Mechanical and Thermal Properties of Biodegradable Polyurethanes Derived from Sericin.

Abstract

In this study, from the viewpoint of biodegradable polymers and waste disposal, polyurethane (PU) foams and films containing sericin were prepared from sericin and diphenylmethane diisocyanate (MDI). Polyethylene glycol (PEG, diol type) and polypropylene glycol (PPG, triol type) were used as a part of the polyol. Mechanical and thermal properties of PU's containing sericin were measured by tensile test and thermal analysis. Sericin could be used as a polyol of PU's and the strength and the glass transition temperature of PU films containing sericin increased with increasing sericin content. The strength of PU foams depended strongly on their apparent density. From the dynamic mechanical analysis (DMA), loss modulus (E) and tan δ curves showed three peaks, α, β, γ in the region from high to low temperatures. The α and β peaks which are assigned to the main chain motion and local mode motion shifted to the higher temperature region with increasing sericin content. The γ peak was almost constant at -130°C.