Rheological properties and crystallization behavior of modified polylactic acid using lauroyl peroxide and glycidyl methacrylate

The molecular structure of polylactic acid (PLA) was modified by lauroyl peroxide (LP) as an alkyl free radical and glycidyl methacrylate (GMA) as a reactive co‐monomer. We investigated the effect of different preparation methods, that is, the melt and solution, on the structure and physical and mechanical properties of glycidyl methacrylate grafted polylactic acid (PLA‐g‐GMA). The Fourier transformed infrared spectroscopy (FTIR) was implemented to characterize the final products in order to confirm that GMA was successfully grafted onto PLA. The gel permeation chromatography showed that the molecular weight and polydispersity of the modified PLA were increased by grafting. However, by varying other parameters such as the reaction time and the LP and GMA concentrations, we observed that the resulting products from the melt method are richer in the rheological properties compared with those properties from the solution method. This is due to the different molecular weights resulted from the either preparation methods. From the DSC characteristics of PLA‐g‐GMA samples, the crystallization degree of the samples prepared from the melt method is greater than that of the solution method. Meanwhile, the cold crystallization for the PLA‐g‐GMA samples derived from the solution method occurs at higher temperatures compared with the cold crystallization of the samples resulted from the melt method.