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An in situ small-angle X-ray scattering (SAXS) study of the structural effects of temperature and draw ratio (DR 1 ) of the hot-drawing process on ultra-high molecular weight polyethylene (UHMWPE) gel fibers was performed with equipment simulating the hot-drawing process on an industrial production line. The UHMWPE gel fibers were prepared from the industrial production line. The results show that the increase of hot-drawing temperature has a significant effect on the kebab but no obvious effect on shish length and misorientation. The increase of temperature is beneficial to the formation of the shish in a suitable temperature range of 124-130 C, while the formation of the shish at higher temperature, 140 C, needs higher DR 1 . Moreover, the increase of DR 1 is beneficial to the formation of shish at all experimental hotdrawing temperatures, while the kebab formation mainly occurs at low DR 1 and the kebab transformation mainly happens at high DR 1 . The shish length and misorientation decreases with the increase of DR 1 .

High density polyethylene (HDPE)/reduced graphene oxide (RGO) nanocomposite bars were prepared by injection molding and the effects of RGO on the HDPE matrix were investigated.

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The gel-spun ultrahigh molecular weight polyethylene (UHMWPE) fibers were prepared at the industrial production line with different gel solution concentration of 10–18 wt %. The effect of gel solution concentration on the structure and performance of UHMWPE fibers was studied by tensile testing, differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), and small-angle X-ray scattering (SAXS). With the increase of gel solution concentration, the ultimate mechanical properties of UHMWPE fibers decreased while the melting temperature increased. And the increase of gel solution concentration made the crystallization and orientation of UHMWPE fibers become worse. Furthermore, the average length (⟨L shish⟩) and misorientation (B ϕ) of shish structure in UHMWPE fibers decreased with the increase of gel solution concentration.

Polyamide 66 (PA66) was chosen as the representative of hydrophilic polymers, to investigate the influence of epitaxial crystals in semi-crystalline polymers/reduced graphene oxide nanocomposite injection-molding bars. A differential scanning calorimeter was used, and the two-dimensional wide-angle X-ray diffraction technique, as well as the two-dimensional small angle X-ray scattering technique, were used to research the crystallization behavior in PA66/RGO nanocomposites. The results indicated that RGO was an effective nucleation agent for PA66. The presence of RGO could enhance the orientation degree of the PA66 crystals and did not influence the crystal structure of the PA66. The non-epitaxial crystals and the epitaxial crystals existed in PA66/RGO nanocomposites. The size of epitaxial crystals was much greater than that of the non-epitaxial crystals. Tensile test results showed that the presence of fewer epitaxial crystals can improve the mechanical properties of a polymer.

Ultra-high molecular weight polyethylene (UHMWPE)/chitin nanocrystals (CNC) and UHMWPE/acetylated chitin nanocrystals (ACNC) fibers were prepared.

Structural evolution of gel‐spun ultra‐high molecular weight polyethylene fibers with high concentration solution via hot stretching process was investigated by in situ small‐angle X‐ray scattering, in situ wide‐angle X‐ray diffraction measurements, scanning electron microscopy, and differential scanning calorimetry. With the increase of stretching strain, the long period continuously increases at relative lower stretching temperature, while it first increases and then decreases rapidly at relative higher stretching temperature. The kebab thickness almost keeps constant during the whole hot‐stretching process and the kebab diameter continually decreases for all stretching temperatures. Moreover, the length of shish decreases slightly and the shish quantity increases although there is almost no change in the diameter of shish crystals during the hot stretching process. The degree of crystal orientation at different temperatures is as high as above 0.9 during the whole stretching process. These results indicate that the shish‐kebab crystals in ultra‐high molecular weight polyethylene fibers can transform continuously into the micro‐fibril structure composed mostly of shish crystals through the hot stretching process. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018, 56, 225–238