The equilibrium melting temperature, as determined from Hoffman-Weeks plots, has been measured as a function of the molecular weight for several batches of polyhydroxybutyrate. In all the batches there is a significant increase in the equilibrium melting temperature with the molecular weight. However, different polymer batches give non-superimposable Hoffman-Weeks plots and equilibrium melting temperatures. In particular, at the highest molecular weights studied, we can find anomalously high equilibrium melting temperatures. The equilibrium melting temperatures vary from ca. 179°C for polymers with molecular weights as low as 20000 to typically 186°C for polymers with molecular weights ca. 100000; however, for a polymer with a molecular weight of ca. 300 000, we have recorded an equilibrium melting temperature as high as 198°C
Посилання на статтю:
On the equilibrium melting temperature of polyhyd roxybutyrate / Sally J. Organ and Peter J. Barham // Polymer. – 1993. – Vol 34. – P. 2169-2174.