The Preparation And Characterization Of Ultra-high Molecular Weight Polyethylene Film Containing Rich Oriented Shish-kebabs And Fiber Of Aggregation Of Shish-kebabs

Firstly, ultra-high molecular weight polyethylene(UHMWPE) films were prepared with self-designed instrument via shear-induced crystallization from solution. The parameters of preparing UHMWPE films containing rich oriented shish-kebabs were analyzed and determined. Results of scanning electron microscope(SEM) show that UHMWPE film containing rich oriented shish-kebabs(film-300) is composed of a large number of oriented shish-kebabs and a small number of amorphous sections, which indicating that film-300 is composed of rich shish-kebabs. Then, the mechanism of film-300 was elucidated. To investigate the influence of existence of shear force or not on the microstructure and mechanical properties of film, UHMWPE films(film-0) were prepared by the method of solution cast. Scanning electron microscope(SEM), two dimension wide angle X-ray diffraction(2D-WAXD) ? two dimension small angle X-ray scattering(2D-SAXS), differential scanning calorimetry(DSC) and tensile test were employed to investigate the microstructure and morphology and mechanical properties of film-300 and film-0. The results show that film-0 is composed of lamellae and amorphous section. The tensile strength, degree of orientation, crystallinity, melting point, thickness of lamellae and size of crystalline grain of the film-300 are higher.However, its number of crystalline grain and elongation at break are lower,respectively.Secondly, UHMWPE fibers were successfully prepared via shear-induced crystallization from solution by another self-designed equipment. The results of SEM show that UHMWPE fiber is composed of shish-kebabs entirely(i.e., the macroscopic aggregation of shish-kebabs, MASK) and the shish-kebabs arrange parallel to the axis of fiber. This MASK fibers show a good flexibility. There is no obvious break in the section of knot. Then, the mechanism of MASK fiber was elucidated. Tensile test shows that the tensile strength of aggregation of shish-kebabs is 111 MPa. To investigate the difference of microstructure between the productscomposed of shish-kebabs entirely and the products without any shish-kebabs,UHMWPE films without shear force(film) were prepared. 2D-WAXD, DSC were employed to investigate the difference of microstructure of MASK fibers and film.The results show that UHMWPE MASK fibers have a larger degree of orientation(0.95) and higher crystallinity(91.7%), while the orientation degree and crystallinity of film without shish-kebabs are 0 and 68.7%, repectively.