High-toughness PLA/Bamboo cellulose nanowhiskers bionanocomposite strengthened with silylated ultrafine bamboo-char

摘要

We prepared poly(lactic acid) (PLA)/bamboo cellulose nanowhiskers (BCNW) bionanocomposite with a high toughness but a low modulus in the previous work. In this paper, a new reinforcement, silane surface-modified ultrafine bamboo-char (UFBC), was employed to strengthen the binary PLA/BCNW bionanocomposite. The ternary bionanocomposite films were fabricated by a solution casting with different contents of surface-treated UFBC in the range of 0.25 wt% to 4.0 wt%. The functionalization of UFBC with (3-mercaptopropyl)trimethoxysilane (A-189) favored its dispersion in the PLA matrix; sea-island and nuclear-shell characteristics were observed by the scanning electron microscopy (SEM) and transmission electron microscopy (TEM). When the UFBC content was 0.25 wt%, the tensile strength and elongation at break increased by 99.26% and 104.93%, respectively, comparing to the neat PLA. Differential scanning calorimetry (DSC) results showed that glass transition temperature, crystallization temperature, crystallization enthalpy and crystallinity increased with the increase of UFBC contents. Thermogravimetric analysis demonstrated that the thermal degradation stability decreased with the UFBC addition. BCNW and UFBC produced a synergistic effect on composites' toughening and strengthening. These results provided a basic understanding of PLA enhancement mechanism and a simple approach for PLA composite manufacture with sound mechanical properties.