Keratins extracted from Merino wool and Brown Alpaca fibres: thermal, mechanical and biological properties of PLLA based biocomposites

Keratins extracted from Merino wool (KM) and Brown Alpaca fibres (KA) by sulphitolysis and commercial hydrolyzed keratin (KH) were used as filler in poly (L-lactic) acid based biocomposites processed by solvent casting in chloroform. Different contents (1 wt% and 5 wt%) of keratins were considered and the morphological, thermal, mechanical, chemical and biological behaviour of the developed PLLA biocomposites was investigated. The results confirmed that surface morphologies of biocomposites revealed specific round-like surface topography function of different microsized keratin particles in different weight content, such as analysis of bulk morphologies confirmed a phase adhesion strictly dependent by the keratin source. Transparency and thermal responses were deeply affected by the presence of the different keratins and their interaction with the PLLA matrix. Tensile tests results underlined the possibility to modulate the mechanical behaviour of PLLA selecting the keratin type and content in order to influence positively the elastic and/or plastic response. It was demonstrated that surface characteristics of PLLA/KA systems also influence the bovine serum albumin (BSA) adsorption, moreover PLLA and PLLA biocomposites based on different kinds of keratins support the culture of human bone-marrow mesenchymal stem cells, indicating that these biocomposites could be useful materials for medical applications.