The effect of chitin nanocrystal on the structural transition of shish-kebab to fibrillar crystals of ultra-high molecular weight polyethylene/chitin nanocrystal fibers during hot-stretching process

Abstract

The pre-stretched ultra-high molecular weight polyethylene/chitin nanocrystal composite fibers after first hot-stretching stage were prepared. The effect of chitin nanocrystal on the structural evolution of shish-kebab to fibrillar crystals of ultra-high molecular weight polyethylene/chitin nanocrystal fibers during hot-stretching process was studied by using in-situ small-angle X-ray scattering, wide-angle X-ray diffraction measurements, and scanning electron microscopy. The results showed that the addition of chitin nanocrystal can improve the stretchability of pre-stretched fibers, and makes the elongation of amorphous layers between lamellae more uniform. The chitin nanocrystal accelerates the fragmentation recrystallization process of kebab crystals (lamellae) at 90, 100, and 110°C and the melting recrystallization at 120°C during hot-stretching process. Moreover, more fibrillar crystals form in UHMWPE/CNC fibers comparing with pure UHMWPE fibers at the same strain and stretching temperatures. These results suggest that the addition of chitin nanocrystal is conducive to the structural evolution of shish-kebab to fibrillar crystals of ultra-high molecular weight polyethylene fibers during hot-stretching process.