bluuebunny/crossref_metadata_2025_split huggingface dataset:
Properties of Hard Rubber. XI. Experiments on Aging
Authors: Church H. F. , Daynes H. A. 
Published: February 2011

Abstract
Tests have been carried out to find how the mechanical properties of hard rubber change with age. On prolonged exposure of the whole specimen to air at 70° C, the impact strength of notched and unnotched test-pieces may fall by 50 per cent or more. On the other hand, the plastic yield temperature increases appreciably with 200 days' exposure. The conditions affecting the improvement in such an important property are worthy of further serious study. When certain faces of the specimen are protected from the air, the rapid loss of impact strength does not take place, and cross-breaking strength may remain unimpaired for as long as 200 days. The deterioration on aging appears to be confined within a very short distance of the surface, the bulk of the material retaining its full strength for very long periods. The retention of strength when certain faces are protected may have an important bearing on questions of design. Examination of old samples of hard rubber shows that the mechanical properties remain good under ordinary conditions of storage for periods of 20–30 years, but that weakness may be caused at surfaces which are severely exposed to sunlight.
Processing Characteristics of Synthetic Rubbers and Their Use in the Manufacture of Extruded Products
Authors: Juve A. E. 
Published: February 2011

Abstract
The difference in processing behavior between synthetic rubbers and natural rubber becomes evident when production facilities designed for processing natural rubber are used for synthetic rubbers. All the synthetic rubbers in one respect or another are harder to process than natural rubber. Under circumstances other than the present emergency, processing equipment suitable for handling the synthetic rubbers would gradually be evolved. In the present situation, synthetic rubbers must be processed with equipment already available. In this discussion natural rubber and the general purpose synthetic rubbers, GR-S, GR-M and GR-I, will be considered. The processing of dry rubber consists essentially of the incorporation of vulcanizing agents, pigments, oils, and other ingredients by a process of kneading, followed by the forming of the mix by extrusion or calendering into shapes suitable for fabrication preparatory to final cure. The mixing step, which is accomplished on a two-roll mill or in an internal mixer, requires that the rubber be within a plasticity range that will permit satisfactory dispersion of the ingredients. If the plasticity is too low the rubber tends to crumble, and if it is too high dispersion is poor. Crude natural rubber is quite tough, and before breakdown has some of the properties of vulcanized rubber, such as high recovery after moderate distortion. In the crude state it is extremely difficult to obtain satisfactory dispersion of pigments. It is therefore necessary to soften it by mastication or other means so that the pigments are more readily incorporated and power requirements are lowered. In addition, its nerve or tendency to recover after distortion is greatly reduced. Synthetic rubbers, in general, differ from natural rubber in their susceptibility to softening by mastication, and they show different relationships between nerve and plasticity than does natural rubber.
Identification of Natural and Synthetic Rubbers
Authors: Burchfield H. P. 
Published: February 2011

Abstract
A method is described for identification of the types of elastomers most frequently encountered in the rubber industry. The initial test depends on qualitative measurement of the pH and specific gravity of the pyrolysis products. It can be carried out in a field laboratory in 3 to 4 minutes and will provide sufficient information for a classification of the sample.
Identification of Raw and Vulcanized Rubber-Like Polymers. I. “Reaction Time” in a Mixture of Nitric and Sulfuric Acids
Authors: Parker L. F. C. 
Published: February 2011

Abstract
The time taken for the start of disintegration of natural and certain synthetic rubbers in a mixture of nitric and sulfuric acids has been used as a simple and reliable aid in the identification of an unknown rubber. With Perbunan, Buna-S, and Butyl types of rubber, this test seems sufficient to establish identity, but other types, including chloroprenes, thioplasts and natural rubber, require additional data. Indication is also given of ratios of quantities in binary mixtures of known “rubbers”. The test does not require a chemical laboratory or special personnel.
Recent Advances in the Physics and Chemistry of Rubber. IV. Crystallization in Rubbers
Authors: Treloar L. R. G. 
Published: February 2011

Abstract
In dealing with elasticity and with swelling, we have thus far considered rubber to be composed of a loose network of randomly-kinked long-chain molecules. This simple picture does not fully represent the structure of rubber under all conditions, and gives no explanation of many of the remarkable physical properties of raw rubber. For a more adequate representation we are forced to include the effects of crystallization. In this Part we shall examine some of these effects, and see what light they throw on the mechanism of the process of crystallization and on the structure of rubber generally. At the outset we may find some difficulty in accepting the theory that rubber may contain a crystalline phase. This is because we are accustomed to think of a crystal as possessing a precise geometrical shape. We cannot identify such geometrical forms in rubber. But, on consideration, we see that the essential attribute of a crystal is the internal regularity of the spacing of its constituent atoms. The external geometrical regularity, where it exists, is derived from this more fundamental internal structural regularity. It is frequently found, however, that the internal regularity is not accompanied by external regularity. This is true, for example, of the metals, which are invariably crystalline. The absence of external regularity is due to the small size of the individual crystallites. The same considerations apply to rubbers.
Gel as a Definitive Property in GR-S Technology
Authors: White L. M. , Ebers E. S. , Shriver G. E. , Breck S. 
Published: February 2011

Abstract
1. Of the gel fraction that may occur in GR-S, only that portion which has low swelling volume in benzene—tight (B) gel—markedly affects processing behavior and quality of product. 2. As the proportion of tight (B) gel increases, mixing operations become more difficult, and the quality of the final vulcanizate is lowered; specifically, decreased tensile strength, increased modulus, and decreased cut-growth resistance result. Where maximum quality is desired, processing conditions which favor the formation of tight gel should be avoided. 3. Conversely, appreciable amounts of tight (B) gel aid the processing operations of calendering and extrusion by reducing shrinkage and roughness. Where ease of processing is paramount and quality defects can be tolerated, heat-plasticization cycles which favor gel formation may be used to advantage. 4. To account for the observed effects of tight gel, the theory is advanced that fillers cannot enter this gel portion. This explanation is supported by a limited amount of direct evidence. 5. Heat-plasticization studies of GR-S at 320° F in the presence and absence of carbon black indicate that the black reduces the tendency to gel formation. For short heat treatments, common to many factory processes, the effect has no significance. For extended heat plasticization, incorporation of the black first may be either advantageous or detrimental, depending on whether maximum quality or ease of processing is the end objective.
The Effects of Proöxygenic Substances on Reclaimed Rubber
Authors: Haehl A. 
Published: February 2011

Abstract
It might at first be assumed that antioxygenic compounds originally present in scrap rubber used in the manufacture of the reclaimed rubber would be sufficient to explain the extraordinary resistance of the reclaimed rubber to the action of proöxygenic compounds. It is, however, highly improbable that these antioxygenic compounds survive caustic soda treatment at 190° C. On the other hand, a crude-rubber mixture, even when protected by an antioxygenic compound, never shows such great resistance to proöxygenic compounds as that shown by the reclaimed-rubber vulcanizates described in the present work. It seems probable, therefore, that this insensitivity of reclaimed rubber to proöxygenic compounds, both during plasticization and during aging after vulcanization, is in some way connected with the actual chemical structure of the reclaimed rubber itself.
The Morphology of Rubber Latex Particles. A Critical Review
Authors: Hauser Ernst A. 
Published: February 2011

Abstract
The morphology of the hydrocarbon particles of latices obtained from several rubber producing plants has in recent years again been the subject of studies applying the most modern tools of research. Lucas used for his studies an ultraviolet light microscope and later ultramicrocinematography. Quite recently Hendricks, Wildman, and McMurdie applied electron microscopy for the first time for this purpose. Since some of the deductions in regard to the form and structure of latex particles which have been drawn from these studies differ in several respects from conclusions based on micrugic and ultramicroscopic studies, some of which were reported twenty years ago, it seems advisable to clarify the picture. Such clarification is most important at present, because a better knowledge of the morphology of natural and synthetic rubber latex particles might offer a valuable aid in explaining some of the differences in the properties of these hydrocarbon polymers, which are not readily explainable on the basis of differences in chemical composition alone.
Vulcanization of Rubber with Synthetic Resins
Authors: Wildschut A. J. 
Published: February 2011

Abstract
Natural and synthetic rubber can be vulcanized with several vulcanizing agents other than sulfur, though sulfur and sulfur compounds are the only agents of practical value. A combination of rubber and synthetic resin can be successful only when chemical bonds are formed. It has been found that this is the case with certain synthetic resins, and that natural and synthetic rubber can be vulcanized with these resins, without adding any other agent or filler, in much the same way as with sulfur. An example of these resins is the resol from pentaphene (p-t-amylphenol) and formaldehyde. Data are given for the technical properties of rubber-resin vulcanizates. Catalysis or a similar effect is produced by magnesium oxide, which increases the tensile strength, while hexamethylenetetramine prevents the reaction. Balata can be vulcanized with the same synthetic resins as rubber; with gutta-percha the effect of heating with rubber-vulcanizing resins is the same as with sulfur. The probable configuration of the rubber-resin vulcanizates consists of two systems of entangled thread-molecules, which are interlinked at a limited number of points by primary valence bonds.
A New Material: Anhydride Rubber. I
Authors: Le Bras Jean 
Published: February 2011

Abstract
In earlier work on the action of various unsaturated compounds on rubber, Compagnon and the present author described briefly a new reaction of maleic anhydride. It should be added, as a matter of record, that the reaction of maleic anhydride and rubber had already been studied by Bacon and Farmer, who, in a very interesting work, described a process for obtaining addition products of rubber and maleic anhydride. It is well, therefore, first of all to describe the principle of their work and the results which were obtained. The first observation made by Bacon and Farmer was that when a toluene solution of milled crude rubber is heated for several hours at about 100° C with maleic anhydride in the presence of benzoyl peroxide, which acts as a catalyst, a definite reaction takes place. The reaction product can be precipitated by alcohol, and can then be recovered in the form of a white or pale yellow resin which does not have any of the elastic properties of rubber. In a more extensive investigation of the reaction, where the experimental conditions were varied, e.g., the proportions of benzoyl peroxide and of maleic anhydride, nature of the solvent, concentration of the solution, and time and temperature of heating, Bacon and Farmer succeeded in obtaining a true series of addition products, whose properties changed progressively with the proportion of chemically combined maleic anhydride. With increase in the proportion of maleic anhydride, there was a gradual transition from products which were still somewhat rubbery to fibrous products, and finally to hard brittle resins which contained more than one-third by weight of chemically combined maleic anhydride and which had none of the physical properties characteristic of rubber. As might be expected, the solubilities likewise changed progressively from products which were soluble in rubber solvents to those which were soluble in solvents for maleic anhydride; e.g., some of the derivatives were soluble in boiling ethyl alcohol.
Anhydride Rubber. II. Production and Vulcanization
Authors: Compagnon Patrice , Bonnet Odette 
Published: February 2011

Abstract
In the first part of this work, Le Bras described the interesting characteristics of the product obtained by combination, on a mill, of rubber and maleic anhydride, and he called attention to the useful potentialities of this reaction in connection with the reaction described previously by Bacon and Farmer. It is intended in the present part of the work to give, first of all, some practical information on the way that the reaction can be carried out. But, since the new modified rubber must be vulcanized to be of any practical value, and since, as might be expected, the conditions of vulcanization are not the same as for ordinary rubber, the means which have been found for carrying out this operation are described. It is obvious that, because of the many accelerators and combinations of accelerators which might have been tried, there was no pretention of obtaining ideal results in this first work ; however, since the results which have been obtained so far are sufficiently promising to be of practical value, a description of the method of vulcanization which has already been developed should be useful as a basis for further work by those who may be interested in these reactions.
New Method for Determining the Filler Content of Vulcanized Rubber
Authors: Hublin R. A. 
Published: February 2011

Abstract
The new reagent, o-nitroanisol makes it possible to shorten to a considerable extent the determination of the total filler content of vulcanized rubber, and to increase the precision of the determination. In addition, the procedure is carried out more easily than are the older classic procedures. It would seem desirable, therefore, to use this more convenient solution method of determining filler content in many cases in place of calcination methods, which, though rapid, are very inaccurate, and in place of the conventional solution methods, which are so inconvenient.
Comparative Study of Plasma-Thiophene and -Acetylene Coated Silica in SBR and EPDM Reinforcement
Authors: Tiwari M. , Datta R. N. , Talma A. G. , Noordermeer J. W. M. , Dierkes W. K. , van Ooij W. J. 
Published: February 2011

Abstract
The surface characteristics of silica were modified by plasma-thiophene and -acetylene film deposition. The plasma-coated fillers were blended with S-SBR and EPDM, and their influence on the final vulcanizate properties was compared with untreated silica and silanized silica. The change in the surface energy of plasma-acetylene (PA) and thiophene- (PTh) coated silica was characterized by immersion tests in liquids of various surface tension, water penetration measurements, Thermo Gravimetric Analysis (TGA) and Time of Flight Secondary Ion Mass Spectroscopy (ToF-SIMS). All techniques gave evidence of a polymeric PA- and PTh-film deposition on the surface of silica. The properties of S-SBR and EPDM, filled with untreated, PA-, PTh- and silane-treated silica, were investigated by measurement of the Payne effect, bound rubber content and weight loss related to bound rubber, the reinforcement parameter, relative ranking of cross-link density and mechanical properties. The results show a lower degree of flocculation for PTh-silica filled EPDM due to a better match of the surface energies compared to untreated and PA-treated silica. EPDM filled with plasma-thiophene coated silica shows the lowest reinforcement parameter value, thus improved dispersion compared to untreated, silane-treated and plasma-acetylene silica. However, PA-silica filled EPDM shows better mechanical properties compared to untreated and plasma-thiophene coated silica. The PTh-silica filled S-SBR shows a higher bound rubber content, which results in better mechanical properties of the S-SBR compound compared to the one with PA-coated silica. The overall results show that the compatibility and interaction of silica with different rubbers can be controlled by tailoring the surface energy of the filler by plasma-polymerization. The different functionalities on the silica surface result in different levels of compatibility and interaction, as well as final vulcanizates properties.
Degradation of the Rubber Network during Dynamic Vulcanization of EPDM/PP Blends Using Phenolic Resol
Authors: Antunes C. F. , Machado A. V. , van Duin M. 
Published: February 2011

Abstract
Physical blends and thermoplastic vulcanizates (TPVs) based on EPDM and PP were prepared in a batch mixer. Dynamic vulcanization of TPVs using resol/SnCl2 was studied as a function of time. Static and dynamic vulcanization of EPDM in the absence of PP were also studied. Crosslinking of EPDM in the absence of PP is more efficient via static than dynamic vulcanization. For EPDM/PP-based TPVs the extent of crosslinking reaction versus time decreases as the amount of EPDM increases. Degradation of the EPDM network occurs during dynamic vulcanization, due to the combined action of shearing and high temperature, and increases as EPDM becomes more and more the continuous phase.
AFM Studies on Silica Dispersion in EPDM Rubber
Authors: Natchimuthu N. 
Published: February 2011

Abstract
EPDM rubber formulations filled with precipitated silica and cross-linked by peroxide vulcanization have been investigated with the objective of realizing better processing characteristics and vulcanizate properties. Dispersion of silica in EPDM rubber in the presence of conventional coupling agents and in the presence of an epoxy resin has been investigated using atomic force microscopy (AFM) and scanning electron microscopy (SEM). AFM results of EPDM rubber compounds containing silica fillers in the presence of the epoxy resin have exhibited improved silica dispersion in terms of scanned height. The latter has been found to be in the range of 0–100 nm for EPDM rubber—silica systems with epoxy resin, while in the absence of the resin, scanned height has been found to be in the range of 0–700 nm. The significant reduction in scanned height in the presence of epoxy resin has been attributed to the reduction in surface roughness which is an indication for good dispersion of silica in the rubber. Morphological studies using SEM, mechanical properties, and Mooney-Rivlin constants all have shown significant improvement in performance properties of EPDM rubber—silica compounds containing epoxy resin and vulcanized with dicumyl peroxide.
Trouser Tearing of a Model Natural Rubber Tire Belt Vulcanizate. Part 1: Effect of Rate of Tearing
Authors: Hamed G. R. , Hiza S. 
Published: February 2011

Abstract
A model natural rubber tire belt vulcanizate (50 phr N330; 5 phr S; 0.75 phr DCBS accelerator) was torn using a trouser tear test piece that had legs 6 mm thick and an intended tear path about 0.8 mm thick. Tearing at 500 mm/min resulted in three distinct tear types. Two of the tear types gave high tearing forces, were stick—slip, and involved deep tearing into the legs (“chunk-out” and “knotty”). In the third, the tear remained in the thin path, alternated between legs (“sawtooth”), and was more-or-less steady. Cracking into the legs sometimes occurs and other times not. This variation appears to be inherent. It is attributed to variations in strain-induced crystallinity at high rates of strain. At a slower test rate of 5 mm/min, only knotty tearing was found. At 5 mm/min, there appears to be ample time for crystallites to develop well, and knotty tearing is always seen.
Trouser Tearing of a Model Natural Rubber Tire Belt Vulcanizate. Part 2: A Brief Note on the Effect of Cure Time
Authors: Hamed G. R. , Hiza S. 
Published: February 2011

Abstract
The effect of test rate on the tearing of a model natural rubber tire belt vulcanizate was previously discussed. We now discuss specimens of the same vulcanizate, cured for various times at 160 °C, which were torn apart. Prior to reversion, tear strength was high and knotty, but specimens tore rather easily when they were cured longer than the time for the onset of reversion.
Bipolar Tetraarylsilanes as Universal Hosts for Blue, Green, Orange, and White Electrophosphorescence with High Efficiency and Low Efficiency Roll‐Off
Authors: Gong Shaolong , Chen Yonghua , Luo Jiajia , Yang Chuluo , Zhong Cheng , Qin Jingui , Ma Dongge 
Published: February 2011

AbstractA series of tetraarylsilane compounds, namely p‐BISiTPA (1), m‐BISiTPA (2), p‐OXDSiTPA (3), m‐OXDSiTPA (4), are designed and synthesized by incorporating electron‐donating arylamine and electron‐accepting benzimidazole or oxadiazole into one molecule via a silicon‐bridge linkage mode. Their thermal, photophysical and electrochemical properties can be finely tuned through the different groups and linking topologies. The para‐disposition compounds 1 and 3 display higher glass transition temperatures, slightly lower HOMO levels and triplet energies than their meta‐disposition isomers 2 and 4, respectively. The silicon‐interrupted conjugation of the electron‐donating and electron‐accepting segments gives these materials the following advantages: i) relative high triplet energies in the range of 2.69–2.73 eV; ii) HOMO/LUMO levels of the compounds mainly depend on the electron‐donating and electron‐accepting groups, respectively; iii) bipolar transporting feature as indicated by hole‐only and electron‐only devices. These advantages make these materials ideal universal hosts for multicolor phosphorescent OLEDs. 1 and 3 have been demonstrated as universal hosts for blue, green, orange and white electrophosphorescence, exhibiting high efficiencies and low efficiency roll‐off. For example, the devices hosted by 1 achieve maximum external quantum efficiencies of 16.1% for blue, 22.7% for green, 20.5% for orange, and 19.1% for white electrophosphorescence. Furthermore, the external quantum efficiencies are still as high as 14.2% for blue, 22.4% for green, 18.9% for orange, and 17.4% for white electrophosphorescence at a high luminance of 1000 cd m−2. The two‐color, all‐phosphor white device hosted by 3 acquires a maximum current efficiency of 51.4 cd A−1, and a maximum power efficiency of 51.9 lm W−1. These values are among the highest for single emitting layer white PhOLEDs reported till now.