Structure And Performance Of Functional LDPE/WGRT TPE And LDPE/EPDM TPV

Thermoplastic elastomers(TPEs)based on low density polyethylene(LDPE)/waster ground rubber tire powder(WGRT)compounds were prepared by melt-compounding,and styrene-butadiene-styrene block copolymer(SBS)was used as compatibilizer.The mechanical properties,micro-morphology,compression Mullins effect and its reversibility of LDPE/WGRT TPE and LDPE/SBS/WGRT TPE with different weight ratio were investigated systematically.The flexible superhydrophobic surfaces based on LDPE/WGRT TPE before and after compatibilization were prepared by using template method where series metallographic sandpapers were used as templates.The influence of sandpaper type and matrix composition on the micro morphology and hydrophobic properties of the molded surfaces were studied systematically;the classical superhydrophobic theoretical model was used to fit the experimental data and explain the superhydrophobic mechanism;the adhesion behavior and self-cleaning behavior were studied through optical images.Thermoplastic vulcanizates(TPVs)based on low density polyethylene(LDPE)/ethylene-propylene-diene terpolymer(EPDM)were prepared via dynamic vulcanization,the superhydrophobic/superlipophilic surfaces based on LDPE/EPDM TPV were prepared by using template method where series metallographic sandpapers were used as templates,the influence of template types on the micro-morphology and hydrophobic properties of the molded surface were investigated systematically;the LDPE/EPDM TPV surface with the best superhydrophobic/super lipophilic properties was used in a straight-through valve as a direct-suction pressure response through valve for oil-water separation.The influence of type of films,film gaps,type of oil and separation pressure in oil-water separation capacity,oil-water separation efficiency and oil-water separation rate of the direct suction pressure response through valve were explored syetematiclly.The main results were shown as below:(1)The mechanical properties and viscoelastic behavior of LDPE/WGRT TPE before and after compatibilization were investigated.The results showed that the elongation at break,tensile strength and tearing strength of the TPE compatibilized by SBS were significantly enhanced;Mullins effect could be observed obvioously during the uniaxial cyclic compression;morevoer,the residual deformation,internal friction loss,tanδand degree of stress softening effect were decreased obviously in the compression,which means the high elasticity of the of the TPE was improved.Increasing the temperature would improve the reversibility of the Mullins effect,and100 ℃ was the best reversibile temperature of the TPE,the reversibility behavior can also be enhanced by using SBS as compatibilizer.(2)The results showed that the superhydrophobicity of LDPE/WGRT TPE could be improved greatly with a certain amount of SBS.The superhydrophobic surface based on molded LDPE/SBS/GTR(weight ratio is 40/15/60)TPE exhibited the excellent superhydrophobicity(with a contact angle of 164.6°±3.0°and a tilt angle of 4.4°±1.9°).Furthermore,abundant tearing microstructure could be found obviously by morphology observation.Optical images indicated the surface possessed of low adhesion force and self-cleaning property.FE-SEM observation shows that there are a large number of fiber-like rough structures in the surface of TPE after molding process,which were produced by the plastic deformation of LDPE,and the thickness of these crimped fiber-like structures was about 40μm;the results calculated by the Cassie model formula were consistent with the experimental results.(3)Flexible superhydrophobic/superoleophilic surfaces based on LDPE/EPDM TPV were prepared by the template method where series metallographic sandpapers were used as templates,the LDPE/EPDM TPV(weight ratio is 60/40)which was prepared by dynamic vulcanization were used as matrix.The effect of template type on the hydrophobicity of molded TPV surfaces was systematically investigated.The hydrophobicity test results showed that the surface of the LDPE/EPDM TPV samples molded with W7 sandpaper showed the best superhydrophobicity and superlipophilicity;FE-SEM observation showed that a large number of fibrous tear bands existed in the molded TPV surface,indicating the plastic deformation of the resin phase during the process of preparation;the results calculated by the Cassie model formula were consistent with the experimental results.(4)The convolute superhydrophobic/superoleophilic LDPE/EPDM TPV film was used in a straight-through valve as a direct-suction pressure response through valve for oil-water separation experiments.The influence of the film type,film gap and oil type on the oil-water separation capability of the direct-suction pressure response through valve were researched,and the influence of film type and separation pressure on oil-water separation efficiency and oil-water separation rate of the direct-suction pressure response through valve were also studied systematically.The results showed that direct-suction pressure response through valve possessed excellent oil-water separation ability;moreover,the film type,film gap and the oil type could affect its oil-water separation ability significantly.It should be noted that the film gap and separation pressure can affect its oil-water separation efficiency and oil-water separation rate significantly.