Study On Properties Of M-PE/PET Blends Processed Via Elongational Rheology

Aiming at the complex recovery process of recycled bottle cap(PE)and bottle body(PET),taking "the solution and theoretical study of the recycling problem of PE and PET" as background,the long-term accumulation and comprehensive advantages of the elongational rheology extruder designed by the team based on new theory of polymer plasticization and transportation dominated by the elongational flow field were employed to study metallocene polyethylene(m-PE)/polyethylene terephthalate(PET)blends.A terpolymer elastomer,ethylene-methyl acrylate-glycidyl methacrylate(E-MA-GMA),was loaded as reactive compatibilizer for comparison.The effect of compatibilizer content,matrix ratio and processing equipment with different mechanisms on morphology,dynamic rheology properties,mechanical properties was studied.Furthermore,the processing equipment with different mechanisms were applied to the recycling of waste PE and PET.The effects of the processing equipment with different mechanisms on the structure and properties of recycled PE/PET blends were studied.Firstly,the matrix ratio of m-PE/PET was fixed at 80/20,and the effect of compatibilizer content on the structure and properties of incompatible blends was studied by an elongational rheology extruder(ERE).During the experiment,it was found that the addition of compatibilizer reduced the tensile strength,elongation at break and flexural strength to a certain extent.The mechanical properties of the blends without compatibilizer reached the highest level.It has a good phase morphology structure and a tightly bonded interface.We hypothesized that two incompatible blends would achieve mandatory compatibilization under the action of elongational flow field.In order to prove the mandatory compatibilization effect of elongational flow field,m-PE/PET blends with different matrix ratios were prepared by elongational rheology extruder.The blends were divided into two groups for comparison: none compatibilizer and 4 wt% compatibilizer.The experimental results reveal that when the content of PET is above 30 wt%,adding compatibilizer can significantly improve the phase morphology and mechanical properties of the blends;when the content of PET is below 20 wt%,adding compatibilizer cannot significantly improve the tensile strength,but greatly reduce the elongation at break.That is to say,when the content of PET is small,the two immiscible phases can be forced to increase compatibility under the effect of elongational flow field.In order to further validate the excellent plasticizing and mixing effect of elongational rheology extruder,m-PE/PET blends with the same component ratio were prepared by twin-screw extruder(TSE).Two groups,none compatibilizer and 4 wt% compatibilizer,were set up for comparison.The experimental results indicate that the blends processed by elongational rheology extruder have more perfect phase morphology and better comprehensive mechanical properties at various matrix ratios,whether or not compatibilizer added.The mechanical properties of blends processed by elongational rheology extruder without compatibilizer are even better than those processed by twin screw extruder with 4 wt% compatibilizer.On this basis,the recycled PE and PET marerials from the waste PET beverage bottles with different matrix ratios were prepared by twin-screw extruder and elongational rheology extruder respectively.High performance recycling of recycled PE/PET blends can be achieved under elongational rheology.The structure and properties of recycled PE/PET blends were studied by processing equipment with different mechanisms without the addition of compatibilizer.The blends processed by the elongational rheology extruder had more perfect phase morphology,higher heat deflection temperature,and higher overall mechanical properties at different matrix ratios.The elongational flow field has practical value in the field of recycling of waste PE and PET,which can reduce resource waste and reduce environmental pressure.