Polylactide (PLA) suffers from poor processability due to its low melt strength and slow
crystallization kinetics and it is thus very challenging to achieve uniformly distributed
fine-celled PLA foams with high void fractions in injection molding process. In this work,
the low-pressure structural foam molding of linear PLA with a relatively high void
fraction of 30% was conducted and by fine tuning the talc content and the foaming
and processing parameters, a relatively uniform fine-celled structure with improved cell
size and cell density was successfully produced. The effects of twin-screw compounding
and the addition of talc on the foaming behavior, structural uniformity, crystallinity, and
mechanical properties of the solid and foamed PLA samples were investigated. The
results showed that the addition of 5 wt.% talc significantly improved the foaming
properties such as cell density, cell size, structural uniformity, and consequently
improved the mechanical properties of foams. The twin-screw compounding before
injection molding did not significantly change the foaming behavior, but adversely
affected the mechanical properties of the solid and foamed PLA samples due to mechanical and thermal degradation. The changes in the mechanical properties were discussed in terms of the crystallinity, talc toughening effect, and foam quality