ABSTRACT
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.
ABSTRACT
The water bamboo husks are the main agricultural wastes of Taiwan in summer. In this study, the fiber obtained from the water bamboo husks was investigated by CP/MAS C13 NMR, elemental analysis, and adiabatic calorimeter. Moreover, the pyrolysis behavior of the fiber was studied by TGA, TGA-GC-MS and Py-GC-MS. The kinetic parameters of the pyrolysis process of the fiber were calculated by the modified Kilzer-Broido model, Coats and Redfern method, Harcourt and Esson relationship, and Ozawa method, respectively. The results imply that the fiber is cellulose I type. Moreover, the kinetic analysis reveals that the pyrolysis of the fiber in nitrogen is more likely to be the model D3 mechanism. However, the pyrolysis of the fiber in air is much more complicated and the activation energies of pyrolysis are quite different from those in nitrogen. Based on the TGA-GC-MS and Py-GC-MS study, the decomposed products from the pyrolysis of the fiber are of interest for their potential use as organic resources.
