Mechanical Properties of PLA Foams

Currently, most studies on microceUuIar PLA are centered on understanding the mechanisms of bubble nucleation, growth, and stabilization. The relationships between morphological and mechanical properties of PLA foams are not well established because their mechanical properties have not been extensively characterized. 

A significant improvement in the impact strength can be achieved in PLA by introducing microceUuIar structure in the matrix. The notched Izod impact strengths of foamed PLA samples are, in general, three to four times larger than those of the unfoamed counterparts depending on the density of the samples (Table 17.10) [2]. 

The compression properties of amorphous PLA foamed in a continuous extrusion process using CO2 as a blowing agent are summarized in Table 17.12. Correlations were found by plotting the compressive modulus E) and stress at yield (tr) as a function of CO2 content. The decreased modulus and strength with the CO2 content is due to the high level of plasticization induced by the residual CO2 for specimens foamed at higher CO2 content [73, 74]. 

TABLE 17.11 Tensile Properties of Unfoamed and Batch MicroceUuIar Foamed PLA [2] 

TABLE 17.13 Static Tensile and Dynamic Properties of Solid (S) and Microcellnlar (M) Injection Molded Neat PLA and PLA/ Cellulose Fiber Composites (PLA-30% CF) [3] 

---