Thermal And Crystallinity Property Study Of Poly(L)-Lactic Acid Blended With Oligomers Of 3-Hydroxybutyrate Or Dendrimers Of Hydroxyalkanoic Acids

Poly (L-lactic acid) (PLA) is a biodegradable polymer with slow crystallization rate. Oligomers of 3-hydroxybutyrate (OHB) and dendrimers of hydroxyalkanoic acids with different molecular weights were blended with PLA in a hope to improve the thermal properties of PLA, respectively. Four thermally degraded PHB products oligomers termed OHB-1, OHB-2, OHB-3 and OHB-4 with various number average molecular weights (Mn) of 4000, 7400, 14000 and 83000, respectively, were blended with PLA. The lower cold crystallization temperature (Tcc) and higher heat of cold crystallization (ΔHcc) for blend of PLA/OHB-1 suggested that thermally-degraded OHB-1 formed suitable crystal size during the cooling process and then acted as nucleation agents for PLA in the subsequent heating process. On the other hand, for the blending systems of PLA/dendrimers of hydroxyalkanoic acids, no obvious change on the thermal properties was observed compared with pure PLA except an improved PLA thermal stability possibly resulted from the cross-linking effects of the dendrimers.