Modification And Applications Of Recycled Polyolefin

The rapid development of plastic industry hasinevitably brought about the large increase of waste plastics production, leading to a very seriousenvironment pollution problem. An effective approach to inhibit“white pollution” is to recyclewaste plastics and reduce the consumption of new plastic materials. At present, thesystemof recycling waste plastics is not perfect yet in China, many available resources are filled in land or incinerated as solid waste.Though it is essential to develop new plastic meaterials,the recycling and reusing of waste plastic also should be considerated.The common problems of waste plastic isthe low molecular weight, containing many kinds of additives or impurities and its poor mechanical properties. The techniques of enhancing the molecular weightof waste plastic are including:(1) blending with virgin plastics;(2) adding cross-linking agent to crosslink. While the methods toremove impurities and additives problemsare:(1) classification of recycling, try to make the sources be single ingredient;(2) the pretreatment procedure should avoid the use of chemical solvent.This paper mainly uses the physical blending modification toreinforce and toughen two kinds of waste polyolefin. These two kinds of waste polyolefin are recycled-polypropylene(rPP) and recycled-polyethylene(rPE).The rPP is recycled from waste automobile bumper, the main components are polypropylene(PP), ethylene propylene diene monomer(EPDM), plasticizer and filler blends. The rPE is recycled from waste woven bag recycling materials, the main component are polyethylene(PE) and fillers. In this paper, the rPP is modified for the application of plastic constructionformwork and automobile fender, rPE is modified for the application of outer wall of double wall corrugated pipe.The industrial standard of plastic construction formwork is JG/T 418-2013. Plastic construction formwork industry standard is JG/T 418-2013. In this paper, calcium carbonate and other four kinds of fillers had been used to reinforce rPP, ethylene vinyl acetate copolymer(EVA) and other six kinds of elastomers had been used totoughen rPP. The analysis of the experimental result showed that, glass fiber(GF) is the ideal filler to reinforce rPP, the optimum content is 40 phr, adding maleic anhydride grafted polypropylene(MAPP) can improve the interfacial compatibility of rPP/GF, and can improve the impact strength and flexural properties of rPP/GF composites, when the weight fraction of MAPP is 8wt%,the rPP has the highestflexural strength and flexural modulus.A commercially available toughening agent(MH-A), EPDM, and ethylene octene copolymer(POE) can improve the unnotched impact strength of rPP/GF/MAPP composite system, but reduce the tensile and flexural strength meanwhile. When the contentof EPDM, MH-A, POE is in the region of 10~20 phr, the compositespossessthe best comprehensive properties.The unnotched impact strength is about 23 kJ/m~2, the flexural strength is about 40 MPa,and flexural modulus is about 2600 MPa, Vicat softening temparatureis about 101℃, shore hardness is about 92. All these experimental datasare higher than the norms of JG/T 418-2013. EVA, butylrubber(IIR) and styrene butadiene rubber(SBR) are also used as impact modifier in rPP/GF/MAPP composites, but the comprehensive mechanics properties are poorer than that of other elastomer, the nitrile butadiene rubber(NBR) modified rPPcan’treach the norms of JG/T 418-2013. In addition, for rPP/GF/MAPP/EPDM(100/40/8%/20)composite, there is no obvious difference in mechanical properties between the banburying forming method and extrusion injection moulding.Recycled-acrylonitrile-butadiene-styrene copolymer(rABS)can enhance the tensile strength and flexural properties of rPP,the optimum content is about 30 phr.The tensile strength of rPP/r ABS(100/30) is about 23% higher than that of rPP, the flexural strength and modulus are increased by 38% and 47%respectively. The addition of IIR can improve impact strength and elongation at break of rPP/rABS blends, the optimum content is 5 phr.The notched impact strength increased by 22%than that of rPP/rABS(100/30). EPDM and EVA can also toughen the rPP/rABS(100/30) blends, but the modification effect is inferior thanthat for IIR. Mechanical testing results showed thatmechanical properties of rPP/rABS/IIR(100/30/5) blends can be improved by twiceextrusion and annealing treatment.The blends can obtain higher propertiesthaneach treatment when both two kinds of treatment are used.The impact strength increased by 54%, the tensile strength increased by 15%, the elongation increased by 44%, the flexural strength increased by 8%, the bending modulus increased by 7%, and the mechanical properties can meet the norms of the automobile fender.The standard of double wall corrugated pipe is GB/T 19472-2004. GF is the ideal filler to enhance rPE, the effect is superior thanthat of the recycled glass fiber(rGF), the optimum content of GF is 20 phr.When the content approach to this value, the tensile strengthand flexural modulus of rPE increased by 20% and 1071 MPa respectively. The addition of MAPP(8wt%) in the rPE/GF blend of can improve the interface performance, and the tensile strength and flexural modulus of rPE can increased by 21% and 29%. The tensile strength, flexural modulus, density, melt index and color appearance of the rPE/GF/MAPP(100/40/8%) compositescan meet the norms of GB/T 19472-2004 by incoporating oleic acid amide and black masterbatch.