Thermal and mechanical properties of chemical crosslinked polylactide (PLA)

To improve the thermal stability and mechanical properties of PLA, crosslinking was introduced via chemical treatment of the melt by adding small amounts of crosslinking agent triallyl isocyanurate (TAIC) and dicumyl peroxide (DCP). A series of crosslinked PLA materials with different gel fraction and crosslink density were prepared. The crosslinked PLA samples were characterized by fourier transform infra-red spectrometry (FTIR). The thermal and mechanical properties of samples were also investigated by means of differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), tensile testing and dynamic mechanical analysis (DMA). The results showed that the crosslinking of PLA started at a low content of either TAIC or DCP, resulting in a decrease of crystallinity and a significant improvement of the thermal degradation initiation and completion temperatures, which indicated better thermal stability than neat PLA. Crosslinking was also responsible for the improved tensile modulus and tensile strength.