Study on the structure and properties of choline chloride toughened polylactide composites

Adding an appropriate amount of plasticizer is a valuable strategy to overcome the brittleness and rigidity of polylactide (PLA). Plasticized PLA films were prepared by the solvent casting method with choline chloride (ChCl). The effect of ChCl on the crystallization behavior and resultant crystalline structure and mechanical performance of PLA was investigated in detail. The results show that ChCl through moisture absorption has an obvious plasticizing effect on the molecular chains of PLA, which is reflected in the decrease of glass transition and cold crystallization temperature and the increase of crystallinity and crystallization rate of PLA. In addition, ChCl strengthens the toughness of PLA/ChCl composites. It is proven that the plasticizing effect of ChCl on PLA originates from its hygroscopicity. Moreover, the annealing-induced cold crystallization of PLA reduces the water absorption of ChCl, which in turn weakens the toughness of PLA composite films.