Rubber compounding basics

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A rubber compound in general consists of following ingredients

a)Rubber: natural or synthetic
b)Activators
c)Antidegradants
d)Fillers
e)Plasticizer,extenders and tackifiers
f)Vulcanization agents
g)Accelerator s and retarders
h)Special additives like colorants, flame retardars and blowing agents.

rubbers are broadly divided into two groups
1. general purpose
2. special purpose


General purpose rubber:

General purpose rubbers are used in general application where high mechanical strength, low head buildup, dynamic stress,is required.
This includes natural rubber,SBR,IR etc.

Special purpose rubber :

As the name implied these rubbers have some special properties such as resistance to oxidation,heat, weathering, ozone,oil fuels,etc.

Rubber generally used in |Polyacrylic, fluroelastomer.

Activator:

zinc oxide and stearic acid is widely  recommended for this purpose.

Antidegradants:

Antidegradants is a chemical used in small amounts in a rubber compound to improve its resistance to degradation.

Fillers:

It is widely used in large quantities as loading agent to increase hardness and other physical properties and also as diluents for cost reduction.

Plasticizer:


The common name need for plasticizewr is softner and process aid. A processing aid is an additive that aids processing. It may help to reduce the compound viscosity or to make the raw material less elastic,during mixing it reduce the heat generation and also enhance filler incorporation.

Vulcanizing agents


vulcanization  is a chemical process for converting raw rubber into more durable materials by the addition of sulfur or other equivalent curatives or accelerators.


sulphut is most widely used as vulcanization agent for general purpose. during vulcanization reaction sulphur makes bridge between two dimensional rubber chains to make it a three dimensional rubber.
















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