Mechanical, thermal and morphological properties of polylactic acid/polypropylene blends
Loading...
Date
2019-07
Authors
Bong Poh Yee
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
In the present study, the mechanical, thermal and morphological properties of polylactic acid/polypropylene (PLA/PP) blends manufactured by single screw extruder followed by injection moulding were investigated. The PLA was blended with PP at different blend ratios, which were 90/10, 70/30 and 50/50. The morphological properties of PLA/PP blends were investigated with scanning electron microscope (SEM). It was found that pure PLA shows smooth and typical brittle fracture surface while all PLA/PP blends exhibit distinct phase separation morphology with smooth fracture surfaces which indicates PLA and PP are immiscible. Melt flow index (MFI) of PLA/PP blends were determined using polymer melt flow indexer. PLA/PP blends showed lower MFI as compared with pure PLA because the PP added has lower MFI which can reduce the flowability and processability of the blends. Mechanical properties of PLA/PP blends were investigated with tensile and impact test, while the thermal properties was determined using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Blending of PLA with PP was found to have lower mechanical properties than pure PLA. This attributes to phase separation, weak interface bonding besides the presence of voids and crack in the immiscible PLA/PP blend which disallow effective stress transfer between phases and act as stress concentration areas. Thermal stability of all PLA/PP blends were increased as PP incorporated is thermally more stable than PLA. PLA and PP were further proved to be immiscible when PLA/PP blends show double melting peaks and Tg of PLA components in PLA/PP blends show no significant shift as compared with pure PLA.