF solution. Cyclodehydration to polyimide was done by heating the films in nitrogen atmosphere for one hour each at 100°, 200°, and 250°C. The color of the films depended on the dopant and was yellow (HgCl2 or SnCl2) or green (CoCl2) Higher percentage weight loss was observed in doped films in nitrogen atmosphere in the temperature range of 250–400°C. No significant difference in thermal behavior of doped and undoped films was observed above 500°C. Doping reduced the tensile strength of polyimide films, maximum reduction was observed in CoCl2‐doped film. The electrical conductivity of polyimide films as a function of temperature and field was studied. Undoped polyimide showed ohmic behavior up to 150°C. In doped films at lower voltages Poole‐Frenkel mechanism was operative, while at high voltages Richardson‐Schottky's mechanism was operative. Dielectric relaxation in polyimide films was also studied.
Chemical modification of polyester fiber surfaces by amination reactions with multifunctional amines
Authors: Avny Yair , Rebenfeld Ludwig 
Published: April 2003

AbstractThe feasibility of incorporating amine groups into the surface of polyester (PET) fibers by reaction with multifunctional amines was investigated. Reactions of diethylenetriamine (DETA), trethylenetetramine (TETTA), and tetraethylenepentamine (TTEPA) with PET monofilaments and with a multifilament yarn were studied. Microspectrophotometric examination of aminated fibers stained with an acid dye at low pH revealed the location and concentration of amine groups. Amination could be confined to the periphery and was found to be uniform on the fiber surface. The rate of the reaction, as revealed by acid dye staining, was characterized by an induction period followed by an autoaccelerated stage. Extent of incorporation of amine groups was found to be similar for the three amines. There is a significant improvement in water wettability due to surface amination, and the interfacial shear strength of TTEPA‐treated PET monofilaments embedded in an epoxy resin matrix was almost doubled. As the amination reaction proceeds, there is a weakening of the reacted zone in the PET due to chain scission leading to a decrease in the interfacial shear strength. Scanning electron microscopy (SEM) studies revealed that failure occurred within the filament most probably between the reacted and unreacted zones. The tensile properties of the TTEPA‐treated PET filaments were hardly affected at the investigated extents of amination.
Plasma, polymerization of ethane and some properties of PP ethane as a protective coat
Authors: Akovali Guneri 
Published: April 2003

AbstractThe structure of plasma polymers of ethane prepared by use of 13.56 MHz radiofrequency discharge in a tubular reactor are examined. The dependency of rate of deposition on power and on tube pressure at a fixed flow rate are presented. The plasma polymer prepared is tested for its performance as a protective coat on NaCl optical components for use in CO2 laser windows. Absorbance, at and around 10.6 μm, water‐vapor transmission, and scratch‐resistance tests are done.
Synthesis of polystyrenes having 2‐pyridylthio group and their use as phase transfer catalysts for the reduction of carbonyl compounds by sodium borohydride
Authors: Kondo Shuji , Nakanishi Minoru , Yamane Kazuyuki , Horibe Atsushi , Tsuda Kazuichi 
Published: April 2003

Abstractp‐(2‐Pyridylthiomethyl)styrene (PTMS) and p‐(2‐pyridylthioethyl)styrene (PTES) were prepared from the reactions of 2‐pyridinethiol with p‐chloromethylstyrene and with p‐bromoethylstyrene, respectively. These monomers are readily polymerized in the presence of AIBN. From the copolymerization of PTMS with styrene, QPTMS = 1.19 and ePTMS = 0.24 were obtained. The resulting polymers can extract alkali metal ions such as sodium and potassium cations. The extraction ability increases with increasing the density of active sites in polymers. Further these polymers serve as phase transfer catalysts for the reduction of carbonyl compounds by sodium borohydride.
Use of a sequential extraction technique to determine the MWD of bulk UHMWPE
Authors: Kusy R. P. , Whitley J. Q. 
Published: April 2003

AbstractThe molecular weight distribution (MWD) of bulk ultrahigh molecular weight polyethylene (UHMWPE) was determined by an increasing temperature sequential extraction technique. Using decahydronapthalene (decalin) as the solvent, 5 g samples of UHMWPE were fractionated stepwise from room temperature to 190°C in 10°C increments. Results via high temperature capillary viscometry show that intrinsic viscosity ([η]) ranges from 12.0 to 37.0 dL/g or that the viscosity average molecular weight (M̄v) ranges from approximately 1.6 to 7.4 × 106. When the integral distribution is plotted against M̄v on logarithmic probability graph paper, a straight line (i.e., a Wesslau distribution) results. Although the present methodology is tedious, many previous problems which have led to degradation are overcome by this technique.
Electrical and other properties of mutual radiation‐induced methacrylic acid grafted polyethylene films
Authors: Omichi H. , Chundury D. , Stannett V. T. 
Published: April 2003

AbstractThe radiation‐induced grafting of methacrylic acid on to polyethylene films was applied to the synthesis of ion‐exchange membranes. The grafting yield increased at first then decreased with the increase in the irradiation dose. The surface area, thickness, volume, and the water uptake of the grafted film increased linearly with the increase in grafting yield. The distribution pattern of carboxyl groups of graft chains in the direction of film thickness followed by EPMA line profiles of potassium which combined with carboxyl groups showed that a homogeneous distribution was not obtained until the grafting yield was more than 10%. When DC current was supplied to the membrane in NaOH solution, the reciprocal of the electric resistance increased with the increase in NaOH concentration. The specific electric resistance decreased exponentially with the increase in the content of ionic functional groups in the membrane. The steady state concentration of Na+ in catholyte and the current efficiency were ca. 15 and 20%, respectively.
Thermal analyses of flame‐retardant twills containing cotton, polyester and wool
Authors: Trask Brenda J. , Beninate John V. 
Published: April 2003

AbstractMedium weight twill fabrics constructed from cotton and cotton blended with polyester and/or wool were analyzed under nitrogen by three thermoanalytical techniques. Fabrics were tested both before and after treatment with [tetrakis(hydroxymethyl)phosphonium] sulfate (THPS), urea, and trimethylolmelamine. The presence of all fibers was distinguishable in differential scanning calorimetric analysis (DSC) of untreated fabrics; the relative positions of the endothermic, decomposition peak temperatures were only slightly changed. After flame‐retardant (FR) treatment, the blended cotton and wool fibers were altered. Both fibers decomposed as exotherms during DSC analysis. These data supported earlier microscopical, X‐ray evidence that wool fibers were actually reacting with the FR treatment. The two DSC peaks for polyester polymer melting and decomposing remained unaffected by either blending with other fibers or the presence of the FR finish on the fabric. There was excellent agreement between DSC peak temperatures and the temperature of maximum rate of weight loss obtained from thermogravimetric analysis (TGA). Blending cotton with either of these fibers increased the residue measured after TGA. The increased residue correlated with increased flame resistance as measured by the 45° angle, edge‐ignition burning rate test.
Fourier transform infrared studies on the thermal degradation of polyvinylimidazoles: Part I
Authors: Eng Frederick P. , Ishida Hatsuo 
Published: April 2003

AbstractThermal degradation of polyvinylimidazoles on potassium bromide plate has been studied. At 300°C heat treatment, the occurrence of oxidation and dehydrogenation leads to the formation of saturated ketones and unconjugated CC bonds in the polymer backbone, respectively. The combination of the two types of reactions also yields α,β‐unsaturated keto compounds. Then at prolonged heat treatment at 300°C, cleavage of imidazole rings also occurs and α,β‐unsaturated cyano structures are formed. At 400°C, a new class of compound, carbodiimides, is being produced while the amount of the α,β‐unsaturated cyano compounds is greatly reduced. Similar to polyacrylonitrile, ladder‐type structures for degraded PVI(1) and PVI(4) are proposed probable.
Fourier transform infrared studies on the thermal degradation of polyvinylimidazoles. Part II
Authors: Eng Frederick P. , Ishida Hatsuo 
Published: April 2003

AbstractOxidative thermal degradation of polyvinylimidazoles on copper have been studied. Degraded products include olefinic, saturated, and α,β‐unsaturated ketones, α,β‐unsaturated and β‐iminonitriles, CN conjugated and NHCC components. At 150°C, the rate of degradation of the polymers is relatively slow. For PVI(1), approximately 50% of the polymer remained nonoxidized after 64 h of heating, whereas 80% of PVI(4) remained nonoxidized after 47 h of heat treatment. At 210°C, the degradation mechanisms involved three stages, with the duration of each stage quite different between the two polymers. No degradation of polyvinylimidazoles is observed in vacuum initially at 400°C. Prolonged heat treatment leads to evaporation of residual water, further complex formation, and, finally, evaporation of the polymer films.
Effects of polar groups of polymer matrix on reinforcement‐matrix interaction in kevlar fiber‐reinforced composites
Authors: Kodama Minekazu , Karino Isamu 
Published: April 2003

AbstractIn order to investigate the interaction between the polar groups of reinforcement and matrix in polymer composite, mechanical properties were studied for the Kevlar fiber‐reinforced composites (Kevlar is a registered trademark of E. I. duPont de Nemours Co. Inc.), in which the kind and fraction of polar components in matrix were varied using blended polymers. For the composites comprised of polymethyl methacrylate and poly(hydroxypropyl ether of bisphenol A) as the matrix, a subtransition, which can be ascribed to the interphase formed on the reinforcement surface by a strong interaction between reinforcement and matrix, appears at a temperature above the primary transition on the E″ versus temperature curves. Such a subtransition is obscured or diminished accompanying the decrease in fraction of the polar components in the matrix. The fiber efficiency factors for strength are also decreased with a decrease in the fraction of the polar components. These results imply that the reinforcement‐matrix interaction is affected depending on the fraction of the polar components in matrix.For the composite comprised of blending the two polar components as the matrix, each component can contribute to the interaction with the reinforcement.The results obtained from the Fourier transform infrared spectroscopy on the matrix polymer‐coated Kevlar cloth do not contradict those obtained by studying the mechanical properties.