Study Of The Internal Structure Change Of Functional Wrapping Film And The Interaction Between Additives And Matrix

Polyolefin has become an indispensable polymer material variety on the market today.Polyolefin materials include many varieties.Among them,polyethylene stretch film is widely used in the industrial field due to its many excellent properties.However,due to special requirements In addition to specific functional requirements,the changes in the structure and properties of the film and the interaction between additives and the substrate have always been a concern.In this study,linear low-density polyethylene(LLDPE)industrial stretch film was selected,and the uniaxial biaxial stretching device and SAXS device were used in combination to gain a preliminary understanding of the relationship between the microstructure and mechanical properties of the film during stretching;Scanning calorimetry(DSC)and wide-angle X-ray diffraction(WAXD)studied the difference between the crystallization kinetics and thermodynamic behavior of the film before and after stretching,as well as the changes in orientation and crystal size;by using DSC,SAXS,polarized microscope,etc.The crystallinity,crystal structure,and surface morphology changes of polyethylene wax and polyethylene mixture,and the compatibility of polyethylene and polyethylene wax are understood;infrared spectroscopy is used to determine the precipitation type of additives and the factors affecting precipitation.A polarizing microscope was used to quantify the migration and precipitation of functional additives.The results show that stretching can increase the crystallinity of the film;during the stretching process,the lamella structure is destroyed and recrystallized under high stress induction,and the stretching increases the crystal orientation and crystal size of the film;the polyethylene industrial stretch film usually When the film is used near the strain of 1.5 times of stretching,the film has been highly oriented in the MD direction and formed stretch-induced crystallization,so the mechanical strength in the MD direction is better;while the lamella structure in the TD direction is still not completely destroyed.It maintains certain mechanical properties,so it has better comprehensive performance.When the ratio of polyethylene wax to polyethylene is 1:9,the two have the best compatibility.The mixture under this ratio does not find small molecule clusters in the surface morphology obtained by polarizing microscope and SEM.Phenomenon: With the increase of polyethylene wax,the compatibility decreases and the lamella structure becomes thinner;infrared results show that the main component that precipitates and migrates to the film surface is polyethylene wax,not rust inhibitor,and the main factors affecting precipitation There are temperature,time,solvent type,etc.