Thermally resolved synchrotron FT-IR microscopy of structural changes in bloodmeal-based thermoplastics

Abstract

Synchrotron FT-IR micro-spectroscopy was used to determine thermally induced structural changes in thermoplastic protein produced from bloodmeal after mixing with sodium sulphite, sodium dodecyl sulphate, urea, tri-ethylene glycol and water. Changes in protein secondary structure at elevated temperature were assessed using second derivative peak height ratios in the amide III region (1,200–1,330 cm⁻¹) and compared with DSC and DMA results over the same temperature range. The results show an increase in ordered β-sheet structures with temperature at the expense of random coils, and that these β-sheets do not melt in the temperature range up to extrusion temperature of 120 °C. The implication of this is that during melt processing, β-sheet clusters may remain intact, similar to dispersed particulate fillers.