Study On Compound Modification With Waste Rubber Powder And Thermoplastic Elastomer For Recycle Polyethylene

Polyethylene is one of the most widely used resins in plastic industry.The comprehensive properties of Polyethylene,such as mechanical properties,electricity performance,low temperature resistance,and the resistance to crack growth,decline due to the partial degradation and aging of its products on the using,resulting in losing usability and becoming waste plastic.Now,the recycle of waste polyethylene or reused after further modification is the main approach for comprehensive utilization of waste polyethylene plastic.This paper studied the effect of compound modifier on properties of waste high-density polyethylene(RHDPE)matrix.The compound modifier was prepared based on linear low density polyethylene(LLDPE),waste rubber powder and thermoplastic elastomer.The main works are as follows.styrene-butadiene-styrene block copolymerFirstly,waste powder with different content was added into two kinds of compound modifier system(G1:LLDPE/POE(ethylene-octene copolymer)/wasterubberpowderand G2:LLDPE/SBS(styrene-butadie ne-styrene)/waste rubber powder).The mechanical test showed that when powder content was 18 wt.%,the tensile strength of G1 and G2 decreased by 30.9% and 10.6%,respectively.The elongation at break of G1 and G2 declined with addition of waste powder and further declined significantly after powder content exceeded 24 wt.%.The melt index test indicated that after adding waste powder,melting viscosity of G1 system gradually increased,while melting viscosity of G2 system first decreased to a minimum value and then increased with powder content of 18 wt.%.The agglomeration and dispersion was gradual observed by scanning electron microscopy,with the increase of waste powder content.In addition,melting temperature,degree of crystallization and thermal stability of G1 and G2 also decreased after adding waste powder.Subsequently,the effect of two thermoplastic elastomer mass ratio(T1: POE,T2: SBS)on properties of compound modifier system(G3: LLDPE/POE/SBS/powder)was investigated.The results suggested that tensile strength of G3 system gradually reduced with the increase of mass ratio of T1/T2.When mass ratio of T1/T2 was one,the elongationat break of G3 system was 507%,higher than G1(424%)and G2(399%).The melt index test showed that with increasing mass ratio of T1/T2,melting viscosity of G3 system gradually decreased.Finally,on the basis of previous test,the best formula of compound modifier system(G4)was obtained and prepared by a twin-screw extruder.The effect of G4 content on properties of recycle high-density polyethylene(RHDPE)was discussed,and found that when G4 content was 20 wt.%,tensile and flexural strength decreased by 20.6% and 16.1%,respectively and notched impact strength increased from 39.3 MPa to 59.6 M Pa,which is 51.4 % higher than neat RHDPE.The melt index test showed that with the increase of G4,melting viscosity of RHDPE decreased,which means the processability of the system went bad.DSC and TGA results showed that the addition of G4 had no obvious impact on degree of crystallization and thermal stability of RHDPE,but integrity of the crystal structure decreased.The impact fracture of the composite was observed by means of SEM,which showed that the toughness has been improved greatly with the increase of G4 content.