Influence of morphology on the dynamic and quasi-static energy absorption of polylactic acid-based lattice structures

The aim of this work was to investigate the difference between energy absorption (EA) of a lattice structure under quasi-static and dynamic loading, as influenced by morphology. Lattices were manufactured from blends of polylactic acid (PLA) and polycaprolactone (PCL), with and without a compatibilizer. Under quasi-static compression, PLA and blends with low PCL content provided the greatest EA. Above 30% PCL, a drastic decrease in EA was observed as the ductility increased. The morphology of the blends under slower loading played little role in affecting EA, as the lattice's performance was mainly dictated by the ductility of the blend. However, under dynamic loading brittle lattices provided poor EA, however, at 30% PCL, EA was significantly higher, improved further with including a compatibilizer. At 10% PCL an erratic dispersion of PCL in the PLA matrix was observed, whilst at 50% the morphology was co-continuous. A uniformly, finely dispersed droplet morphology was observed at 30% PCL. The ductility and morphology of the matrix paired with the complex loading scenario led to optimal EA under dynamic loading. The partial bonding between PCL and PLA provided clear improvement to EA, however, this effect was vastly different under quasi-static loading.

Automated summary

This study investigated the difference in energy absorption (EA) of a lattice structure under quasi-static and dynamic loading, and the influence of morphology. The results showed that EA under dynamic loading was closely related to morphology, ductility, and the addition of a compatibilizer. Under quasi-static loading, EA was mainly determined by the ductility of the blend, and morphology had little effect.