Rubber

Rubber is elastic material acquired from the permeation of certain tropical plants (natural rubber) or taken from petroleum and natural gas (synthetic rubber).  Because of its elasticity property, durability, and stiffness, rubber is the main component of the tires applied in automotive vehicles. Rubber produced which is goes into automotive tires surplus more than 50% of all rubber production. The principal chemical component of rubber is elastomers, or “elastic polymers,” which are extremely large molecules that can recover their properties after drawling.

Natural rubbers

Natural rubber is consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds, plus water. The main producers of rubber worldwide are Thailand and Indonesia. The first step in producing natural rubber is harvesting latex from the rubber trees. This raw material then turned into rubber by further qualifications and processes.

Other names of natural rubber:

• India rubber
• Latex
• Amazonian rubber
• Caucho 
• Caoutchouc

Synthetic rubbers

Synthetic rubbers are polymers manufactured from petroleum products. Two third of all world rubber production is referred to as synthetic rubbers. It is predicted that the global earning of this industry will rise up to US$56 billion in 2020. The application of this kind of rubber mostly is like natural rubbers in automotive vehicles. One of the most important chemicals is polychloroprene. One of the famous synthetic rubbers in the industry is Emulsion styrene-butadiene rubber (E-SBR).

Some kind of synthetic rubber:

• Neoprene rubber or chloroprene
• Silicone rubber or polysiloxane
• Nitrile rubber or NBR
• EPDM Rubber or Ethylene propylene Diene monomer rubber
• SBR Rubber or styrene-butadiene rubber
• Butyl Rubber or isobutylene isoprene
• Fluorosilicone Rubber or FVMQ

Each rubber product contains these components

• Rubber
• Fillers
• Processing aids
• Accelerators
• Inhibitors
• Antioxidant and antiozonant
• Foaming agent blowing
• vulcanization system

Accelerator

In the rubber industry and all related industries, accelerators are referred to as any of multiple chemical components that lead to vulcanization of rubber to occur more swiftly and at less temperatures.  Accelerators contain wide variety ranges of chemicals but the most applicable materials in this industry containing sulfur and nitrogen, particularly benzothiazole derivation. Accelerators are grouped as Primary and/or Secondary accelerators based on the final compound that we need some special characteristics of them. In general Thiazoles and Sulfenamide accelerators because of their particular characteristics in cross-linking procedure grouped as primary accelerators.  Sometimes for activation of primary accelerators, there is a need to use secondary accelerators. Some examples for the secondary accelerator are Guanidines, Thiurams, and Dithiocarbamates The quantity of the secondary accelerators is commonly between 10-40% of the amount of the primary accelerator.

Vulcanization

Vulcanization is a cross-linking procedure in which single polymer molecules are transferred into a three-dimensional network of polymer chains through chemical reactions in which sulfur is a part. This procedure was found in 1839 and the people accountable for this discovery was Charles Goodyear in the USA and Thomas Hancock in England. Both people detected the application of Sulfur and White Lead as a vulcanization procedure for Natural Rubber. The process of vulcanization just by sulfur is an extremely slow process and also it does not access a specific and acceptable efficiency. This procedure takes about 6 hours to complete and in 140°C Temperature. From an economic point of view, it is not justified. Because of some inefficiency in using vulcanizers alone, the procedure needs chemicals to improve the vulcanization process. These limitations were dominating through the creation of accelerators which eventually became a part of the rubber industry and bring about more R&D parts in factories. Sulfur as a chemical vulcanizing agent has a restriction that, the elastomers must include unsaturated bonds in order to cross-link the process. Other chemicals that are utilized for cross-linking or vulcanization of polymers are Sulfur Monochloride, Tellurium, Selenium, Thiuram accelerators, Polysulphide polymers, p-Quinonedioximes, Metallic Oxides, Organic Peroxides, Di-isocyanates, etc.

Classification of Accelerators

Each accelerator has its specific characteristics which help manufacturers to choose the best one for their final application.

Shanghai Chemex Rubber Additives

Some of the rubber additives which is available for sale on the Shanghaichemex website are mentioned below:

References

• https://www.britannica.com/science/rubber-chemical-compound
• https://www.britannica.com/technology/accelerator
• https://www.explainthatstuff.com/rubber.html
• https://en.wikipedia.org/wiki/Synthetic_rubber
• http://www.nocil.com/Downloadfile/DTechnicalNote-Vulcanization-Dec10.pdf