LLDPE流延膜厚度调控对其结构和性能的影响OA

Linear low-density polyethylene cast films with thicknesses ranging from 9 to 135 μm were prepared by varying the feed screw speed.The crystalline structure and surface morphology of these films were characterized using differen-tial scanning calorimetry(DSC),wide-angle X-ray diffraction,small-angle X-ray scattering,light scattering,and white light interferometry.The influence of thickness reduction on haze and mechanical properties was systematically investi-gated.The results show that when the film thickness decreases below 33 μm,significant structural changes occur across multiple length scales,including the unit cell,lamellae,and spherulites.In particular,at a thickness of 9 μm,the(110)crystal plane diffraction peak exhibits pronounced splitting,and the Hermans orientation factor of the lamellae increases.No spherulites are observed in the thinnest films,and the shoulder peak in the DSC melting curve becomes more dis-tinct.As thickness decreases,haze initially declines and then rises.Tensile strength in the machine direction remains rel-atively stable,whereas that in the transverse direction decreases.Elongation at break shows little change initially and then decreases with further thinning.Tear strength in the machine direction first decreases and then increases,while puncture strength exhibits an overall increasing trend.