Melt strength modification of poly(lactic acid) blends for packaging film production

Abstract

This research explores the possibility of improving PLA's properties to satisfy and extend its processing applications such as in blown film production. Branched PLA (B-PLA) and linear/branched PLA (L,B-PLA) samples were blended with polyethylene glycol (PEG) with Mw of 1,000 g/mol, as a plasticizer, in various PEG concentrations (0, 5 and 10 wt%). Melt strength measurement by Rheotens experiment was used to verify the possibility of using some of those blends for packaging film production by blown film extrusion. The results showed that the neat B-PLA and L,B-PLA exhibited similar level of melt strength properties. The increase of PEG content decreased the melt strength values, but increased the drawability. The L,B-PLA system showed greater strain hardening behaviour than B-PLA system. Hence, the most beneficial composition (L,B-PLA with 10 wt% of PEG) was used to produce film at varying blow-up ratios of the bubble at 2.5:1 and 3.2:1. It was found that blending of linear and branched PLA, with the addition of PEG as a plasticizer, can be tailored to meet the requirements for film manufacturing as well as the achievement in film extensibility