PLA/ESO/MWCNT nanocomposite: a study on mechanical, thermal and electroactive shape memory properties

In the present study, solvent casted bio-based blends of polylactic acid (PLA) and epoxidized soybean oil (ESO) were prepared at varied composition of PLA: ESO of 95:5, 90:10, 85:15, 80:20 and 75:25 wt%. The shape memory polymer (SMP) nanocomposite films of optimized PLA/ESO blend (80:20) were prepared using same solvent casting method at three different loadings (1, 3 and 5 wt%) of acid functionalized multiwalled carbon nanotubes (COOH-MWCNT). The FTIR spectra confirmed acid functionalization of MWCNT and the molecular interactions by intermolecular hydrogen bonding between PLA and ESO. Mechanical properties of the PLA, plasticized PLA with 20 wt% of ESO and its nanocomposites were investigated by tensile measurements. Thermal properties such as T_m, T_c, T_g, X_c, degradation temperature of PLA and its modified forms were studied using DSC and TGA. SEM was used to observe surface morphology of plasticized PLA. Among all, PLA + 20wt%ESO + 3wt%COOH-MWCNT shows optimum mechanical and thermal performance, which was taken to perform electroactive shape recovery test. Finally, the electroactive shape recovery of the resulting nanocomposite with 3 wt% COOH-MWCNT was investigated by a fold deploy “U”-shape bending test.