Structural changes as a result of processing in thermoplastic bloodmeal

Abstract

Bloodmeal (BM) can be thermoplastically processed resulting in a material with good mechanical properties by using a correct combination of additives. In this article, combinations of water, sodium sulfite (SS), sodium dodecyl sulfate (SDS), and urea were compounded with BM, and water absorption, solubility, thermal stability, and protein secondary structure were assessed. Thermal stability of processed plastics was reduced when using 2 or 3 pphbm (parts per hundred parts BM) SS and 20 pphbm urea, mostly indicative of a reduction in covalent crosslinking. SS was required for chain mobility during processing, however, without sufficient plasticization degradation will occur instead of melt formation. SDS further improved processability and consolidation leading to increased water absorption and solubility, indicative of a reduction in chain interactions. It was found that BM proteins are highly denatured and thermoplastic processing reduced ordered structures further. Additional minor structural changes occurred as a result of reduced covalent and noncovalent interactions after processing. It was concluded that the increase in water absorption and solubility was due to changes in intermolecular and intramolecular interactions, rather than substantial structural changes.