Compatibility and thermal properties of poly(3-hydroxybutyrate)/poly(glycidyl methacrylate) blends

Poly(3-hydroxybutyrate) (PHB)/poly(glycidyl methacrylate) (PGMA) blends were prepared by a solution-precipitation procedure. The compatibility and thermal decomposition behavior of the PHB/PGMA blends was studied with differential scanning calorimetry, thermogravimetric analysis, and differential thermal analysis (DTA). The blends were immiscible in the as-blended state, but for the blends with PGMA contents of 50 wt % or more, the compatibility was dramatically changed after 1 min of annealing at 200 degreesC, In addition, PHB/PGMA blends showed higher thermal stability, as measured by maximum decomposition temperatures and residual weight during thermal degradation. This was probably due to crosslinking reactions of the epoxide groups in the PGMA component with the carboxyl chain ends of PHB fragments during the degradation process, and the occurrence of such reactions can be assigned to the exothermic peaks in the DTA thermograms. (C) 2001 John Wiley Sons, Inc.