Study On High-performance Engineering Plastics Alloy Prepared By Recycled PET Bottles

Different types of PE-g-MAH are prepared by reactive extruder as the modifiers of the recycling PET flakes(r-PET)for engineering plastics.The mechanical properties,processing condition,morphology,crystallization and thermo-properties of r-PET/PE-g-MAH alloy are studied in different kinds of extruders.The most appropriate modifier,the equipment and the high performance of alloy are explored.Firstly,grafting rate and melt flow rate(MFR)of different kinds of PE are studied systematically.Experiment results show that,as the initiator DCP content increases,the graft rate of PE increases and then decreases,MAH connects with the molecular chain of PE by chemical bond.The sequence of grafting ability is LLDPE＞LDPE＞LLDPE/LLDPE'＞LLDPE/HDPE＞HDPE.The MFR of the grafting products are lower than the raw materials.The relationship between the moisture content and the drying condition(vacuum,drying temperature and drying time)has been studied.The results show that,at the conditions of 0.1 MPa vacuum,120℃,drying for 1 hour can make moisture content drop to below 0.5%.Using twin-screw extruder and condensation-reaction extruder,extrusion process of r-PET/PE-g-MAH is very stable,the product has no impurities;r-PET/LLDPE-g-MAH alloy has good mechanical properties;morphology study by SEM show that,PE-g-MAH and r-PET are mixed evenly.But using the single screw extruder and graft-reaction extruder,the blendings are mixed unevenly;the appearance of product is not smooth enough.Using twin-screw extruder or condensation reactive extruder respectively,the modified result with different modifiers has been inspected.The Results show that the compatibility of r-PET and PE-g-MAH are much better than that of r-PET and LLDPE.Modified effect of LLDPE-g-MAH is the best of all.By adding 20%LLDPE-g-MAH,the r-PET/LLDPE-g-MAH toughness improves significantly,impact strength with notch increases by 70%than the r-PET;impact strength without notch increases by 140%;crack elongation increases by 170%. Melt flow rate of r-PET modified by LLDPE-g-MAH is also greatly improved.The grafting rate of modifier can affect the mechanical properties of the alloy.WAXD and DSC analysis show that the crystallization property of r-PET improves by adding LLDPE-g-MAH.