bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermoanalytical characteristics of polycarboxylic acids investigated as durable press agents for cotton textiles
Authors: Trask‐Morrell B. J. , Andrews B. A. Kottes 
Published: April 2003

AbstractPolycarboxylic acids are of great interest to the cotton textile industry as durable press agents because they do not release substances that require mandatory monitoring. Differential scanning colorimetric (DSC), thermogravimetric (TG), and differential thermogravimetric (DTG) techniques were used to study the thermal characteristics of a series of 10 polycarboxylic acids. Samples included di‐, tri‐, and tetra‐functional compounds some of which contained olefinic linkages, hydroxyl substituents, and cyclic structure. Thermogravimetric data at simulated fabric cure temperatures was used to assess the potential of a compound for use as a textile finishing agent. In high‐temperature studies the compounds were readily distinguishable in DSC analyses. General characteristics such as increases in total heats of reactions were found to be related to the number of functional groups. These results also provided support for a mechanism for the reaction of polycarboxylic acids with cellulose through an anhydride intermediate.
The nature of adhesion in composites of modified cellulose fibers and polypropylene
Authors: Felix Johan M. , Gatenholm Paul 
Published: April 2003

AbstractCellulose fibers were surface modified with polypropylene–maleic anhydride copolymer. The physical properties of such fibers were characterized by contact angle measurements, and the chemical structure was identified with ESCA and FTIR. ESCA showed that the modifying agent was localized at the surface of the fibers. The modified fibers were compounded with polypropylene, and composites with various amount of fibers were manufactured by injection molding. All mechanical properties were improved when treated fibers were used. SEM showed improved dispersion, wetting of fibers, and adhesion. The nature of adhesion was studied using FTIR. It was found that the surface modifying agent is covalently bonded to the fibers through esterification. The degree of esterification is enhanced by activating the modifying agent before fiber treatment. This study has shown the effects of treatment conditions on activation of reactive species and chemical reaction between fiber and modifying agent. Moreover, a better understanding has been achieved of the nature of adhesion for the system.
Real‐time monitoring of the cure reaction of a TGDDM/DDS epoxy resin using fiber optic FT‐IR
Authors: George G. A. , Cole‐Clarke P. , St. John N. , Friend G. 
Published: April 2003

AbstractThe feasibility of using remote FT‐IR spectroscopy to monitor the gelation reaction of an epoxy resin used in advanced composite materials has been studied. The commercial epoxy resins MY720 and MY721, consisting mostly of tetraglycidyl 4,4′‐diaminodiphenyl methane (TGDDM) were cured with diaminodiphenylsulfone (DDS) in a microcapillary cell connected to an FT‐IR spectrometer by single silica fiber optics. By operating in the near‐IR, direct measurement of the consumption of epoxide and primary amine and growth in hydroxyl groups was possible. It was found that the primary amine band at 5067 cm−1 was the most sensitive for rapid and accurate real‐time monitoring of the cure reaction up to gelation. The temperature dependence of amine consumption from 135 to 180°C gave an activation energy of 70 kJ mol−1 for the cure reaction in agreement with DSC. Several artefacts involved in using fiber optic FT‐IR in this way have been identified.
Polymer‐supported molybdenum and vanadium catalysts for epoxidation of alkenes by alkyl hydroperoxides
Authors: Stamenova R. T. , Tsvetanov C. B. , Vassilev K. G. , Tanielyan S. K. , Ivanov S. K. 
Published: April 2003

AbstractPolymer‐supported molybdenum and vanadium catalysts were synthesized using gel‐type crosslinked copolymers with microheterogeneous structure. The supports were composed of inert ethylene–propylene rubber and crosslinked high molecular weight poly(ethylene oxide) matrices and polymeric ligands grafted or forming interpenetrating networks: poly(acrylic acid), poly(methacrylic acid), poly(4‐vinylpyridine), and polyvinyl alcohol. Catalytic activity and selectivity of some of these complexes were tested in epoxidation of styrene by ethylbenzene hydroperoxide. Molybdenyl cations are strongly coordinated with pyridine‐containing copolymers giving catalysts of high activity and selectivity. They provide conversion and selectivity above 70%. Because of the microheterogeneous mosaic‐like structure of the supports, better accessibility of the active sites is achieved.
The flocculation of cane sugar muds with acrylamide–sodium acrylate copolymers
Authors: Crees O. L. , Senogles E. , Whayman E. 
Published: April 2003

AbstractThe flocculation of cane sugar muds with commercial acrylamide–sodium acrylate copolymers has been investigated through the measurement of settling rates and residual turbidities. The flocculation efficiencies of the copolymers were observed to depend on their composition, microstructure, and molecular weight, and the zeta potential of the mud particles. Adsorption of polymer at the surface of the particles was shown to occur through interaction with the acrylate groups. The experimental results are consistent with a bridging mechanism for the flocculation process, in which an observed optimum copolymer composition is associated with polymer adsorption which is sufficiently strong to resist mild shear forces yet allows the extension of polymer “loops” and “tails” into solution.
Kinetics of hydrolysis and thermal degradation of polyester melts
Authors: Seo Kab S. , Cloyd James D. 
Published: April 2003

AbstractPolyester melts exhibit two discrete degradation rates depending on the moisture content in the solid state. The initial fast rate is very sensitive to the moisture content while the later slow rate is not sensitive to the moisture content. The former is attributed to hydrolysis and the latter is attributed to thermo‐oxidative degradation. A combined kinetic equation which represents both hydrolysis and thermo‐oxidative degration of the polyester melt is proposed. The model equation agrees well with the experimental data. A method to determine hydrolytic and thermal degradation rate constants, moisture content, molecular weight for polyesters by means of a melt viscometry is discussed.
Effect of mineral and organic acids on radiation grafting of styrene onto polyethylene
Authors: El‐Assy Nasef B. 
Published: April 2003

AbstractA study has been made on the effect of mineral and organic acids on the radiation‐induced graft polymerization of styrene onto low‐density polyethylene films. Effects of different solvents and dose rate of irradiation on the grafting yield were also investigated. The influence of irradiation time and monomer concentration in the presence and absence of acid on the initial rate and grafting yield was studied. The dependence of the grafting rate on monomer concentration was found to be of the order 1.34 (in absence of acid), 0.61 (in presence of HCl), and 1.25 (in presence of oxalic acid). Such acid enhancement of the radiation grafting process is of practical importance from an economical point of view.
Development of seawater‐resistant polyurethane elastomers for use as sonar encapsulants
Authors: Stack G. M. , Miller J. M. , Chang E. Y. 
Published: April 2003

AbstractPolyurethane systems based on aliphatic diisocyanates were evaluated for suitability for use as underwater transducer encapsulants. A preliminary evaluation was performed to select the most promising urethane systems for further development. An investigation was then undertaken to determine the effect of compositional changes on the properties of these urethanes. The compositional parameters investigated were the soft‐segment molecular weight, the prepolymer isocyanate content, the composition of the cure formulation, and the cure stoichiometry. These urethanes were subjected to long‐term aging in seawater. It was found that this exposure did not significantly effect the physical or dynamic mechanical properties of the urethane.
Sorption and transport of aqueous salt solution in polyurethane membrane at 25, 44, and 60°C
Authors: Harogoppad Shivaputrappa B. , Aminabhavi Tejraj M. , Balundgi Ramachandra H. 
Published: April 2003

AbstractSorption and transport of aqueous salt solutions in polyurethane elastomer has been investigated over the temperature interval of 25–60°C by using an immersion/weight gain method. The size of the ions has no significant effect on the penetrant transport coefficients. The sorption data have been explained in terms of the simple Fickian model. Attempts have also been made to estimate the transport parameters by applying corrections to include the spatial diffusivity of the liquids within the polymer sample. Temperature dependence of the transport coefficients has been used to estimate the activation parameters from the Arrhenius plots.
Depolymerization of poly(ethylene terephthalate) resin under pressure
Authors: Chen J. Y. , Ou C. F. , Hu Y. C. , Lin C. C. 
Published: April 2003

AbstractThe process of depolymerization of PET resin by EG glycolysis under pressure is investigated. The kinetics of this pressurized depolymerization of PET resin is discussed. It was found that the rate of depolymerization is dependent of temperature, pressure, and concentration ratio of EG to PET. The rate of depolymerization is proportional to the square of EG concentration and faster than that under atmospheric pressure. Glycolyzed products under pressure consist of the PET monomer, BHET, and oligomers, mostly dimer and trimer. An equilibrium between BHET and oligomers is attained quickly soon after the depolymerization step is completed in the case of a higher ratio of EG/PET used. In the case of lower ratio of EG/PET, the final product now consists of higher molecular weight of oligomers rather than monomer, dimer, and trimer.
Characterization of imidazole‐cured epoxy–phenol resins
Authors: Heise M. S. , Martin G. C. , Gotro J. T. 
Published: April 2003

AbstractThe physical and chemical properties of the diglycidyl ether of bisphenol A (DGEBA) cured with different concentrations of bisphenol A (BPA) and 2‐ethyl‐4‐methylimidazole (EMI‐24) were examined using Fourier transform infrared spectroscopy, differential scanning calorimetry, dynamic mechanical and dielectric analyses, and solvent extraction studies. The effects of the phenol‐epoxide and the secondary hydroxyl (R‐OH)‐epoxide reactions on the network formation process were analyzed using a recursive modeling technique to obtain expressions for the weight‐averaged molecular weight, the weight fraction solubles, and the gel point as a function of the extent of cure and the epoxide‐phenol reactant ratio. The sol fraction and the gel point predictions from recursive modeling studies of the network formation process agreed with the results obtained from the extraction studies. The results from the network modeling studies were also related to the thermal and rheological properties of the resin during cure.
Ion‐exchange copolymers based on tetrafluoroethylene, hexafluoropropylene, and acrylic acid
Authors: Kostov G. K. , Atanasov A. N. 
Published: April 2003

AbstractPeroxide‐induced copolymerization of tetrafluoroethylene (TFE) with hexafluoropropylene (HFP) and acrylic acid (AA) at different molar ratios of monomers, reaction time, pressure, and initiator concentration was studied. By means of IR spectroscopy and temperature and phase characteristics of the copolymers obtained it was proved that a ternary copolymer of TFE, HFP, and AA was synthesized. Fluoro‐containing polymers with ion‐exchange capacities up to 0.8 meq/g were obtained. The composition of binary TFE‐HFP and ternary TFE‐HFP‐AA copolymers and some of their characteristics were determined. Copolymerization takes place mainly in the stationary state with an induction period. Polymerization rate R ∼ [In]0.7, which is presumably connected with chain transfer reaction to AA.
Comparison of gas permeation in vinyl and vinylidene polymers
Authors: Mohr J. M. , Paul D. R. 
Published: April 2003

AbstractThe gas transport properties of several simple vinyl and vinylidene polymers are compared to examine the effect of pendant group type (H, CH3, F, Cl) and symmetry of placement. The literature contains extensive information about these polymers, which has been critically reviewed to obtain consistent data for interpretation of the effect of structure on gas permeability. The gas transport data available for many of these polymers are quite variable because of differences in additives, thermal history, and crystallinity. The values used here are from studies where the physical properties of the film were reported along with the transport data. The appropriate data were not available for poly(vinyl fluoride) or poly(vinylidene chloride). For poly(vinyl fluoride), permeability measurements and thermal analysis were done to supply this information. Results for poly(vinylidene chloride) were obtained by extrapolation of copolymer permeation properties. Estimates of the permeability of oxygen in the amorphous phase of each polymer are discussed in terms of the estimated fractional free volume of that phase. In this way, the intrinsic effects of molecular structure on gas permeation exclusive of crystallinity effects have been evaluated.
Synergistic effects in fluorocarbon elastomer seals produced by a combined temperature and radiation environment
Authors: Bartko John , Siemon John T. 
Published: April 2003

AbstractFluorocarbon elastomer seals were subjected to single stress radiation and temperature tests and combined stress tests with the seals immersed in silicone oil, to obtain a service life estimate. Their sealing capability was mechanically tested during the tests. In single environment tests the seals were resistant to temperature‐induced stresses and very hard to radiation, showing no failures up to 108rads. The combined tests, using three matched pairs of temperature and radiation dose rate, indicated a reduction in service life from 40 years at 145°C with no radiation to 21 years at 50°C with radiation, pointing to a significant synergism between radiation and temperature.
Temperature dependence of diffusion of a disperse dye in the multiple layers of nylon fabric
Authors: Sasaki Hiroaki , Honma Yoshio , Kidoh Hanpei , Karasawa Mikio 
Published: April 2003

AbstractThe apparent diffusion coefficients of a disperse dye in the multiple layers of nylon fabric at 45‐75°C are determined as the dyeing model of the textile assembly. The modified pore model is introduced to explain the diffusion behavior in the multiple fabric. The Arrhenius plot of the diffusion coefficient of dye in the spaces or pores of nylon fabric gave a straight line and the activation energy of diffusion was about 9.4 kcal/mol. The temperature dependence of the dye diffusivity in polymer matrix was quantitatively described by a WLF‐type relation,

where aT is a shift factor of diffusion and Ts is the reference temperature.
Induced crystallization of cellulose in never‐dried cotton fibers
Authors: Iyer P. Bhama , Sreenivasan S. , Chidambareswaran P. K. , Patil N. B. , Sundaram V. 
Published: April 2003

AbstractIn the present investigation, we have made a systematic study of the induced crystallization in never‐dried cotton fiber, by allowing it to desiccate under different conditions of humidity and temperature. The resulting structural changes have been followed using x‐ray diffraction and infrared absorption techniques. A slow rate of drying coupled with a high temperature was more conducive for maximum crystallization. Analysis of the effect of temperature on the induced crystallization showed possible existence of a thermal transition in cellulose around 30°C. The induced crystallization brought about by slow drying as well as those produced using intercrystalline swelling agents, have been shown to be resulting from a proper channelization of the interfibrillar mobility existing in the never‐dried fibers.
A comparative study of sorption of water vapor by oligomeric triblock copolymers of ethylene and propylene oxides
Authors: Petr̂ík S. , Bohdanecký M. , Hadobaŝ F. , Ŝimek L. 
Published: April 2003

AbstractEquilibrium sorption of water vapor by oligomeric block copolymers (PEP) of ethylene and propylene oxides was measured at 23°C at five values of the relative vapor pressure, 0.32 ≦ p/p0 ≦ 0.90. Sorption isotherms were described by a simple empirical two‐parameter equation. The effect of the copolymer composition on the parameters was established. The Lundberg‐Zimm clustering function, the mean size of clusters of water molecules, and the Flory‐Huggins interaction parameters were estimated. Their dependencies on copolymer composition and water content in the system are discussed.
Solvent self‐diffusion in crosslinked polymers
Authors: Vrentas J. S. , Vrentas C. M. 
Published: April 2003

AbstractA theory is developed for predicting the solvent self‐diffusion coefficient in a crosslinked, amorphous polymer. The theory is based on a modification of the free‐volume theory of transport for the presence of crosslinks in the polymer. The general predictions of the theory for the variations of the self‐diffusion coefficient with temperature, concentration, degree of crosslinking, and solvent size are compared with general experimental trends.
Temperature dependence of contact angles on elastomers
Authors: Budziak C. J. , Vargha‐Butler E. I. , Neumann A. W. 
Published: April 2003

AbstractContact angle measurements with three different liquids were performed on: (i) butyl rubber PB 101‐3 (Polysar Ltd.) and (ii) Dow Corning 236 dispersion. Contact angles were measured at different temperatures within the range from 23°C (room temperature) to 120°C. The surface tensions, γsv, of the polymeric coatings at each temperature were calculated from the contact angles. The temperature coefficients of the surface tensions, dγsv/dT, i.e., the surface entropies, were established for the temperature range covered.
Improvement of plybond strength of paperboard by corona treatment
Authors: Sakata Isao , Morita Mitsuhiro , Furuichi Hiroshi , Kawaguchi Yoshifumi 
Published: April 2003

AbstractIt was found that the treatment of the surfaces of wet pulp sheets (moisture content; up to 85%) in a corona discharge improved greatly the plybond strength of the paperboard obtained when the treated wet pulp sheets were laminated together, pressed, and then dried. Treatment was carried out by use of a corona apparatus which had variable driven roll electrodes for transporting the wet pulp sheets through a corona field and was attached to a high‐voltage generator (∼ max 500 W, ∼ 16 kV at 5 kHz). The plybond strengths of the paperboards were examined by means of Tappi RC‐273 and JIS P8139 methods. Some experiments regarding the chemical effects of the corona treatment on the surface modification of wet pulp sheets were made with the aid of dye adsorption methods. Both untreated and corona‐treated pulps adsorbed basic dyes, methylene blue, etc., with the same extent of dyeing. This indicates that no measurable acidic sites (carboxyl groups) increased on the surfaces of the pulp sheets during the corona treatment. To detect aldehyde groups, the dyeing examination of the pulps with Schiff's reagent was made, and the results showed a higher dyeing ability for the corona‐treated pulps compared to the untreated, indicating that aldehyde groups on the pulp surfaces increased with an increase in the degree of corona treatment. The corona treatment seems to produce on the surface layer lightly oxidized and fairly degraded polysaccharide chains, which will tend to swell in water and thus act as an adhesive in plybonding the pulp sheets.
The chemical and physical properties of electrochemically prepared polyaniline perchlorate (PAP)
Authors: Choi Kyung Moon , Lee Eun Ju , Park Joon Woo , Kim Keu Hong 
Published: April 2003

AbstractPolyaniline perchlorate (PAP) was synthesized by electrochemical oxidation from 0.2 M aniline in acetonitrile solution containing 0.1 M tetraethylammonium perchlorate as supporting electrolyte. From polarographic and cyclic voltammetry results, the values of the half‐wave potential (E1/2), transfer coefficient (α), and number of electrons related to the electrode reaction (n) were calculated to be 825 mV, 0.894, and 1, respectively. The morphology of the PAP film was observed by using an SEM analyzer. From thermal analysis of the PAP sample, the reaction rate (R) for its thermal decomposition was obtained from the TGA result and a exothermic peak at 330°C was also observed in the DSC curve. The electrical conductivity of the PAP pellet was measured at temperatures from −170 to 25°C. From a plot of conductivity vs. 1/T, the activation energy (Ea) was obtained to be 0.14 eV. The conduction mechanism in a pressed pellet of PAP is suggested to be electronic hopping conduction. The values of the ESR parameters were calculated from an ESR curve for PAP at room temperature.
Studies on the preparation and properties of conductive polymers. IV. Novel method to prepare metallized plastics from metal chelates of polymides–imides
Authors: Huang Chueh‐Jung , Yen Chih‐Chao , Chang Teh‐Chou 
Published: April 2003

AbstractA new type of polyamide–imides (PAI) was synthesized by direct polycondensation. A series of polyamide–imide metal chelate films was prepared by the transition‐metal salts (AgNO3, CuCl2, and CoCl2) mixed with the polyamide–imides in NMP solution. These polyamide–imide metal chelate films were reduced by various reducing agents, and the reduced films exhibited low surface resistivity around 100−101 Ω/cm2. The surfaces of these conductive films were proved to be metallized by means of X‐ray analysis. The metal adhered on the film was believed to be responsible for the improvement of electrical conductivity. The effects of kinds and concentrations of metal salts, kinds and concentrations of reducing agents, and reduction time on the conductivity of metallized films were investigated. The IR spectra and SEM observations of unreduced and reduced polymer chelate films were also studied.
Diffusion and sorption of organic liquids through polymer membranes. II. Neoprene, SBR, EPDM, NBR, and natural rubber versus n‐alkanes
Authors: Harogoppad S. B. , Aminabhavi T. M. 
Published: April 2003

AbstractDiffusion and sorption of n‐alkanes (C6–C10) through commercial polymer membranes such as neoprene, styrene butadiene rubber, ethylene propylene diene terpolymer, nitrile butadiene rubber, and natural rubber have been studied from 25 to 60°C. The diffusion results have been explained in terms of the size of liquid molecules and the diffusion mechanism was found to follow the Fickian trend. Nitrile butadiene rubber and neoprene showed much smaller values of diffusivities and sorption constants than the other polymer membranes. Arrhenius parameters for the activated diffusion process and the thermodynamic quantities for the process of equilibrium sorption have been estimated.
Application of the dynamic SIMS technique to the study of silicone release coatings
Authors: Stein Judith , Leonard Tracey M. , Smith Gary A. 
Published: April 2003

AbstractSecondary ion mass spectrometry (SIMS) depth profiling has been used to determine elemental compositions of cured silicone release coatings as well as the location of controlled release additives (CRAs) in the cured polymer matrix. The two CRAs examined were found to be uniformly distributed throughout the matrix with no apparent increase at either the air or adhesive interface. As CRAs are required for tight release, this suggests that a minimum concentration at the surface is necessary but this concentration is not greater than that found in the bulk.