Mechanical, rheological, and crystallinity properties of polylactic acid/polyethylene glycol-polydimethylsiloxane copolymer blends by melt blending

Polylactic acid (PLA) is high in strength and modulus, but its applications are limited partly due to its inherent brittleness. It is difficult to keep the toughness and transparency of modified PLA without damaging its tensile strength and crystallinity. To improve the properties of PLA, polyethylene glycol-polydimethylsiloxane copolymer (PEG-PDMS) was incorporated to PLA via melt blending. By incorporating only 5 wt% of PEG-PDMS into PLA matrix, the elongation at break of the blends increased from 6% to 58% and the tensile strength was found to be 48.8 MPa. Differential scanning calorimetry demonstrated that the crystallinity of PLA/5%PEG-PDMS blends reached 33.5%. At the same time, the energy storage modulus (G) and complex viscosity (eta*) of the blends had been improved. UV-vis test showed the light transmittance of the PLA/5%PEG-PDMS blends was slightly decreased. The toughened materials are sufficient to cope with the challenges brought by complex environments, achieving an efficient toughening effect.