21. Characterization of Oil Palm Frond-Based Biochar-Filled-Recycled PET Bio-composites

Polyethylene terephthalate (PET) is a common engineering thermoplastic. Thus, higher waste was generated. Recycled PET (rPET) has poorer properties as a result of degradation during recycling and/or residues contamination from the residues present on the rPET. One of the approaches to improve the mechanical properties of rPET is by incorporating a filler material. Biochar (BC) is a sustainable filler obtained from the pyrolysis of biomass. The focus of this paper is to investigate the applicability of oil palm frond-based BC (OPF-BC) in reinforcing effect of rPET at the loading range of 0–40 wt%. FTIR results showed the absence of any new chemical structure from the melt mixing of rPET with OPF-BC. Thus, DSC analysis does not show any significant difference in the glass transition temperature (T_g) and melting temperature (T_m), but a variation on melting capacity as evidenced forms the melting enthalpy (∆H_m). ∆H_m was reported to be consistent with the increment of OPF-BC loading. It is postulated that the variation on the bio-composites ∆H_m is a result of higher thermal conductivity of OPF-BC in comparison with the matrix. X-ray diffraction (XRD) analysis reported a significant variation in crystallization characteristics of the bio-composite with the OPF-BC loading. This suggesting that the porous OPF-BC might be acting as the nucleating agent and affects the degree of crystallinity. Based on DMA, the presence of OPF-BC affected the viscoelasticity. No obvious trend was observed on the storage modulus (E′), loss modulus (E″), and damping (tanδ). The “interpenetrating” of rPET molecular chains into to the porous filler, and the nucleating effect of OPF-BC might have taken place concurrently leading to these results. In overall, the optimum OPF-BC loading is suggested to be between 20 and 30 wt% based on the results obtained.