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 principle chemical component of rubber are elastomers, or “elastic polymers,” that are extremely large molecules which can be recover their properties after drawling.
Natural rubbers
Natural rubber are consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds, plus water. Main producers of rubber worldwide are Thailand and Indonesia. First step in producing natural rubber is harvesting latex from rubber tree. 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 refer to synthetic rubbers. It is predicted that global earning of this industry will rise up to US$56 billion in 2020.Application of this kind of rubber mostly is like natural rubbers in automotive vehicles. One of most important chemicals is polychloroprene. One of famous synthetic rubbers in 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 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. Some times for activation of primary accelerators there is a need to use secondary accelerators. Some examples for secondary accelerator are Guanidines, Thiurams, and Dithiocarbamates The quantity of the secondary accelerators are commonly between 10-40% of the primary accelerators amount.
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 which sulfur is a part of that. This procedure was found in 1839 and the people accountable for this discovery were Charles Goodyear in 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 extremely slow process and also it does not access to a specific and acceptable efficiency. This procedure takes about 6 hours to complete and in 140°C Temperature. In economy points of view it is not justified. Because of some inefficiency in using vulcanizers alone the procedure needs chemical to improve the vulcanization process. These limitations were dominate through creation of accelerators which eventually became a part of 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 process. Other chemicals that is 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.
| Accelerators | Chemical Group | Vulcanization Speed |
| BA, HMT | Aldehyde Amine | Slow |
| DPG, DOTG | Guanidine | Slow |
| MBT, MBTS, ZMBT Semi | Thiazole | Ultra-fast |
| ZBDP | Thiophosphate | Ultra-fast |
| CBS, TBBS, MBS, DCBS | Sulfenamides | Fast-Delayed action |
| ETU, DPTU, DBTU | Thiourea | Ultra-fast |
| TMTM, TMTD, DPTT, TBzTD | Thiuram | Ultra-fast |
| ZDMC, ZDEC, ZDBC, ZBEC | Dithiocarbamate | Ultra-fast |
| ZIX | Xanthates | Ultra-fast |
Shanghai chemex Rubber Additives
Some of rubber additives which is available to sale on Shanghaichemex website are mentioned below:
| Accelerators | Antioxidants | Stearate |
| · Accelerator MBT (M) | · Antioxidant TMQ(RD) | · Stearic Acid |
| · Accelerator MBTS(DM) | · Antioxidant 6PPD(4020) | · Zinc Stearate |
| · Accelerator CBS(CZ) | · Antioxidant IPPD(4010NA) | · Lithium Stearate |
| · Accelerator NOBS (MBS,MOR) | · Antioxidant SP | · Sodium Stearate |
| · Accelerator DPG(D) | · Antioxidant BHT(264) | · Calcium Stearate |
| · Accelerator TMTD(TT) | Vulcanizator | · Potassium Stearate |
| · Accelerator TMTM(TS) | · DTDM | · Magnesium Stearate |
| · Accelerator ZDEC (ZDC,EZ) | · Insoluble sulfur (IS-HS , OT) | Plasticizer |
| · Accelerator ETU(NA-22) | · Zinc Oxide | · ATBC |
| · Hexamine | Antiscorcher | · DBP |
| Curing agent | · PVI (CTP) | · DOS |
| · RE | Reinforcer | · DOTP |
| · PFE | · Silica | · Butyl Stearate |
| · Resorcinol |
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
