bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cationic polymerization of α‐methyl styrene from polydienes. II. Tensile properties of poly(butadiene‐g‐α‐methyl styrene) and poly(styrene‐b‐butadiene‐g‐α‐methyl styrene) copolymers
Authors: Ambrose R. J. , Newell J. J. 
Published: April 2003

AbstractTensile properties of poly(butadiene‐g‐α‐methyl styrene) copolymers have been investigated on molded samples. These graft copolymers show thermoplastic elastomer behavior because of their graft copolymer structure. Both modulus and strength increase with increasing α‐methyl styrene content and tensile strength is highest at the 45–50% by weight α‐methyl styrene level. Tensile strength at elevated test temperatures is considerably higher for these poly(butadiene‐g‐α‐methyl styrene) copolymers than for styrene‐butadiene‐styrene triblock polymers. This is attributed to the higher glass transition temperature for poly(α‐methyl styrene) segments compared to polystyrene segments. The oil acceptance of these graft copolymers appears to depend on the number of loose polybutadiene chain ends. Thus, the tensile strength of oil‐extended poly(butadiene‐g‐α‐methyl styrene) copolymers was considerably lower than oil‐extended poly(styrene‐b‐butadiene‐g‐α‐methyl styrene) copolymers even though both copolymers contained equal hard segment contents.
Thermally stimulated discharge current studies on low‐temperature relaxation in epoxy resin
Authors: Su W‐F. A. , Carr S. H. , Brittain J. O. 
Published: April 2003

AbstractThermally stimulated discharge current (TSDC) analysis has been used to characterize the low‐temperature (100–300 K) molecular relaxation processes (β relaxation) of an epoxy resin. Experiments were performed on a resin system composed chiefly of tetraglycidyl‐4,4′‐diaminodiphenyl‐methane and diaminodiphenyl sulfone (TGDDM/DDS). Polarization of the epoxy of the resin appears to be due to preferential orientations of dipoles in the temperature range studied. The broad β‐dispersion peak exhibits considerable “structure,” and it promises to prove rich in information related to polarization and relaxation processes in the epoxy resins. It is seen that TSDC can reveal clearly the difference between the degree of curing for epoxy resins. Temperature dependence of a mean activation energy calculated from the discharging processes reveals several temperature ranges over which common molecular relaxation events are probably occurring.
Effect of free monomer content on the drawing behavior of poly(methyl methacrylate)
Authors: Hope P. S. , Duckett R. A. , Ward I. M. 
Published: April 2003

AbstractCold drawing has been used to produce oriented samples of various molecular weight grades of poly(methyl methacrylate), all of which exhibited marked strain hardening characteristics over a range of drawing temperatures. The differences between the yield and drawing behavior of the grades did not correlate with molecular weight but could instead be attributed to the plasticizing effect of additional free monomer, generated by degradation during melt processing of the polymer.
Chlorinated poly(vinylidene fluoride)
Authors: Bacskai R. 
Published: April 2003

AbstractChlorinated poly(vinylidene fluoride) (PVF2) was prepared by introducing chlorine gas into a CCI4 suspension of PVF2 at reflux temperature. Polymer crystallinity and softening point decrease, while solubility and adhesion increase with the degree of chlorination. In contrast to PVF2, the chlorinated polymer is soluble in low‐boiling common organic solvents, such as acetone, methyl ethyl ketone, and 1,2‐dimethoxyethane. Chlorinated PVF2 is resistant to dehydrochlorination and is thermally more stable than PVF, chlorinated PVF, PVC, or chlorinated PVC. Chlorinated PVF2 coatings on wood, prepared by solution casting at room temperature, show outstanding weathering resistance.
Analytical study of the additives system in polyethylene
Authors: Lehotay Jozef , Daněček Jaroslav , Líška Otakar , Leško Ján , Brandšteterová Eva 
Published: April 2003

AbstractOn the basis of standards of identification of substances in the additive system of polyethylene has been performed. Different methods for separation such as adsorption thin‐layer chromatography, high‐performance liquid chromatography with chemically bounded phases, and gas chromatography have been used. The fir al identification has been made with mass spectrometry. The substances have been extracted from polyethylene with hexane and chloroform.
Gel permeation chromatography using controlled‐porosity glass. II. Polyacrylamide aqueous solutions
Authors: Onda Nobuhiko , Furusawa Kunio , Yamaguchi Noriko , Tokiwa Masatoshi , Hirai Yasumasa 
Published: April 2003

AbstractIn a study of polyacrylamide in solutions we have required the rapid characterization on chromatographies. The application to the aqueous solution of the GPC using controlled‐porosity glass has been examined from both the viewpoint of the effect of salt addition and the GPC mechanism. An adequate addition to neutral salt, 0.005M KCI to the eluent, gave rise to the elution behaviors being in accord with the hydrodynamic volume concept of the GPC separation.
Sintering of latex particles in pigmented coatings. II. Influence of the latex particle size
Authors: Alince B. , Lepoutre P. 
Published: April 2003

AbstractThe light‐scattering coefficient S of coatings formulated from a mixture of an inorganic pigment and polystyrene latex particles may be enhanced significantly when the dry coating is heated in order to cause sintering of the polystyrene spheres. The relative increase in S depends on the size and the amount of the latex particles and the type of the inorganic pigment. Of the latexes examined (0.5, 0.2, 0.1, and 0.03 μm in diameter) the 0.2μm latex is the most effective in blends with platelike delaminated clay. The coatings based on spherelike precipitated calcium carbonate are less responsive to the heat treatment. The gloss of the clay–latex coatings is not significantly altered by the heat treatment up to 20 pph of latex; the gloss of the calcium carbonate coatings generally decreases upon heating.
Novel ion‐containing reverse osmosis membranes. I. Preparation and selected properties
Authors: Bittencourt E. , Stannett V. , Williams J. L. , Hopfenberg H. B. 
Published: April 2003

AbstractGrafting and subsequent quaternization of 2‐and 4‐vinylpyridine to poly(vinyl chloride) (PVC) and to poly[3,3‐bis(chloromethyl)oxetane], Penton, films have been exploited to prepare novel ion‐containing membranes. 2‐Vinylpyridine‐grafted “Penton” films are the most attractive system for further study since the PVC grafts were unstable under the requisite extraction conditions. Although the sterically less hindered 4‐vinylpyridine‐grafted films were easier to quaternize, weight gain calculations indicated that complete quaternizations were only achieved with the 2‐vinylpyridine‐grafted films. High ionic concentrations were obtained in the grafted membranes. The mechanical properties of the wet films were measured. Salt absorption studies demonstrated that significant salt exclusion was achieved at relatively high salt concentrations although the grafted films sorbed up to 30 vol % water.
Rubber‐modified epoxies. II. Morphology and mechanical properties
Authors: Manzione L. T. , Gillham J. K. , McPherson C. A. 
Published: April 2003

AbstractA wide range in morphology paralleling a spectrum of phase separated and dissolved rubber, can be developed in rubber‐modified epoxies through control of rubber‐epoxy compatibility and cure conditions. These morphologies result in different stress response mechanisms. Dissolved rubber promotes plastic deformation and necking at low strain rates that provide large increases in the elongation to break. Dissolved rubber is ineffective in providing improvement at impact rates. Phase separated rubber domains can also increase the elongation to break since cavitation is promoted at the interfacial boundary. The elongation is limited to the extent of cavitation and therefore large increases in the energy to break are not found. The presence of rubber domains was found to be a necessary but not sufficient condition for impact energy improvement. Optimum materials contained a relatively large amount of dissolved rubber and a low volume fraction of phase separated rubber. These combine high elongations at low strain rates with improved impact properties.
Reinforcement of siloxane elastomers by silicas. Comparison between fumed and precipitated silicas in their interactions with an oligomer of poly(dimethylsiloxane)
Authors: Berrod G. , Vidal A. , Papirer E. , Donnet J. B. 
Published: April 2003

AbstractComparison between fumed and precipitated silicas in their interactions with an oligomer of poly(dimethylsiloxane) showed both materials to exhibit general identical behavior depending on the experimental temperature range. However, the results obtained suggest on the one hand that these interactions are directed more by morphological and structural characteristics than by chemical properties and on the other hand that the distribution of surface silanol groups on precipitated silicas is not the same as on fumed silicas. Both siloxane‐modified fillers exhibit high thermal stability.
Effect of container diameter on β‐radiation‐induced polymerization of acrylamide
Authors: Verma Satyajit , Callihan Clayton D. , McIlhenny Robert C. 
Published: April 2003

AbstractBeta particles emitted by radioactive nuclei have a finite depth of penetration in a given medium and hence a certain linear energy transfer value depending upon their initial energy. This property can be utilized to achieve different rates of radiation induced reactions. Various diameter capillaries containing saline solutions of acrylamide and radioactive phosphorus‐32 were used in the experiment and the change in viscosity of acrylamide solution was used as an indicator of the amount of energy transferred. Distinctly different rates were observed which were roughly proportional to the diameters of the capillaries containing the solutions. It also appears that irradiation of the polymer solution at 80°C even in the absence of oxygen has an adverse effect on the viscosity. The experimental conditions were chosen to approximate those existing in oil reservoirs.
A method of calculating copolymerization reactivity ratios
Authors: Kuo Jen‐Feng , Chen Chuh‐Yung 
Published: April 2003

AbstractAn improved linearization method is proposed for determining the monomer reactivity ratios of free‐radical copolymerizations by fitting the data of cumulative copolymer compositions and overall weight fractional conversions, or cumulative copolymer compositions and residual monomer compositions of the reaction mixture. The reactivity ratios of monomers for four different copolymerization reactions are determined. The results are very close to those of literature reports and account well for the experimental results.
Surfactant interactions in poly(vinyl acetate) and poly(vinyl acetate–butyl acrylate) latexes
Authors: Vijayendran B. R. , Bone T. , Gajria C. 
Published: April 2003

AbstractSaturation adsorption and penetration adsorption of several anionic surfactants at model poly(vinyl acetate–;acrylate) latex/water interfaces are described. The effects of molecular weight and structure of anionic surfactants, latex composition, and the presence of adsorbed layers on latex particles on penetration type surfactant interactions leading to the formation of solubilized polymer–surfactant complex and latex thickening are considered. In the case of saturation‐type adsorption of nonionic surfactants, surfactant adsorption at a vinyl acrylic latex/water interface is correlated satisfactorily with the polarity of polymer surface, in agreement with earlier surfactant adsorption studies.
Gamma irradiation of polypropylene fibers in the presence of carbon tetrachloride
Authors: Ramanan G. , Rao M. H. , Rao K. N. 
Published: April 2003

AbstractPolypropylene (PP) fibers have been irradiated with 60Co γ rays in the presence of carbon tetrachloride, in the absence of oxygen. Irradiations have been carried out between dose rates of 0.078 and 0.664 Mrad/hr, and the effects of absorbed dose and temperature on the CCl formation in the PP fibers have been investigated. G(CCl) values were higher at lower dose rate. G(HCl) values were found to be much higher than the G(CCl) values, and IR absorption studied indicated increasing unsaturation with increasing dose. The number average molecular weights (M̄n) were evaluated from intrinsic viscosity measurements in decalin at 408 K and the M̄n values decreased with increasing dose and temperature. G(scission) − G(crosslinking) values were calculated and it was found that the Gs − Gx values are higher at lower doses and higher dose rates. The thermal characteristics of the irradiated fibers were investigated by thermogravimetry (TG) analysis in air or argon and with differential scanning calorimetric (DSC) studies. The TG data indicated slightly less thermal stability for the modified fibers both in air as well as argon. The DSC data indicated very little change in the melting points of the samples, the melting points being around 444 ± 2 K.
Catalytic effect of a portland cement filler on the cure of water‐compatible resorcinol phenol–formaldehyde polymer concrete
Authors: Sugama T. , Kukacka L. E. , Horn W. 
Published: April 2003

AbstractAggregate with a water content <1 wt % is normally needed for the production of polymer concrete (PC). This increases the cost and complexity of the process. In this study, PC with a compressive strength of >2000 psi (>13.78 MPa) at an age of 1 hr at 24°C was produced by mixing resorcinol phenol–formaldehyde (RPF) resin with portland cement and aggregate containing 1–10% water. The addition of ∼14.7–17.5% type III portland cement to the PC formulation produced an acceleration in the rate of the condensation‐type polymerization reaction and improved the properties of the composite. The cause of the accelerative effect was found to be the electropositive bivalent metallic ions of calcium and magnesium released from the cement grains in an aqueous medium. Conversely, the trivalent metallic ions from cement such as Al3+ and Fe3+ have no effect on the rate of polymerization of RPF resin.
Reaction with metal ions of chloromethylated polystyrene resin containing dithiocarbamate group
Authors: Hiratani Kazuhisa , Onishi Yasuhiro , Nakagawa Tsutomu 
Published: April 2003

AbstractThe derivatives of poly(chloromethylstyrene) resin (PCMS) with N‐methyl‐N‐carboxylmethyl‐dithiocarbamate (1), N,N‐di(β‐hydroxyethyl)dithiocarbamate (2), N‐methyl‐N‐carboxylmethylamino (3), and di(β‐hydroxyethyl)amino (4) groups were prepared, and the metal ion reactivity of the polymer resins with these functional groups were investigated. Additionally, the effect of γ irradiation on the reaction with metal ion was also investigated. In the reaction of PCMS under the same conditions, the substitution ratio order is as follows: (2) > (1) > (4) > (3). In the reaction of the resins with cupric ion, the reaction amount reached a maximum of 4.17 mequiv/g for resin (1) and 4.75 mequiv/g for (2). The polymers containing sulfur atom have a large reactivity toward metal ion in comparison to the polymers without sulfur atom. The reactivity of polymer (1) toward metal ions decreased in the following order: Ag(I) ≫ Cu(II)> Zn(II) ≳ Ni(II) ≳ Co(II). The other metal ions, except Ag(I) and Cu(II), hardly reacted with polymer (2). Thus, polymer (2) has a remarkable selectivity. It was also found that the reaction amount of polymers containing sulfur after γ irradiation is almost the same as that before γ irradiation.
Rapid measurements of elastic modulus and density in polypropylene sheet during aging
Authors: Baum J. S. , Schultz J. M. 
Published: April 2003

AbstractNew methods for rapidly obtaining elastic modulus and density measurements during isothermal polymer aging are given. The elastic measurements are performed using a Rockwell hardness tester. In this case, the elastic recovery is measured. Rapid density measurements are performed using a “double drop” density gradient columan method. Here, a fully aged and a freshly quenched specimen are dropped simultaneously into the column. Simultaneous column height differences directly measure the density difference of the two specimens. The results of these two experiments extend previously reported aging measurements to relatively low times of aging. A log (time) law for both properties is found to the smallest times measured.
Studies on suspension and emulsion. XLVI. Emulsifier‐free emulsion polymerization of styrene in acetone–water
Authors: Okubo Masayoshi , Yamada Akira , Shibao Susumu , Nakamae Katsuhiko , Matsumoto Tsunetaka 
Published: April 2003

AbstractEmulsifier‐free emulsion polymerization of styrene in acetone–water medium was carried out using potassium persulfate as initiator. Below acetone content of 40 vol %, stable emulsion was prepared and polymerizations were remarkably fast compared with those in pure water. The particle size decreased from 0.5 to 0.17 μm with an increase in acetone content in the range 0–40 vol %, and the distributions were very sharp. The optimum polymerization for the preparation of the stable emulsion was: styrene, 20 vol %; acetone/water, 40/60 (v/v); KPS, 3.4 × 10−3 mole/l; temp., 90°C.
Glass‐reinforced composites of antifouling organotin epoxy polymers
Authors: Subramanian R. V. , Williams R. S. 
Published: April 2003

AbstractThe use of a new class of thermoset organotin epoxy polymers as matrix resin for composites has been evaluated. Copolymers of maleic anhydride with hexene‐1, decene‐1, or styrene were partially esterified with tributyltin, and the residual carboxyl groups were crosslinked with glycidyl methacrylate when preparing glass fabric‐reinforced composites. Glass composites were also prepared from DGEBA cured by tributyltin 3,5‐diaminobenzoate. The tensile, flexural, and impact strengths of the composite specimens warrant their use in structural applications requiring antifouling protection.
Local disturbances preceding a running crack front in a viscoelastic solid
Authors: Kobayashi Akira , Munemura Masayuki , Ohtani Nobuo 
Published: April 2003

AbstractThe local disturbances ahead of a running crack front in a viscoelastic solid were measured through noncontact electro‐optical tools. It was observed that the very high local strain rate up to 200/sec exists even in the present quasistatic loading case. It may be concluded that the running crack propagation velocities, not the conventional average strain rates ranging from about 10−4/sec to 10−2/sec, govern the local disturbances, as the crack propagation velocities always exceed 200m/sec for both average strain rates, while the local strain rates observed do not show much differences between both average strain rate cases.
Electric strength of epoxide resins and its relation to the structure
Authors: Takahama Takashi , Hayashi Osamu , Sato Fumihiko 
Published: April 2003

AbstractEpoxide resins having various ratios of ether and ester bonds were investigated as to the relation between electric strength and polymer characteristics. The electric strength over a wide range of temperature is presented here. A marked reduction of strength characteristics of the epoxide resins occurs at a critical temperature indistinguishable from the glass transition temperature Tg, which is related to the free volume and molecular relaxation process. At temperatures exceeding Tg, the electric strength has a strong dependence on polymer structure, film thickness, and applied pulse width. This behavior is considered to obey the thermal breakdown mechanism, and it is assumed that the ion is important in the precursory region of electric breakdown.
Permeation of gases through modified polymer films. V. Permeation and diffusion of helium, nitrogen, methane, ethane, and propane through γ‐ray crosslinked polyethylene
Authors: Macdonald R. W. , Huang R. Y. M. 
Published: April 2003

AbstractThe permeation and diffusion of helium, nitrogen, methane, ethane, and propane through γ‐irradiated polyethylene films were investigated. These studies were carried out with two objectives in mind: (1) to determine the effect of crosslinking by γ irradiation on permeability and diffusivity using the gas molecules as molecular probes; and (2) to study the plasticizing effects of the low hydrocarbons on the polyethylene film. The γ‐ray‐induced crosslinking efficiency of polyethylene was investigated in the following irradiation atmospheres: vacuum, acetylene, and nitrogen–acetylene mixtures. Results showed that irradiation in acetylene decreased the crosslinking efficiency while an acetylene–nitrogen atmosphere increased the efficiency compared to irradiation in vacuum. Both the permeation constants and the diffusion coefficients were found to decrease with increasing irradiation dose while the activation energies increased. The permeation constants of the organic gases through polyethylene increased with molecular diameter while the diffusion coefficients decreased. This increase in permeability was attributed to an increase in the solubility due to solubilization of the membrane by the penetrant. For example, the molecular diameter of propane is 4.397 Å compared with 2.807 Å for methane; however, propane permeated the polyethylene film at a rate twice that of methane. Nitrogen and methane have approximately the same molecular diameters—2.7085 and 2.807 Å, respectively—but owing to the plasticizing effect of methane, it permeated the film at a rate three times greater than that of nitrogen. It is interesting to note that the stronger the plasticizing ability of the penetrant, the greater the effect of the irradiation dose. The permeability of propane decreased by 40.7%, while the permeability of helium decreased by 6.4% after an irradiation dose of 50 Mrad.
Solubility of isobutane in two high‐density polyethylene polymer fluffs
Authors: Parrish W. M. R. 
Published: April 2003

AbstractSolubility and rate of desorption of isobutane vapor in high‐density polyethylene (HDPE) polymer fluff and a HDPE‐hexene‐1 copolymer fluff for isotherms between 65.5 and 93.3°C are reported. The data were obtained for pressures to near the vapor pressure of isobutane. Solubilities were correlated using Henry's law, Flory–Huggins theory, and weight fraction activity coefficients. The last approach gave the best correlation of data over the entire temperature and pressure range. The estimated rate of sorption of isobutane is 1.5 × 10−4 mol iC4H10/g fluff/bar/min over the range studied.
Cellular affinity of polyamides having various functional groups. I. Platelet adhesion
Authors: Ogata Naoya , Sanui Kohei , Tanaka Hozumi , Takahashi Yoichi , Sakurai Yasuhisa , Akaike Toshihiro , Okano Teruo , Kataoka Kazunori 
Published: April 2003

AbstractVarious polyamides having a different density of hydrogen bonding, of hydrophilic character, and containing ionic groups have been synthesized and their blood compatibilities were evaluated in terms of the adhesion behavior of blood platelets on polyamide by the microsphere column method. Polyamides containing anionically charged groups such as carboxylate or sulfonate groups adsorbed fewer blood platelets than those with undissociated carboxylate groups. Polyamides having thioether groups adsorbed fewer platelets than those having ether groups. Introduction of a rigid piperazine unit caused an increase in platelet adhesion.