bluuebunny/crossref_metadata_2025 huggingface dataset:
Freezing and nonfreezing water in cellulose acetate membranes
Authors: Frommer Moshe A. , Lancet Doron
Published: April 2003

The relative amounts of freezing and nonfreezing water in various cellulose acetate (CA) membranes were determined by differential scanning calorimetry. It was found that: (1) A significant fraction (17–40%) of the water (1.0–3.1 g H2O per gram dry CA) in any membrane does not freeze at temperatures as low as −60°C. (2) The amount of nonfreezing bound water (0.4–0.7 g nonfreezing water per gram dry CA) depends upon the nature of the membrane and is significantly higher than the total amount of water (all of which is nonfreezing) absorbed from liquid water by a dense film of the same polymer (∼0.18 g water per gram dry CA). The structures of the membranes were studied by scanning electron microscopy. The results suggest that the amounts of nonfreezing water in cellulose acetate membranes decrease with the increase in the packing density (compactness) of the polymer within the membrane. In dense films, the extent of polymer–polymer interactions within the polymeric matrix is high, and therefore the macromolecular chains are less accessible to bind water.
Chain conformations in cellulose I and cellulose II
Authors: Manjunath B. R. , Peacock N.
Published: April 2003

There is strong evidence in the literature that cellulose chains have different conformations, as well as forming different crystalline lattices, in cellulose I and cellulose II. New data on the birefringence of amine‐treated fibers (cellulose III) support this view.
Radiation‐induced copolymerization of vinylphosphonic dichloride with methyl methacrylate and styrene
Authors: Fujii Shigetada , Maeda Katsuaki
Published: April 2003

The γ‐ray‐induced copolymerization of vinylphosphonic dichloride (VPDC) with methyl methacrylate (MMA) and styrene (St) was studied at 25°C (liquid phase) and −78°C (Solid phase). The reaction mechanisms are discussed. The reactivity ratios for the copolymerization of the VPDC–MMA system were determined as follows:

The difference between the reactivity between the liquid‐phase (25°C) and solid‐phase (−78°C) copolymerization is mainly attributable to the r2 value. The behavior of the liquid‐phase copolymerization of the VPDC–St system was anomalous, the r1 value being negative in the range from 0 to 80 mole‐% of VPDC monomer. In the solid‐phase (−78°C) copolymerization for the VPDC–St system, the reactivity ratios r1 and r2 were 0.097 and 1.6, respectively. The rate of copolymerization (Rp) at 25°C, for both the VPDC–MMA and VPDC–St systems, passes a maximum point at a certain monomer concentration, suggesting that the composition of copolymer is considerably affected by Rp. This phenomenon was interpreted by the assumption that an energy transfer reaction from VPDC monomer to the other vinyl compound can easily occur.
Radiation‐induced graft copolymerization of mixtures of styrene and n‐butyl acrylate onto cellulose and cellulose triacetate
Authors: Matsuzaki Kei , Nakamura Shigeo , Shindo Shuichi
Published: April 2003

Mixtures of styrene and n‐butyl acrylate of various compositions were grafted onto cellulose and cellulose triacetate fibers preirradiated with γ‐rays at 0°C in air. Monomer reactivity ratios of the grafted copolymers were found to be different from those of the nongrafted copolymers or those of AIBN‐initiated copolymers. The active species initiating the graft copolymerization were trapped radicals for cellulose and peroxides for cellulose triacetate. Kinetic investigations of the graft copolymerization of styrene onto preirradiated cellulose triacetate fibers were also carried out, and it was found that the kinetic scheme for radical polymerization is also applicable to graft copolymerization in a heterogeneous system.
Bond rupture during ozone cracking of torsional loaded styrene–butadiene
Authors: Devries K. L. , Moore N. B. , Williams M. L.
Published: April 2003

The molecular bond rupture rate during ozone attack of torsionally loaded rubber was determined from electron paramagnetic resonance (EPR) measurements. The rupture rate was successfully correlated by a Griffith‐type energy balance to the strain‐energy release rate in the samples. These observations substantiate the results from a similar study on tensile loading previously reported. In both cases there is a one‐to‐one correspondence between the rate of bond rupture (or crack growth) and the rate of energy release from the strain field and external work. A fracture energy, γn, of approximately 5×10−12 (±20%) ergs per free radical formed during the cracking was experimentally determined.
Polyurethane foam process development. A systems engineering approach
Authors: Campbell Gregory A.
Published: April 2003

A seven‐step systems engineering approach is described and applied to the integral‐skin foam system. Through the use of a hybrid computer simulation of a dynamic mathematical model, the two process variables with the greatest lever on the skin‐forming process are determined. These data are then utilized to develop a new foam concept which makes it possible to control skin thickness and core foam density independently.
A new physicochemical technique for studying native and modified structures of polymer fibers: The continuous measurement of length variations, under tension, in a swelling medium of continuously variable concentration
Authors: Hagege R. , Tung Do Mau
Published: April 2003

A device for linear variation of the concentration of a binary mixture in function of time is described. This device is used to study the dimensional variations of cotton yarns immersed in an aqueous caustic soda solution under a fixed tension while the concentration is increased from 0 to 10N. This method is very sensitive and seems of particular interest for the study of fibrous polymer structures.
Effect and analysis of induced thermal stresses in a plotted cylindrical inductor
Authors: Vlastaras A. S.
Published: April 2003

Thermal stresses developed during the cooling of a cured potted inductor from higher processing temperatures, resulting from the difference in the thermal expansion coefficients of the ferrite core and the epoxy polymer, cause a drop in inductance. The inductance drop was followed with time and temperature under various conditions. An attempt is made to explain the inductance drop based on experimental observations and theoretical considerations. A mathematical model was constructed to aid the thermal stress analysis at the ferrite core–polymer interface. It is shown that lower‐temperature epoxy curing results in greater stresses (inductance drop) than higher‐temperature curing.
Composite permselective membrane by desposition of an ultrathin coating from a plasma
Authors: Stancell A. F. , Spencer A. T.
Published: April 2003

Permselectivity was vastly improved when ultrathin crosslinked coatings, of the order of 0.5 microns thick, were deposited from a plasma onto relatively permeable film substrates. In one example, the hydrogen‐to‐methane permeability ratio was increased from 0.87 to 33, and the hydrogen permeability was decreased by just 20% when benzonitrile was plasma deposited onto a silicone–carbonate copolymer film. In another example, the hydrogen‐to‐methane permeability ratio was increased to 297 when cyanogen bromide was plasma deposited onto a poly(phenylene oxide) film. Such coatings, while effective for the hydrogen/methane pair, had little effect on modifying film permselectivity for isobutene/butene‐1, a pair nearly identical in molecular size and solubility. It appears therefore that the coatings can very effectively distinguish between molecules differing significantly in size. Also, since the coatings are so thin, the overall permeability of the coating–substrate composite can be high.
Viscosity slope constants for solutions of nylon 6 and polytetrahydrofuran
Authors: Howard N. , Huglin M. B. , Richards R. W.
Published: April 2003

Measurements of the viscosity slope constant k were made on solutions of nylon 6 and polytetrahydrofuran under different conditions of temperature, solvent, and molecular weight of polymer; θ‐conditions were included so that the expansion factor α could be determined in each case. The value of k was influenced somewhat by the particular equation employed to derive it, and generally the Schulz‐Blaschke equation (yielding kSB) was the most reliable. Slope constants (kcalc) calculated according to an expression of Sakai were plotted as a function of α3 and were compared with the corresponding curves in terms of experimental values of k. The agreement was moderately good for PTHF but poor in the case of nylon 6. An expression (due to Imai) involving experimental values of k and α was examined in order to establish a unique value of the slope constant kθ under θ‐conditions by an extrapolation procedure. Although individual value of kθ for nylon 6 measured under θ‐conditions were dependent on molecular weight, the Imai plot yielded a unique value of 0.50 and a slope similar in magnitude to that found for other polymer/solvent systems.
Cross‐checking between dielectric measurements, DTA, and other methods of thermal analysis in research and production
Authors: Yalof S. , Wrasidlo W.
Published: April 2003

Differential thermal analysis, or DTA, is a technique for determining the properties of materials from the thermodynamic and kinetic points of view. Dielectric measurement is also a powerful tool for probing the structure of materials, but from another direction. Dielectric analysis is a measure of the dipole response within dielectric materials to an applied electric field. This response is controlled by the spatial arrangement and viscoelastic properties of dielectric materials. Dielectric thermal analysis is being increasingly used in research and process control, offering the advantages of being nonobtrusive and easily instrumented and having a broad theoretical basis which can be correlated with results from other methods such as dynamic mechanical relaxation measurements, NMR, neutron relaxation, birefringence, and, of course, DTA. Because of the nonobtrusive nature of dielectric measurement, it can be run concurrently with other analytical techniques without disturbing their results. When dielectric analysis is run concurrently with other methods of analysis such as DTA, we often receive fresh insights and cross‐checking on such behavior as polymeric crosslinking, molecular weight increase, and Tg—viscoelastic behavior in general. The results and conclusions drawn for such investigations are described.
Effect of entrance geometry on the capillary flow of cellulose acetate–acetone solution
Authors: Chen F. C.
Published: April 2003

Capillary flow data were obtained for a 27.5% solution of cellulose acetate in acetone. The solution temperature was 50°C, and the range of apparent shear rates investigated was 1.7 × 105 to 1.7 × 106 sec−1. Capillaries having tapered entrance angles of 37.88° to 120.63° were used. A power‐law model was adequate to describe the shear stress at the wall (τw) and the corrected shear rate \documentclass{article}\pagestyle{empty}\begin{document}$(\dot \gamma )$\end{document} relationship. Entrance angle affected the entrance pressure drop corrected for kinetic energy, (ΔP0,c); ΔP0,c increased as the angle widened. Treating the entrance flow as an elongational flow situation facilitated superposition of the Delta;P0,c data on a single curve. Estimated elongational viscosities decreased with increasing applied stress.
Formation and decomposition of zinc cellulose xanthate in acid media
Authors: Svensson Sven , Törnell Bertil
Published: April 2003

Complex 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

The 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

Relaxation 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

The 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

The 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

The 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

An 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

A 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

Paul 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

Titanium 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

Linear 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

The 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

The 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

Thermal 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

The 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

The 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

Polybutadienes 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

Of 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

A 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

Copolymers 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

The 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

As 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

Membrane 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.
Kinetic analysis of the radiation polymerization of methyl methacrylate–kaolin clay composites
Authors: Beeson J. J. , Mayhan K. G.
Published: April 2003

In the first of a two‐part series, a kinetic study has been made on the effects of gamma rays (60Co) in air and inert gas on the polymerization of a 50:50 weight‐mixture methyl methacrylate (MMA)–kaolin clay system. The effect of dose rate (7.35–24.9 rads/sec), temperature (25° to 75°C), and total dose on the percentage conversion of monomer to polymer was studied. The rate of formation of polymer at 25°C in the composite system was found to be faster when compared to a bulk MMA system at the same dose rate. This acceleration showed that the clay had a catalytic effect on the formation of polymer. The effect decreased as temperature increased. Two types of poly(methyl methacrylate) (PMMA) were formed in the composite. One type was called homopolymer and could be removed from the composite by extraction with organic solvents. The other type was called inserted polymer and could only be removed by dissolving the clay matrix with hydrofluoric acid. The total polymer conversion was the summation of these two types of polymer formed. The kinetic analysis examined the orders of reaction and activation energies of the homopolymer, inserted polymer, and total polymer. The initial reaction orders of the homopolymer and total polymer based on dose were −0.46 and −0.49, respectively. These indicate a definite free‐radical reaction. The reaction order of the inserted polymer was temperature dependent.

The activation energies for the homopolymer and total polymer in both atmospheres were approximately 1 kcal/mole less than the bulk activation energy at the same conditions. The inserted polymer had an activation energy which was dose rate dependent.
Characterization of poly(methyl methacrylate) from radiation‐induced polymerization in the presence of a kaolin clay substrate
Authors: Beeson J. J. , Mayhan K. G.
Published: April 2003

Two types of polymer are formed in the radiation‐initiated polymerization of methyl methacrylate (MMA)–kaolin clay complexes. Homopolymer can be extracted from the complex by the use of organic solvents. Inserted polymer must be removed by dissolution of the polymer–clay complex with hydrofluoric acid. The polymers formed show no differences in structure (as determined by infrared analysis), had high molecular weights (1–5 × 106), and had similar molecular weight distributions (as determined by GPC). The molecular weights of the homopolymer increased as temperature increased (25°–75°C), and dose rate decreased (24.9–7.35 rads/sec). The isotacticity of the polymers when compared to irradiated bulk polymer decreased as follows: inserted > homo > bulk. The compressive properties of the irradiated composite compared well with those of commercial bulk polymers. Degradation temperatures were 20° to 30°C higher for the composite than for the commercial chemically initiated bulk polymer.
Solution properties and molecular structures of EPM and EPDM
Authors: Morimoto M. , Okamoto Y.
Published: April 2003

The solution properties of EPDM were investigated based on EPM as a model compound of linear molecules. The glass transition temperature and the propylene content in EPDM were measured as a function of the molecular weight. Good agreement between the solution behaviors of EPM and EPDM was observed. This was correlated to change not only in the propylene composition but also in the monomer sequence distribution.
Chemorheological treatment of crosslinked EPDM. II
Authors: Tamura Saburo , Murakami Kenkichi
Published: April 2003

Stress relaxation mechanisms were investigated on three kinds of ethylene–propylene terpolymers (EPDM), differing only in the structure of the crosslinkage, in both nitrogen and air at 160°C. The crosslinking site in these polymers consists of a carbon–carbon bond, a polysulfide linkage, and a carbon–carbon bond and a polysulfide linkage, respectively. Stress relaxation in air for peroxide‐cured EPDM was based on the oxidative scission of the main chain. Analysis of the stress relaxation data of sulfur‐cured EPDM in nitrogen indicated the presence of stable mono‐ and disulfide linkages and that the main relaxation process resulted from an interchange reaction between polysulfide linkages. In air, in addition to the interchange reaction, oxidative cleavage of mono and disulfide linkages occurred. Further, the stress relaxation for peroxide–sulfurcured EPDM polymers containing various amount of sulfur was observed in air and nitrogen and was discussed in the connection with highly crosslinked polymers.
Gel permeation and thin‐layer chromatographic characterization and solution properties of butadiene and styrene homopolymers and copolymers
Authors: White James L. , Salladay David G. , Quisenberry David O. , MacLean Donald L.
Published: April 2003

Gel permeation chromatographic (GPC) and thin‐layer chromatographic (TLC) studies of polystyrene, polybutadienes (BR), and their copolymers (SBR) have been carried out. GPC primarily separates them on the basis of molecular size, and TLC, on the basis of composition. Methods of obtaining absolute molecular weight distributions for BR and SBR based upon variations of the Strasbourg Universal Calibration procedure are described. In particular, [η]–M relationships in both the GPC solvent (THF) and in a second solvent (toluene) were used; in addition, results of statistical mechanical calculations for \documentclass{article}\pagestyle{empty}\begin{document}$\overline {s^2 }$\end{document} (based on the assumption of negligible steric hindrance and freely rotating bonds) were applied. An experimental comparison of these methods was carried out, and use of the [η]–M relationships for both solvents was found to give satisfactory results. The predictions of the statistical theory were too low. A detailed study of polymer–solvent–gel interaction in the GPC unit was made through investigation of ternary phase equilibrium in the (polystyrene)–THF–(polymer) system. The polymers studied included BR and SBR with varying styrene contents. Experimental techniques for TLC separations of BR, SBR, and polystyrene according to the composition are described.
A thermoanalytical study of chemical reactions of durable press and acrylic soil release textile finishing agents
Authors: Warburton C. E.
Published: April 2003

Chemical reactions in systems with durable press reagents and acrylic soil release polymers are analyzed using differential scanning calorimetry. Self‐condensation of N‐methylol compound is the preponderant chemical reaction when a film with 70% methacrylic acid/30% ethyl acrylate copolymer and dimethylolethylene urea (DMEU) or dimethyloldihydroxyethylene urea (DMDHEU) is heated. This reaction proceeds through formation of transitory methylene ether bridges with methylene bridges as the thermodynamically favored product. An exotherm is observed under certain circumstances in DSC thermograms of films containing DMEU or DMDHEU and is attributed to a rapid shift of methylene either to methylene bridges. Appreciable anhydride formation occurs in the polymer only above about 160–170°C. Esterification of polymer by methylol reagent probably also occurs to a limited extent, especially above about 160–170°C. Soil release of fabrics treated in a one‐bath process is often unsatisfactory because polymer is embedded in a matrix of condensed N‐methylol compound which restricts swelling of polymer and, therefore, its utility as a soil release agent. The limited extent of reaction between polymer and methylol compound is of minor importance compared with this adverse morphology. However, in some cases, ester formation may be responsible for significantly inferior soil release of fabrics cured at higher temperatures, for example 210°C/30 sec rather than 160°C/3 min. In such cases, polymer may be trapped chemically as well as physically in the resin matrix.
Thermal regeneration of the tensile properties of hydrolytically degraded polyimide film
Authors: Deiasi R.
Published: April 2003

Heat treatment at temperatures of 224° to 310°C of hydrolytically degraded polyimide film has been shown to regenerate the ultimate tensile strength from 15.1 ksi to 24.3 ksi after 80 hr at 224°C and to 25.8 ksi after 2 hr at 310°C, whereas the elongation to failure is simultaneously increased from 6.3% to 38.3% at 224°C and to 50.7% at 310°C. Prior to degradation, the film had an ultimate tensile strength of 26.6 ksi and an elongation to failure of 62.0%. The kinetics of this regeneration indicate that the reaction corresponds to the two‐step recombination of the hydrolytically attacked amide linkages that were initially present in the “as received” polyimide film. The regenerated polyimide exhibits a much improved hydrolytic stability over the untreated material and specimens heat treated directly without prior aqueous degradation.
Crosslinked polyesters from “bisacid A2.” The mechanical properties of glass fiber‐reinforced laminates
Authors: Lenk R. S.
Published: April 2003

This paper reports the flexural and tensile test results on glass fiber laminates prepared from solutions in styrene of polyesters containing bisacid A2 and from standard commercial liquid polyester resins. The results are compared with each other. Suggestions are made for differences in strength, modulus, and strain. The results are presented in tables which give a statistical evaluation of numerous tests in terms of mean, range, and standard deviation.
Characterization of homopolymers and copolymers by the coupling of gel permeation chromatography and automatic viscometry
Authors: Grubisic‐Gallot Z. , Picot M. , Gramain Ph. , Benoit H.
Published: April 2003

An improvement in gel permeation chromatography for polymer characterization has been effected by combining it with an automatic viscometric technique. This allows not only determination of the molecular weight distribution but also the intrinsic viscosity for any kind of homopolymer. Moreover, it permits determination of the viscosity–molecular weight relationship for linear polymers and the degree of branching for branched polymers. The use of this technique, coupled with UV or IR spectrometric measurements, provides information with respect to composition and molecular weight distribution in the case of copolymers. It is thus possible to characterize copolymers from the double point of view of composition and molecular weight polydispersity.
An improved numerical interconversion for creep compliance and relaxation modulus
Authors: Knoff Warren F. , Hopkins Irving L.
Published: April 2003

An imporved method for the numerical evaluation of the convolution integral in the relationship between creep compliance and relaxation modulus is discussed. The better approximation is obtained by the assumption that both functions can be assumed to be linear within a series of increasing time intervals which do not change as the calculation progresses. The calculation is carried out on both hypothetical and real examples which substantiates its applicability and accuracy.
The color of absorbing scattering substrates. I. The color of fabrics
Authors: Allen E. Hope , Goldfinger G.
Published: April 2003

A treatment of the color of textile materials is proposed which is an extension of G. G. Stokes' “pile of plates” problem. Unlike the conventional treatment of this subject, e.g., that by Kubelka and Munk, this approach permits independent determination of all variables: coefficient of absorption of the dye, refractive indexes of the fibers, the effect on color of the geometry of the fabric and yarn, and the distribution of the dye within the fiber. Here, cylindrical, optically homogeneous fibers in a parallel array are assumed. Experimental data show that this treatment predicts far more satisfactorily the color of fabrics at high dye concentrations and low reflectance values than does the Kubelka‐Munk approach.
Study of the pyrolysis of saturated chlorinated polyethylene fibers
Authors: Saglio N. , Berticat Ph. , Vallet G.
Published: April 2003

The thermal degradation of saturated chlorinated polyethylene in powder and fiber form has been studied. Direct observations of fiber length variations have enabled us to prove the reactional mechanisms proposed. In the temperature range of 200°–300°C, the material exhibits some fluidity. Its degradation is explained by intrachain and interchain dehydrochlorination reactions, followed by an arrangement of conjugated double bonds obtained in the shape of polyacenic cycles. Between 300°C and 800°C, the polyacenic cycles react with each other to give a pregraphitic structure which is responsible for the increase in rigidity of the material. The fibers of saturated chlorinated polyethylene can be used as a precursor of carbon fiber.