bluuebunny/crossref_metadata_2025_split huggingface dataset:
The filler–elastomer chemical link and the reinforcement of rubber
Authors: Le Bras Jean , Papirer Eugene 
Published: April 2003

AbstractReinforcement, the improvement of the service life of rubber goods, is dependent on the behavior of the carbon black–elastomer interface. It is generally believed that the interaction between the filler and the matrix involves physical and chemical forces. The aim of this work is to demonstrate the significance of the chemical interaction. In order to demonstrate the influence of the chemical bond without interference of physical forces, the problem is approached in a different way. The chemical bond is first realized by grafting the polymer onto the carbon surface. Then, two mixes are prepared by avoiding milling: one with the grafted black and the other with regular black. The comparison of the static and dynamic mechanical properties highlights the influence of the chemical bonding of the elastomer onto the black: the grafted black bestows much higher performance to the corresponding vulcanizate than does the regular black. However, the degree of reinforcement observed is somewhat lower than the one obtained by dry milling.
The pyrolysis of cellulose derivatives
Authors: Brown W. P. , Tipper C. F. H. 
Published: April 2003

AbstractThe thermal degradation in vacuo of ethyl cellulose and cellulose acetate in the form of very thin films or bulk material between 230° and 320°C has been studied. With the ethyl cellulose films, volatilization (as measured by weight loss) was a first‐order process up to about 50% reaction, with an activation energy of 208 kJ/mole. This is about the same as that associated with the initial drop in intrinsic viscosity of the solid during bulk pyrolysis, in which very high molecular weight material, probably crosslinked, was formed at a later stage. The volatile products from ethyl cellulose included H2O, CO, CO2, C2H4, C2H6, C2H5OH, CH3CHO, unsaturated aliphatic compounds, and furan derivatives. Acetic acid and acetyl derivatives of D‐glucose were produced from cellulose acetate. It is suggested that the polymers degrade by radical chain mechanisms, and a number of possible elementary steps are proposed.
Degraded products in weathered polymers
Authors: Shimura Yukio 
Published: April 2003

AbstractStyrene–methyl vinyl ketone copolymers, methyl methacrylate–methyl vinyl ketone copolymers, and styrene–methyl vinyl ketone–2,6‐di‐t‐butyl‐4‐acroylaminomethylphenol terpolymers as well as polystyrene and polypropylene have been weathered either by artificial irradiation or by outdoor exposure. The weathered products were analyzed using GC mass spectrometry, liquid chromatography, IR, UV, NMR, and wet analytical methods. Most of the weathered products proved to be low molecular weight polymers with various functional groups, and many low molecular weight compounds were identified. From the degradates of styrene copolymers, acetone, acetic acid, acetophenone, benzoic acid, formic acid, phenol, benzaldehyde, etc., were identified; from the degradates of methyl methacrylate copolymers, acetone, acetic acid, methanol, methyl methacrylate, methyl vinyl ketone, etc., were identified; and from the degradates of polypropylene, aliphatic acids up to propionic were analyzed. In many cases, the most abundant species was acetic acid. From polypropylene weathered outdoors for two years, 1.2 μl/g acetic acid was obtained. The degradates of styrene copolymers were found to contain fluorescent substances.
Viscosity index. III. Thermodynamic parameters for side chain crystallinity in pour point‐modified blends containing n‐octadecyl acrylate
Authors: Jordan Edmund F. , Smith Stephen , Zabarsky Ruth D. , Wrigley A. N. 
Published: April 2003

AbstractThe melting transitions and heats of fusion were obtained by differential scanning calorimetry for the crystalline phase of the same mixtures whose rheological properties were reported in the previous two papers. Pour point temperatures were also determined. In addition, the same thermodynamic quantities were also collected for higher polymer concentrations in this work, thus encompassing the entire concentration range. The DSC scans revealed that the distribution of crystallite sizes characteristic of the bulk copolymers was retained in the blends. Phase diagrams indicated isomorphism in all systems studied. An equation was derived to predict the influence of diluent concentration on melting point depression of copolymers, in which one component crystallizes through its side chains but in which the side chains of the other remain amorphous. The difference between the experimental heats of fusion and the value for entirely crystalline poly(n‐octadecyl acrylate) were used to estimate extent of apparent cocrystallization of the different copolymers with the base oil. While this tended to increase with pour point‐depressant ability, concomitant crystallinity of wax and depressant were essential to successful wax crystal modification. A mechanism is proposed in which whole molecules of hexagonally packed copolymers are attached to wax nuclei and accumulate slowly a t low diffusion rates. Thus, growth occurs over small crystal areas and is considered responsible for the directing influence of copolymer depressant. The resulting small crystal sizes, accompanied by fast growth of rapidly diffusing paraffins on uncontaminated surfaces, promote more compact habits, like dendrites that postpone network formation to lower temperatures. It was concluded that a melting point difference of less than 25°C between bulk copolymer and base oil is required for successful pour point depression. Consequently, in this base oil, only copolymers with long amorphous side chains in a limited composition range, such as the n‐octadecyl acrylate–2‐ethylhexyl acrylate copolymers, possessed sufficient lattice disorder to meet the specification. The rest produced gelation at higher temperatures.
Permeability of poly‐L‐methionine membrane and its oxidized membrane to water vapor
Authors: Minoura Norihiko , Fujiwara Yukihiko , Nakagawa Tsutomu 
Published: April 2003

AbstractThe permeability of poly‐L‐methionine (PLM) membrane and its oxidized form to water vapor was studied. Permeability coefficients of the PLM membrane were large, of the order of 10−7 cm3 (S.T.P.)·cm/cm2·sec·cm Hg. The sorption and permeation behavior of the PLM membrane was hydrophobic. The oxidized membrane was prepared by treating one or both sides of the PLM membrane with an aqueous solution of hydrogen peroxide. The membrane oxidized from one side is probably not layered but has a gradient of composition from one surface to the other. The amounts of water sorbed by the modified membrane increased with increase in oxidation time. The permeability coefficients of water vapor through the modified membrane were of the order of 10−6 cm3 (S.T.P.)·cm/cm2·sec·cm Hg.
Interrelation of mechanical and optical properties of plasticized epoxy polymers
Authors: Theocaris P. S. , Prassianakis J. 
Published: April 2003

AbstractA series of cold‐setting epoxy polymers, plasticized with different amounts of plasticizer, ranging between 0 and 90% by weight of the amount of the epoxy prepolymer, were studied for their mechanical, optical, and fracture behavior properties. Quantities defining the mechanical properties were considered: the elastic modulusE, Poisson's ratiov, and fracture tensile stress σf. These were accurately measured with electric strain gauges in specimens tested in a 5‐ton Instron tester. The optical behavior was characterized by the stress optical coefficients of the materials in both principal directions, α and β, as well as by the coefficient of optical anisotropy, ζ. The values of these quantities were measured by a Fizeau interferometric method. Finally, the optical method of caustics was applied to cracked epoxy polymer specimens to provide a new experimental technique for determining the stress optical properties of these polymers in terms of their mechanical properties. This method was used to check the previous results found by established experimental methods.
A thermomechanical investigation of highly cold‐drawn polycarbonate
Authors: Kato T. , Kambe H. 
Published: April 2003

AbstractA new technique detecting molecular motions in drawn polymers was applied to highly cold‐drawn polycarbonate of bisphenol A. It is shown that the sample exhibits thermal shrinkage in three steps with the temperature increase up to above the glass transition temperature. The molecular relaxation at the highest temperature is due to the glass transition. The other two molecular motions at the lower temperature are those of main chain in the glassy state and they correspond to the molecular motions as revealed in dielectric measurement by Sacher.1 By using the general theory of the thermal analysis by Ozawa,2 the apparent activation energies of these molecular motions were obtained: for the highest temperature 110 kcal/mole, and for the lowest temperature, 33.5 kcal/mole. The impact strength and the cold workability of this polymer are also discussed in relation to these molecular motions.
A unified concept of melt flow instability during extrusion
Authors: Lenk R. S. 
Published: April 2003

AbstractThe mechanism of melt flow instability at drawdown rates below and up to that necessary to compensate for die swell and at drawdown rates exceeding the former is explained with the aid of diagrams and appropriate comment. It is suggested that there is no fundamental difference between the causes of commonly encountered extrudate defects and “draw resonance” which appears in fiber spinning at excessive drawdown rates. It is argued that both are manifestations of viscoelastic phenomena which affect extrudate appearance either not at all due to effective suppression or which give rise to defects of increasing severity when control of the process—including die design and proper consideration of the forces at the die/melt interface—is inadequate.
Preparation of modified poly(vinyl chloride) containing N,N‐di(β‐hydroxyethyl)dithiocarbamate and its reaction with metal ions
Authors: Hiratani Kazuhisa , Matsumoto Yoko , Nakagawa Tsutomu 
Published: April 2003

AbstractReaction of N,N‐di(β‐hydroxyethyl)dithiocarbamate ion with poly(vinyl chloride) (PVC) was undertaken, and the reaction with metal ions of the polymer obtained was investigated. The effect of γ‐irradiation on the reaction with metal ion was also studied. The modified PVC (PHDC) obtained from the reaction with N,N‐di(β‐hydroxyethyl)dithiocarbamate ion is pale yellow even after reaction at 100°C for 5 hr in dimethylformamide (DMF); it is soluble in dipolar solvents and its chlorine content is decreased considerably. This polymer reacted well with acetate salts of copper(II), nickel(II), zinc(II), and silver(I) heterogeneously in aqueous solution because of the introduction of hydrophilic groups (two hydroxy groups). The reactivity of the metal ions toward the polymer was of the order Ag(I) ≫ Cu(II) > Ni(II) > Zn(II). From the result of the reaction of γ‐irradiated polymer with cupric ion, the polymer was judged to have fairly good antiradiation property.
Ignition properties of polymers evaluated from ignition temperature and ignition limiting oxygen index
Authors: Morimoto Takayoshi , Mori Takashi , Enomoto Susumu 
Published: April 2003

AbstractAn apparatus for measuring ignition temperature and ignition‐limiting oxygen index was devised in order to study ignition properties of polymers. Ignition limiting oxygen index, which was suggested by the limiting oxygen index (ASTM D2863‐70), was defined as the minimum volume fraction of oxygen required for ignition to occur in a slowly rising gaseous atmosphere. The ignition temperatures and the ignition limiting oxygen indexes of typical polymers were measured by this apparatus. Polymers which produced more ethylene by pyrolysis tend to have lower ignition temperatures. In the case of the same kinds of polymers, plots of ignition temperatures versus ignition limting oxygen indexes gave nearly straight lines (Fig. 3), but the straight line of depolymerization‐type polymers differed from that of random degradation‐type polymers differed from that of random degradation‐type polymers. In most polymers, ignition limiting oxygen indexes were nearly proportional to limiting oxygen indexes, but in the cases of hard poly(vinyl chloride) and soft poly(vinyl chloride), the plots did not follow this relation (Fig. 4). Ignition properties of self‐extinguishing polymers were also studied.
Effects of sterilization procedures on the tensile properties of polycarbonate
Authors: Weyers R. E. , Blankenhorn P. R. , Stover L. R. , Kline D. E. 
Published: April 2003

AbstractThe tensile properties of polycarbonate were investigated for specimens subjected to three sterilization procedures—(autoclaving, gassing, and gamma irradiation). Generally the tensile modulus decreased and the percent elongation at yield increased for all sterilization procedures. The ultimate stress was decreased by the ethylene oxide and gamma radiation procedures, while it was increased by the autoclave procedure. The total elongation at break generally increased with all sterilization procedures investigated. For repeated sterilizations, it appears that the autoclave procedures would be less detrimental to the tensile properties of polycarbonate, particularly if the maximum sterilization temperature does not exceed 260°F (127°C). Any of the sterilization methods described can probably be used on polycarbonate for a single application, although the autoclave and gamma sterilization procedures appear to be somewhat better than the gas sterilization procedures in relation to the tensile properties.
Photochemical reactions in commercial poly(ethylene 2,6‐naphthalate)
Authors: Allen N. S. , McKellar J. F. 
Published: April 2003

AbstractThe photodegradation of poly(ethylene 2,6‐naphthalate) is examined by absorption and emission spectroscopy and by flash photolysis techniques. A comparison of the emission spectra with that of a model compound 2,6‐dimethynaphthalate (DMN) shows that the chromophoric species responsible for light absorption in the near ultraviolet is the unit structure of the polymer itself. A flash photolysis study of DMN indicates that the major primary process in photodeterioration of the polymer involves scission by decarboxylation at the naphthyl‐carbon bond.
UV screen progenitors. Thermally labile urethane derivatives of hydroxyphenylbenzotriazoles and hydroxybenzophenones
Authors: Olson Daniel R. , Schroeter Siegfried H. 
Published: April 2003

AbstractUV‐curable formulations do not UV cure when hydroxybenzophenone or hydroxyphenylbenzotriazole UV screens are added to them. Reaction of these UV screens with alkyl or aryl isocyanates gives urethane derivatives in high yields. These derivatives do not impede UV cures when they are incorporated in UV‐curable formulations at relatively high levels (3%–5%). After completion of the UV cure, the urethane derivatives are catalytically decomposed by heating to regenerate the corresponding UV screen within the cured coating.
Thermal degradation of polymers. Part XIX. The thermal cyclization and characterization of quinazolone pre‐polymers
Authors: Chan H. S. O. , Still R. H. 
Published: April 2003

AbstractA series of pre‐polymers prepared from 4,4′‐diaminodiphenyl‐3,3′dicarboxylic acid and aromatic diacetamido compounds have been thermally cyclized and their structures have been investigated using infrared spectroscopy, combustion analysis, and weight loss techniques. The structures obtained on cyclization are discussed in terms of concurrent cyclization and decarboxylation reactions resulting in incomplete cyclization. Specific structural features due to the lability of main chain bonds at the cyclization temperatures are also discussed. Dynamic thermogravimetry and isothermal weight loss studies have been used to evaluate thermal stability and kinetic parameters. The results are discussed in terms of the overall complexity of the polymer structure and the complexity of the degradation process. It is concluded that in such systems, where the structural variations are large, it is not possible to define a meaningful stability sequence because like systems are not under comparison.
Effect of ethanol–water mixture as gelation medium during formation of cellulose acetate reverse osmosis membranes
Authors: Tweddle T. A. , Sourirajan S. 
Published: April 2003

AbstractBy using ethanol–water mixtures in a wide range of alcohol concentrations and temperatures, cellulose acetate membranes with a wide range of surface porosities can be obtained. Two different casting solution compositions were used, involving cellulose acetate, acetone, and aqueous magnesium perchlorate (composition I) or formamide (composition II). All reverse osmosis experiments were carried out at 250 psig using a 3500 ppm NaCl–H2O feed solution at laboratory temperature. The effective area of film surface was 12 cm2 in all cases. With composition I, with pure water gelation medium at 0°C, the resulting membrane gave a solute separation of 5% and product rate of 220 g/hr, whereas with 95% alcohol as gelation medium, the resulting membrane gave a solute separation of ∼1% and product rate of 1240 g/hr under otherwise identical experimental conditions. With composition II membranes, the maximum product rate of 360 g/hr with the corresponding minimum solute separation of ∼1% was obtained with 71.2% alcohol–water gelation medium at 0°C. Increase in the temperature of the gelation medium in the range 12° −25°C tends to increase the average size of pores on the membrane surface. These results offer a basis for the development of cellulose acetate ultrafiltration membranes.
Thermal analysis of styrene–alkyl methacrylate polymers. I. Glass transition temperatures
Authors: Lin Jacob W. , Wen Walter Y. 
Published: April 2003

AbstractThe glass transition temperatures (Tg's) of several polystyrenes and styrene–alkyl methacrylate copolymers and terpolymers were measured using thermomechanical analysis (TMA) and differential scanning calorimetry (DSC). The polymers studied had number‐average molecular weights from 3000 to 250,000 g/mole. The results indicate that the composition dependence of the Tg's for the copolymers and terpolymers can be satisfactorily described by a general Fox equation. In general, the measured Tg's of the copolymer and terpolymer samples depend more on the steric effects of the constituent pendent groups than on their molecular weights. The chain flexibility rather than the size of the pendent group is the determining factor in the glass transition properties of the styrene polymers.
Thermal analysis of styrene–alkyl methacrylate polymers. II. Thermogravimetric kinetics
Authors: Wen Walter Y. , Lin Jacob W. 
Published: April 2003

AbstractThe thermal stability and degradation kinetics of several polystyrenes and styrene–alkyl methacrylate copolymers and terpolymers with a number‐average molecular weight (M̄n) of 6000–250,000 g/mole have been studied using dynamic thermogravimetry (TG). The degradation kinetics of each polymer sample have been successfully attributed to a sample first‐order reaction expression. The results indicate that the thermal stability and degradation kinetics of the polymers are independent of the size of the molecules within the molecular weight range investigated. The steric hindrance effects of the pendent groups appear to be responsible for the improved thermal stability and resistance of CC bond scission in the styrene–alkyl methacrylate copolymers and terpolymers.
Wetting behavior of human hair fibers
Authors: Kamath Y. K. , Dansizer C. J. , Weigmann H.‐D. 
Published: April 2003

AbstractThe wetting behavior of human hair in water has been investigated using a technique based on the Wilhelmy balance principle. The experimental technique makes it possible to study the relaxation effects occurring at the solid–liquid–air interface. The results strongly suggest that interactions between the solid and the liquid make important contributions to wettability of the solid surface because of reversible reorientation of polar groups at the interface. The effects of scale structure, weathering, and mechanical damage on wettability of the fiber surface are discussed. Surface roughness of the fiber plays an important role in wetting hysteresis.
Permeation of water vapor through cellulose triacetate membranes in hollow fiber form
Authors: Pan C. Y. , Jensen C. D. , Bielech C. , Habgood H. W. 
Published: April 2003

AbstractA modification of the carrier gas method for measuring permeability of a hollow fiber to a vapor is described with particular application to water vapor permeation through asymmetric cellulose triacetate in hollow fiber from. Conventional methods are inadequate because the high flux of permeation vapor combined with its low pressure on the permeate side and the small diameter of the fiber lead to an excessive buildup of pressure in the permeate stream—in some cases so great as to render much of the fiber length ineffective. The method described in this paper involves the permeation from the outside to the inside of the fiber of a binary mixture consisting of the water vapor and a fairly highly permeable carrier (helium). There is a significant pressure drop along the fiber, but a theoretical treatment is presented to take this into account and to permit a determination of the vapor permeability. Experiments at 35°C over a range of water vapor pressures up to 1.7 cm Hg gave a water flux of 9 × 10−3 cc(S.T.P.)/cm2‐sec‐cm Hg, with an apparent slight decrease with increasing pressure. Over the same range of water vapor pressure the helium flux decreased from 2.3 × 10−4 to 1.85 × 10−4 cc(S.T.P.)/cm2‐sec‐cm Hg.
X‐ray diffraction orientation studies on blown polyethylene films. II. Measurements on films from a commercial blowing unit
Authors: Maddams W. F. , Preedy J. E. 
Published: April 2003

AbstractX‐Ray diffraction pole figure measurements have been made on a series of films, blown under various conditions from three high‐density polyethylenes. The results are interpreted in terms of two distinct types of orientation. The first, and probably the more normal, is the result of the type of stress crystallization process described by Keller and Machin and has the a and c axes inclined at an angle to the plane of the film. The second type of orientation is crystallographically analogous to that found in cold drawn polyethylene in having the c‐axis distribution substantially along the machine direction. This is termed high‐stress orientation. The type of orientation obtained is dependent both on the blowing conditions and the particular polyethylene. With an experimental Rigidex grade and with Shell LPPE 040 there are always substantially amounts of the conventional low‐stress orientation although certain combinations of machine conditions predispose towards the high‐stress form. This latter type forms readily in the case of Hostalen GM 9955F over a rather wide range of machine conditions and appears to be favored by slower cooling conditions.
Dielectric relaxation in epoxy‐polyglycol elastomers
Authors: Gilbert A. S. , Pethrick R. A. 
Published: April 2003

AbstractDielectric relaxation data is reported on a series of elastomers formed between bisphenol A and either polyethylene glycol or polypropylene glycol. The observed dispersion may be ascribed to relaxation of the “soft” block and is found to vary with both change in the glycol block length and with the ratio of bisphenol A to polyglycol. Elastomers prepared with a poly‐glycol component of mixed composition allowed the relaxation frequency at a particular temperature to be shifted over a frequency range of almost three decades. Activation parameters obtained from the temperature dependence of the mean relaxation frequency are used in evaluation of the factors influencing the molecular motion of the “soft” block.