Study On The Modification Of Recycled HDPE And The Material For Pipeline

The rapid development of the plastic industry has inevitably brought a large number of waste plastics,and the pollution of the environment is also increasingly serious.In order to restrain the "white pollution",it has become a worldwide problem to recycle the waste plastics to replace some of the new materials.At present,the system of recycling waste plastic is not perfect in our country,many resources which can be recycled are treated as garbage.Therefore,recycling of waste plastic is now no time to delay.Compared with the new material,the waste plastic is in generally low molecular weight,containing various types of complex additives and impurities,poor-performanced.Therefore,the modification of waste plastics is an important proposition.In order to improve the performance of waste plastics,commonly used or modified by force / chemical method or blending with virgin plastics.This paper mainly uses physical modification for one kind of recycled HDPE,which is recycled from waste turnover basket.Two methods was used to reinforce and toughen it.Firstly,this paper used recycled HDPE(r-HDPE)as the matrix resin,in accordance with GB/T 19472-2004,r-HDPE/ broken-bathtub-material composite used to prepare pipeline material.The effect of Glass fiber(GF),processed(r-GF)and unprocessed broken-bathtub-material on composite was studied,and it is found that the order of enhancement effect is GF>r-GF> broken-bathtub-material.Considering the mechanical properties of materials and the cost,the r-GF at the amount of 20 phr was the best.Adding 5% PE-g-MAH can improve the interfacial properties and improve the flexural modulus with 36% while improving the tensile strength with 10%.After adding black masterbatch,the composite can meet the norms of GB/T 19472-2004 in tensile strength,flexural modulus,density,melt index and the color appearance.Then,this paper takes r-HDPE as matrix resin to prepare wood plastic composites.And the effects of wood powder,titanate,and effects of PE-g-MAH and POE on the mechanical properties of the composite were investigated.After analysising the experimental data,it is found that the optimum amount of wood powder is 15phr;titanate can effectively improve the mechanical properties of the composites,but it will not change the changing trend of mechanical properties of the composite;PE-g-MAH can improve the interface compatibility,and improved the mechanical properties at the dosage of 10 phr as the best;POE as toughening agent can improve the composite notched impact strength and elongation,but will reduce the tensile strength and flexural properties of composite materials,dosage in 10 phr when the best overall performance.Finally,thermogravimetric analysis under nitrogen was used to investigate the thermal decomposition process of high-density polyethylene(HDPE).The thermal degradation kinetic parameters of virgin and modified r-HDPE was studied.The Kissinger,and Flynn-Wall-Ozawa methods was used to determine the apparent activation energy(Ea)of the thermal degradation of the virgin and modified r-HDPE.And Crane equation was used to study the reaction order of thermal degradation.The results showed that,from TG and DTG profiles,both virgin and modified resin was one-step-degradation reaction,while the thermal hysteresis of the modified PE was more serious with the increase of heating speed.From calculated kinetic parameters,thermal stability of virgin r-HDPE was lower than those of modified r-HDPE.Interestingly,the result gotten by Flynn-Wall-Ozawa methods showed the degradation process of modified r-HDPE is more complex.From calculated reaction orders,both subject degraded in random nucleation and growth mechanism.