Influence of Crosslinking on Rheological Properties, Crystallization Behavior and Thermal Stability of Poly(lactic acid)

In this study, a series of crosslinked poly(lactic acid) (PLA) with different gel fractions were obtained by adding small amounts of bis(tert-butyl dioxy isopropyl) benzene (BIBP) and triallyl isocyanurate (TAIC). The rheological properties, crystallization behavior and thermal stability of all samples were investigated. The results showed that some crosslinked structures were formed according to the gel fraction and the molecular weight. The crosslinked structures were also responsible for the increased modulus and complex viscosity, which extended its processing methods, such as foaming and film blowing. And different relaxation processes were observed for different samples by Han and Cole-Cole plots. Moreover, the results showed that the crosslinked structures played the role of nucleation site for the blends, which enhance the crystallization temperature (Tc). The glass transition temperature (Tg) and melt temperature (Tm) gradually decreased with increasing gel fraction. Crosslinking also had the positive effect on the thermal stability of PLA.