bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermoreversible Crosslinking Rubber Using Supramolecular Hydrogen Bonding Networks
Authors: Chino Keisuke , Ashiura Makoto , Natori Junichiro , Ikawa Masahiro , Kawazura Tetsuji 
Published: February 2011

Abstract
Thermoreversible crosslinking rubber (TRC-IR) was easily synthesized by modification of isoprene rubber (IR) with maleic anhydride followed by the addition of 3-amino-1,2,4-triazole (ATA), in solid phase. The mechanical properties of the resulting rubber were more similar to the sulfur-vulcanized rubber than general thermoplastic elastomers (ex. SEBS). Although the tensile strength and elongation at break were lower than those of a corresponding sulfur-vulcanized rubber, the moduli were as high as those of sulfur-cured rubber. Re-molding of TRC-IR could be repeated more than 10 times without significantly changing its mechanical properties. Differential scanning calorimetry (DSC) and infrared analyses revealed that the superior mechanical properties and good recyclability are attributable to the strong hydrogen bonding. The TRC-IR showed an endothermic transition peak at around 185 °C on the DSC chart, indicating cleavage of the hydrogen bonding. Infrared analyses also revealed that the absorption peaks of carboxylic acid were shifted to a lower region by the strong hydrogen bonding. The thermoreversible crosslinking system was also applied to EPM, EBM (ethylene-butene rubber), and IIR. These rubbers also showed superior mechanical properties as well as excellent recyclability.
The Interaction between Rubber and Liquids. V. the Osmotic Pressures of Polymer Solutions in Mixed Solvents
Authors: Gee Geoffrey 
Published: February 2011

Abstract
An expression is obtained for the free energy of dilution of a ternary mixture of polymers + two liquids by one of the liquids. This is used to consider the osmotic equilibrium between a solution of a polymer in a mixture of two liquids, and a second phase containing only the two liquids. It is shown that the osmotic behavior of the ternary solution is very similar to that of a polymer in a single liquid, and in particular that van't Hoff's law holds at infinite dilution. The distribution of the two liquids between solvent and solution is also calculated. The experimental difficulties involved in the use of mixed solvents are discussed.
The Interaction between Rubber and Liquids. VI. Swelling and Solubility in Mixed Liquids
Authors: Gee Geoffrey 
Published: February 2011

Abstract
The equations derived in the previous paper for the osmotic equilibrium between a ternary mixture of polymer + two liquids and a mixture of the two liquids are applied to the swelling of cross-linked polymers in mixed liquids and to the solubility of linear polymers in mixed liquids. A mixed liquid has solvent properties intermediate between those of its components only when these mix ideally. The larger the heat of mixing of the liquids, the greater is the solvent power of the mixture relative to those of the components. This conclusion forms the basis of an explanation of the enhanced swelling of rubbers in pairs of dissimilar liquids and of the fact that a mixture of two nonsolvents may be a solvent over a certain range of concentration. Experimental results are given for the swelling of vulcanized rubbers and the critical solubility limits of unvulcanized rubbers. It is shown that these can be explained qualitatively from the cohesive energy densities of the three components, and semiquantitatively from the measured heats of mixing of the three binary mixtures. The work described in these two papers forms a part of the program of fundamental research on rubber undertaken by the Board of the British Rubber Producers' Research Association.
The Melting of Crystalline Polymers
Authors: Frith Elizabeth M. , Tuckett R. F. 
Published: February 2011

Abstract
The thermodynamic equilibrium which exists between crystalline and amorphous polymeric phases is discussed in terms of a fringed micelle model, as indicated by x-ray data. An expression derived for the melting point of a crystalline polymer is found to depend on the proportion θ of amorphous material in the structure: this unsharp melting point depends ultimately on a nonlinear relationship between θ and the free energy of the system. Calculated values of the crystalline amorphous equilibrium ratio over a range of temperature are in good agreement with experimental data. An attempt has been made to extend the calculations to the case of stretched polymers and a qualitative agreement has been found. This work has been carried out in the Department of Colloid Science, Cambridge, and we should like to thank Professor E. K. Rideal for much stimulating criticism. This paper arose out of discussions with Professor Sir R. H. Fowler: his advice and encouragement during its development have been invaluable to us, and we should like to record here our grateful thanks to him.
The Structure of Polyisoprenes. II. The Structure of β-Gutta-Percha
Authors: Jeffrey G. A. 
Published: February 2011

Abstract
The x-ray diffraction data at present available from β-gutta-percha are shown to be insufficient to distinguish fine details of molecular structure. Since a qualitative estimate of the intensities on the fibre diagram can be adequately satisfied by a model having normal interatomic distances and valency angles, no evidence exists for the improbable distortion of the methyl group out of the plane of the double bond previously ascribed to the molecule.
Limiting Law of the Reinforcement of Rubber
Authors: Smallwood Hugh M. 
Published: February 2011

Abstract
1. Analysis shows that, subject to certain limitations, the modulus of a loaded stock (M*) depends on the modulus of the rubber matrix (M), according to the equation: M*=M(1+2.5ϕ) where 100ϕ is the volume percentage of filler. When these limitations are fulfilled, the effect of compounding on modulus is, therefore, independent of the particle size of the filler. The assumptions on which this equation is founded are as follows: (1) the filler particles are spherical; (2) there is complete adhesion between rubber and filler; (3) the elongation is small; (4) the filler is completely dispersed; (5) the volume loading is small; (6) the filler particles are sufficiently large that the molecular structure of the rubber may be neglected. 2. The stresses about a filler particle have been derived mathematically. 3. Experimental data check the calculations for the following fillers: P-33, Thermax, and whiting. Catalpo clay presents some anomalies because of its acicular particles. 4. Carbon black does not conform to the calculations. This is attributed to the fact that it is strongly flocculated in rubber. 5. Zinc oxide (Kadox or XX zinc oxide), which should conform, because it is well dispersed in rubber, causes abnormally large increases in modulus, presumably because of alteration of the type of cure and consequent alteration of the modulus of the rubber matrix.
Some Low Temperature Properties of Elastomers
Authors: Conant F. S. , Liska J. W. 
Published: February 2011

Abstract
The low-temperature Young's modulus of copolymers of the butadieneacrylonitrile (B/A) type was found to be lowered by a reduction in the acrylonitrile content of the copolymer. Mass- and emulsion-polymerized butadiene were found to possess considerably different low temperature physical characteristics. Certain plasticizers (employed to improve low-temperature properties) imparted a time-stiffening effect to compounds which, in the absence of the given plasticizer, showed no time effect. An experimental method for the measurement of primary creep of elastomers at low temperatures is described. Calculation of a creep constant, as defined, appears to yield a critical temperature which may be useful as a serviceability index.
Electrostatic Properties of Rubber and GR-S
Authors: Havenhill R. S. , O'Brien H. C. , Rankin J. J. 
Published: February 2011

Abstract
A new electrostatic modulator has been described for measuring the electrostatic charges on rubber, synthetic rubber, and various materials. In this apparatus the electrostatic lines of force established between the charged specimen and a stationary electrode plate connected to the grid of an audiofrequency amplifier are cut or modulated at audiofrequency by a small four-bladed, motor-driven fan. This produces in effect an alternating current voltage which can be readily amplified by the audio amplifier and quantitatively measured on a meter in the output circuit. This device, in conjunction with a mirror-surfaced metal plunger system for contacting the rubber samples, has been used to measure the contact potential of various rubber and GR-S compounds. Electrostatic contact potential data are shown for both rubber and GR-S compounds with and without organic and inorganic reinforcing agents, and these data bear out the formulation of an electrostatic contact potential theory of reinforcement in which the reinforcement of rubber and GR-S is explained on the basis of contact potentials and resultant electrostatic attractive forces which exist between the rubber and the reinforcing agents. By the application of this theory, organic materials which have a highly positive electrostatic charge, such as polymerized trimethyldihydroquinoline and Flectol-H (an acetone-aniline condensation product), have been found to increase the tensile strength of the pure-gum type of GR-S compounds as much as fivefold and nearly to double the tensile strength of high zinc oxide loaded GR-S compounds.
Some Relations between Stress, Strain, and Temperature in a Pure-Gum Vulcanizate of Gr-S Synthetic Rubber
Authors: Roth Frank L. , Wood Lawrence A. 
Published: February 2011

Abstract
Some relations between stress, strain and temperature have been investigated for a pure-gum vulcanizate of GR-S to furnish experimental information for use in theoretical consideration of its elastic behavior. The results of the work also yield some practical information about the tensile properties at high and low temperatures. In this work stress was studied as a function of temperature, with the elongation, or sometimes the length, constant. In this way effects of friction and flow accompanying changes in length of specimens were minimized. The general methods employed in this study were first outlined by Meyer and Ferri, who in common with other observers applied them to natural rubber. Peterson, Anthony, and Guth, in the only studies of this sort dealing with synthetic rubber, did not include GR-S or other butadienestyrene copolymers.
Speed of Retraction of Rubber
Authors: Stambaugh R. B. , Rohner Margaret , Gehman S. D. 
Published: February 2011

Abstract
The results obtained with this apparatus show that interesting information can be obtained by making measurements of the speed of retraction under various conditions and by comparing different compounds and polymers. This information should be of value both for a better understanding of the molecular structure and the forces involved and also as a practical means for properly qualifying the material as to its elastic properties. The device appears to have an immediate practical application as an aid to the compounder in determining the “best” cure. The apparatus is quite simple to use and if properly designed is sturdy and dependable. Reliable measurements could be made at the rate of about fifty per hour without requiring much skill. Thus, the speed of retraction measurement would be practical for a routine, standard test.
Comparison of Abrasion Resistance with Other Physical Properties
Authors: Upham F. N. 
Published: February 2011

Abstract
The measure of the curing rate of rubber stocks has, for many years, been based on tensile strength values or factors involving tensile strength. From these data, a number of rubber stocks have been termed flat-curing, but if the rate of cure be related to the resistance to abrasion, the stocks would not be regarded as possessing that property. It appears that the abrasion test is more sensitive to changes in the state of cure than the tensile strength test, and it is therefore suggested that curing rates should be based on abrasion test data.
Fatigue Failure of GR-S Tread Stocks
Authors: Winn Hugh , Shelton J. Reid 
Published: February 2011

Abstract
The fundamental nature of fatigue failure in rubber during flexing has been widely studied and is known to be complex. Among the more important factors involved (aside from variations in compounding) are state of cure, temperature of test, and oxidation. The object of this paper is to review and extend these studies as they apply to GR-S. Several investigators have studied the effect of time of cure on the flex cracking resistance of rubber. Busse found that, as the degree of cure was advanced, the flex resistance reached a maximum and then decreased. Similar studies on GR-S show that undercures flex better than either normal cures or overcures. Prettyman, using a different type of machine, showed a maximum near the optimum cure. Cadwell, Merrill, Sloman and Yost and Rainier and Gerke report that the rate of cracking of rubber increased with the temperature of flexing. Similar results have been demonstrated with GR-S by Breckley and by Carlton and Reinbold. Neal and Northam flexed rubber in air, oxygen, and nitrogen on a du Pont type flexing machine. They report no difference between the flexing behavior in air and oxygen. In nitrogen, however, an uninhibited stock flexed five times longer than in air before any failure was evident. The presence of an antioxidant did not change the behavior in nitrogen, but doubled the normal flex-life in air. These workers concluded that the failure of rubber on flexing is due to oxidation rather than to mechanical fatigue. No comparable work on GR-S has yet been reported. The present authors previously showed that oxygen plays an important part in the hardening of GR-S vulcanizates during accelerated aging tests in the 100° C air oven. Since high temperatures are developed during flexing, which might well result in a similar hardening by oxidation, it seemed desirable to determine whether oxygen plays a part in the flex-cracking of GR-S. For this purpose a typical tread stock was selected and flexed in air and in nitrogen which contained various small percentages of oxygen. The effect of state of cure and testing temperatures on the resistance of GR-S to flex-cracking was included in the study.
Mastication and Rate of Set-Up. Part II
Authors: Buchan S. 
Published: February 2011

Abstract
In the earlier communication it was shown that the length of time of milling of a mixed rubber exerted a marked effect on the rate at which it commenced to scorch. The longer the time of milling, the slower was found to be its rate of set-up. It is intended in this paper to give a brief account of some experiments which were undertaken with a view to deciding which factor or factors in the process of mastication are responsible for this retardation of the initial stages of vulcanization. During the milling of rubber only a limited number of factors can be considered as having any effect on its subsequent behavior as far as its rate of set-up is concerned. These are, decomposition of the accelerating components due to heat and pressure, softening of the rubber due to mechanical working, disaggregation or other causes, breakdown of the ultimate rubber particles, depolymerization, or, finally progressive oxidation of the rubber throughout the milling and mixing process. The possibility of decomposition of the accelerator during milling was examined by adding the accelerator to one batch at the beginning of the mixing process, adding it to another at the end and comparing the results of the rates of set-up on the two rubbers. Softening of the rubber without resorting to mechanical means was carried out by adding various softeners to the rubber while in solution and dispersing these by gentle stirring. It is of interest to note that the addition of softeners to the mixing without simultaneous mechanical working resulted in only a slight lowering of the plasticity reading (Y value), which seems to indicate that, for the effective development of softening action, mechanical working or the catalytic effects induced during mechanical working are essential.
Comparison of Methods of Examining the Scorching of Rubber Stocks
Authors: Morley J. F. , Scott J. R. , Willott W. H. 
Published: February 2011

Abstract
A comparison has been made between the plasticity and solubility methods of examining the scorching of accelerated rubber stocks; trials with a third method, based on the gelling of a solution of the stock, were unsuccessful. In a comparison using 10 different stocks the plasticity and solubility methods arranged these in practically the same order as regards tendency to scorch, showing that the two methods measure essentially the same property. The plasticity method usually detects an earlier stage of scorching than the solubility method using benzene as the solvent. Attempts to improve the sensitiveness of the latter method by using a less powerful solvent did not give promising results, as petroleum ether and diethyl ether behaved very similarly to benzene, while cyclohexanone did not readily dissolve the unscorched stock. The solubility method is unsuitable for stocks containing considerable percentages of gas black, e.g., tire tread stocks, and presumably also for those containing other strongly reinforcing fillers, because the unscorched stock does not dissolve in benzene. In determining the period for which a stock can be kept at a given temperature, or the temperature at which it can be kept for a given period, without practically serious scorching taking place, the plasticity method is to be preferred on account of its greater sensitiveness. It has the further advantage of giving a quantitative measure of the degree of scorching. However, for purely comparative purposes (but excluding stocks of the type referred to in 4 above) the solubility method is just as reliable, and has the advantage of being much simpler and quicker. By this method, also, it would usually be possible to decide whether any given piece of stock were scorched or not, whereas by the plasticity method this could not be done unless an unscorched piece of the same stock was available for comparison. In using the parallel-plate plastimeter for scorching tests, a relative long period of compression (10 minutes or more) gives the most sensitive indication of the change in plasticity produced by scorching. In the stocks examined the rate of scorching is, on the average, approximately doubled by a temperature rise of 10° C.
Carbon—Silica Dual Phase Filler, a new Generation Reinforcing Agent for Rubber: Part IX. Application to Truck Tire Tread Compound
Authors: Wang Meng-Jiao , Zhang Ping , Mahmud Khaled 
Published: February 2011

Abstract
The application of carbon-silica dual phase fillers (CSDPF) to natural rubber compound was investigated. It was found that these new fillers give significantly better overall performances in comparison with the conventional fillers—carbon black and silica. In a typical truck-tread compound, due to its high polymer—filler interaction and lower filler—filler interaction, the CSDPF E shows a comparable laboratory abrasion resistance and more than 40% reduction in tan δ at 70 °C, a parameter for rolling resistance, compared to compound filled with its carbon black counterpart, N1 10. These properties can, to a certain degree, be further improved by the addition of a small amount of coupling agent, bis(3-triethoxysilylpropyl)tetrasulfane (TESPT). In the case of wet skid resistance measured using the British Portable Skid Tester, the data show that CSDPF gives better performance than the conventional fillers, with and without coupling agent.
Mechanical and Elastic Properties of Sulfur Vulcanized EPDM as a Function of Third Monomer Content
Authors: van Duin Martin 
Published: February 2011

Abstract
A comparison is made of the vulcanization kinetics as studied with rheometry and of the mechanical and elastic properties for 65 ethylene—propylene—diene rubbers (EPDMs) vulcanized with an activated sulfur system according to the ISO 4097 recipe. The selected 50 commercial EPDMs and 15 development grades provide a broad range of chemical and physical structures, including different third monomer (TM) structures and contents ([TM]). At low [TM] (up to 40 mmol TM/100 g EPDM: for example ∼4.5 wt % 5-ethylidene-2-norbornene, ENB) the mechanical and elastic properties of EPDM are strongly affected by [TM], but at higher [TM] they are more or less unaffected. For fully-cured EPDMs this transition at ∼40 mmol TM/100 g is independent of the TM type (ENB, dicyclopentadiene, DCPD, 1,4-hexadiene, HD, etc.). In previous Fourier transform Raman (FT-Raman) spectroscopy and 1H NMR relaxation time studies it was established that for the ISO 4097 vulcanization system the average length of the sulfur crosslinks is ∼3 S-atoms/crosslink. From this it can be calculated that at ∼35 mmol TM/100 g EPDM a stoichiometric point is reached, where all sulfur is used for crosslinking. As a result, the properties of ISO 4097 EPDM vulcanizates level off when [TM] is increased beyond the stoichiometric point. The scatter in data at high [TM] is due to both experimental errors and differences in ethene/propene ratio, molecular weight (distribution) and/or degree of branching. It should be noted that the maximum cure rate (RH), being a kinetic parameter, remains dependent on [TM] over the whole chemical composition range although it also levels off at very high [TM]. In contrast to other studies it was found that RH is first order in both [TM] and [sulfur] at low [TM].
In Situ Filling of Silica onto “Green” Natural Rubber by the Sol—Gel Process
Authors: Kohjiya S. , Murakami K. , Iio S. , Tanahashi T. , Ikeda Y. 
Published: February 2011

Abstract
The sol—gel reaction of tetraethoxysilane produced the fine and well-dispersed in situ silica particles in the “green” natural rubber (NR) matrix before curing. This new method was developed for a NR/silica composite material, and a good reinforcement effect of in situ silica was observed on the NR vulcanizate. The method is expected to be an industrially practical technique. The in situ silica did not much inhibit the accelerated sulfur curing. Thus, it is estimated that the concentration of silanol groups on the in situ silica surface was smaller than those on the conventional silica surface. The silica—silica interaction of in situ silica seems to be weaker to result in better dispersion in the rubber matrix compared with the conventional silica. Atomic force microscopy suggested that the wettability of NR onto in situ silica was higher than that onto conventional silica. The hardness, modulus at 50% elongation and the storage modulus at room temperature of in situ silica-filled NR vulcanizate were smaller than those of conventional silica-filled NR vulcanizate, although the crosslinking density of the former was larger than that of the latter and their silica contents were comparable. These unique characteristics of in situ silica-filled vulcanizate seem to be ascribed to the fine and well-dispersed in situ silica particles in the NR matrix. These observations suggest that NR (a renewable resource)/in situ silica composite has much potential as an ecologically “green” material in the rubber industry.