The Thermal Vulcanization of Synthetic Rubber

1958 ◽  
Vol 31 (1) ◽  
pp. 132-146 ◽  
Author(s):  
H. Luttropp
Keyword(s):  
Thermal Treatment ◽  
Natural Rubber ◽  
Dynamic Stress ◽  
Effect Of Temperature ◽  
Synthetic Rubber ◽  
Aging Phenomena ◽  
Lower Tensile Strength ◽  
Soft Rubber ◽  
Acrylonitrile Copolymers ◽  
Butadiene Styrene

Abstract It is shown that synthetic rubbers, in contrast to natural rubber, can be vulcanized to soft rubber by a simple thermal treatment without any previous admixture of sulfur or accelerators. This process has been designated as “Thermovulcanization” to distinguish it from the regular vulcanization procedure under heat with the addition of sulfur and accelerators. Various synthetic rubbers of Schkopau production have been investigated for their behavior in the process of thermovulcanization. Both butadiene-styrene and butadiene-acrylonitrile copolymers as well as the butadiene block polymerizate lend themselves to vulcanization by this thermal treatment. For the butadiene-styrene copolymer with higher styrene content, thermovulcanization leads to products which are not equivalent to the regular sulfur-accelerator vulcanizates. Natural rubber cannot be vulcanized to soft rubber by thermovulcanization. The investigation of the effect of temperature revealed that a temperature of 195° C, for example, was applicable for all the synthetic rubbers studied. The addition of active carbon was found to accelerate the thermovulcanization process and certain properties of the vulcanizates are improved. The results of some comparative studies are presented, and it is pointed out that thermovulcanizates and normal vulcanizates show agreement in some of their properties and vary in others. The thermovulcanizates, as compared with normal vulcanizates, show somewhat lower tensile strength and somewhat lower fatigue resistance. Also their resistance to swelling is lower. On the other hand they are better in abrasion, have somewhat improved elastic properties, and show improved resistance to aging including surface aging phenomena under static and dynamic stress.

Properties of Ebonite. XXXVII. Electrical Properties of Synthetic Rubber Ebonites

1949 ◽  
Vol 22 (4) ◽  
pp. 1084-1091
Author(s):  
D. G. Fisher ◽  
L. Mullins ◽  
J. R. Scott
Keyword(s):  
Natural Rubber ◽  
Power Factor ◽  
Power Loss ◽  
Ionic Conduction ◽  
Effect Of Temperature ◽  
Plastic Yield ◽  
Styrene Copolymers ◽  
Synthetic Rubber ◽  
High Dielectric ◽  
Butadiene Styrene

Abstract Experiments were carried out to explore the possibility of making good electrical ebonites from various types of synthetic rubber. The ebonites produced were tested for permittivity and power factor over wide ranges of temperature and frequency. Thioplasts (Thiokols AZ and FA) apparently do not produce hard ebonitelike vulcanizates by the normal procedure. Neoprenes (GN and I) give ebonites, but with such high dielectric power loss as to be unsuitable for use as high-frequency dielectrics; moreover, if the mix contains zinc oxide, the ebonite has a very hygroscopic and therefore electrically unsatisfactory surface. Butadiene copolymers containing polar groups (butadiene-acrylonitrile types and Thiokol RD) give ebonites with high power loss, hence are not suitable for making high-grade electrical ebonites. Polybutadiene (Buna-85) and butadiene-styrene copolymers (GR-S, Hycar-EP, Buna-S) are much nearer to natural rubber as far as the radio-frequency (100 to 2,500 kc. per sec.) power loss of their ebonites is concerned. The GR-S ebonite examined was not so good as natural rubber at room temperature, but was superior above about 50° C. Buna-85 and Hycar-EP were superior to natural rubber over the whole temperature range; indeed, the high-styrene copolymers, as represented by Hycar-EP and Buna-SS, appear to be the best type of synthetic rubber for making ebonite with low power loss, especially at high frequencies and temperatures. The effects of changing temperature and frequency on permittivity and power factor are discussed. Attention is drawn to the big effect of temperature on power factor; this was less with polybutadiene and butadiene-styrene ebonites than with natural rubber ebonite, in keeping with the greater heat resistance of the former as judged by plastic yield tests. Comparison of the effects of rising temperature and decreasing frequency shows that these produce broadly similar effects on power factor, as would be expected on theoretical grounds, but that rising temperature superposes a second effect (an increase), presumably due to increased ionic conduction.

Effect of Temperature on Resilience of Natural and Synthetic Rubber

1943 ◽  
Vol 16 (4) ◽  
pp. 881-887
Author(s):  
H. C. Jones ◽  
E. G. Snyder
Keyword(s):  
Natural Rubber ◽  
Effect Of Temperature ◽  
Synthetic Rubber ◽  
Natural And Synthetic

Abstract The necessity of the substitution of synthetic elastomers for natural rubber has been forced on the rubber compounder by the exigencies of war. His background of a hundred years of research and compounding is his principal weapon for making this conversion in the shortest possible time. Too often he finds that this background fails and that practices invaluable in the development of natural rubber stocks are worthless in the case of synthetic rubber, or at least are subject to a different interpretation.

Low-Temperature Behavior of Butadiene-Styrene Copolymers. Effect of Compounding Variables

1950 ◽  
Vol 23 (4) ◽  
pp. 760-769
Author(s):  
R. D. Juve ◽  
J. W. Marsh
Keyword(s):  
Low Temperature ◽  
Natural Rubber ◽  
Compression Set ◽  
Similar Work ◽  
Styrene Copolymers ◽  
Synthetic Rubber ◽  
Low Temperature Flexibility ◽  
Extended Exposure ◽  
Butadiene Styrene ◽  
Elastic Characteristics

Abstract Synthetic rubbers and natural rubber increase in stiffness at low temperatures and tend to lose their elastic characteristics. This stiffening and hardening phenomenon occurs in varying degrees with various elastomers. Natural rubber and certain synthetic rubbers crystallize during extended exposure at low temperature, whereas other synthetic rubbers such as GR-S remain amorphous. In a general review of the low temperature properties of synthetic rubber, Liska has shown that decreased styrene in butadiene-styrene copolymers improves the flexibility at low temperature. The low temperature flexibility of vulcanized articles made from any particular rubber or synthetic rubber is influenced by the compounding ingredients admixed with the elastomer. This paper shows the results of some studies of the effect of these compounding ingredients on the low temperature serviceability of butadiene-styrene copolymers. Somewhat similar work on the effect of a large number of plasticizers in GR-S has been conducted at the Rubber Laboratory, Mare Island Naval Shipyard, with particular emphasis on compression set at low temperature.

Carbon Blacks in GR-S

1946 ◽  
Vol 19 (1) ◽  
pp. 100-122 ◽  
Author(s):  
D. Parkinson
Keyword(s):  
Tensile Strength ◽  
Carbon Black ◽  
Natural Rubber ◽  
Carbon Blacks ◽  
Styrene Copolymer ◽  
Synthetic Rubber ◽  
First Approximation ◽  
Different Types ◽  
Almost All ◽  
Butadiene Styrene

Abstract The importance of different types of colloidal carbon as reinforcing agents for the butadiene-styrene copolymer, GR-S, has been stressed in recent papers. It has been shown that, to a first approximation, the effect of carbon blacks in this type of synthetic rubber is similar to that in natural rubber, but it has been shown also that the extremely low tensile strength and poor tearing properties of uncompounded vulcanized GR-S necessitates the addition of some form of carbon black to almost all types of compounds. The present paper considers the influence of carbon blacks in vulcanized GR-S compounds. Earlier papers have discussed the effect of carbon blacks in natural rubber.

Heat Build-Up and Destruction of Vulcanizates under Dynamic Stress

1955 ◽  
Vol 28 (1) ◽  
pp. 153-185 ◽  
Author(s):  
P. Kainradl ◽  
F. Händler
Keyword(s):  
Thermal Decomposition ◽  
Natural Rubber ◽  
Temperature Rise ◽  
Dynamic Stress ◽  
Dynamic Properties ◽  
Carbon Blacks ◽  
Synthetic Rubber ◽  
Heat Build Up ◽  
Natural Rubber Vulcanizates

Abstract The classification of various mixtures of natural rubber and of synthetic rubber and of synthetic rubbers with respect to heat build-up under dynamic stress depends on the experimental conditions under which the vulcanizates are tested. In many cases a reversal of the order of the mixtures is found when the latter are compared at constant deformation instead of at constant periodic stress. This is true also of flexing to the point of destruction of various types of vulcanizates. The dependence of the dynamic properties on the temperature and on the stress is characteristic of the type of vulcanizate. Hence, any classification of various mixtures depends not only on the character, but also on the magnitude of the stress. These differences were found within the temperature range encountered in practice, as in tires. Consequently, no definite conclusions about the temperature rise in the range of heat build-up extending to the point of destruction can be drawn from measurements of the dynamic properties at room temperature. Changes of the dynamic properties can also take place during dynamic stressing without any considerable rise of temperature. In general, the temperature rise in the static state and the flex life are related in the sense that the higher the temperature, the shorter is the flex life, if the preceding facts are taken into consideration. However, the experiments on the temperatures of destruction show that the flex life of different vulcanizates differs even when the rise of temperature is the same. For a flex life of 100 minutes, natural-rubber vulcanizates containing active carbon blacks were destroyed at higher temperatures (170°–185° C) than was the base mixture containing no filler (about 160° C). The synthetic-rubber mixtures showed greater heat build-up (190°–220° C). These differences are found with different, as well as with equal, mechanical stress on the vulcanizate. The nature of the destruction for a given stress depends to a considerable degree on the structure of the vulcanizate. When flexed to the point of destruction, natural-rubber vulcanizates containing zinc oxide or SRF carbon blacks, and all synthetic-rubber vulcanizates, crack from the core outward, without showing any extensive thermal decomposition. On the other hand, natural-rubber vulcanizates containing active carbon blacks or Aerosil showed definite evidence of heat decomposition in the center, i.e., stickiness and porosity. This distinction in the destruction patterns gives the impression that the cause of destruction in the first case is chiefly a mechanical attack, whereas in the latter, it is chiefly thermal decomposition. It must be concluded from all the experimental results that several chemical reactions of destruction, having different temperature coefficients, proceed simultaneously, and that direct mechanical attack by the external forces is, to a greater or less extent, added to the heat effect.

Mastication of Rubber. II. Interpolymerization of Natural Rubber and Neoprene on Cold Milling

1956 ◽  
Vol 29 (2) ◽  
pp. 427-437
Author(s):  
D. J. Angier ◽  
W. F. Watson
Keyword(s):  
Free Radicals ◽  
Natural Rubber ◽  
Small Molecules ◽  
The Other ◽  
Polymer Molecules ◽  
Commercially Important ◽  
The Individual ◽  
Cold Mill ◽  
General Method ◽  
Butadiene Styrene

Abstract The softening of elastomers on cold milling results from scission of the polymer molecules by the applied shearing forces. The ruptured chains are free radicals, which can undergo mutual combination, interaction with oxygen and various additives, and branching (grafting) on to other polymer molecules. A general method of producing graft and block interpolymers between elstomers is therefore indicated, namely, to cold-mill the polymers together in the absence of small molecules which can terminate the polymeric radicals in order that the radicals may cross-terminate or graft onto the polymer molecules of the other type. A survey of several pairs of the commercially important elastomers, natural rubber, butadiene-styrene, Neoprene, and butadiene-acrylonitrile, has shown that cold milling does effect interlinking. Detailed results for the rubber-Neoprene system are reported in this communication. Experimental verification of polymer interlinking was obtained from the solubility properties of the milled elastomers. Cold milling of Neoprene under nitrogen produces gel, whereas of natural rubber does not, but the milling of mixtures gives gels containing natural rubber. Also, the solubilities and precipitation of the milled mixtures cannot be accounted for by these properties of the individual polymers. Finally, Neoprene-natural rubber mixtures, after and not before cold-milling, can be cross-linked by magnesium oxide, with rubber bound into the vulcanizate.

Effect of Temperature on Ozone Cracking of Rubbers

1966 ◽  
Vol 39 (3) ◽  
pp. 643-650
Author(s):  
A. N. Gent ◽  
J. E. McGrath
Keyword(s):  
Polymer Chains ◽  
Effect Of Temperature ◽  
Ozone Molecule ◽  
Segmental Mobility ◽  
Network Chain ◽  
Styrene Copolymers ◽  
Rates Of Growth ◽  
Rate Controlling Step ◽  
Limiting Value ◽  
Butadiene Styrene

Abstract The rates of growth of single ozone cracks have been measured for vulcanizates of a series of butadiene—styrene copolymers, over a temperature range from − 5° C to 95° C. The rates appear to be determined by two mechanisms. At low temperatures, near the glass transition temperature, they are quantitatively related to the segmental mobility of the polymer. The principal rate-controlling step in this case is concluded to be movement of the polymer chains after scission to yield new surface. At high temperatures the rate approaches a limiting value of 10−3 cm/sec/mg of ozone/1. This is about 1/1000 of the maximum possible value when instantaneous reaction of one incident ozone molecule causes scission of one network chain.

Chlorinated Isoprene Rubbers in Adhesive Composites

2017 ◽  
Vol 44 (5) ◽  
pp. 25-28 ◽  
Author(s):  
A.A. Zuev ◽  
L.R. Lyusova ◽  
N.P. Boreiko
Keyword(s):  
Natural Rubber ◽  
Scientific Research ◽  
Scientific Research Institute ◽  
Physicomechanical Properties ◽  
Butadiene Rubber ◽  
Technological Factors ◽  
Nitrile Butadiene Rubber ◽  
Synthetic Rubber ◽  
Adhesive Materials ◽  
Isoprene Rubber

Now there is not a single area of industry that can do without adhesive elastomer materials. Composites based on synthetic rubbers comprise 75% of the total volume of adhesive materials produced, which is due to the combination of unique properties typical of the elastomer base of the adhesive. The base of many imported adhesives for the bonding of rubber to metal is chlorinated natural rubber. As an alternative, chlorinated synthetic isoprene rubber has been proposed, developed at the Scientific Research Institute for Synthetic Rubber in St Petersburg. The chlorinated isoprene rubber was compared with imported chlorinated natural rubber in adhesive composites, and the physicomechanical properties of mixes based on a blend of chlorinated rubber and nitrile butadiene rubber were investigated. The investigation was conducted on chlorinated natural rubber of grade Pergut S20, chlorinated isoprene rubber SKI-3, and nitrile butadiene rubbers of grades BNKS-28AMN and SKN-26S. The influence of the ratio of chlorinated rubber to nitrile butadiene rubber and the technological factors of mix preparation on the properties of films produced from them was established. It was shown that, in terms of the level of properties, home-produced chlorinated rubber can be used as the base for adhesives for hot bonding of rubber to metal instead of imported Pergut S20.

scholarly journals Sustainability and Competitiveness of Thailand’s Natural Rubber Industry in Times of Global Economic Flux

2017 ◽  
Vol 14 (1) ◽  
pp. 169
Author(s):  
Palapan Kampan
Keyword(s):  
Natural Rubber ◽  
Positive Relationship ◽  
New Technologies ◽  
Pearson Correlation ◽  
The United States ◽  
Bivariate Correlation ◽  
Synthetic Rubber ◽  
Reinforcing Factors ◽  
Strong Positive Relationship ◽  
Correlation Tests

This study assesses economic, legal, and environmental conditions that Thai rubber farmers face, and evaluates actions they can take to increase incomes. Statistical analyses determine relationships between prices of oil, natural and synthetic rubber. Pearson correlation tests found a strong positive relationship (r = 0.887) between the price of Brent crude and Thai ribbed smoked sheets, and a moderate positive relationship between price changes in Brent and synthetic rubber (r = 0.648). Regression analysis showed Brent oil price is a good predictor of natural rubber prices. Moderate to strong positive relationships were also found between natural rubber price and gross domestic product of Japan, China, and the United States. Criminal antitrust behavior in rubber industries appeared to interfere with normal pricing in rubber markets. No significant bivariate correlation was found between rainfall in Thailand and natural rubber price, production, or export although flooding and other environmental issues clearly affected rubber farms. A survey of options showed Thai rubber farmers can improve livelihoods best through collective purchase and use of new technologies, and by integrating into downstream supply chain industries. At very least, farmers are urged to abandon monocrop methods and supplement incomes with fruit, fish, livestock, or pigs. stment budget, 2) architectural Aesthetic, and 3) utilization. Additionally, background of the interviewees is one of reinforcing factors for decision on universal design investment.

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