Analysis of structure transition and compatibility of PTT/PC blend without transesterification

Poly(trimethylene terephthalate)/polycarbonate (PTT/PC) blends were prepared by solvent mixing to avoid transesterification during high temperature blending. The influences of compositions on the thermal behavior, crystallization morphology and structure of the blends were studied. FTIR results indicated that there was no COO linking to two phenyl groups on each side chain and DSC results supported no transesterification reaction. DSC curves showed that T _c and T _mc increased to maximum range when PC contents were between 7 wt%-15 wt%, however, T _m decreased constantly with the increase of PC contents. It was observed from POM that PTT spherulitic morphology and crystallization kinetics were obviously influenced by the change of PC contents. Structural evolutions during cooling were investigated by SAXS which showed L _c of PTT remained a constant with different PC contents and also fixed during crystallization, nevertheless, it revealed a maximum value of L _nc for sample PTT₉₃. It was concluded that PC chains could be permeated into not only amorphous crystallite structure but also amorphous lamellae structure and 7 wt% PC content was supposed to be the “proper” penetration amount into PTT lamellae structure which led to a maximum capacity of amorphous lamellar layer. Fringedmicelle crystal model was adopted to illustrate semi-crystalline physical structures of the blend in two kinds of component aggregation states.