Mixing, shaping and curing are the main three stages in rubber processing. Mixing with different compounding ingredient is done to increase chemical and physical properties of the rubber. That also known as rubber compounding. There are three general processes for shaping called molding, extrusion and calendering. after shaping curing is done for improve hardness of rubber product by forming cross links in rubber chains. That is also called vulcanizing.
Now a day’s both natural rubber and different synthetic rubbers are used for rubber processing.
- Natural rubber(NR)
 |
| Chemical structure of Natural Rubber |
Natural
rubber is latex taken from the tree Heavea Brazilianzis
which is generally
known as rubber tree. NR has excellent tensile strength and elongation. Its abrasion resistance, tear resistance, fatigue resistance and electrical resistance also high. NR formula has unsaturated double bonds, so its weather resistance is poor. Not only that natural rubber is dissolved in non polar chemicals like oils, petroleum based fuels etc.
Natural rubber is used as both liquid (latex rubber) and solid
form (dry rubber) for processing. Some applications of these two types, some processing methods and advantages & disadvantages are summarized below.
Applications
|
Processes
|
Advantages
|
|
Latex rubber
|
Gloves, Balloons
|
Dipping, tubing
|
Simple machinery can use,low energy consumption
|
Dry rubber
|
Tires, o rings, engine mounts
|
Extrusion, molding
|
Easy to transport and
store
|
- Synthetic rubbers
Synthetic
rubbers are made by polymerisation of different petrolium based monomers. Some of
synthetic rubbers are Isoprene rubber(IR), Styrene Butadiene Rubber(SBR),
Isoprene Isobutaline Rubber(IIR), Ethelene Propelene Rubber(EPR), Chloroprene
Rubber(CR), Silicon Rubber etc.
Those synthetic rubbers have different properties, so they have different applications and different processing methods. they will be explained in future.
