bluuebunny/crossref_metadata_2025_split huggingface dataset:
Solventless processing of modified poly(vinyl fluoride) and its properties
Authors: Stallings John P. , Paradis Robert A. 
Published: April 2003

AbstractThe properties of fluorocarbon plastics have made them very desirable for numerous new applications. The DALVOR X‐6500 series of fluoropolymers can be easily fabricated without the use of solvents. General compound information, including pigmentation, lubrication, and rheology data, is presented as well as chemical resistance, weathering, and electrical data. Processing parameters for producing both flat and blown films are given, along with recommended types of equipment. Data are presented on fluid bed coating and various other applications are discussed.
Extraparticle diffusional effects in gel permeation chromatography. I. Theory
Authors: Biesenberger J. A. , Ouano A. 
Published: April 2003

AbstractA systems approach is applied to the analysis of chromatogram resolution dispersion, or zone broadening, in gel permeation chromatography (GPC). Three possible sources of dispersion are considered; these are: the packed columns; the empty tubing between pump and columns, columns and detector, etc.; and the detection system, viz., the differential refractometer cell. It is shown that empty tubing can contribute significantly to the degree of dispersion and to skewness of elution curves and that this dispersion should depend on molecular weight of solute (polymer) and diameter and length of the tubing. The importance of dispersion in the empty tubing is compared with that in the packed columns and refractometer cell.
Diffusion coefficients of liquids in polymer membranes by a desorption method
Authors: Fels Morton , Huang Robert Y. M. 
Published: April 2003

AbstractA method to obtain the diffusion coefficients and free volume parameters from desorption data for organic liquids in polymer films is presented. The method consists of fitting a numerical solution of the diffusion equation to experimental desorption data. Some problems that arise in the solution of the diffusion equation are discussed and results for a benzene–polyethylene system are presented.
Infrared determination of the composition of copolymers and terpolymers of propene and butene‐1 with and without octene‐1
Authors: Wegemer N. J. 
Published: April 2003

AbstractAn infrared spectrophotometer was calibrated for the quantitative determination of butene‐1 in copolymers with propene, and of butene‐1 and limited concentrations of octene‐1 in terpolymers with propene. 14C‐tagged standards were used for the butene‐1 calibration while standards for the octene‐1 calibration were prepared from a homopolymer by blending. Films were pressed from the standards, and the absorbance per mil thickness was correlated with composition. For our instrument, wt‐% C4 = 510 (A/mil) at 766 cm−1, and wt‐% C8 = 539 (A/mil) at 725 cm−1. No special steps were required to eliminate the effects of crystallinity.
The maximum extent of reaction in gelled systems
Authors: French David M. , Strecker Ruediger A. H. , Tompa Albert S. 
Published: April 2003

AbstractJust how far reactions can go after gelation during the cure of telechelic prepolymers has been a debatable point for some time. Utilizing a recently devised method,7 the curing reactions of some telechelic prepolymers were followed after the gel point. Extents of reaction above 90% occurred only in systems of average functionality close to two, functionality being the average number of reactive groups per molecule. Among systems of higher functionality, maximum extents of reaction of about 70% were most common. The final extent of reaction was only a few per cent above the extent of reaction at the gel point. The maximum extent of reaction varied with the concentration of reactive species and the relationship was a linear one at each functionality of the system. The data were consistent with PA2/r = {0.88/[(h − 1)(j − 1)]} + 0.10 where PA is the fraction of prepolymer reactive groups initially present which have reacted, r is the ratio of the initial number of crosslinking groups to prepolymer reactive groups, and h and j are weighted average functionalities of the two reactants. It is suggested that the limiting factor in defining the final extent of reaction in these systems is the accessibility of reactive groups as determined by solid geometry rather than thermodynamics or reaction kinetics. The final extent of cure is regularly dependent on functionality and one cannot regard functionality and maximum extent of reaction as independent variables.
The effect of crosslinking on the swelling of cotton in solutions of sodium hydroxide and cadoxen
Authors: Evans G. M. , Jeffries R. 
Published: April 2003

AbstractThis paper describes the effects of prior crosslinking in dimethylol ethyleneurea (DMEU) on the swelling of cotton fiber in aqueous solutions of sodium hydroxide and in cadoxen solutions (solutions of cadmium oxide in mixtures of ethylenediamine and water). The degree of swelling in the weaker swelling solutions is markedly reduced by the crosslinking, but in the stronger solutions (particularly in concentrated sodium hydroxide) the effect of prior crosslinking is only small; this is accounted for in terms of a fibril‐tearing mechanism in these stronger solutions. Crosslinking cotton reduces the mercerizing effect of strong alkali solutions (i.e., the disordering and the cellulose I → II lattice change), and also reduces the solubility of the fiber in solutions of cadoxen and cuprammonium hydroxide.
Dilatometric study of the melting point of three high‐pressure crystallized samples of marlex polyethylene
Authors: Waldman N. , Beyer G. H. , Griskey R. G. 
Published: April 2003

AbstractThe melting points of three polyethylenes differing in molecular weight distribution from 47,000 to 147,000 were determined as 141°C ± 0.5°C by dilatometric techniques. Sample preparation procedures were developed to ensure uniform thermal history prior to measuring length as a function of temperature in a precision dilatometer. The specific volume data were reproducible within 0.02%, reflecting the careful annealing procedure used and the extended time allowed for equilibrium to be attained.
Effect of casting conditions on the performance of porous cellulose acetate membranes in reverse osmosis
Authors: Kunst B. , Sourirajan S. 
Published: April 2003

AbstractSeveral sets of porous cellulose acetate membranes were made using the same casting solution composition and gelation conditions but varying the casting solution temperature and solvent evaporation conditions. The films were tested in reverse osmosis experiments at 250 psig using aqueous feed solutions containing 3500 ppm NaCl. The results show that the product rate obtained at a given level of solute separation is independent of evaporation time in the range tested and, for a given casting solution composition, the temperature of the casting solution and conditions of solvent evaporation during film formation together constitute an important interconnected variable governing the porous structure of the resulting membranes. These results offer a new approach to the problem of developing more productive reverse osmosis membranes and have led to a new class of porous cellulose acetate membranes capable of giving product rates 100% to 150% higher than those of the best membranes reported, at any given level of solute separation under the experimental conditions used. These results are of practical importance in low‐pressure reverse osmosis applications.
The time dependence of surface energy in cohesive fracture
Authors: Bennett S. J. , Anderson G. P. , Williams M. L. 
Published: April 2003

AbstractThe time‐temperature dependence of the cohesive fracture energy is deduced from experiments on a centrally cracked sheet of butadiene‐acrylonitrile‐acrylic acid viscoelastic terpolymer crosslinked with an epoxy curing agent. Analytic results based upon a cylindrical flaw model of the crack permit the segregation of the fracture energy time dependence from that of the relaxation modulus.
Characterization of two polypentadienes of differing tacticity by physical methods
Authors: Fielding‐Russell G. S. , Smith G. H. 
Published: April 2003

AbstractThe preparation of isotactic and syndiotactic 1,4‐polypentadienes with a cis content of at least 70%–75% using i‐Bu2AlH/Ti(i‐OPr)4 and AlEtCl2/thiophene/Co(acetylacetonate)2 catalysts, respectively, is reported. Physical characterization of the vulcanizates, prepared by a common recipe, involving infrared analysis, DTA, simple stress–strain and swelling measurements, and dynamic mechanical measurements over a frequency range of 2 decades and temperature range of −60°C to +20°C indicated that no isomerization had taken place during vulcanization and that stereoregularity of the polymer chains affected the resultant cure: the isotactic form was found to have a greater crosslink density than the syndiotactic form. Master curves covering an extended frequency range were constructed from the reduced dynamic mechanical data and the calculated quantities—thermal expansion coefficients of free volume and the fractional free volumes at the glass transition temperatures—agree with the accepted values. Glass transition temperatures of the isotactic and syndiotactic polymers are −37°C and −42°C, respectively, and for their vulcanizates, −33°C and −40°C, respectively.
Stress–birefringence study of styrene–butadiene multiblock copolymer
Authors: Nishioka A. , Furukawa J. , Yamashita S. , Kotani T. 
Published: April 2003

AbstractThe styrene–butadiene block copolymers of SB, SBS, and SBSBS types were investigated by means of the stress–birefringence technique to elucidate the effects of the block multiplicity on the mechanical properties of copolymers. The SBS‐type and the SBSBS‐type block copolymers exhibit nonlinear stress–birefringence relations, which were classified into three regions. They are a low stress‐optical coefficient region (optical creep), an increasing coefficient region, and a region of retarded increase in coefficient, as pointed out by Henderson et al.8 It was found that optical creep is associated with the polystyrene continuum. The third region, however, originates not only from the phenyl groups of the polystyrene block but also from a form‐birefringence due to the orientation of the polystyrene domain. The multiblock copolymer of SBSBS type was found to be rheo‐optically similar to the SBS type, both being affected solely by the details of the terminal styrene block.Pure gum vulcanizates of the SB‐type and SBS‐type block copolymers also exhibit optical creep. In a vulcanized block copolymer having both chemical and physical crosslinks, the latter seemed to disappear at elevated temperatures. At decreasing temperatures, the vulcanizates of block copolymers showed higher modulus of elasticity and lower stress‐optical coefficients.
Molecular weights of grafted polystyrene onto γ‐preirradiated cellulose diacetate
Authors: Munari Stelio , Tealdo G. Carlo , Canepa Giacomo , Rossi Corrado 
Published: April 2003

AbstractThe behavior of molecular weights of grafted polystyrene onto γ‐preirradiated cellulose diacetate was studied. The grafting of styrene onto cellulose diacetate was kinetically followed with particular attention paid to the polystyrene molecular weight behavior. The molecular weight was evaluated with the polymer fractions obtained by acid hydrolysis of the grafted copolymer. From the experimental results it appeared that the grafted chain molecular weight is completely controlled by the physical properties of the polymeric matrix either during a “bulk” or a “front” grafting.
Graft copolymerization to cellulose. Effect of sodium thiosulfate on hydrogen peroxide initiator system
Authors: Ogiwara Yoshitaka , Kubota Hitoshi 
Published: April 2003

AbstractThe effect of sodium thiosulfate on the graft copolymerization of methyl methacrylate to cellulose in the hydrogen peroxide initiator system was investigated. The addition of sodium thiosulfate in general was effective for decreasing the per cent grafting and the average molecular weight of grafts and increasing the formation of homopolymer, and the effects became pronounced with increasing hydrogen peroxide concentration. Moreover, the addition of sodium thiosulfate slightly suppressed the formation of grafts at a hydrogen peroxide concentration of 3 mmole/l., but greatly promoted it at 20 mmole/l. Traces of metallic ions present in cellulose could not be eliminated sufficiently by treatment with 3N hydrochloric acid. Such ions were found to interact with hydrogen peroxide and thus participate directly in the initiation and termination of the polymerization reaction. EDTA, the chelating agent, was highly effective for suppressing such participation of metallic ions. In the hydrogen peroxide initiator system applied to the EDTA‐treated samples, sodium thiosulfate caused an effective initiation of graft formation.
The determination of unsaturation in ethylene propylene terpolymers and butyl rubber with pyridinium bromide perbromide
Authors: Tunnicliffe Marjorie E. 
Published: April 2003

AbstractThe reagent pyridinium bromide perbromide (PBPB) has been investigated for the determination of unsaturation in model olefins and in polymers of low total unsaturation. Model olefins give 92%–100% reaction for a 1‐hr reaction period. Ethylene propylene terpolymers react quantitatively without substitution or elimination and without second addition reactions when the termonomer unit is 1,4 hexadiene, methylene norbornene, ethylidene norbornene, or cyclooctadiene. Dicyclopentadiene terpolymers react incompletely. These reactions take place in carbon tetrachloride/10% methanol solution, the reagent being added as a methanolic solution. Iodine chloride can also be used under specified conditions for the more reactive termonomer units in this solvent mixture. Under the same conditions the PBPB reagent reacts stoichiometrically with butyl rubber, without second addition or substitution reactions. The unsaturation results also agree with those obtained using bromine or iodine monochloride in carbon tetrachloride solution, but both of these reagents give slight substitution reactions.
The solubility parameter concept applied to disperse dyeing of polymers
Authors: Ibe E. Chianakwalam 
Published: April 2003

AbstractThe solubility parameter concept offers a logical link between the theory of solutions and of nonionic (disperse) dyeing. An attempt has been made to apply the concept to correlate the solubility of several disperse dyes in secondary cellulose acetate, cellulose triacetate, and polypropylene with the calculated solubility parameters of both the polymers and the dyes. When the dyes are applied on hydrophilic polymers from an aqueous dispersion, the correlation between the solubility parameter concept and the dye solubility is not close. One of the reasons for this may be the fact that dyeing of the fibers is, in fact, not a solution in the dry fibers, but consists essentially either in displacement of water molecules from the water swollen fibers and/or, perhaps, in additional swelling by the dye. Consideration of this fact and also correcting for the contribution of hydrogen bonding and dipole interactions to the cohesive energy density brings the disperse dye solubility data into a better agreement with the concept. The concept should be applicable without complications to the dyeing of nonpreswollen fibers, such as polypropylene from aqueous dispersion, or any fiber by the Thermosol process and particularly to dyeing from the vapor phase. The few data available appear to support this view.
Ultraviolet absorbers. The protective ability of aromatic nitro compounds in plasticized poly(vinyl chloride)
Authors: Raciszewski Zbigniew , Mullins D. H. 
Published: April 2003

AbstractInvestigated were three types of aromatic nitro compounds: (a) a derivative of o‐nitrophenol capable of forming an intramolecular hydrogen bond, (b) simple aromatic nitro compounds, and (c) the intramolecular charge transfer complexes, i.e., compounds incorporating in a single molecule the donor and the acceptor moieties, the latter substituted with the nitro groups. Samples of plasticized poly(vinyl chloride) were stabilized with these compounds and tested in an Atlas Weatherometer. The extent of degradation was determined by measuring the tensile strength, elongation, and the blue light reflectance before and after 270 and 500 hr of exposure. Samples without the stabilizers and samples containing 2,4‐dihydroxybenzophenone were used as standards for comparison. Little protection was provided by simple nitro compounds. The derivative of o‐nitrophenol and the donor‐acceptor compounds were either better or comparable to 2,4‐dihydroxybenzophenone in preserving the tensile strength and elongation. It appears that the protective ability of the derivative of o‐nitrophenol was associated with the hydrogen‐bonded six‐membered ring whereas the protection rendered by the donor‐acceptor compounds was determined by the extent of the contribution of the charge transfer states and the number of benzylic hydrogens capable of undergoing photochemical reactions. However, the mechanistic interpretation of the protective ability of the donor‐acceptor compounds was complicated by the color changes occurring during the exposure.
Gelation of poly(ethylene oxide) solutions by gamma radiation: Effects of molecular weight and irradiation conditions
Authors: Van Brederode R. A. , Rodriguez F. 
Published: April 2003

AbstractReticulation of a dilute aqueous solution of poly(ethylene oxide) in a 60Co gammaradiation field yields a weak gel which is characterized by its damped sinusoidal oscillation in a free‐swinging torsion pendulum. A storage and a loss modulus are calculated from the log decrement and frequency of oscillation, and the crosslink density is obtained from the storage modulus using the kinetic equation of rubber elasticity. The number of crosslinks added to the polymer per 100 eV of energy absorbed in the polymer above and below the gel point and the fraction of gamma energy absorbed directly by the polymer were determined from the dose‐to‐gel and modulus data. The effect of oxygen on the crosslinking reaction and the temperature on the gel's mechanical properties were experimentally observed.
The kinetics of thin film polyesterification
Authors: Campbell Gregory A. , Elton Edward F. , Bobalek Edward G. 
Published: April 2003

AbstractThe goal of this work was to investigate the increase in the rate of polyesterification that takes place as surface‐to‐volume ratio is increased. The polymer used in this reaction was derived from the esterification of adipic acid (hexanedioic acid) and propylene glycol (1,2‐propanediol). The effect of three variables—film thickness, water concentration of the nitrogen atmosphere, and temperature—was studied to determine their effect on the reaction rate. The water content of the atmosphere was found to severely retard the progress of the esterification and this fact reaffirms that the reverse reaction, hydrolysis, is much more important than was realized by earlier investigators. The reaction in the film was found to have an activation energy of 22,600 cal/mole compared to 12,600 cal/mole in the batch reaction, indicating a possible change in controlling rate from the batch to the film system. New evidence was found which illustrates the possible role of reactant mobility at high conversions. It is suggested that a possible explanation for the change in controlling rate may be due to a complex surface phenomenon such as the alignment of reactive groups at the surface or the orientation of water molecules at the gas–liquid interface.
Polyquinoxalines. I. Synthesis and preliminary mechanical properties as laminating and adhesive resins
Authors: Hergenorther P. M. , Levine H. H. 
Published: April 2003

AbstractA study on polyquinoxaline synthesis was conducted which provided a method of obtaining processable, reproducible high molecular weight polymers as solutions in m‐cresol; these solutions had excellent storageability at ambient temperatures. Polyquinoxaline solutions in m‐cresol were readily used for prepreg and tape preparation. Laminate and adhesive data showed the excellent potential of the polyquinoxalines for high temperature applications.
Thermal decomposition of phenol formaldehyde resins modified with cyanuric acid
Authors: Alaminov H. , Andonova N. 
Published: April 2003

AbstractThe thermal decomposition of cured cyanurophenol—formaldehyde oligomers (CPFR) was studied by derivatography, IR, spectra and EPR spectra. During the heating of CPFR, processes of restructuring and decomposition take place. Up to 330°C the weight losses of CPFR are smaller compared to those of phenol–formaldehyde oligomers (PFR), while above 330°C the opposite is true. Under these conditions the isocyanuric ring is destroyed. The carbonyl absorption sharply decreases at 400°C, and at 500°C there is practically no absorption. This reduction is probably a result of rearrangement of the isocyanuric rings to a secondary polymer in which nitrogen is combined in the form of cyanic links. The energy of decomposition as determined from the thermogravimetric curve is 17 to 24 kcal/mole. On the basis of the EPR sepctra and the low activation energy of destruction, we propose that radical processes play an important part during the process of curing and thermal decomposition of CPFR.
Effects of monomer impurities on the emulsion polymerization of chloroprene and properties of polychloroprene. II. Effect of monovinylacetylene
Authors: Sufčák Miloslav 
Published: April 2003

AbstractThe free‐radical emulsion polymerization of chloroprene containing monovinylacetylene in concentrations from 0% to 10% has been studied. It was found that in the presence of monovinylacetylene, a polymer with a great gel content, increased values of plasticity, and deteriorated physical and mechanical properties is formed. Monovinylacetylene has been proved to copolymerize with chloroprene under the conditions used. Acetylenic groups remain unchanged in the copolymer; they cause the crosslinking of polychloroprene macromolecules and corresponding changes in polymer properties. Copolymerization reactions of monovinylacetylene with chloroprene together with the crosslinking effect of monovinylacetylene cause a substantial lowering of the crystallization rate of polychloroprene.
Predicting joint sealant performance of elastomers by computer simulation. I. Justification of method
Authors: Catsiff E. H. , Hoffman R. F. , Kowalewski R. T. 
Published: April 2003

AbstractA computerized method has been developed for the analysis of the behavior of a sealed joint. The method is based upon the use of fundamental time‐dependent mechanical properties of a polymeric sealant, which can be easily determined in the laboratory, to feed a digital computer program that performs internal force balances within a given joint seal configuration by dividing the joint seal into a large number of “finite elements” in which the sealant properties are invariant. The computational method is an outgrowth of stress analysis programs that have been developed for use in the study of stress distributions within solid rocket propellant “grains.” Output from the computer program consists of a prediction of the overall geometric deformation of the sealant and the distribution of stresses and strains within the joint seal. Essential to the ideologic development of this method is the “separability” of time‐dependent and strain‐dependent aspects of the behavior of the material properties. However, the method should be operable even when this “separability” is only approximately maintained, as in many real materials. Fundamental properties have been determined on several typical sealant materials. A description is given of the mode of operation of the computational method, but detailed results are given in a companion article.