Compatibilization of Protein Thermoplastics and Polybutylene Succinate Blends

Reactive extrusion was used to prepare blends of Novatein thermoplastic protein (NTP) and poly(butylene succinate) (PBS) compatibilized with poly-2-ethyl-2-oxazoline (PEOX) and polymeric methylene diphenyl diisocyanate (pMDI). PEOX improved the dispersion of NTP in PBS and in conjunction with pMDI led to improved water resistance and a tensile strength exceeding that of NTP and PBS. The secant modulus, elongation as well as energy to break were also improved. The glass transition temperature (Tg) of compatibilized blends remained unchanged, however, the melting enthalpy and temperature decreased. This suggested that the crystalline structure of PBS has been disrupted by NTP as a result of compatibilization.