Research On Processbility Of Recycled Crosslinked Polyethylene Powder Filled High Density Polyethylene

Cross-linked polyethylene(XLPE)has a good overall performance and is widely used,but it is difficult to recover due to its infusibility and insolubility.Thus Recycling XLPE cross-linked polyethylene scientifically and effectively is of great significance for resource regeneration and environmental protection.This paper adopts Pulverization recovery method to recycle crosslinked polyethylene.The mechanism of XLPE crushing process was analyzed,and the properties of the recycled crosslinked polyethylene(RXLPE)were analyzed based on thermal and rheology.At the same time,RXLPE was used for injection molding,rotational molding and foam molding.(1)A process method for preparing crosslinked polyethylene recovery powder by mechanical comminution-milling was established,and the influence of the particle size of the powder on the mechanical properties,thermal properties and the surface of the HDPE-extruded material was investigated.The recycling process of RXLPE is divided into slicing,smashing,milling and other phases.In this process,the cross-linked polyethylene is subjected to mechanochemical interaction,the degree of cross-linking is reduced,and the gel content is decreased.The particle size of the recovered powder is decreased,the crystallinity of the molded product is increased,and the impact strength of the product is decreased.Adding HDPE to RXLPE can improve its extrusion appearance,and a maximum loading of 50%for the RXLPE is used in this article.(2)The properties of RXLPE/HDPE blends were studied by DSC,parallel plate rotation rheometer and capillary rheometer.And the crystallization and mechanical properties of injection molded products were analyzed.The results of DSC show that RXLPE takes obviously effect on heterogeneous nucleation.The viscosity of RXLPE/HDPE increases with the increasing of the RXLPE content,Which was obtained by rotational rheometer frequency scan,and the fluidity of the system deteriorates.The increasing of RXLPE makes the linear range of the viscoelasticity of the blends decrease.In the capillary rheology test,the zero shear viscosity of the RXLPE/HDPE blends is increased and the viscous flow activation energy is decreased.With the increasing of RXLPE content,the impact strength of injection molded products is higher than that of pressed products.The impact strength of different HDPE matrix filled with the same recycled material R1006 increases with the increasing of RXLPE content.(3)The effects of two mixing methods on the properties of RXLPE/XLPE composites were compared.DSC and rotary rheometer were used to study the crystallization and rheological properties of the blends.The rotomolding pilot test of 20:80 RXLPE/XLPE was performed.The results show that RXLPE can absorb part of the cross-linking agent,which do not participate in the cross-linking reaction resulting in a decreasing in the gel content.However the twice extrusion will reduce its absorption and has a higher gel content,so that the products are with good performance.DSC results show that the addition of RXLPE to XLPE reduces the vertical free energy of crystallization and accelerates the rate of crystallization.The XLPE filled with RXLPE can still be rotomolded,but the.performance of the product is poor.(4)The tensile and rheological properties of RXLPE/HDPE were analyzed by melt elongation rheometer and the foaming properties of the material were studied.It has been found that the addition of RXLPE to HDPE improves the melt strength,elongational viscosity of HDPE,its "strain hardening" effect and the foaming performance of HDPE.Adding foaming aids ZnO and ZnSt2 can reduce the blowing agent decomposition temperature from 205? to 160?.The sample with 30:70 RXLPE/HDPE gets highest foaming rate about 6 times.The amount of RXLPE increasing can obtain small particle size of the cell.RXLPE/HDPE blends,like HDPE foaming,exhibit typical three-zone characteristics under compressing.Adding inorganic foaming aids to 30:70 RXLPE/HDPE significantly improves the properties of the medium-deformation collapsed plateau zone and the high-pressure compression densification zone,but decreases the small-strain stiffness.This article systematically studied the properties of waste cross-linked polyethylene recycling materials,composite materials and their regeneration application methods,and achieves the recycling and reuse of cross-linked polyethylene,which laid the foundation for engineering applications.