Yingde Cui

Preparation and characterization of a dialdehyde starch crosslinked feather keratin film for food packaging application

Feathers, a byproduct of the poultry industry, have long been considered as a solid waste, posing a series of environmental and economic problems. However, feather keratin (FK) extracted from feathers is a valuable source of the biodegradable and biocompatible polymer. The aim of this study was to develop and characterize novel casting films based on feather keratin (FK) crosslinked by dialdehyde starch (DAS) and plasticized with glycerol for applications in biomedicine. The microstructure, crystallization behavior, light transmission, moisture content, solubility, tensile properties, water vapor barrier property, and cytotoxicity of the FK–DAS films were investigated. The fracture surface of the crosslinked film showed a more compact microstructure than that of the control film, and the crosslinked films were completely amorphous and very transparent (transparency value <2). These results indicate that the addition of DAS increased the transparency value and moisture content and decreased the solubility, indicating the crosslinking between the FK and DAS. The films with 2% DAS showed increased tensile elongation and water vapor permeability compared to the control films, whereas the tensile strength of the film decreased, most probably because the crosslinking effect was counterbalanced by the plasticization of DAS. DAS increased the water resistance of the FK films, thus expanding their potential application in food packaging.

Fabrication and characterization of electrospun feather keratin/poly(vinyl alcohol) composite nanofibers

Feathers, which contain more than 90% of keratin, are valuable natural protein resources. Moreover, recycling waste feathers to develop biomaterials contributes to environmental protection. The aim of this study was to fabricate and characterize both random and aligned feather keratin (FK)/PVA composite nanofibers through an electrospinning process. The morphology, molecular interaction, crystallization behavior, and tensile properties of the nanofibers were investigated. The electrospinning process appeared stable and successful for solutions containing no more than 40 wt% of FK. Smooth and bead-free FK/PVA random nanofibers were obtained for all the experimental samples. The fiber average diameter decreased for the random nanofibers and the degree of fiber orientation increased for the aligned nanofibers as the FK content increased. The crystallinity of the nanofibers reduced with the incorporation of FK but the orientation of nanofibers was favorable to crystallization. Random nanofibers exhibited an increased tensile strength when the FK to PVA ratio increased. Tensile strength and elongation at break in the direction of the aligned fibers were improved compared to the random nanofibers at the same FK content. This work demonstrates the potential of expanding the application of nanofiber-based products in the biomaterial field.

Thermomechanical relaxation and different water states in cottonseed protein derived bioplastics

Thermomechanical relaxation events and different water states in cottonseed protein bioplastics are presented whilst investigating the effects of aldehyde cross-linking agents. Thermomechanical relaxation of cottonseed protein bioplastics associated with protein denaturation, moisture absorption and broad glass transitions (Tg) were observed from DSC and DMA measurements. It was shown that variation of the aldehyde influences the storage modulus at very low temperature (below Tg). From measurements of the water fusion point, enthalpy, vaporisation, and weight loss, three water states in the water-absorbed bioplastics are suggested; namely strongly-bound-to-polymer, weakly-bound-to-polymer and bulk-like water. The water content and unreacted cross-linking agents are influential factors in controlling formation of the different water states, whilst the selection of different aldehydes was found to be negligible. These results could be valuable for adjusting the thermomechanical relaxations of protein based bioplastics, and tailoring their properties in wet environments.