New biodegradable material based on RF plasma modified starch

The work presents an application of potato starch as a filler for a composite material with high density polyethylene. It was assumed that, in order to improve miscibility of starch with polyethylene matrix, its surface should be made hydrophobic. Therefore, radio frequency (RF) plasma rotary reactor was applied to the surface modification of grains of starch. asma reactor was a capacitively coupled RF system equipped with external electrodes. Methane (CH4) was used as working medium. Measurements of a height of water capillary rise were applied to assess the hydrophilic properties of the grain surface. Starch, when modified with methane RF glow discharge, possessed considerably altered surface properties. It was substantially more hydrophobic—the modification process was able to lower capillary rise effect several times. , modified in such a way, was used to prepare composite materials with polyethylene. Tensile strength and elongation at break of the composites were measured. The measurements showed a substantial improvement of mechanical properties of polyethylene samples filled with modified starch, compared to those filled with unmodified starch. Other techniques, such as Scanning Electron Microscopy (SEM) and Differential Scanning Calorimetry (DSC) were also used to characterize the composites. The results of the latter suggest that it was the deagglomeration effects of starch grains resulting in an enhancement of filler dispersion, rather than matrix–filler interaction, that was primarily responsible for the improvement of mechanical properties.