Characterization of the Structural and Physical Properties of the Thermoplastic Starch Film with Kaolinite and Beeswax Addition

The aim of the study was to investigate the influence of kaolinite (KA) and beeswax (BW) addition on the structural and physical properties of thermoplastic starch (TPS) films. The casting method was applied and glycerol was used as a plasticizer. Microstructure analyzes were made by a stereoscopic and a scanning electron microscope. Tensile tests were carried out under static load conditions at three different deformation velocities of V=0.0001, 0.001, and 0.01 m/s. The studies of surfaces characteristic were performed using water contact angle and water vapor isotherm measurements. The most homogeneous structure of the surface with higher mean values of failure stress and elasticity modulus was observed for thermoplastic starch films with kaolinite addition. The significant reduction in dynamics changes of water contact angle (10%) of BW films in the time 0-20s as well as tensile strength decrease was noted (compared to pure TPS films). The research results suggest the validity of using BW and KA to improve the barrier and mechanical properties of TPS films. Further research should focus on to improve the starch-beeswax-kaolinite combination and increase the homogeneity of the structure of films in order to upswing their simultaneous impact on barrier and mechanical properties.