ABSTRACT
Thermoplastic polymer blends are important in a number of applications and are required to provide optimal performance. Most polymer combinations are not miscible and frequently a high degree of incompatibility is actually desirable to best exploit the properties of all components. Interfacial interactions, including adhesion, are essential in determining both processing behavior and mechanical properties of blends. They are studied mainly by morphological observations and indirectly by end-use-related properties. However, some novel techniques are being developed to obtain more direct quantitative data about them.
The methods utilized for optimizing interfacial/interphasial behavior belong to two main categories: generating some chemical bonding between different phases, or utilizing compatibilizers (either as a separate ingredient or generating them in situ). Specific examples relative to poly(ethylene terephthalate) (PET) are considered here. The first case is the reactive mixing of polyethylene terephthalate) with polyolefins grafted with reactive monomers, which exploits the reactivity of PET hydroxyl and carboxyl end-groups for improving interfacial adhesion. The second case is the formation in situ of poly(ethylene terephthalate-co-2,6-naphthalene dicarboxylate) (PENT) in order to act as a compatibilizing agent for PET–PEN (poly(ethylene 2,6-naphthalene dicarboxylate)) blends.
