High performance branched poly(lactide) induced by reactive extrusion with low-content cyclic organic peroxide and multifunctional acrylate coagents

In this work, acrylates with various functionalities are employed as the branching coagent for improving the properties of long chain branched polylactide (LCB-PLA) induced by reactive extrusion with low content of cyclic organic peroxide (COP). It is discovered that the heat resistance and foaming performance of COP-initiated LCB-PLA are remarkably improved by the coagent. Specifically, the Vicat softening temperature and expansion ratio of 0.3 wt% COP-initiated LCB-PLA with 0.3 wt% coagent are sharply increased to above 150 degrees C and 27.0-fold, respectively (60 degrees C and 9.8-fold for 0.3 wt% COP modified PLA). This is due to the simultaneously enhanced melt strength and crystallization properties of LCB-PLA induced by the obviously enhanced branching degree by the coagent. Moreover, the branch-promotion efficiency of various coagents is found to be independent of the functionality due to the steric hindrance. The possible mechanisms on the formation of topological structures of COP modified PLA with coagents are proposed.