Morphological, mechanical, and thermal properties of injection molded polylactic acid foams/composites based on wood flour

In this work, injection molding was used to produce polylactic acid foams using azodicarbonamide as a chemical foaming agent and to study the effect of wood flour concentration (15, 25, and 40% wt.) on morphology (scanning electron microscopy), density (gas pycnometry), as well as mechanical (tensile, flexural, and impact) and thermal (differential scanning calorimetry) properties. In particular, density reduction was controlled by the amount of material injected (shot size). The results showed that polylactic acid properties increased with wood content, but decreased with density reduction. Nevertheless, specific flexural modulus (per unit weight) always increased with foaming. Foaming was also shown to significantly increase polylactic acid crystallinity.