Common Polymers and Additives used for Processing - Introduction to Polymeric Composites with Rice Hulls - page 51

• Erucamide , which migrates slowly to the surface of a polymer and, due to its low
volatility, remains on the surface longer.
• Oleamide , which migrates faster than erucamide and is known as a fast blooming
(migrating) slip additive. In general, it is the choice for large-volume processing.
• Stearamide is used in conjunction with erucamide and oleamide and provides an
anti-blocking effect.
4.7.3 Plasticisers
Plasticisers are solvents mixed into a polymer to alter its rheological or mechanical
properties. Plasticisers also function as processing aids because they have the same
effect as raising the temperature of a polymer, resulting in lowering of its viscosity,
thus reducing the risk of thermal degradation during processing. Plasticisers are also
used to alter the mechanical properties of a polymer, such as stiffness, toughness and
strength.
4.7.4 Stabilisers
Polymer degradation can occur due to a combination of heat and oxygen. During
processing, heat or energy produces free radicals that react with oxygen to form
carbonyl compounds, giving rise to yellow or brown discolourations in the final
product.
4.7.5 Antioxidants
Addition of an antioxidant suppresses thermal degradation during polymer processing.
Antioxidants also can be classified as stabilisers and, to achieve optimal results, good
practice would be to use a blend of stabilisers to create a synergistic stabilising effect.
Irrespective of the system used, they will not fully eliminate thermal degradation but
will slow it down. Once the stabilisers have been consumed by the reaction with
oxygen, the polymer is no longer protected against thermal degradation.
4.7.6 Flame Retardants
Most polymers are flammable due to their organic origins, and have always been
a serious technical problem. However, some additives that contain halogens