The effect of poly(vinyl alcohol) type and radiation treatment on the properties of starch-poly(vinyl alcohol) films

Our present study concerns the effect of application of various PVA substrates and the influence of ionising radiation on the properties of films based on starch and PVA. Four PVAs revealing various molecular masses (in the range of 11–145 kDa) were selected for this purpose. The films characterized by starch: PVA ratios of 40:60 were prepared by solution casting and irradiated with ⁶⁰Co gamma rays (under nitrogen) and with fast electrons (under air) applying the absorbed dose of 25 kGy. Mechanical properties of the films (tensile strength, elongation at break and Young Modulus) were examined, as well as the contact angle to water and swelling in water, in regard for evaluation of the hydrophilic/hydrophobic properties. Gel content in the samples was also determined. Physicochemical properties of the films and their sensitivity to irradiation strongly depend on the applied PVA substrate. This can be related to differences in the capability of particular PVAs for forming the crosslinked starch-PVA network during the films' synthesis and future treatment. In particular, the usage of the PVA characterized by the high molecular mass has appeared more rewarding as compared to those based on the low molecular mass PVAs. Additionally, properties of these films were not affected or improved after irradiation. - Highlights: • Starch-PVA (60:40) films were prepared using four PVAs differing in molecular mass. • The films were irradiated in gamma chamber (nitrogen) and in electron beam (air). • Mechanical properties, wetting angle, swelling in water and gel fraction were tested. • The best films were prepared basing on PVA with the highest Mw (145 kDa). • The results reference abilities of PVAs to form crosslinks with starch.