Based on the effects of crosslinking agent on the rheological properties of polylactic acid (PLA)

the cellular structure of crosslinked PLA foams was investigated via batch foaming. The results showed that when adding the crosslinking agent to the PLA

its loss tangent and complex viscosity in low frequency region and its melt strength and extensional viscosity increased. In the initial cell growth stage

the cell wall was stretched

which dramatically increased the high complex viscosity of the crosslinked PLA slowed down the cell growth rate. In the later cell growth stage

the melt strength and extensional viscosity and so increased the strength of the cell wall. Then

cell coalescence was abviously reduced and the cellular structure of the crosslinked PLA foam samples was more regular and uniform. The amount of gas loss decreased because of the high melt strength of the crosslinked PLA

which resulted in an increased expansion ratio of the PLA foam samples. The PLA foam had a maximum volume expansion ratio of 41 when adding 0.4 phr crosslinking agent.