Studies on Stress Relaxation Process in Biodegradable Starch Film

In the paper the effects of keratin and polyvinyl alcohol additives on the stress relaxation course in thermoplastic starch film were presented. The 3-parameter Zener model was used to describe the behavior of film under loading taking into account sample sizes and initial deformation velocity. The effects of air relative humidity, initial deformation velocity and the way of sample cutting on model parameters were also determined. The increase of keratin content resulted in the decrease of E0 parameter, whereas the increase of polyvinyl alcohol caused its increase.