Additives

Abstract

The basic polymers to which the plastics industry owes its existence are in most cases unsuitable for processing into useful articles, in their pure unmodified form. This is especially true of the thermoplastics which are mainly responsible for the explosive growth of the plastics industry since the Second World War. Polyolefins, for example, are extremely susceptible to oxidative degradation, particularly under the conditions of heat and pressure necessary for their extrusion or injection moulding, and must be protected with a suitable antioxidant before becoming commercially viable materials. Similarly, polyvinyl chloride (PVC), another high tonnage thermoplastic, is in its pure form a hard horny material, difficult to process and extremely susceptible to rapid degradation at the temperatures necessary for its processing. However, the addition of suitable plasticisers, stabilisers, lubricants and other additives can transform it either into a soft flexible material with pronounced rubbery characteristics, or alternatively into a tough rigid material suitable for water pipes, roof sheeting and a host of other applications.