Crystallization Using X-ray Diffraction Characterization Of Polyethylene Film Distribution

Linear Low Density Polyethylene (LDPE) thin film is a kind of widely used film, which can be made by blowing method and casting method. During processing, tensile caused by traction will affect crystalline structure of thin film and then affect the film performance. Because the cooling rate of polyethylene in the surface and inert of thin film is different, crystalline structure will be different in the surface and inert of thin film, which will affect the film performance. However this is not well studied due to the lack of characterization method. The appearance of grazing incident X-ray diffraction (GIXRD) brings a new chance for such kind of study. GIXRD is a novel kind of method for thin film. By varying the incident angle it can detect the crystalline structure in different depth. Here we use GIXRD to study the crystalline structure distribution in PE thin film.Experiment using transmission X-ray diffraction method to obtain film in the stretching direction of structural information and found that the molecular chain along the long axis direction (horizontal) orientation. Polyethylene film showings in the role of the crystal axis stretching more along the stretch direction of orientation in the polyethylene film in the presence of spherulite deformation occurred, and the majority of the molecular chain in order to horizontally arranged.The use-of-plane grazing incidence X-ray diffraction analysis of polyethylene film thickness direction of the crystal structure of the distribution. With silver mirror reflected in the PE film deposition of Ag film side, respectively, in a different incident angle on the silver polyethylene film X-ray diffraction results show that when the incidence angle of 0.6°when the X-rays can penetrate thin film, and the use of an ideal smooth plane derived formulas to calculate the results of trend. Shows using this formula for approximate calculation is possible. The study also shows that as the angle increases, the crystallinity and grain size has continued to grow, indicating the thickness of the film is not fully consistent with the direction of crystallization, PE film inside and outside the crystal is also inconsistent.We studied the 3D crystalline structures of PE thin film by using out-of plane and in-plane Synchrotron GIXRD. The results show that the 3D crystalline structures of PE thin film are different in the surface and inert. The PE in the surface has higher crystallinity degree and smaller crystallites size.