bluuebunny/crossref_metadata_2025_split huggingface dataset:
Formation and decomposition of zinc cellulose xanthate in acid media
Authors: Svensson Sven , Törnell Bertil 
Published: April 2003

AbstractComplex formation between zinc (5 × 10−2−5 × 10−4M) and cellulose xanthate and its effect upon the rate of dexanthation by 0.25M sulfuric acid were studied. The determinations were based on spectrophotometric measurements on dilute solutions of cellulose xanthate with γ‐numbers from 140 to 30. The results showed that the tendency of the xanthate groups to enter into complexes with zinc increased as the γ‐number decreased. The stabilization toward decomposition by acid produced by complex formation was also found to vary with the γ‐number and was much smaller at low than at high γ‐numbers. These findings indicate that cellulose xanthate, because of local differences in the steric arrangement of potential ligand groups along the molecule, can form a whole set of zinc complexes, differing in thermodynamic stability and reactivity toward acid.
NMR study of adsorbed water on acrylic acid‐grafted and methacrylic acid‐grafted cellulose
Authors: Ogiwara Yoshitaka , Kubota Hitoshi , Hayashi Shoichi , Sekine Kiyoharu 
Published: April 2003

AbstractThe water‐adsorbing properties of cellulose samples which had been graft copolymerized with hydrophilic vinyl monomers using ceric salt as an initiator were investigated by means of the width of the high‐resolution NMR absorption spectrum, water retention, and moisture regain of the samples. In the change of the width at half‐value of the spectrum with per cent grafting, a maximum value followed by a minimum value was observed on samples both grafted with acrylic acid and methacrylic acid. Thus, the effect of grafting on the water‐adsorbing properties appeared not to be simple. Though no special change in the water retention by grafting was observed, the per cent grafting dependence on the moisture regain in high relative humidity showed a peculiar and definite relation. The per cent grafting giving maximum moisture regain was about 8% and 18% for acrylic acid and methacrylic acid, respectively, and this agreed very well with the minimum widths at half‐value. The change in the glass transition temperature of the sample—water system caused by grafting is also described.
Polydisperse polymers: Relations among molecular weight distribution, stress relaxation, and distribution of relaxation times
Authors: Menefee E. 
Published: April 2003

AbstractRelaxation times in polydisperse polymers were calculated on the basis of more realistic viscosity mixing rules than have previously been used. These relaxation times and mixing rules are in turn used to calculate viscoelastic functions such as stress relaxation following sudden straining or steady shearing. Inversion of these functions provides an accurate way to estimate the molecular weight distribution. This method is useful for insoluble or otherwise intractable polymers.
Study of dynamic mechanical properties of poly(vinyl chloride)–ethylene vinyl acetate copolymer and poly(vinyl chloride)–chlorinated ethylene vinyl acetate copolymer mixtures
Authors: Marcinčin K. , Romanov A. , Pollák V. 
Published: April 2003

AbstractThe compatibility of the mixtures poly(vinyl chloride)—ethylene vinyl acetate copolymer and poly(vinyl chloride)—chlorinated ethylene vinyl acetate copolymer was studied by the method of dynamic mechanical testing. The character of G′ and G″ was confronted with the Takayanagi model. In all cases a limited compatibility of the components was observed.
Rubber elasticity on chemical relaxation
Authors: Murakami Kenkichi , Hisue Gin‐ho 
Published: April 2003

AbstractThe applicability of the formula f(t) = n(t)RT(α − α−2) suggested by Tobolsky as the basis of chemorheology has been discussed. In this expression, f(t) is the stress after t hours, n(t) is the crosslinking density (mole/cc) after t hours, R is the gas constant, T is the absolute temperature, and α is the extension ratio. We have discussed the applicability of this formula, in another words, whether the degraded stress f(t) calculated from this formula would be consistent with the initial stress ft(0) of other polymer if the degraded crosslinking density values n(t) are equal to those of nt(0), the initial density values n(0) of other polymer. Natural rubber vulcanizates and SBR vulcanizates were used as samples in these experiments. Assuming n(t) = σ(t) n(0), α(t′) = 1, the applicability of the above formula was recognized from our experimental results.
Performance relationships in PVC–plasticizer dry blending
Authors: Glass J. E. , Fields J. W. 
Published: April 2003

AbstractThe phenomenon of plasticizer acceptance by poly(vinyl chloride) (PVC) in hotprocess dry blending is examined via scanning electron microscopy, mercury intrusion porosimetry, and torque rheometer measurements. The effects of granule porosity, resin molecular weight, and synthesis recipe in PVC manufacture by the suspension process are related to the rate of plasticizer acceptance. For a PVC resin to dry blend, i.e., to become a free‐flowing powder when mixed with plasticizer under hot‐processing conditions, the resin granules must be porous. Porosity arises from interstices between primary PVC particles. At a given granule porosity, an increase in primary particle agglomeration adversely affects dry blend performance. At constant molecular weight and for resins manufactured by a given recipe, dry‐blend performance is quantitatively described by granule porosity. With an increase in resin molecular weight, a greater granule porosity is required to maintain an equivalent dry‐blend time (DBT). Accordingly, for most suspending agent recipes, DBT is dependent directly upon granule porosity and inversely upon molecular weight. However, if the suspending agent used in resin manufacture is an excessively rapid film former, dry‐blend performance with molecular weight variation is dependent upon the suspending agent's concentration, not upon granule porosity, which must be adequate, nor upon the resin's molecular weight. An interfacial film‐forming suspending agent enhances fusion of primary PVC particles at the suspension granule—water interface, increasing the granule's “pericellular membrane” thickness. This membrane, a PVC skin, does not significantly influence dry‐blend performance with low‐ or intermediate‐viscosity plasticizers. The particle skin does impede dry‐blend rates with high‐viscosity, poorly solvating plasticizers, but this effect can be negated in part by increasing the diameter of pore openings in the topographical skin. Dry blending occurs below the glass transition temperature (Tg) of PVC with low‐viscosity plasticizers and above the Tg with high‐viscosity, poorly solvating modifiers. The influence of resin and plasticizer variables indicates the dry‐blend phenomenon to be a diffusion‐controlled process. The rate of dry blending is dependent upon two mechanisms: (1) the rate of pore penetration—which exposes the plasticizer to a much greater surface area than if it remained exterior, encapsulating the granule—and (2) the rate of plasticizer diffusion into the PVC matrix.
The plasma polymerization of vinyl monomers. I. The design, construction, and operation of an inductively coupled plasma generator and preliminary studies with nine monomers
Authors: Thompson L. F. , Mayhan K. G. 
Published: April 2003

AbstractAn apparatus was constructed which would allow vinyl‐type monomers (and others) to polymerize at ambient temperatures in the presence of an inductively coupled RF field. The details of the construction of the system are reported along with preliminary results obtained from nine monomers: styrene, methylvinyldichlorosilane, vinyl acetate, acrylonitrile, vinyl fluoride, 1,1‐difluoroethylene, vinyl chloride, ethylene, and 1,3‐butadiene.
The plasma polymerization of vinyl monomers. II. A detailed study of the plasma polymerization of styrene
Authors: Thompson L. F. , Mayhan K. G. 
Published: April 2003

AbstractA study has been made on the plasma polymerization of styrene monomer in a cold, low‐power, inductively coupled RF plasma. Styrene monomer yielded an insoluble, crosslinked film which was slightly colored. A kinetic study is reported for styrene. The effects of power level, bleed rate of monomer, pressure, and reactor geometry on the rate of polymer formation are reported. A mechanism is postulated for plasma polymerization. It was found that the initiation step was the rate controlling step and that the reaction followed a cationic polymerization scheme. Both crosslinking and discoloration of the polymers occur at the time of polymerization and are not a result of exposure of the reacted polymer to the plasma. The polymerization was shown to take place in the bulk phase as well as on the reaction wall surfaces.
Use of a gee relationship in a diffusion study
Authors: Schneier B. 
Published: April 2003

AbstractPaul and Ebra‐Lima6 reported on the pressure‐induced transport of 12 organic liquids through a highly swollen rubber membrane. Gee10 examined the capability of a liquid to swell a rubber and the interaction between liquid and rubber from the standpoint of the Hildebrand‐Scatchard solubility parameter. In this presentation, the swelling function of Gee was expressed by [V0(δ0 − δr)2(1 − v0)2]1/2 where V and δ are the molar volume and solubility parameter of the liquid 0 and the rubber r and (1 − v) represents the volume fraction of rubber when the rubber is fully swollen by that liquid. The data of Paul and Ebra‐Lima are analyzed in terms of the swelling function. It is principally assumed that the flux is a function of the swelling power of the liquid. The analysis indicates that the use of the Gee relationship provides values for the energetics of the various steps in the transport process and a means for differentiating between various types of penetrant liquids.
Determination of the photocatalytic activities of titanium dioxides and other white pigments
Authors: Irick Gether 
Published: April 2003

AbstractTitanium dioxide, zinc oxide, and other white pigments are widely used in protective coatings and textile applications. An undesirable property of such pigments is their behavior as photo‐oxidation catalysts. As a measure of the activities of various pigments, quantum yields were determined for the photo‐oxidation of isopropyl alcohol to acetone in a system where the pigment was the only absorbing species. An absolute quantum yield of 0.5 was found for reagent‐grade anatase; relative quantum yields were determined for various commercial anatase and rutile titanium dioxides, zinc oxide, barium sulfate, and barium tungstate. A good correlation was found between the photodegradation rates of pigmented polypropylenes, the photodegradation rates of the dyes in pigmented cellulose acetate butyrate, and the activities of the pigments determined by the isopropyl alcohol oxidation method.
Surface crosslinking of polyethylene using a hydrogen glow discharge
Authors: Hudis Martin 
Published: April 2003

AbstractLinear high‐density polyethylene is crosslinked by exposing it to a hydrogen glow discharge and alternatively by exposing it to a low‐pressure Hg–A ultraviolet lamp in a dry nitrogen atmosphere. For the UV lamp case, the crosslinked gel is measured as a function of the radiation dose. For the plasma case, the crosslinked gel is measured as a function of the exposure time. The two gelation curves are alternatively compared to an exponentially attenuated light theory and a diffusion theory. Excellent agreement exists between the measured gel‐versus‐dose curve and the theoretical curve based on the light theory for a monochromatic light beam at 1849 Å. The gelation curve for the hydrogen glow discharge case can be explained using the identical theory but applied to a spectrum of light covering the range from 1200 Å to 1900 Å. The different curves can be explained in terms of the different spectra. Energy transfer between the plasma and the polymer due to excited atoms, and/or charged particles, is not required to account for the different gel curves.
Photodepolymerization of hydroxypropylmethylcellulose
Authors: Davies D. H. , Dixon G. D. 
Published: April 2003

AbstractThe light‐induced degradation of aqueous hydroxypropylmethylcellulose (HPMC; D.S. 1.9) solutions has been investigated under a variety of conditions. The HPMC was sensitized to short‐wavelength radiation (<500 nm) by the addition of sodium nitrite, the degradation being accompanied by increased acidity and the generation of oxides of nitrogen. Addition of eosin dye increased the sensitivity to visible light (>500 nm), and the effect was considerably more pronounced when strong electron donors were added. Analysis of the shear–viscosity relationship of the solutions, during the degradation, indicated that both chain disentanglement and chain scission occurred but that the primary process was the depolymerization of the cellulose chain. It is proposed that both the dye‐ and nitrite‐induced depolymerizations are a consequence of peroxide attack on the β‐glucosidic ether link. The results indicate that, in the case of sodium nitrite addition, the peroxide was generated by the aqueous photolytic decomposition of the nitrite ion. The peroxide formation in the eosin—TEA system was a consequence of leuco‐dye production, under the influence of the light, followed by the reduction of traces of dissolved oxygen by this activated dye.
Degradation of poly(vinyl chloride). II. Kinetic investigation of thermal and radiation‐induced polyene formation at low temperatures
Authors: Palma G. , Carenza M. 
Published: April 2003

AbstractThe degradation arising from purely thermal treatments as well as with accompanying exposure to γ‐radiation has been followed under vacuum by visible and ultraviolet spectroscopy in the temperature range from 80° to 130°C. As corroborated by extensive literature reports, absorbance changes have been considered suitable to provide valuable information on the unsaturation sequences produced. In agreement with the results obtained in the same conditions by following the evolution of HCl,1 a catalytic action has been ascribed to HCl depending on the efficiency of removal of HCl. Furthermore, both the purely thermal and radiation‐induced uncatalyzed degradations yield length distribution functions that are constant with time and have been found to be accounted for by the previously formulated free‐radical mechanism, also from a quantitative point of view.
Prediction of polymer degradation kinetics at moderate temperatures from tga measurements
Authors: Papazian H. A. 
Published: April 2003

AbstractThermal degradation under vacuum, as measured by weight loss of polymer, has been studied for a variety of polymers and composites. Small‐sample (∼10 mg) TGA studies have been made on polymeric materials. Isothermal studies, at much lower temperatures, have been made on the same materials of much larger size and weight (4–6 g). Comparison of the results shows that TGA can accurately predict the isothermal kinetics.
The effects of initial nonconstant transient cross‐head speed on the stress–strain curve of viscoelastic material
Authors: Kobayashi Akira , Ohtani Nobuo 
Published: April 2003

AbstractThe effects of initial nonconstant transient cross‐head speed inherent to every tensile tester, especially in high‐speed tension, on the shape of stress–strain curves of viscoelastic materials were studied. In case of brittle polymers, the specimen was subjected to variable strain rates throughout the test loading, although the constant strain‐rate tension is planned, since the cross‐head speed stays within the initial nonconstant transient range due to its small total elongation until fracture and never reaches the prescribed constant cross‐head speed achieved after considerable cross‐head travel. As the polymers were quite strain‐rate sensitive, it was necessary to employ a device to extend the specimen at constant strain rate, i.e., the constant cross‐head speed from the beginning to obtain the stress–strain curve at the exactly prescribed constant strain rate for such brittle polymers. The “slack grip” concept was then introduced and its effectiveness was experimentally verified. In conclusion, the effects of such initial transient cross‐head speed are not negligible for brittle polymers and can be avoided by using the “slack grip.”
Properties of dexsil 300 rubbers
Authors: Mininni Robert M. , Tobolsky Arthur V. 
Published: April 2003

AbstractThe physical and elastomeric properties of several DEXSIL 300 (10‐SiB‐3) samples were investigated. Modulus—temperature studies were used to determine the glass transition temperature Tg, the melting temperature Tm, and the oxidative crosslinking temperature Tox. Stress relaxation in air at elevated temperatures was used to compare the oxidative stability of the various formulations. It was found that the Tg of DEXSIL 300 is some 30°C lower than that of DEXSIL 200 (10‐SiB‐2) polymers, extending the elastomeric properties of DEXSIL 300 to lower temperatures. At high temperatures, both silica filler and ferric oxide are found to increase Tox to an ultimate value of 320°C. The effects of cure were also investigated, and γ‐radiation‐cured samples exhibit a slight degree of crystallinity with a melting temperature Tm = +40°C. No crystallinity was detected in similar peroxide‐cured samples. Stress relaxation results are presented in support of the modulus—temperature studies. Formulations with a low Tox show oxidative effects earlier than those with a higher oxidation temperature. Silica‐and ferric oxide‐filled samples exhibit improved oxidative stability, as do samples filled with diphenylsilanediol.
Characterization of networks from the peroxide cure of polybutadiene
Authors: Hergenrother W. L. 
Published: April 2003

AbstractPolybutadienes with molecular weights varying between 12,500 and 92,000 and containing from 23.4% to 93% 1,2‐structure were cured with 1 to 8 parts per hundred of dicumyl peroxide at temperatures ranging from 130° to 175°C. The cured samples were swollen in toluene and the crosslink densities were determined by application of the Flory‐Rehner equation. The unsaturation remaining after cure was measured by infrared and was found to be in good agreement with the unsaturation level calculated from the swelling data. From these measurements it was found that a molecular weight between crosslinks of less than 100 g/mole could be obtained. The number of double bonds consumed per radical formed was found to vary from 6 to 185. The highest values were obtained with polymers highest in 1,2‐content cured with the lowest initiator levels and at the lowest temperatures.
Submicron polymer powder in electrodeless radio frequency‐induced plasma‐initiated polymerization
Authors: Liepins R. , Sakaoku K. 
Published: April 2003

AbstractOf the 30 monomers and monomer combinations investigated, 11 were polymerized into essentially all powder, 17 into predominantly a film, and two could not be polymerized in an electrodeless rf plasma‐initiated gas phase polymerization. Efficient powder formation was mainly determined by the type of the monomer, the monomer partial pressure, the type of inert gas used, and the design of the polymerization chamber. The powders examined consisted of spherical particles of submicron size and were almost completely or partially soluble; and in the case of polystyrene, the powders possesses a very narrow particle‐size distribution. In all cases, the soluble material was of a very low molecular weight. The best conversion to powder achieved was 18%.
The preparation of block copolymers of styrene and methacrylic acid
Authors: Brown C. W. , White I. F. 
Published: April 2003

AbstractA new method of preparing block copolymers of styrene and methacrylic acid is described. It is based upon use of the anionically initiated “living chain” method to prepare block copolymers of styrene and methyl methacrylate, with subsequent hydrolysis of the methyl methacrylate block to methacrylic acid.
Correlating mooney viscosity to average molecular weight
Authors: Kramer O. , Good W. R. 
Published: April 2003

AbstractCopolymers of styrene and butadiene of the same chemical conposition, but widely different molecular weight distributions, were characterized by gel permeation chromatography. A very good correlation was obtained between the logarithm of the Mooney viscosity and the logarithm of the geometric mean of the number‐ and weight‐average molecular weights. Instead of this molecular weight average, one can equally well use the very convenient “Av log M,” which is a weight‐average molecular weight, using a logarithmic molecular weight scale. This correlation makes it possible to predict the Mooney viscosity from GPC data with a precision of about 15% (± one standard deviation), independent of the molecular weight distribution of the polymer. The obtained correlation was much better than with either weight‐average molecular weight or viscosity‐average molecular weight with α = 0.67.
Radiation grafting of vinyl monomers onto wood pulp cellulose. II
Authors: Radi F. S. , Hopfenberg H. B. , Stannett V. 
Published: April 2003

AbstractThe effect of radiation dose rate and beating time on the mutual radiation grafting of styrene to unbleached and bleached kraft wood pulp was studied. Companion studies on the effect of beating time, peroxidation grafting, and order of monomer addition on the preirradiation graft copolymerization of acrylamide and diethylaminoethyl methacrylate were conducted on bleached wood pulp. The grafting rate of styrene increased with dose rate, but the kinetics suggests a significant diffusional resistance to the observed grafting rate. The per cent graft measured at fixed grafting conditions decreased markedly as pulp beating (effected prior to grafting) was increased. It is suggested that the decrease in grafting with beating is due to an increase in the accessibility and swelling of the beaten fibers. Dimethylaminoethyl methacrylate appeared to inhibit the grafting of acrylamide, and double grafting had to be used to graft both hydrophilic polymers to the pulp. The mechanical properties of high‐yield pulp and groundwood were improved by the addition of the grafted pulps. The double grafts appeared to show promise as fibrous beaten additives for dry strength improvement. The styrenegrafted pulps were found not to respond at all to the beating process.
Modification of poly(vinyl chloride). XIX. Electroplating of poly(vinyl chloride)
Authors: Nakamura Yoshiro , Mori Kunio , Sugimoto Kazumi , Tamura Kosaku , Saito Yoshiko 
Published: April 2003

AbstractAs a preliminary treatment in the PVC‐electroplating procedure, treatment with dimethylformamide followed by sensitization leads to a finely roughened and a highly hydrophilic surface with reducing power. This is caused by the formation of an ionic complex compound between dimethylformamide and tin(II) chloride absorbed in the PVC surface. A much more finely and deeply etched surface which exhibits higher adhesion through the mechanical interlocking effect is obtained with the PVC blends containing the plasticizer with a low value of interaction parameter and with a solubility parameter approximate to that of PVC. Adhesion of the metal layer to the PVC surface thus obtained is improved about 1.5 times by thermal aging at 120°C for 20 min.
Electrochemical behavior of a snake‐cage cation exchange membrane. Membrane potential
Authors: Jerome R. , Desreux V. 
Published: April 2003

AbstractMembrane potential differences of a polymethacrylate–polyacrylamide snake‐cage membrane were measured at 25°C. The principal theories of membrane potential have been tested. The fixed‐charge theory is only valid in a range of high membrane permselectivity. The relation developed by the kinetic approach and the thermodynamics of irreversible processes verify the experimental results, but the calculation of some parameters, often improperly assumed to be constant, is not unquestionable. Quasithermodynamics (Scatchard's relation) probably give the best estimates of the membrane potential on the basis of the independent values of transport numbers of counterion and water.