Rubber, abrasion resistance Tensile strength

The example chosen here to illustrate this type of composite involves a polymeric phase that exhibits rubberlike elasticity. This application is of considerable practical importance since elastomers, particularly those which cannot undergo strain-induced crystallization, are generally compounded with a reinforcing filler. The two most important examples are the addition of carbon black to natural rubber and to some synthetic elastomers and silica to polysiloxane elastomers. The advantages obtained include improved abrasion resistance, tear strength, and tensile strength. Disadvantages include increases in hysteresis (and thus heat buUd-up) and compression set (permanent deformation). 

Demanded by the rubber industry to improve the impact resistance, tensile strength, hardness and abrasion of rubber... 

Elastomers are often compounded with finely divided solids to reinforce the rubber and to reduce costs. The most important fillers are carbon blacks, silica and silicates, clays and whiting (calcium carbonate). " The particles are the source of reinforcement through their interactions with the rubber, among themselves and with the chemistry of the cross-linking process. Abrasion resistance, tear strength and tensile strength are simultaneously improved. However, hysteresis, heat build-up and compression set (permanent deformation) are also known to increase as the reinforcing ability of the filler becomes more pronounced. 

Vulcanization changes the physical properties of rubbers. It increases viscosity, hardness, modulus, tensile strength, abrasion resistance, and decreases elongation at break, compression set and solubility in solvents. All those changes, except tensile strength, are proportional to the degree of cross-linking (number of crosslinks) in the rubber network. On the other hand, rubbers differ in their ease of vulcanization. Since cross-links form next to carbon-carbon double bonds. 

Elastomers resulting from a series of organic reactions, e.g., a polyglycol ester of adipic acid reacted with an aromatic diisocyanate and cured with water, glycol or further reaction with an aromatic diisocyanate. These elastomers have high tensile strength, very high abrasion resistance, and lower hysteresis than natural rubber. A major use is in the manufacture of foamed polymers. 

This term was originally limited to the chemical reaction of rubber with sulphur to bring about the following effects (a) reduced thermoplasticity, (b) increased tensile strength and resistance to abrasion, and (c) reduced solubility in organic solvents. Since many other substances can bring about the above changes the term has now been widened to include any treatment which will introduce crosslinks in the rubber matrix. Vulcanised Latex... 

The carboxylated types (XNBR) contain one, or more, acrylic type of acid as a terpolymer, the resultant chain being similar to nitrile except for the presence of carboxyl groups which occur about every 100 to 200 carbon atoms. This modification gives the polymer vastly improved abrasion resistance, higher hardness, higher tensile and tear strength, better low temperature brittleness, and better retention of physical properties after hot-oil and air ageing when compared to ordinary nitrile rubber. 

Rubber becomes brittle in cold weather and tacky in hot weather, and it is odorous and perishable. It also has very low tensile strength and low resistance to abrasion. One of the major advances in the improvement of rubber was in the discovery by Charles Macintosh in Scotland in 1820 that coal-tar naphtha is a cheap and effective solvent for rubber. He placed a solution of rubber and naphtha between two fabrics, and in so doing he covered up the sticky or brittle surfaces that had been common in earlier single-texture garments treated with rubber. Macintosh patented the process in 1823. These double-textured waterproof cloaks, which were first introduced to the public in 1824, have been known ever since as mackintoshes. 

Carbon black increases the tensile strength of an SBR vulcanisate to its 10 to 20-fold (which would, otherwise, be very low), as well as its abrasion resistance. Natural rubber can, because of its stereospecific (cis) chain structure crystallise under strain, and, therefore, reach higher values of its tensile strength for a good abrasion resistance carbon black is also of importance with NR. 

The retention of the maximum tensile strength at elevated temperatures is greater for radiation cured than for chemically cured natural rubber. The physical properties after high-temperature aging are not improved, however. Lower flex life and higher abrasion resistance of radiation cross-linked NR were reported. Other properties, such as permanent set, hardness, and resilience, were found to be nearly equal. 

Carboxylated nitrile rubber (XNBR), a high-performance elastomer, is remarkable for providing vulcanizates that exhibit enhanced tensile strength, elastic modulus, hardness, and improved resistance to tear, abrasion, and the deleterious action of... 

The physical properties of natural rubber and synthetic rubber compounds are affected greatly by the type and amount of fillers used. Carbon black is the most commonly used filler. Increasing amounts of carbon black increases the hardness and modulus of the vulcanizates. Resilience and resistance to impinging type abrasion decrease along with elongation. Tensile strength and tear strength... 

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