Petroleum-based polymers such as polystyrene are widely used for their light weight and excellent properties. However

the petroleum-based polymers are difficult to degrade in the natural environment and casue the issue of "white pollution" . Therefore

it is urgent to develop green and environmentally friendly polymeric foam to replace petroleum-based polymeric foam. Poly(lactic acid) (PLA) is a kind of green polymer made from renewable resources. PLA has good processing and mechanical properties

and foaming makes it with good sound absorption

heat insulation and cushion effect. It is an ideal bio-based polymer to replace petroleum polymer

and PLA can be used in packaging

architecture

tableware and tissue scaffolds. However

due to the low melt strength and slow crystallization rate of PLA

it is difficult to obtain PLA foam with uniform cell distribution and high expansion ratio. In this study

we review the research progress on improving the foaming behavior of PLA in recent years

including the preparation of PLA foam via different foaming technologies

modification methods of PLA foam

influencing factors of mechanical properties and its expanding application fields.