Insights into the functionalities of cellulose acetate and microcrystalline cellulose on water absorption, crystallization, and thermal degradation kinetics of a ternary polybutylene succinate-based hybrid composite

The kinetic behavior of a polymer material filled with natural and/or functionalized reinforcement can evolve regarding water absorption, crystallization, and thermal degradation (TD) processes. This study investigates the separate and combined influence of microcrystalline cellulose (MCC) and cellulose acetate (CA) on changes in the water absorption percentage (WAP), crystallization, and TD kinetics of polybutylene succinate (PBS) based materials. Disc-shaped neat PBS (n-PBS), binary (PBS/CA, PBS/MCC), and ternary hybrid (PBS/CA/MCC) specimens were produced via extrusion and injection. SEM observations of the hybrid micrographs revealed that MCC was whitish-coated by a CA layer that forms an "amphiphilic"-like co-continuous interphase between PBS and fibers. The CA encapsulation activity limited the hybrid's WAP in the first week of water conditioning tests. In contrast, in the second immersion period, the WAP was increased by 19 % compared to that for PBS/MCC due to the synergistic activities of plasticized fillers. Avrami outcomes at 80 degrees C degrees C showed that the hybrid's half- crystallization time (t0.5) 0.5 ) increased by 64 % and 104 % compared to n-PBS and PBS/MCC, respectively, indicating that the enrobing CA layer restrained the slight nucleating effect of MCC fibers. The hybrid activation energy (Ea) a ) values determined at lower conversion rates (alpha <= 0.25) following the Flynn-Wall-Ozawa (F-W-O) model showed that they were up to 14 % higher than those for PBS/MCC, evidencing that CA delayed the TD of MCC fibers. For higher conversion rates (alpha >= 0.5), the synergy of both fillers postponed the TD of PBS. The Ea a values obtained from the Kissinger method confirmed previous findings.