Influence of methyl methacrylate‐butadiene‐styrene copolymer on plasticized polylactide blown films

Abstract

Polylactide (PLA) was first toughened with methyl methacrylate‐butadiene‐styrene (MBS) copolymer. Then the toughened PLA was further blended with diethylene glycol monobutyl ether adipate (DGBEA) using a twin‐screw extruder. Finally, the extruded samples were blown using the blown film technique. The PLA/DGBEA/MBS blends were characterized by dynamic rheometer, dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC). Rhelological investigation demonstrated that there was a significantly dependence of viscosity on composition. DMA results displayed that the PLA/DGBEA/MBS blends showed a single peak, which suggested that PLA and the shell of MBS be compatible. So, DGBEA could act as a plasticizer and improve the miscibility of PLA/MBS blends. The crystallization morphology, mechanical properties, optical properties, the morphology of the tear‐fracture surfaces, and enzymatic degradation of the PLA/DGBEA/MBS films were further studied. The Maltese cross pattern phenomenon weakens and the spherulite size becomes smaller from the observation of the polarized microscope. With an increase of MBS content from 3% to 12%, the tensile strength of the films decreased from 38.2/37.5 MPa (MD/TD) to 25.2/26.4 MPa (MD/TD), however, the elongation at break increased significantly from 72.3/83.1% (MD/TD) to 289.5/286.8% (MD/TD), which indicated the toughening effects of the MBS on PLA. POLYM. ENG. SCI., 58:E4–E13, 2018. © 2017 Society of Plastics Engineers