Outstanding reinforcing effect of highly oriented chitin whiskers in PVA nanocomposites

To utilize the extreme reinforcing performance of chitin whiskers (ChWs), the current work was undertaken to fabricate nanocomposites embedded with highly uniaxial oriented ChWs into the matrix polymer. Fibers of poly(vinyl alcohol) (PVA)/ChWs were prepared by gel spinning and the fibers were subjected to a hot drawing to their maximal draw ratio. WAXD analysis revealed the very high orientation of ChWs in the PVA matrix. DSC measurements showed that, upon ChWs loadings, crystallinity of PVA increased and non-isothermal cooling crystallization peak of PVA shifted towards lower temperature, indicating the interaction of PVA with ChWs. Measurement of infrared dichroism suggested that the orientation of overall PVA chains increased with the increase in ChWs loading due to the possible dragging of PVA chains attached with ChWs during drawing, which resulted higher PVA crystallinity in the composites. The stress transfer in PVA/ChWs interface quantified by X-ray diffraction evidenced the strong adherence between the two. The stress transfer between PVA and ChWs interface, and higher PVA crystallinity induced by ChWs were reflected to the outstanding enhancement in mechanical- and anti-creep properties of nanocomposite fibers.