Heterogeneous nucleation of poly(ethylene terephthalate)

The effect of various metal salts as nucleating additives for poly(ethylene terephthalate) (PET) has been investigated. In the case of sodium benzoate and probably for all other effective nucleating additives, the nucleation process can be divided into a “heterogeneous particle nucleation” performed by the unreacted salt and a “homogeneous nucleation” due to the polymer–sodium (metal) salt formed during the extrusion. This polymer–sodium (metal) salt is the major nucleating agent in these systems. We have also shown the fundamental difference between the concept of a nucleating additive and that of a nucleating agent.