TRANSESTERIFICATIONS IN A POLYBLEND OF POLY(BUTYLENE TEREPHTHALATE) AND A LIQUID-CRYSTALLINE POLYESTER

Transesterification between a liquid crystalline polyester and poly(bu tylene terephthalate) was followed quantitatively by analyzing C-13-NM R spectra of the 50:50 blend after heat treatment at 290 degrees C for varying lengths of time. Differential scanning analysis was employed to follow the interchange reactions. From analysis of triad sequences of the transesterified blends, it was clear that measurable exchange r eactions occurred when the blend was kept at 290 degrees C for 20 min. The distribution of sequences tends to approach that of a statistical binary copolymer as the heat: treatment period is Increased. The resu lts obtained from this investigation show that polyblends between an L C polyester and conventional polyesters must be handled carefully. Oth erwise, ester interchange reactions are inevitable.