Elastomer system

Elastomers are long-chain polymers which are capable of cross-linking which is referred to as vulcanization.

The vulcanization process cross-links the polymer chains via chemical bonds creating the elastic rubbery or memory properties

Rubber Compounds

In any molded rubber product, the three major influences of part quality that we control are the mold, the process and the rubber formulation. By far the most influential is the latter. In plastics, designers can use material suppliers’ specification data to determine what material will work best in their application, but in rubber, that information is not readily available. The reason is the plastic molder purchases their materials in a ready to process form and the resulting physical and environmental resistance properties are controlled by that supplier. In contrast, the rubber molder purchases ingredients from many suppliers and mixes them to form the material that is processed in the mold, therefore, each molder controls the material’s and resulting end product’s properties.

Compounding can be broken into five main systems as follows :

1. Elastomer System
One or more elastomers for characteristics
Elastomer for improved processing

2. Filler System
Reinforcing filler
Semi and non-reinforcing fillers

3. Protectants

4. Process Aids
Mixing Aids
Molding Aids

5. Cure System
Vulcanizing Agents
Scorch Retarders

The following is a useful procedure to guide compound development
  • Set specific objectives (properties, price, etc.).
  • Select base elastomer(s).
  • Study test data of existing compounds.
  • Survey compound formulations and properties data presented by material suppliers in their literature.
  • Choose a starting formulation.
  • Develop compounds in laboratory to meet objectives.
  • Estimate cost of compound selected for further evaluation.
  • Evaluate processability of compound in the factory.
  • Use compound to make a product sample.
  • Test product sample against performance specification.