Conformational changes after foaming in a protein‐based thermoplastic

ABSTRACT Novatein is a biopolymer produced from blood meal and can be foamed for use as a packaging material. The effect of foaming on protein ordered structures such as α‐helices and β‐sheets was investigated using synchrotron Fourier transform infrared (FTIR). Foaming caused a reduction in ordered structures due to an increase in random coils. FTIR also revealed a higher proportion of plasticizer (triethylene glycol, TEG) and β‐sheets toward the surface of enclosed bubbles. Increased TEG will assist foaming with greater plasticization aiding nucleation, while β‐sheets contribute to bubble stabilization. These structural changes occur as foaming takes place close to the degradation temperature of Novatein, and coincide with melting of α‐helices and/or β‐sheets. A more amorphous polymer is therefore produced which is subsequently easier to foam due to its increased elasticity. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46005.