bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Molecular-Weight Distribution on Physical Properties of Natural and Synthetic Polymers
Authors: Johnson B. L. 
Published: February 2011

Abstract
The molecular weights of rubberlike polymers are average values for mixtures of macromolecules which differ greatly in size. The heterogeneity of natural rubber was recognized as early as 1929 by Whitby. The fact that solutions of higher quality crude rubbers are more viscous than lower quality rubbers was observed by Axelrod in 1905. Other workers have separated rubber solutions into fractions of differing molecular weight and have studied the properties of the fractions. In the case of synthetic polymers, these heterogeneous mixtures of molecules have been characterized by fractional precipitation and construction of molecular-weight distribution curves. The particular type of distribution determined in this investigation is that obtained from weight average properties based on viscosity measurements of fractions of the polymers. Application of these methods to the characterization of natural polymers confirmed observations that a variety of molecular-weight distributions existed in the case of the natural polymers. The physical properties of the natural polymers having these diverse molecular-weight distributions were well known. Therefore a correlation of their physical properties and weight distributions seemed pertinent to an evaluation of the fractionation technique. Such a correlation had not been possible on early butadiene-styrene copolymers because of the similarity of the distributions then obtained, even under different polymerization conditions.
A Study of the Deactivating Effect
Authors: Hildenbrand René 
Published: February 2011

Abstract
It has already been shown by Le Bras that certain substances protect vulcanized rubber from deterioration by oxygen without retarding to any significant extent its rate of oxidation. In this case the phenomenon is different from a true antioxygenic effect, where protection is evident by a notable retardation of the rate of oxidation. The phenomenon was first manifest in a systematic comparison of a series of antioxygenic agents of different chemical types with respect to their influence on the oxidizability of a vulcanizate and the protection which they impart in the artificial accelerated aging of the vulcanizate. It was proved that, in conformity with the mechanism of the antioxygenic effect, there was in general a retardation of the rate of oxidation and protection against deterioration by oxygen at the same time. Only a vulcanizate containing mercaptobenzimidazole (a substance classed among antioxygenic agents, since it is known to increase resistance to accelerated aging) showed an anomalous behavior with respect to the rate of oxidation. Although this particular vulcanizate showed good resistance to artificial aging, its oxidizability was of the same order as that of the control vulcanizate containing no protective agent, which deteriorated very rapidly. In this case, consequently, the protection against deterioration by oxygen involved a mechanism quite different from that characteristic of the classic antioxygenic effect.
Chromatographic Analysis
Authors: Bloomfield G. F. 
Published: February 2011

Abstract
As a part of a general study of vulcanization reactions, the British Rubber Producers' Research Association has been concerned with the fate of accelerators during cure. The recent paper by Bellamy, Lawrie, and Press (Trans. Inst. Rubber Ind. 22, 308–324 (1947); Rubber Chem. Tech. 21, 195–219 (1948)), describing chromatographic methods of separating and identifying accelerators and their decomposition products, was therefore of interest. Mercaptobenzothiazole found in an eluate from an alumina column does not, however, necessarily show that benzothiazoyl disulfide originally present in a vulcanizate is converted to mercaptobenzothiazole during vulcanization.
The Mooney Viscosity and Gel Plasticity Relationship for GR-S-Xylene Gels
Authors: Driskell J. C. , Kracke R. D. 
Published: February 2011

Abstract
1. A new method for measuring plasticities of highly viscous GR-S-solvent gels is described. 2. The coefficient and the standard error of estimate for the regression of plasticities of 35 per cent GR-S-xylene gels on Mooney viscosity (ML 4/212) of the rubber have been calculated. 3. An explanation for an observed shift from the relationship established for Mooney viscosity and gel plasticity caused by hot or cold milling of the polymer is suggested.
Basic Reactions Occurring during Rubber Reclaiming. I. The Influence of Reclaiming Media, Antioxidant, and Defibering Agents on Vulcanized Natural Rubber at 195 Pounds Per Square Inch Gauge Pressure (196.6° C)
Authors: Le Beau D. S. 
Published: February 2011

Abstract
The influence of surrounding atmosphere, antioxidant, and defibering agents at 196.6° C on the hydrocarbon of rubber was studied by subjecting a laboratory prepared, pure-gum, natural rubber compound to reclaiming in the absence of any reclaiming oils or chemicals. Data obtained on the amount of acetone and chloroform extracts and on the unsaturation of the reclaims and the chloroform extracts could therefore be interpreted in terms of the effect of the factors mentioned above on the rubber hydrocarbon and not as the effect of any chemicals added to the rubber to promote reclaiming. It was found that the effect of the surrounding atmosphere during reclaiming is the predominant factor in the reaction. Acidic surrounding atmospheres result in a slow and rather uniform rate of molecular breakdown and in the formation of small amounts of oxidation products. Apparently no secondary oxidative attack occurs at the double bonds. An open steam atmosphere provides the greatest amount of oxidized products and also a high initial molecular breakdown, followed by a slow progressive increase in it as the reclaiming periods are lengthened. A decrease in the unsaturation value of the acetone extracted reclaim indicates that secondary oxidative attack at the double bonds occurs at long reclaiming intervals. Alkaline reclaiming atmospheres provide little if any oxidation products and result in a very high initial rate of molecular breakdown. Longer reclaiming periods do not change further the amount of molecular breakdown. The very small amounts of oxygen necessary to promote the reclaiming reactions, the dependence of the course of these reactions on the acidity or alkalinity of the surrounding reclaiming media, together with the high initial rate of molecular breakdown reactions under conditions where such rate would be speeded up, permit the tentative explanation of these reactions on the basis of hydroperoxidic chain reactions. Further experiments along this line are being carried out.
Relationship between Gough-Joule Coefficients and Moduli of Vulcanized Rubbers
Authors: Conant F. S. , Hall G. L. , Thurman G. R. 
Published: February 2011

Abstract
The Gough-Joule coefficients (1) at constant stress and (2) at constant strain are defined and methods of measurement of each on vulcanized rubbers are given. It is shown mathematically and experimentally that the ratio of (3) to (4) is equal to the “tangent” modulus. The quotient of the Gough-Joule coefficient at constant stress divided by the stress and the quotient of the Gough-Joule coefficient at constant strain divided by the strain are shown to be constants which are independent of the stress-strain-temperature conditions. Experimental data are given for stocks based on Hevea, GR-S, Neoprene-GN, Butyl Rubber, and Butaprene.
Light Phenomena on Elongating Vulcanized Rubbers
Authors: Van Rossem A. 
Published: February 2011

Abstract
A description is given of a light phenomenon, first observed by W. C. Smith, when carrying out tear tests on some loaded vulcanized rubbers in a dark room. This phenomenon has been studied more systematically by high-speed extension tests. It appears that this light effect has nothing to do with the choice of accelerators, but with the compounding ingredients of loaded vulcanized rubbers. In general, those compounding ingredients which belong to the filler class, such as whiting, talc, and ground barium sulfate, show this light phenomenon very distinctly, while vulcanized rubbers with reinforcing compounding ingredients, such as zinc oxide, titanium dioxide, and carbon black, do not show any light effect when quickly extended. In accordance with this, Kalite and Calcene, which behave as reinforcing compounding ingredients, do not show any light phenomenon. It seems probable, that, on elongating the vulcanized rubbers containing fillers, the adhesion of rubber-filler particle is broken, and electrical charges appear on an extremely large surface, which lead to innumerable discharges into surrounding vacuoles, causing the general light phenomenon observed.
The Hydrochlorination of Rubber in Latex
Authors: van Veersen G. J. 
Published: February 2011

Abstract
A careful consideration of the influence of solvents on the hydrochlorination of rubber in solution has led to a fundamentally new technical process for the preparation of rubber hydrochloride. If hydrogen chloride is passed through latex stabilized with cationic or non-ionic emulsifying agents, rubber hydrochloride is formed. The rate of reaction, which is slow at normal temperature and pressure, can be increased considerably by carrying out the reaction under pressure. From the fact that rubber hydrochloride prepared from latex has a chlorine content very near the theoretical value, it may be concluded that hydrochlorination of rubber in latex is not accompanied by cyclization.
Thermodynamics of Crystallization in High Polymers. VI. Incipient Crystallization in Stretched Vulcanized Rubber
Authors: Fox Thomas G. , Flory Paul J. , Marshall Robert E. 
Published: February 2011

Abstract
Experimental determination of the elongation at which crystallization commences in vulcanized rubber has been attempted through measurement of density changes by a hydrostatic method. The critical elongation for incipient crystallization appears to depend on the temperature, in approximate accordance with theoretical prediction. Crystallization sets in at an elongation well below that at which the stress-strain curve assumes a steep slope.
Free Retraction of Elongated Rubbers
Authors: Boonstra B. B. S. T. 
Published: February 2011

Abstract
The speed of retraction of the ends of elongated rubber rings relative to each other for a number of elastomers was measured at room temperature by a comparatively simple method. The results, plotted as elongation vs. time curves, indicate that the mechanism of retraction is complicated and cannot be described by a simple mathematical equation. In the present case the so-called permanent set plays a part in the retraction velocity. A mathematical equation is given to account for this phenomenon. Elasticity is judged in terms of speed of retraction and permanent set.
The Low-Temperature Performance of Butyl Inner Tubes
Authors: Adams R. J. , Buckler E. J. , Wanless G. G. 
Published: February 2011

Abstract
Standard Butyl inner tubes in passenger car service, when operated at temperatures below zero Fahrenheit for continued periods, develop buckles which may eventually cause chafing failures. This effect is believed to be due to increase in the viscous modulus compared with the elastic modulus of Butyl at low temperatures. The effect on performance of such factors as tire pressure, casing composition, and acceleration have been investigated, improved formulations consisting of highly plasticized, high-molecular-weight Butyl have been studied and correlations established between tube performance and physical characteristics, such as rebound, rate of retraction, modulus function, and oil viscosity. While commercial evaluation of such formulations is proceeding, other approaches are being studied by Canadian and United States groups, particularly involving polymers which may be brought to a more complete state of vulcanization.
The Interpretation of Plasticity Measurements
Authors: Scott J. R. , Whorlow R. W. 
Published: February 2011

Abstract
After consideration of the various factors whose influence must be included in any complete assessment of the fundamental flow properties of uncompounded raw rubber, a comparison is made of results from various instruments. It is shown that a plot of log (shear stress) against log (strain rate) is straight or slightly curved at low shear rates, but may be markedly convex to the log stress axis at higher rates. Reference is made to the limitations of the methods of Scott for the interpretation of the results of parallel-plate compression tests; attempts to apply the Nutting equation to the large strains in the usual compression tests with rubber are shown theoretically, and by experiments on materials of known characteristics, to be invalid. Consideration of the instruments available for factory control purposes shows that the one figure obtained from conventional tests is inadequate for the evaluation of a new mix or even a new plasticizing or mixing technique, and alternative procedures are considered; for the control of nominally identical batches a single figure may be adequate. Finally, the essential requirements for research and control instruments are compared, and available instruments in each group surveyed in the light of the earlier discussion.
New Types of Highly Elastic Substances, Vulcollans
Authors: Bayer O. , Müller E. , Petersen S. , Piepenbrink H. F. , Windemuth E. 
Published: February 2011

Abstract
It is shown that new types of highly elastic products with remarkable properties can be obtained by a process of diisocyanate poly-addition, which involves the transformation of linear polyesters of glycols and dicarboxylic acids with an excess of certain special “expansive” diisocyanates in the presence of a very small proportion of water. The terminally bifunctional polyesters react first with the diisocyanate, with resultant lengthening of the chains. A network is subsequently developed from urea groups, which are formed from isocyanate groups and water, and which then react with the diisocyanate. The chemical mechanism of this process is discussed in detail. In addition, the processing and possible applications of this new class of elastomers is reviewed.
Oxidation of Compounds Structurally Related to GR-S
Authors: Lawrence J. W. , Shelton J. Reid 
Published: February 2011

Abstract
The rates of oxidation of 1-phenyl-3-pentene, 1-phenyl-4-hexene, and 1-phenyl-3-vinylbutane have been measured at 100° C and 1 atmosphere of oxygen pressure. 1-Phenyl-2-butene has also been included to complete the sequence 1–4, 1–3, and 1–2 with respect to the structural relationship between the phenyl radical and the point of unsaturation. Information concerning the course of the reaction was obtained both from the rate data and from chemical analysis of the oxidized products. Three stages of oxidation were noted: (1) a very short induction period; (2) an autocatalytic stage which is characterized by a rapidly increasing rate and in which the primary products appear to be peroxides; and (3) a period characterized by a constant rate of oxygen absorption with the formation of such products as acids, esters, carbon dioxide, and water.
Oxidation Processes in Latex of Hevea Brasiliensis
Authors: de Haan-Homans L. N. S. 
Published: February 2011

Abstract
The occurrence of catalase, tyrosinase, oxidase and peroxidase in latex of Hevea brasiliensis has been investigated. These enzymes are present in fresh latex. With the exception of catalase they are accompanied by inhibitors, some of which are powerful reducing substances, and by nonenzymatical oxygen-absorbing substances. Thus latex contains a complicated redox system. Several properties of the enzymes and some properties of the reducing substances were determined. An explanation is given for the spontaneous blue discoloration which frequently appears on the surface of latex, and the possible significance of the results on the formation of the rubber in the tree is indicated.
Mechanical Stability Test for Hevea Latex
Authors: Dawson H. G. 
Published: February 2011

Abstract
The mechanical stability test is a rapid, simple method of estimating the colloidal stability or quality of Hevea latex by high-speed stirring. Latex particles start to agglomerate as soon as the peripheral speed of the agitator reaches a certain minimum value. Progressive flocculation continues until mechanical coagulation occurs. The end point is defined as the time in seconds required to coagulate 0.5 to 1.0 per cent of the total solids. If the shear is constant, the time is proportional to the colloidal stability, which depends upon the interfacial film between the latex particles and the serum. The mechanical stability time depends critically on the size, the total solids, and the temperature of sample.
Agreement in Detecting Glaucomatous visual Field Progression by using Guided Progression Analysis and Humphrey Overview Printout
Authors: lester Michele , Corallo Guido , Capris Elisabetta , Capris Paolo 
Published: February 2011

Purpose To examine the level of agreement among 3 clinicians in assessing glaucoma visual field progression by using 2 different methods. Methods Each visual field was assessed by Humphrey Field Analyzer (HFA), program SITA standard 30–2 or 24–2. In each printout the first 3 fields were excluded to minimize learning effect: the fourth and fifth full-threshold or SITA Standard examinations were used as baseline. Three clinicians assessed the progression status of each series using both HFA overview printouts and the guided progression analysis (GPA). The level of agreement among the clinicians was evaluated using a weighted kappa statistic (κ). Results A total of 510 tests, comprising 83 eyes with an average of 6.1 tests each, was assessed by the 3 specialists. The mean follow-up time was 5.8±1.75 years (mean ± standard deviation). When the intraobserver intermethod agreement was evaluated, κ ranged from 0.5 to 0.7. When the interobserver agreement was analyzed, if HFA overview printouts were used, κ ranged from 0.4 to 0.7. But when GPA was used, κ ranged from 0.2 to 0.6. The level of agreement on progression status between the clinicians was always higher when they used HFA overview printouts (median κ = 0.54) than when they used GPA (median κ=0.37). Conclusions Agreement among expert clinicians about visual field progression status was moderate when GPA printouts were used. Clinicians’ agreement about patients’ visual field progression status was better when HFA overview printouts were used than with GPA printouts.
Thermo‐oxidative decomposition kinetics of elastomeric composites based on styrene‐(ethylene‐butylene)‐styrene triblock copolymer and organomontmorillonite
Authors: Saikrasun Sunan , Amornsakchai Taweechai 
Published: February 2011

AbstractThe elastomeric nanocomposites based on organomontmorillonite (OMMT) and styrene‐(ethylene‐butylene)‐styrene (SEBS) thermoplastic elastomer were prepared by melt processing using maleic anhydride grafted SEBS (SEBS‐g‐MA) as compatibilizer. Thermo‐oxidative decomposition behavior of the neat components and the nanocomposites were investigated using thermogravimertic analysis (TGA) in air atmosphere. The isoconversional method is employed to study the kinetics of thermo‐oxidative degradation. The heating modes and the composition of nanocomposites were found to affect the kinetic parameters (Ea, lnA and n). The Ea and lnA values of SEBS, OMMT, and their composites are much higher under dynamic heating than under isothermal heating. The reaction order (n) of OMMT was lower than those of SEBS and their composites. The obtained TG profiles and calculated kinetic parameters indicated that the incorporation of OMMT into SEBS significantly improved the thermal stability both under dynamic heating and under isothermal heating. The simultaneously obtained DSC data showed that the enthalpy of thermal decomposition decreased with OMMT loading. No significant change in the nonisothermal and isothermal stability of the nanocomposites with addition of SEBS‐g‐MA. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Highly transparent and organosoluble polyimides derived from 2,2′‐disubstituted‐4,4′‐oxydianilines
Authors: Chen Jyh‐Chien , Rajendran Kuppachari , Chang Ya‐Hui , Huang Sheng‐Wen , Chern Yaw‐Tern 
Published: February 2011

AbstractTo improve the optical transparency and organosolubility of aromatic polyimides derived from 4,4′‐oxydianiline (4,4′‐ODA), two new aromatic diamines, 2,2′‐diiodo‐4,4′‐oxydianiline (DI‐ODA) and 2,2′‐bis[(p‐trifluoromethyl)phenyl]‐4,4′‐oxydianiline (BTFP‐ODA) were synthesized by using 4,4′‐ODA as a starting material. Novel polyimides were prepared from these two diamines with various commercially available aromatic dianhydrides via a one‐step high‐temperature polycondensation procedure. Most of these polyimides showed enhanced solubility in common organic solvents compared with those corresponding polyimides derived from 4,4′‐ODA. Especially, polyimide derived from BTFP‐ODA and rigid pyromellitic dianhydride (PMDA) was also soluble in DMF, DMAc, DMSO, NMP, and m‐cresol at room temperature. These polyimides had inherent viscosities from 0.41 to 1.26 dLg−1 in NMP or m‐cresol at 30°C. Transparent, flexible, and tough films can be obtained by casting from their DMAc or m‐cresol solutions. These films had the UV onset wavelengths in the range of 347–391 nm and the wavelengths at 80% transmission of 445–544 nm, indicating high optical transparency. They also exhibited good thermal stability with glass transition temperatures in the range of 260–327°C. The decomposition temperatures of these polyimides at 5% weight loss under nitrogen were 429–609°C. Because of the weak carbon‐iodine bond, polyimides derived from DI‐ODA decomposed at lower temperatures than polyimides derived from BTFP‐ODA. The effects of the substituents at the 2 and 2′ positions of 4,4′‐ODA on the properties of polyimides are also discussed. High optical transparency and good solubility combined with high thermal stability make these polyimides potential candidates for soft electronics applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Alcohophilic gels: Polymeric organogels composing carboxylic and sulfonic acid groups
Authors: Kabiri K. , Azizi A. , Zohuriaan‐Mehr M. J. , Marandi G. Bagheri , Bouhendi H. 
Published: February 2011

AbstractPolymeric organogels based on acrylic acid (AA) and sodium allyl sulfonate (SAS) were prepared through solution polymerization using a persulfate initiator and a polyethylene glycol diacrylate (PEGDA) crosslinker. FTIR spectroscopy, elemental, and rheological analyses were used for a preliminary characterization. Thermo‐mechanical analysis was also carried out for characterizing samples. Glass transition temperature (Tg) of copolymer was decreased after acid treatment which could be attributed to detachment of ion pairs during the post‐treatment. Due to counterion binding of Na+ to form ionomer, the poly(AA‐SAS) gels showed no polyelectrolyte behavior to have high swelling capacity in conventional alcohols, i.e., ethanol and methanol. It was postulated that modification via removing Na+ could help breaking ion pair aggregates which leads to swelling enhancement. Thus, poly(AA‐SAS) was treated with hydrochloric acid to remove (Na+) counterions. This modification led to the gel transform from ionomer regime to a polyelectrolyte regime in which free mobile ions were existed in the network. The gel swelling capacity was increased due to raise of mobile ions after the treatment. It was found that both of the acid concentration and treatment time had constructive influence on the gel alcohophilicity. The acid‐treated samples could imbibe ethanol and methanol as high as 25.8 and 39.5 g/g, respectively. They may be superior candidates for applications such as pharmaceuticals gels and fire starters. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011