Rubber products are connected to almost every part of modern day life; from tyres and automotive components to industrial hoses, flooring, food and medical applications and adhesives rubber products can be found virtually everywhere.
Globally twenty five million tonnes (25,000,000 t) of natural and synthetic rubber are produced, traded and consumed every year. As the world economy grows with increasing industrialisation of emerging economies demand for rubber products and rubber continues to increase.
Natural rubber is the oldest type of rubber but still accounts for more than 40% of the total volume, currently a little more than ten million tonnes per year and its usage continues to grow. Natural rubber is produced from the cultivation of the Hevea Brasiliensis tree, which as the name suggests originated in South America.
Natural rubber is a naturally occurring high-cis poly-isoprene. In a sample of natural rubber approximately 94% will be poly-isoprene with the balance made up of some naturally occurring resins and proteins, together with small amounts of ash, dirt and water. It is the resins and proteins together with the high-cis poly-isoprene which give natural rubber its unique properties.
The main natural rubber producing countries are nowadays Thailand, Indonesia, Malaysia, India, Vietnam and China. Also West Africa is becoming a more significant Natural Rubber producing region. Natural rubber was originally processed into visually graded types, such as Ribbed Smoked Sheets (RSS), numbered 1 – 5, and Brown and Pale Crepes. The Technically Specified Rubber (TSR) scheme was introduced in Malaysia about 50 years ago in order to provide consumers with measurable data of rubber properties. Now TSR grades such as SMR-10, SIR-20 and SVR-CV60 account for roughly 80% of global production and consumption.
Synthetic rubber was first produced in Germany in the middle of the 20th Century and now synthetic rubber grades and types account for the majority of rubber demand. Synthetic Rubber is produced by the polymerisation of monomers typically Styrene and Butadiene which are polymerised to produce Styrene Butadiene Rubber, SBR and also Poly-Butadiene Rubber, BR. Subsequent developments have seen the introduction of other monomers such as ethylene and propylene which are used in the production of EPDM. Other types of synthetic rubber include: Butyl, more correctly know as Isobutylene Isoprene Rubber, and this can be modified with halogen atoms such as Chlorine or Bromine to produce Chlorobutyl and Bromobutyl, together known as Halo-Butyls and Nitrile (acrylonitrile butadiene). There is even a synthetic version of natural rubber called Polyisoprene.
Synthetic rubber is now produced all over the world, with the major producing countries being China, the United States of America, Japan, Republic of Korea and Germany.
Applications for both natural and synthetic rubber include a wide and diverse product range including tyres, tyre re-treading, adhesive and adhesive tapes and labels, rubber flooring, industrial hoses, gaskets, rubber to metal bonded parts and anti-vibration system components, pharmaceutical products, dipped goods such as latex gloves, condoms and catheters and many others.
Rubber type | Benefits | Limitations | Typical applications |
Natural Rubber | Widest range of hardness Very strong & naturally self reinforcing Good compression set Good resistance to inorganic chemical | Lack of oil and organic fluids resistance Max temperature 75 - 100°C Poor ozone resistance | Sealing and shock absorption Conveyor belting Truck tyres |
EPDM | Rubber with greatest water resistance Very inert structure Stable over long periods of time Very good weather resistance Easy to compound and process | Not resistant to oil and oil products Relatively poor compression set | Automotive weather strips Windows and doors sealing Automotive hoses (not fuel) |
SBR | Good physical strength Good tear and abrasion resistance | Poor oil and fuel resistance Poor weather resistance | Non-mechanical high volume products Shoe soles and car tyres |
Polybutadiene | Good abrasion resistance Low glass transition temperature High resilience | Very poor ozone resistance | Tyres Conveyor belts Polystyrene and ABS modification |
Butyl Rubber Isobutylene Isoprene | The highest performing rubber for impermeability Good flexural properties Good ozone resistance | Poor abrasion resistance | Tyre linings and inner tubes Roofing products Fuel and lubricant additive |