Direct thermoforming manufacture of cellulose transparent products employing nanospheres

Abstract

Cellulose limited by fusibility and solubility is impossible to be directly thermoformed, of which the existing progress crucially relies on larger liquids, making it hard to achieve a direct all-green manufacture. Here, we propose an innovative strategy that the surface molecular chains of cellulose nanospheres are activated at 100 °C and intertwined under 500 MPa because of the high molecular activity on the surface of nanospheres and the reduction of activation energy after ball-milling. It is confirmed that only physical changes are involved, according to infrared spectrum. Results show that applicable mechanical properties (hardness and modulus reach 0.44 and 9.66 GPa, respectively) are successfully obtained. Simultaneously, the optimum optical performance of all-cellulose substrate reaches more than 80 % at visible light. Combined with their intrinsic properties, these cellulose-based products could be potentially utilized as biomass substrates. Therefore, our innovative strategy opens up a door for the direct thermoforming of cellulose.

Keywords: Biomass substrate; Cellulose nanospheres; Direct thermoforming; Green manufacture; Physical changes.