Properties of linear poly(lactic acid)/polethylene glycol blends

Poly(lactic acid) (PLA) has great potentials to be processed into films for packaging applications. However, film production is difficult to carry out due to the brittleness and low melt strength of PLA

Physical and rheological properties of plasticized linear and branched PLA

Extrusion of Poly(lactic acid) (PLA) is difficult to carry out due to the brittleness and low melt strength of PLA. In this investigation, linear Poly(lactic acid) (L-PLA) and branched (B-PLA) were plasticized with poly(ethylene glycol) (PEG) having $M_w$ of 1,000 g/mol in various PEG concentrations (0, 5, 10, 15 and 20 wt%). In addition rheological, thermal and mechanical properties were also investigated in this study. In relation to the plasticizer content, dynamic rheological studies showed that the plasticized linear and branched PLA with higher PEG loading have lower viscosity and elastic properties than that of pure PLA. Storage modulus decreased with PEG loading at all frequencies and exhibited weak frequency dependence with increasing PEG content. As expected, plasticizing both linear and branched PLA lowered the glass transition temperature and modified the crystallization characteristics. Moreover, the toughness was increased by plasticizing up to 15 wt% of B-PLA and up to 10 wt% of L-PLA. However, there was decreasing in toughness due to phase separation of PEG phase in the PLA matrix at 20 wt% and 15~20 wt% of B-PLA and L-PLA, respectively. Therefore, the combination usage of branching and plasticizing showed the better properties both the melt stability and the ability to plastic deformation of PLA to meet the requirements for further

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

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