bluuebunny/crossref_metadata_2025_split huggingface dataset:
Carbon Black—Latex Masterbatches
Authors: Janssen H. J. J. , Weinstock K. V. 
Published: February 2011

Abstract
The steady increase in production of black latex masterbatches over the past three years makes it appear probable that the process has become firmly established the “second time aroud”, and its potential value in various development projects promises even greater importance in the future. The following list of advantages and disadvantages of the process has been compiled from many of the articles to which we have already referred. In addition, statements by Drogin, Forrester, LaPorte, Malone, and Samuels are used.
Oxidation of TiCl3 in Hydrocarbon and Aqueous Media
Authors: Belonovskaya G. P. , Dolgoplosk B. A. , Chernova Zh D. 
Published: February 2011

Abstract
It was found that tho oxidation of TiCl3, with oxygen and isopropyl benzene hydroperoxide, is accompanied by the development of radical reactions leading to the degradation and crosslinking of polymers. The mechanisms of the processes for oxidizing TiCl3 were examined on the basis of the experimental data. It was shown that it is possible to prevent the development of crosslinking and degradation processes in the polymer, by making use of inhibitors.
A Compact Test Instrument for Determining the Indentation Failure of Elastomers
Authors: Livingston Daniel I. , Hildenbrand Leurene E. 
Published: February 2011

Abstract
There exists a considerable area in which conventional methods for the evaluation of physical properties of polymeric materials are either inconvenient or practically impossible. This is the case for very small specimens, irregularly-shaped regions, or composite structures of vulcanized elastomers. Here micro test procedures are indicated, and tests of local indentation are particularly appropriate; for when the indenter diameter is small compared to the dimensions of the test region, the results become independent of the dimensions, and little or no special preparation of the sample is required. We have extended the scope of indentation tests, from the measurement of stress-strain properties alone, to include the capability of securing measurements of the ultimate strength and indentation. These indentation failure properties should be pertinent to the service life of many fabricated articles. This paper describes the use of a compact instrument designed to perform indentation tests up to failure in a rapid and reliable fashion. A synchronous motor raises the test specimen against the indenter, a flat-ended cylinder of 0.014-inch diameter, until failure occurs, whereupon the machine stops automatically. Readings of a dial gage dynamometer and revolution counter on the platform drive are converted into puncture force and depth. Applications of the instrument to the evaluation of some typical reinforced rubbers have been illustrated, and the relationship of these measurements to other mechanical properties discussed.
Linear Thermal Expansion of Elastomers in the Range 300° to 76° K
Authors: Robbins R. F. , Ohori Y. , Weitzel D. H. 
Published: February 2011

Abstract
From the relations between Tg's of the component homopolymers with that of the resulting copolymer, one sees that the limit of the Tg of copolymers is that of the homopolymers. To obtain a low Tg one must avoid polymers with polar groups and/or bulky groups. Polar groups afford opportunities for intermolecular links which hinder rotation necessary for “rubberyness.” Bulky groups cause stiffness, and also serve as obstructions to contractions. On the other hand, the same reasons that polar and bulky groups raise Tg serve to lower overall thermal contraction, since αr is always greater than αg. Fillers can be used to lower contraction, and new ceramic fillers with negative coefficients of expansion might be combined with specific polymers to obtain a material with a desired contraction. The authors feel that the data presented here, together with design data available from commercial sources, should enable the design engineer to find many new uses for elastomers at cryogenic temperatures.
The Fraction of Effective Sulfur Crosslinking in High Sulfur-Natural Rubber Vulcanizers
Authors: Meltzer T. H. , Dermody W. J. , Tobolsky A. V. 
Published: February 2011

Abstract
Shear modulus measurements as a function of temperature for smoked sheet natural rubber vulcanized with sulfur in amounts between 2 and 34 per cent show the crosslinking efficiency of sulfur to be much lower in natural rubber than in SBR-1000, at least for the particular curing recipe here used. The ratio of crosslinks to total sulfur atoms computed from the rubbery plateau modulus is below 0.07 for all of the natural rubber mixtures. Ratios up to 0.20 were found in SBR mixtures. The shape and slope of the modulus-temperature curves of natural rubber vulcanizates are similar to those of SBR mixtures and are typical of crosslinked amorphous polymers. Consistent displacement of the curves toward higher temperatures and higher rubber modulus as the percentage of sulfur in the recipes is increased also follows the same general pattern found for SBR. Cyclization is concluded to be the primary cause of the low sulfur efficiency in crosslinking both polymers, although polysulfide formation in natural rubber may further reduce the ratio of crosslinks formed per atom of sulfur combined.
Predicting Elastomer-Fluid Compatibility for Hydraulic Systems
Authors: Beerbower A. , Pattison D. A. , Staffin G. D. 
Published: February 2011

Abstract
Elastomers used in sealing hydraulic and similar systems are frequently swelled or shrunk by prolonged contact with the fluids. The fundamental properties, especially the Hildebrand Solubility Parameter, of the fluid and elastomer components are related to these tendencies. Basically, the Solubility Parameter concept has been used to predict suitable elastomeric sealing materials for various fluids by avoiding close matches in solubility parameter. The present studies have shown that: (a) copolymer performance cannot always be predicted by averaging the properties of the homopolymers; (b) mixtures of solvents may not behave like an imaginary single fluid of average properties; and (c) chemical interactions, hydrogen bonding, and molecular shape factors introduce major complications. New correlations are proposed to enable the hydraulic engineer to obtain Solubility Parameters from the more common properties of heavy petroleum fractions.
The Permanence Properties of Flexible Urethan Foams
Authors: Steingiser Samuel , Darr W. C. , Saunders J. H. 
Published: February 2011

Abstract
The acceptance of urethan foam as a commercial product has hinged to an important extent on its permanence as a foam under all conditions of actual end use. Customer experience with commercial flexible urethan foams has confirmed the satisfactory service life of these materials. However, in the development of this industry, it was necessary to be able to predict the performance of experimental systems which later were to become fully commercial. Most often, this prediction had to be made very early, long before the materials were allowed to be put into end service. The common way to do this is by accelerated testing, wherein the time axis is condensed by stepping up the aging process well beyond any normal conditions. Considerable time and expense are saved in this kind of test; however, there is always the question that such an accelerated step-up of test conditions is not representative of actual use, and/or causes reactions in the sample which do not occur in normal use. It is important that these questionable features be reconciled before the intercomparability of accelerated and shelf-life testing is accepted.
Thermomechanical Study of Polyisobutylene by Stretching and Indentation
Authors: Fomenko B. A. , Volodin V. P. , Sidorovich A. V. , Kuvshinskii E. V. 
Published: February 2011

Abstract
1. Thermomechanical studies of polyisobutylenes of various molecular weights under conditions of uniaxial stretching showed that the thermomechanical behavior of PIB is analogous to the behavior of other linear polymers. 2. Comparison of thermomechanical curves obtained by the method of uniaxial stretching by a constant force, and by the method of indentation by dynamometric weights showed that, in spite of the qualitative similarity of the curves, the quantitative comparison is impossible because of the great difference in the nature of the strained state of the samples studied under the different methods. 3. It was shown that for polyisobutylene, just as for other amorphous polymers, deformation corresponding to the steep branch of the thermomechanical curve is of a highly elastic nature.
Representation of the Mechanical Damping Possessed by Rubberlike Materials and Structures
Authors: Snowdon J. C. 
Published: February 2011

Abstract
Discussed in detail is the manner in which the damping possessed by rubberlike materials and structures experiencing sinusoidal vibration may be represented by the ratio of the imaginary to the real part of a complex elastic modulus. Examples are given of the way in which the damping possessed by low- and high-damping rubbers depends on frequency. Equations that predict the response to vibration of such distributed systems as damped rods and beams, and a simple structure comprised of two damped beams and a lumped element of mass are derived; and representative computations of input impedance and transmissibility are presented.
The Relation between the Friction and Viscoelastic Properties of Rubber
Authors: Grosch K. A. 
Published: February 2011

Abstract
This paper describes a study of the friction of several types of rubber against hard surfaces over a wide range of temperatures and sliding velocities. The highest velocity did not exceed a few centimeters per second so that frictional heating was negligible. The results show that the friction increases with the sliding velocity to a maximum value and then falls. The application of the Williams, Landel and Ferry transform shows that the frictional behavior of a rubber sliding at various velocities and temperatures on a given surface can entirely be described by a single master curve and the glass transition temperature of the material. The master curve on a rough abrasive track shows, in general, two peaks—one of these occurs at a velocity related to the frequency with which the track asperities deform the rubber surface. This maximum is absent on a smooth track and thus reflects the deformation losses produced by the passage of the asperities over the rubber surface. The other peak occurs in general at much lower velocities; it coincides in position with the single maximum obtained on a smooth surface. Introduction of a fine powder (MgO) into the interface between the rubber and track eliminates this peak on both smooth and rough surfaces; it is therefore attributed to molecular adhesion. Comparison with the relaxation spectrum of the rubber gives a fundamental jump distance of the order of 60 A. It appears, therefore, that friction arises from adhesion and deformation losses, and that both are directly related to the viscoelastic properties of the rubber.
Effect of Deformation on the Crystallization of Supercooled Cured and Uncured Rubbers
Authors: Bukhina M. F. 
Published: February 2011

Abstract
1. The dependence of the polymer crystallization rates on temperature is considered on the basis of the general theory of crystallization kinetics for supercooled liquids. The coefficients in the equations relating the crystallization half time, τ½, to the degree of supercooling are calculated for natural rubber. 2. An approximate expression is obtained which relates the equilibrium melting temperature of deformed rubber with the mechanical stress applied when crystallization starts. 3. The acceleration of crystallization which is induced by deformation is shown to be basically associated with an increase of the equilibrium melting temperature. 4. The possibility of calculating the crystallization rate at all temperatures and stresses from the results of a small number of experiments is established.
Rheological Properties of Two Unvulcanized Rubber Compounds as Determined on an Extrusion and a Rotational Viscometer
Authors: Devine F. E. , Ross J. A. 
Published: February 2011

Abstract
The viscometer manufactured by A. Macklow-Smith Ltd., which operates at constant rate of extrusion, is a capillary instrument designed for the determination of flow properties of plastics. The instrument has been used for examining the rheological characteristics of rubber compounds and it has been possible to derive the shear stresses required to extrude material at various shear rates between 2 and 1050 sec−1. The general method of operation of the instrument for this purpose is discussed including the determination of preheat time before extrusion and the aspect of incipient vulcanization in the viscometer during extrusion. The effects of various lengths and diameters of dies on rheological parameters and entrance effects are discussed. An important aspect of the work is the observation of a piston height effect in the extruder barrel. Two different compounded polymers have been examined and in one case, the extrusion pressure was found to decrease with piston height whilst in the other highly elastic material, it was found that as the piston descended, the extrusion pressure increased to an equilibrium value. The importance of this effect in obtaining consistent shear stress data is discussed. Results of the work have been expressed in terms of apparent viscosity and also in terms of the parameters which describe a power law relating shear stress and shear rate within the capillary die. Rheological data have been obtained at various temperatures within the range of processing temperatures of the compounds. The effects on rheological properties of mastication and relaxation time after mastication have been examined. Results have been compared with figures obtained on conventional laboratory viscometers such as the Mooney Plastometer and the Wallace Rapid Plastimeter. A biconical, rotational viscometer has also been used at the lower range of shear rates and the results are compared with those obtained from the extrusion viscometer.
Relative Contributions of Viscoelasticity and Aging to the Relaxation of Cured Rubber
Authors: Thirion P. , Chasset R. 
Published: February 2011

Abstract
Relaxation in relatively stable pure gum natural rubber vulcanizates has been studied to determine the effects of viscoelasticity and aging, respectively, using a dark air oven. A quantitative analysis of experimental results shows that, in the case of a dicumyl peroxide vulcanizate and at 100° C, relaxation is caused by aging, except in its initial stages. Stress decreases as a linear function of time, in agreement with theoretical assumptions. Conversely, at 30° C, the influence of aging is negligible. At this temperature the difference between actual stress and stress extrapolated to infinite time, is proportional to a negative power of time. At intermediate temperatures, both phenomena occur simultaneously over a time interval ranging from 3 minutes to 150 hours.
Surface Area of Nonporous Carbon Blacks and Area of the Adsorbed Nitrogen Molecule
Authors: Voet Andries 
Published: February 2011

Abstract
Surface areas of completely nonporous carbon blacks of widely varying particle chain formation (structure) have been determined by means of the nitrogen adsorption method as well as by electron micrography. Accurately determined densities in helium were used as the basis of calculations in the latter approach. It was found that the ratio of areas measured by nitrogen adsorption to electron micrographically determined surface areas is greatly dependent upon chain formation. A higher structural build-up leads to a lower ratio, explained by the observation that fusion areas in carbon chains are necessarily, though erroneously, counted as surfaces in electron micrography. The ratio differs markedly from unity, however, in low structure blacks, where fusion areas are negligible. By accepting the area of a nitrogen molecule adsorbed in a monolayer as being equal to that in the solid state, 13.8 A2, the ratio becomes unity for nonporous low structure blacks. It appears likely, therefore, that all surface area data based on the area of a nitrogen molecule in the liquid state of 16.2 A2 are too high by about 15 per cent of presently accepted values.
Vulcanization. Part III. Rapid Methods for Characterizing Rubber Networks
Authors: Coran A. Y. 
Published: February 2011

Abstract
Equilibrium swelling determinations have long beea used as a means of estimating crosslink density, usually through the Flory-Rehner equation. Most of the reported methods for determining equilibrium swelling in rubber vulcanizates have required long periods of swelling before equilibrium was reached, due to the fact that thick specimens were used. The method presented here makes use of thin films as specimens for swelling, and equilibrium can be reached in periods of one to five minutes. In addition, the use of thin films makes possible the semiquantitative determination of the types of chemical bonds responsible for the crosslinks in rubber vulcanizates. In thin films the reaction of polysulfide crosslinks with lithium aluminum hydride (in benzene-tetrahydrofuran) is rapid. The determination of crosslink density after such a reduction is indicative of only those crosslinks which are not reducible by the hydride and the difference between crosslink densities before and after the reduction is a measure of the number of crosslinks of the polysulfidic type. The work described here has been limited to natural rubber gum stocks. The methods used are undoubtedly applicable to other types of stocks, though in some instances a certain amount of modification will be required.
Vulcanization. Part V. The Formation of Crosslinks in the System: Natural Rubber-Sulfur-MBT-Zinc Ion
Authors: Coran A. Y. 
Published: February 2011

Abstract
The response of the delay time and specific rate of vulcanization (treated as first order) to changes in starting concentrations of accelerator, sulfur and activator in the system: natural rubber-sulfur-MBT-Zn++ was defined by empirically derived relationships. The effects of compounding variables on the number and types of crosslinks formed in the vulcanizate were also studied. A reaction scheme was proposed to explain the role of soluble Zn++. The scheme is consistent with the fact that increases in the concentration of soluble Zn++ give slower specific rates of crosslink formation but more crosslinks. In the scheme, it was proposed that Zn++ chelates certain crosslink presursors.
Molecular Sieves in the Vulcanization of Rubber
Authors: Blokh G. A. , Neĭmark I. E. , Borodushkhina Kh. N. , Boguslavskiĭ D. B. , Shevchenko Yu G. 
Published: February 2011

Abstract
1. The effect has been studied of accelerators, introduced into a rubber mix in the absorbed state on molecular sieves, on the scorch resistance of the mixes at 110°–130° C. 2. Molecular sieves can be used to introduce ultra-accelerators (triethylammonium dibutyldithiocarbamate) and activators (ethanolamines) into rubber mixes, so permitting vulcanization to be accelerated without the danger of scorching during mixing. 3. Molecular sieves can be used to introduce gaseous ammonia into rubber mixes; ammonia considerably accelerates vulcanization and can replace, either completely or partially, such accelerators as MBTS or DPG.
Iodimetric Determination of Milligram Amounts of Rubber Hydrocarbon
Authors: Middleton K. R. 
Published: February 2011

Abstract
An iodimetric method is described for determining rubber hydrocarbon; it is based on the bromination of the rubber molecule, and is sensitive to 2 mg of rubber dissolved in benzene. By comparing it with a standard procedure, it has been shown that the proposed method will determine accurately the rubber hydrocarbon content of field latex. The precision with which solutions of pure rubber in benzene can be determined by the method corresponds to a coefficient of variation of about 0.5 per cent and rubber hydrocarbon in latex can be determined with a precision of about 1.5 per cent.
New Synthetic Rubbers from Copolymerization of Butadiene and ENE-YNE Diols
Authors: Nikitin V. I. 
Published: February 2011

Abstract
Of the large number of different industrial synthetic rubbers the foremost is butadiene rubber, first produced by the polymerization of butadiene by Lebedev. Nowadays, in order to improve the mechanical properties of the rubber the polymerization is carried out in conjunction with some copolymerizing additive: styrene, acrylonitrile, etc. Styrene rubbers (SKS) and nitrile rubber (SKN) have a number of quite high chemical and mechanical properties and are produced on a full industrial scale. Hydroxyl rubbers, i.e., those where the selected substance for copolymerizing with the butadiene is a hydroxyl-containing monomer, are able to offer a great deal to industry, since the presence of the hydroxyl groups considerably improves their mechanical properties. However, they do not figure among the available industrial grades of synthetic rubber; yet from the data from American scientists they have considerable value. Good results have been given by work effected by Nagibina and others in the Inst. Khim. Nauk SSSR on producing a rubber on the basis of the joint polymerization of butadiene with dimethyl vinyl acetylenyl carbinol under various conditions.
New Dispersible Carbon Blacks
Authors: Voet Andries 
Published: February 2011

Abstract
It has been shown that the process of pelletization of a carbon black carried out to permit easier transportation through bulk handling, leads to irreversible changes in properties. There are strong indications that the pelletization process of carbon black involves free radical reactions, leading to chemical particle bonding. The superior physical properties of vulcanizates reinforced with unpelletized blacks indicate that chemical particle bonding is undesirable, since it reduces interaction between carbon black particle and polymer. In order to overcome chemical bonding of carbon black particles during pelletizing, carbon blacks were prepared the particles of which were covered withat least a monolayer of an oleaginous material compatible with the polymer. It was found that the product obtained could be pelletized to form predominantly physically adhering particles. These carbon black compositions disintegrate spontaneously in solvents for the oleaginous liquids, in view of the dissolution of the pellet binding material. The new carbon black compositions are ideally suited for black solvent masterbatching. In addition, they also show improved physical properties upon dry mixing with polymers in conventional dispersing equipment. Finally, they provide for a simple, rapid and efficient way to incorporate processing oils into polymers in conventional mixing equipment.