Polymer blend formulation and processing, with reference to the nature and the behaviour of pigmented polycarbonate -poly(butylene terephthalate) (PC-PBT) blends

Polymers, and even more so polymer blends, are selected for their particular properties and processing characteristics. It is often necessary to include additives in the polymer formulations, either to facilitate processing, or to extend the life of the polymeric product that is created. Colourants are additives that are principally used for aesthetic purposes. However, the addition of a colourant to a thermoplastic system can lead to unexpected and sometimes detrimental changes in the material properties of that system. In this review, the general characteristics of polymer blends and the processes involved in manufacturing them are discussed. Additives that may be included in the formulation and the interactions that can arise among the blend components are also described. The relevance of these components and processes are then discussed in regard to blends of polycarbonate and poly(butylene terephthalate).