Toughening of PLA stereocomplex by Impact modifiers

Abstract

We tried to blend PLLA and PDLA at overall compositions to form PLA stereocomplexes (SC). The presence of the SC crystalline phase in the PLLA matrix was verified by differential scanning calorimetry (DSC). As a result, a various PDLA composition of the PLA SC blends can influence PLA SC formation. And the largest amount of PLA SC crystallites was formed when PLLA/PDLA ratio is 50/50. In addition, we have tried to do PLA SC toughening with two impact modifiers in 92/8, 85/15 ratio of PLLA/PDLA to enhance the mechanical properties such as impact strength. Thermal and mechanical properties of PLA SC were investigated by DSC, HDT, Izod impact tester and UTM. PLA SC formation decreased when 10-20 wt% of Strong120 (impact modifier) was added. On the other hand, there is no effect on PLA SC formation when 10-20% of Elvaloy (impact modifier) was added. HDT values dramatically increased over 100℃ with the addition of PDLA. However, HDT decreased as Strong120 and Elvaloy content increased. Finally, we could find well balanced composition of toughened PLA SC with 10wt% of impact modifier in flexural modulus and impact strength.

Composition dependence of the synergistic effect of nucleating agent and plasticizer in poly(lactic acid): A Mixture Design study

“…Moreover, it is worth noting that the highest amount of LAK and the lowest amount of PDLA leads to the highest value of ! y, as illustrated in Figure 3 (two components mix [36], because the formation of these complexes inside the blend structure leads to an increased structural rigidity due to the formation of a branched/crosslinked system but when the content of PDLA is lower in melt processed blend a decrease in these properties was recently observed [44,45]. Probably the melt extrusion, having a short residence time, cannot allow an optimal dispersion of PDLA in PLA.…”

Tuning the compatibility to achieve toughened biobased poly(lactic acid)/poly(butylene terephthalate) blends

“…13,15,18 On the other hand, improvement on notched impact strength of PLA and its blends aer blending with ethylene-butyl acrylate-glycidyl methacrylate (EBA-GMA) compatibilizer was reported as well. 64,65 This indicates that the EBA-GMA functional group can be an effective compatibilizer to react with carboxylic and hydroxyl functional groups of PLA or PBT which can improve their compatibility and toughness aer blending. The EBA-GMA compatibilizer containing reactive GMA group is a good compatibilizer 66 and toughening agent 67 to improve the properties of the polymer blends.…”