Study of mechanical, optical properties and surface hydrophobicity of modified starch based bionanocomposites containing cellulose nanocrystal and titanium dioxide nanoparticles

Cellulose nanocrystal (CNC) is a type of nanomaterial which is produced by partial hydrolysis of cellulose and elimination of its amorphous regions. CNC has several advantages such biodegradability and safety toward human health. In this study، CNC was produced from cotton linters and methods such transmission electron microscopy which were used for confirmation of nanoscale size production of cellulose crystals. Due to the disadvantages of pure starch films، in the present research، for improving the properties of plasticized starch-PVOH films، from nanoparticles CNC and TiO2 are used together، then effects of nanoparticles and glycerol determined on physical properties by response surface methodology (RSM). CNC and GLY showed significant linear effects on ultimate tensile strength (UTS) of nanocomposit and there were significant interaction effects between TiO2 and CNC، and also between GLY and TiO2. The optimum levels of TiO2، CNC and GLY for obtaining maximum UTS were as 0. 118، 0. 6 g and 1. 06 ml، respectively. In addition، the TiO2 concentration had linear and quadratic effect on the contact angles of bionanocomposites and optimum levels of TiO2، CNC and GLY for obtaining maximum contact angles were 0. 112، 0. 299 g and 1. 06 ml، respectively. UV-visible spectroscopy studies in the wavelength range 200–800 nm showed that adding of CNC and TiO2 decrease the light transmission and increase the opacity، adding of glycerol increase the light transmission and decrease the opacity.