Resistance of poly(lactic acid)/starch composites to weathering effects

In order to produce a completely bio-based and cost-effective filled polymer, PLA and native potato starch as a filler were compounded by twin screw extrusion. Subsequently injection molded test specimens were manufactured and subjected to artificial weathering as well as different storages (high temperature, high humidity, freeze, water) for 504 h with a view to long-term resistance. Depending on the starch content a significant reduction of up to 100% in tensile strength can be seen, as the starch accelerates or inhibits the triggered aging effects. As a result of the influence of humidity and water as well as artificial weathering, stress cracks are formed in starch-containing samples. Storage at an elevated temperature (70 degrees C, 50% RH) leads to polymer degradation of the PLA. This degradation can be inhibited by the addition of starch. Freezing storage has no significant influence on the mechanical and structural properties of the PLA starch composites. Native potato starch was used as a filler for PLA. The composites were subjected to artificial weathering as well as different storages to investigate the resistance. Humidity and water leads to swelling effects of starch and a significant reduction in tensile strength. High temperature leads to hydrolysis-related polymer degradation. All composites show insufficient resistance, although the strength increases the crystallinity.image