This study found that biochar made from grapevines (GVC), an agricultural waste product, can be used as a nucleating agent to promote the crystallization of polylactic acid (PLA). Differential scanning calorimetry (DSC) analysis of GVC/PLA composites showed that different particle sizes (200 and 100 mesh size) and amounts (1 wt%, 10 wt%) of biochar affect the re-crystallization of PLA, with 200 mesh GVC in the amount of 10 wt% being the most significant. In addition, it was found that there were two peaks related to imperfect and perfect crystals in the Tm part for GVC/PLA composites. TGA analysis showed that adding GVC tends to lower the maximum decomposition temperature of PLA, revealing that GVC may accelerate the degradation reaction of PLA. This research also studied the effects of GVC in various particle sizes and amounts on the mechanical properties and degradation of PLA. The results revealed that the tensile and impact strengths of GVC/PLA composite could reach 79.79 MPa and 22.67 J/m, respectively, and the increments were 41.4% and 32.1%, greater than those of pristine PLA. Moreover, the molecular weight of PLA decreased as the amount of GVC increased. Therefore, GVC particles can be used as reinforcing fillers for PLA to improve its mechanical properties and adjust its molecular weight. These agricultural-waste-reinforced biocomposites can reduce both greenhouse gas (GHG) emissions and the cost of biodegradable polymers and achieve the goals of a circular economy.

Uniform distribution and strong interaction of carbon nanotubes in a polymer matrix have resulted in improved performance of the pure polymer. In this work, MWCNTs (CNTs) and carboxylic acid functionalized MWCNTs (CNTs-COOH) were dispersed into the epoxy resin to improve the intrinsic damage sensing property of woven carbon fiber reinforced epoxy (CFRP) composite laminates. We prepared the MWCNT-modified CFRP composites (CNT_CFRP and CNT-COOH_CFRP) with varying MWCNT concentrations (0.25 wt% ˗ 1 wt%) and studied the effect of functionalization and concentration of MWCNTs on the mechanical, and electrical properties of CFRP laminates. A pronounced increase in the tensile strength and tensile modulus of CFRP laminate was achieved with the introduction of 0.5 wt% CNTs and CNTs-COOH. The damage sensing capability of modified CFRP laminate was investigated by measuring electrical resistance upon loading.