bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymer polarity and surfactant adsorption
Authors: Vijayendran B. R. 
Published: April 2003

AbstractThe effect of polymer polarity on surfactant adsorption from aqueous solution is discussed. The analysis assumes that surfactant adsorption at the polymer–water interface follows a Langmuir‐type adsorption isotherm and the free energy of adsorption is controlled by the interfacial tension of the interface. Saturation adsorption given by the area per molecule of surfactant at the critical micelle concentration (CMC) of the surfactant is related to the polymer–water interfacial tension and the polarity of the polymer surface, calculated from the polar and dispersion contributions to the polymer surface energy. Available data on the area per molecule of sodium lauryl sulfate on various polymer surfaces have been used to test satisfactorily the above analysis. The analysis is used to interpret some of the observations relating to surfactant adsorption encountered in the emulsion polymerization of polar monomers and particle size determination of latexes by the soap titration method. Further, potential utility of such area per molecule data to characterize the nature of polymer surfaces is also discussed.
Molecular weights of natural rubbers from selected temperate zone plants
Authors: Swanson C. L. , Buchanan R. A. , Otey F. H. 
Published: April 2003

AbstractMolecular weights and molecular weight distributions are compared by gel permeation chromatography for rubbers from 33 north temperate zone plants, guayule, and Hevea. Rubbers isolated from all the northern plants had much lower weight‐average molecular weight (Mw) values (9.72 × 104–4.95 × 105) than milled Hevea (1.31 × 106) or guayule (1.28 × 106) rubber. Pycnanthemum incanum, Lamiastrum galeobdolon, Monarda fistulosa, and Vernonia fasciculata produced potentially useful natural rubbers having Mw values above 4 × 105 and polydispersity factors of 3.1–4.5.
Pyropolycarboranes: The base for self‐lubricating materials with gas lubricant
Authors: Korshak V. V. , Gribova I. A. , Chumaievskaya A. N. , Mgeladze B. M. 
Published: April 2003

AbstractThis paper reports the results of an investigation of pyropolycarboranes, nondeformable thermally stable cross‐linked polymeric materials obtained by pyrolysis of carborane‐containing polymers. Carborane‐containing polyamides and polyesters were heated in air under pressure and analyzed by thermomechanical and thermogravimetric methods. Moreover, the friction properties of the filled materials have been investigated. The effect of hydrogen liberation on the friction of filled pyropolycarboranes at elevated temperatures was used in developing self‐lubricating materials with friction coefficients at 300–400°C.
Polymerization of methyl methacrylate with H2O2‐thiourea redox initiator system
Authors: Ghosh Premamoy , Banerjee Madhu Sudan 
Published: April 2003

AbstractPolymerization of MMA was done in aqueous media and in a bulk (nonaqueous) system employing a H2O2‐TU redox initiator system. Kinetic features differ significantly depending on the nature of the reaction media. The redox system is much more efficient as a chain initiator in aqueous media than in bulk MMA, where conversion to polymer, thermally and even under photoactivated conditions, is very slow and sluggish. In the bulk media, pronounced inhibition and retardation effects appear to be due to formation of unstable reaction intermediate presumably through dimerization of Ṡ(:NH)·NH2 radical generated in the primary redox reaction.
Partial miscibility of cellulose–polyacrylonitrile blends
Authors: Savard Sylvain , Lévesque Denis , Prud'Homme Robert E. 
Published: April 2003

AbstractCellulose‐polyacrylonitrile (PAN) blends have been prepared by the regeneration of 2% concentration solutions in dimethylformamide–NO2 solvent. The blends are transparent when containing between 0 and 50% by weight of PAN. Dynamic mechanical measurements indicate a shift in glass transition temperature Tg of PAN for the blends, suggesting partial miscibility between cellulose and PAN. Experimental density values larger than those predicted theoretically are also in agreement with this conclusion.
1‐chlorobutadiene–butadiene rubber. III. Determination of hydroxyl group content
Authors: Yamashita Shinzo , Sando Katsumi , Kohjiya Shinzo 
Published: April 2003

AbstractThe hydroxyl group content in 1‐chlorobutadiene–butadiene rubber prepared by emulsion polymerization (CB–BR) was determined by UV spectroscopy. CB–BR was allowed to react with phenyl isocyanate at room temperature, and the resulting N‐phenyl carbamate was assayed by UV measurement. The present method allowed the determination of a very small amount of hydroxyl groups contained in a high molecular weight hydrocarbon polymer. The hydroxyl group content in the hydroxyl‐terminated liquid polybutadiene was also determined. The value agreed closely with that obtained by the usual titration method. Hydroxyl groups in CB–BR are presumed to be produced by the hydrolysis of the active chlorine contained in CB–BR. This hydrolysis is dependent on the work‐up conditions of CB–BR, and the quantitative results were discussed with reference to the microstructure of the 1‐chlorobutadiene unit in CB–BR.
Characterization and use of radio frequency plasma‐activated natural polymers
Authors: Ward T. L. , Jung H. Z. , Hinojosa O. , Benerito R. R. 
Published: April 2003

AbstractA group of natural materials having anhydroglucose units linked by glycosidic bonds, as well as other related compounds, were irradiated with plasmas generated by a radio frequency field (13.56 MHz). Reactive sites created were characterized by electron spin resonance, chemiluminescence, infrared, and x‐ray photoelectron spectroscopy. The free radicals are related to the number of glycosidic bonds, and their decays result in chemiluminescence. In the absence of moisture and oxygen, however, the radicals are stable. During plasma irradiation, carbonyl groups as well as free radicals are formed on surfaces, and the atom ratio of oxygen to carbon on surfaces increases. Within the reactor, thin films of polymers can be deposited on cotton fabrics by allowing the monomer to enter the reactor above the fabric that is in a horizontal position downstream from the external electrodes.
Durable‐press cotton with improved retentions of strength and abrasion resistance via N‐methylolpolyethyleneurea D.P. 2
Authors: Bertoniere Noelie R. , Rowland Stanley P. 
Published: April 2003

AbstractDiethylenetriamine was reacted with urea to form a noncyclic analog of ethyleneurea (one of the lowest members of a series of linear polyethyleneureas) which was characterized spectroscopically. Its reaction with formaldehyde to yield the N‐methylol derivative (N‐methylolpolyethyleneurea, degree of polymerization 2; NMP‐2) was investigated. The polymerization characteristics of the NMP‐2 were studied and compared with those of N‐methylol derivatives of cyclic ethyleneurea (related structurally) and melamine (related polyfunctionally). The NMP‐2 was applied to cotton fabrics by a pad–dry–cure process with Al2(OH)5Cl·2H2O as the polymerization crosslinking catalyst. Fabrics treated with the experimental reagent developed high levels of resilience (durable press appearance) and were characterized by significantly higher than conventional levels of retained strength and abrasion resistance. Analyses by electron microscopy of fibers treated with NMP‐2 and with the predominant conventional reagent, dimethyloldihydroxyethyleneurea, are reported. Attractive performance properties are discussed and attributed, at least in part, to rapid polymerization accompanying, or in advance of, etherification of cellulosic hydroxyl groups.
The birefringence of nitrocellulose fibers and pastes
Authors: Lewis T. J. 
Published: April 2003

AbstractThe optical path difference of nitrocellulose fibers and pastes were measured on the polarizing microscope using three different compensation techniques, and a method is suggested for converting these path differences into birefringencies. By taking measurements on a sufficiently large number of fibers it is possible to estimate the average nitrogen content with an accuracy approaching that achieved by other methods on much larger samples. The distribution of nitrogen between individual fibers shows that material prepared by the displacement process differs from that made by the mechanical process and indicates that denitration occurs during displacement process manufacture. Solvents and plasticizers either increase or decrease the birefringence, and the structure of nitrocellulose pastes is discussed.
The beta relaxation in epoxy resin‐based networks
Authors: Williams John G. 
Published: April 2003

AbstractThe dynamic properties of epoxy–amine networks have been studied using a torsion pendulum, and the effect of replacement of resin by monoglycidyl ethers on the beta relaxation has been determined. It is shown that the loss peak is not sensitive to glyceryl units derived from the monofunctional diluents. From the effect of mixtures of aliphatic and aromatic‐based epoxy resins on the relaxation and from the loss properties of systems with varying ratio of resin to curing agent and catalytically cured systems, it is suggested that the loss peak has at least two basic components. One is related to the presence of glyceryl units derived from polyfunctional glycidyl compounds, while the other may be related to the presence of diphenylpropane units in the resin.
Compositional variation as a function of elution volume in gel permeation chromatography of copolymers and physical blends
Authors: Ogawa Toshio 
Published: April 2003

AbstractThis paper is concerned with the theoretical aspects of the gel permeation chromatography of copolymers and physical blends, such as polypropylene homopolymer and copolymers. Such considerations have become important with the advent of modern UV and IR chromatographic detectors. The behavior of the compositional variation observed as a function of elution volume is investigated by a simulation technique. As an example, ethylene–propylene copolymers having a bivariate normal distribution for molecular weight and composition are taken for calculations. We deal with the effects of the molecular weight distribution, the compositional distribution, and the correlation coefficient between molecular weight and composition on the detected compositional variation. It is concluded that these three factors are equally important in evaluating the curves fo the variation. Therefore, the difference between compositional distributions of copolymers is detectable only under limited conditions where the other factors are kept constant.
Crystallization of cyclic oligomers on the surface of nylon 6 fibers
Authors: Fujiwara Yasuharu , Zeronian S. Haig 
Published: April 2003

AbstractWhen scoured nylon 6 filament was exposed to either water vapor or n‐alcohol vapor, a portion of the cyclic [NH(CH2)5CO]x, with x = 2 through 7, and the ϵ‐caprolactam present migrated to the filament surface and crystallized. A variety of crystal forms were observed. The variations depended partly on the vapor to which the sample had been exposed. During water vapor exposures, the cyclic dimer migrated more easily to the filament surface than the cyclic monomer and the cyclic tetramer migrated more easily than the cyclic trimer. It is postulated that the secondary valence forces acting between the dimer and the nylon 6 polymer are weaker than that between the ϵ‐caprolactam and the polymer since the dimer forms intramolecular hydrogen bonds. Consequently, the dimer migrates more easily than the monomer, which can form hydrogen bonds with the polymer. Also the cyclic trimer can form hydrogen bonds with the nylon 6 polymer and thus migrates less easily than the cyclic tetramer, which can form intramolecular hydrogen bonds. In alcohol vapor exposures, the n‐alcohol used influenced the concentration of cyclic monomer and oligomer, which migrated to the surface of the nylon 6 filament. The variation of the monomer and oligomer concentration on the fiber surface with the alcohol used in the exposure is discussed.
Bis(diisopropyl)thiophosphoryl sulfides in vulcanization reactions
Authors: Pimblott J. G. , Scott G. , Stuckey J. E. 
Published: April 2003

AbstractA synergistic combination of bis(diisopropyl)thiophosphoryl disulfide, dimorpholyl disulfide, and sulfur is used to produce an efficient vulcanizing system for a range of rubbers. This produces vulcanizates with the exceptional thermal and thermal‐oxidative stability characteristic of sulfur donor vulcanizates and the rapid and extensive crosslinking reaction normally associated with a conventional sulfur–accelerator combination. A pronounced induction period is noted. The crosslinks initially produced in cis‐1,4‐polyisoprene rubbers are predominantly polysulfide but reduce to mono‐ and disulfides at optimum and extended cures. The crosslinks of the ethylene–propylene terpolymer and the styrene–butadiene vulcanizates are initially mainly disulfide but are rapidly reduced to monosulfides at the high curing temperatures (180°C) used. A comparison with vulcanization systems based on tetramethylthiuram disulfide and bis(diisopropyl)thiophosphoryl tri‐and tetrasulfides as sulfur donors and with a conventional cyclohexylbenthazyl‐2‐sulfenamide–sulfur combination, respectively, shows it to have distinct advantages.
Gel permeation chromatography using controlled‐porosity glass. I. Polyacrylamide–formamide solution
Authors: Onda Nobuhiko , Furusawa Kunio , Yamaguchi Noriko , Komuro Shūgi 
Published: April 2003

AbstractThe process of characterizing polyacrylamide and its partially hydrolyzed materials by gel permeation chromatography was examined. The use of controlled‐porosity glass and formamide as the stationary phase and the eluent, respectively, resulted in chromatographic behavior in accord with the hydrodynamic volume concept for polyacrylamide fractions. The addition of a salt (KCl) to the eluent was found to retard the elution of the hydrolyzed polyacrylamide.
Entanglement network model relating tensile impact strength and the ductile‐brittle transition to molecular structure in amorphous polymers
Authors: Bersted B. H. 
Published: April 2003

AbstractA model is presented to account for the large variations in tensile and tensile impact strength of amorphous polymers from a consideration of an idealized entanglement network. The material strength under tensile impact conditions is shown to be predictable and to increase with the “fineness” of the entanglement network; a higher entanglement density leading to more molecular chains supporting the stress. The entanglement density is, in turn, shown to increase with number‐average molecular weight and the quotient of the length to the molecular weight of the chemical repeat unit (empirically found to be related to the critical enganglement molecular weight). Ductile behavior is demonstrated to occur under tensile impact conditions when the material strength σB exceeds the yield stress σy and brittle behavior when σy > σB. It is further demonstrated that the large variation in tensile impact strength among the amorphous polymers studied can be adequately accounted for in terms of the large and predictable variation in σB; the larger σB is relative to σy, the more the polymer can draw (absorbing energy in the process) until σB is reached. Surprisingly, the predictions of strength for high‐molecular‐weight polycrystalline materials also gave good agreement with experimental data.
Flame resistant cotton by photoinitiated graft copolymerization
Authors: Harris James A. , Arthur Jett C. , Goynes Wilton R. 
Published: April 2003

AbstractPhotoinitiated, free‐radical reaction of cotton fabric with vinyl phosphonate oligomer (molecular weight 500–1000) and N‐methylolacrylamide monomer from aqueous solutions to form copolymer gave a textile product that had flame resistance (FF 5‐74 test). The initiating free radicals were formed on the cellulose molecule when cotton fabric was exposed to ultraviolet radiation. The effects of wavelengths of ultraviolet radiation (254, 300, and 350 nm), reaction time (0–9 ksec), solids in solution (10%–60%), atmosphere (air, nitrogen, and oxygen), and oligomer‐to‐monomer concentration (1:0.00 to 1:1.20 mole ratio) on efficiency of monomer and oligomer conversion to copolymer (maximum efficiency 70%–80%) were determined. Evaluation of the flame resistant cotton fabric by transmission electron microscopy showed deposits of copolymer throughout the cross sections of the fibers. However, scanning electron microscopy and energy‐dispersive x‐ray analysis showed that copolymer and phosphorus tended to be more concentrated between and on the surfaces of the fibers.
New coating materials and their preparation by radiation polymerization. III. Antifogging coating composition
Authors: Kaetsu I. , Yoshida M. 
Published: April 2003

AbstractCompositions for good antifogging and mar‐resistant coatings were investigated. A mixture of hydrolyzed aminoalkylalkoxysilane and hydrophilic vinyl monomer was the best combination. Control of suitable viscosity for coating was carried out conveniently by irradiation. The prepolymer was coated and cured by heating to form an antifogging membrane on various base materials such as inorganic glass, CR‐39 resin, and poly(methyl methacrylate). These conditions were studied in relation to some physical properties of the membrane. It was found that antifogging and mar‐resistant properties were inconsistent in many cases. A possible way to achieve the best balance between the two properties is discussed.
Computer optimization of reverse osmosis processing of soy whey with cellulose acetate modules
Authors: Baker E. C. , Moosemiller M. D. , Mustakas G. C. 
Published: April 2003

AbstractIn processing full‐fat soy flour to an acid‐precipitated lipid protein concentrate a byproduct whey fraction results which, because of its high biological oxygen demand, represents a serious disposal problem. Processing of food waste streams by reverse osmosis has received considerable attention because of its low theoretical energy requirement since no phase change is involved. In a previous study at this Center a mathematical model was developed for the diffusive transport of soy lipid protein concentrate whey across cellulose acetate membranes. In this study, pumping energy and power costs combined with membrane life and replacement costs were incorporated into the original model to provide a basis for optimization from an energy cost standpoint. Computer‐simulated runs were compared with experimental pilot‐plant runs, and the agreement between predicted and actual results was quite good. Water flux rates were in the range of 3 to 7 gal/ft2/day. Computer runs were used to optimize the processing of 100,000 gal/day of soy whey at 8000 ppm biological oxygen demand (BOD). Costs were at a minimum with a six‐stage tapered flow primary reverse osmosis treatment over a porous cellulose acetate membrane, followed by a six‐stage tapered flow reverse osmosis over a tighter membrane. BOD reduction was 94% at a cost of $5.45/1000 gal.
Superstructural description of deformation process in uniaxial extension of preoriented isotactic polypropylene
Authors: Yamada Kenji , Takayanagi Motowo 
Published: April 2003

AbstractThe strains on uniaxial extension of preoriented isotactic polypropylene are separated over the whole range of deformation into three processes: crystallite boundary slip (A1 process), uniform shear deformation of crystallites (A2 process), and restoration of molecular orientation from the sheardeformed state (Ā2 process). They are separately evaluated by the use of the parameters of superstructure varying in deformation. Both the A1 and A2 processes predominate before the A2 → Ā2 transition takes place. Wide‐ and small‐angle x‐ray goniometries detect this transition. After the A2 → Ā2 transition takes place, the specimen cannot be deformed by the A1 or A2 process, but by a molecular process such as pulling out the isolated extending chains from the folded chain crystals followed by their refolding. From the quantitative evaluations of the strains associated with the A1 and A2 processes it is deduced that the initial shear compliance for the A1 process is smaller than that for the A2 process.
The effect of additives on impact poly(vinyl chloride)
Authors: Chang Eng Pi , Kirsten Rudolf , Salovey Ronald 
Published: April 2003

AbstractThe two‐phase nature of a graft copolymer of ethylenepropylene‐1:4 hexadiene (EPDM) and poly(vinyl chloride) (PVC) has been established by dynamic mechanical measurements. The interaction of different additives with the isolated graft copolymer has also been inferred from their dynamic mechanical and thermal properties. Carbon black and titanium dioxide act as inert filler, while the effect of including straight‐chain hydrocarbons (e.g., n‐hexadecane and n‐hexatriacontane) is strongly dependent upon the melting point of the hydrocarbons. Sunflex 110 plasticizes the rubber phase of the graft copolymer while dioctyl (di‐2‐ethyl hexyl) phthalate (DOP) plasticizes the PVC phase and reduces Tg. At lower temperatures, however, the elastic modulus is increased by an “antiplasticization” effect. The local environment of PVC chains in the graft copolymer is modified by the presence of the rubber and PVC chains are less mobile.
Radiation‐induced polymerization of ethylene in a pilot plant. I. Bulk process
Authors: Takehisa Masaaki , Machi Sueo , Watanabe Hiromasa , Ueno Takashi , Takahashi Seiichi , Tsuchiya Ryoji , Otaguro Kanji , Motoda Isao , Takasaka Yoshio , Miyanaga Kazukiyo , Kawakami Waichiro , Yamaguchi Kouichi , Sugo Takanobu , Nakajima Hayato , Watanabe Terutaka , Hinachi Chuhei 
Published: April 2003

AbstractRadiation‐induced bulk polymerization of ethylene was carried out with use of a pilot plant with a 10 liter reactor at pressures of 225–400 kg/cm2, temperatures of 30–95°C, ethylene feed rates of 5–28 kg/hr, and dose rate of 3.8 × 105 rad/hr. Characteristics of the process are mild polymerization conditions and capability of producing medium density polyethylene in powder form. The spacetime yield and molecular weight of polymer were in the range of 3.5 to 13.1 g/liter hr and 2.2 × 104 to 14 × 104, respectively. The space‐time yield increased with mean residence time and 2.4 powders of pressure, and decreased with temperature. Molecular weight changed similarly with the reaction conditions. These results were consistent with those of the bench plant experiment and the scale effect was small. Polymer deposit to the reactor wall limited a period of continuous operation of the plant. The amount of deposited polymer was increased with the square of reaction time. The rate of polymer deposit was proportional to polymer concentration and to the cube of pressure. The polymer deposit cannot be solved in the bulk process.
Ionically crosslinked poly(acrylic acid) membranes. III. Reverse osmosis results for dry cast membranes
Authors: Dickson J. M. , Lloyd D. R. , Huang R. Y. M. 
Published: April 2003

AbstractThe reverse osmosis properties of ionically crosslinked polyacrylic acid membranes were investigated in terms of the salt separation of a 0.1% NaCl solution and water flux. The membranes were synthesized and crosslinked with the metal ion Al3+ via the dry casting technique described in a previous paper. The effect of such variables as the polymer concentration in the casting solution, the ratios of solvents used (DMF/H2O), the ratio of monomer to the crosslinking agent (AA/Al), the evaporation time and temperature, and the nonsolvent nature and treatment times were studied in some detail. The most important variable was found to be the length and nature of the treatment in the nonsolvents acetone and methanol. In the best series of the membranes that were synthesized, fluxes of more than 3.0 gfd, with salt separations at the 80%–85% level, were obtained.