| High-density polyethylene(HDPE)is widely used water pipes,gas pipe materials for its outstanding chemical stability,corrosion resistance and long service life.The application of HDPE is limited due to its low intension,labile shape,thermolabile and inflammable properties.In this paper,HDPE/OMMT,HDPE/CaC03 and HDPE/OMMT/CaC03 nano-composites were prepared by melt blending method.The microstructure,crystalline properties,mechanical properties and heat resistance were systematically study,HDPE-g-MAH compatibilizing inorganic particles mechanism,OMMT strengthening mechanism,nano-CaCO3 toughening mechanism and OMMT,nano-CaCO3 synergistic strengthening and toughening mechanism were discussed,fracture behavior of HDPE/OMMT/CaCO3 nano-composites was also discussed.Firstly,structure and performance of HDPE/OMMT,HDPE/CaC03 nano-composites with different HDPE-g-MAH content were studied.Experimental results show that an appropriate amount of HDPE-g-MAH can improve the dispersion of nano-CaCO3,OMMT and their compatibility with the HDPE matrix.Mechanical tests show that when the ratio is nano-CaCO3:HDPE-g-MAH = 1:1 HDPE/CaCO3 nano-composites has the best toughness and when the ratio is OMMT:HDPE-g-MAH = 1:2,HDPE/OMMT nano-composites has a maximum yield strength.Secondly,under the condition of OMMT:HDPE-g-MAH = 1:2 and nano-CaCO3:HDPE-g-MAH = 1:1,the effect of OMMT and nano-CaCO3 content on the structure and performance of HDPE binary composites were studied.XRD results showed that intercalated structure form in HDPE/OMMT composites,and with the increase amount of OMMT,the intercalating of HDPE molecular chains to OMMT layer becomes more difficult.SEM observations show that a small amount of OMMT and nano-CaCO3 in HDPE matrix has better dispersion and compatibility,a large amount of OMMT and nano-CaCO3 can form agglomerated particles.Mechanical test analysis showed that nano-CaCO3 improves toughness of HDPE and the maximum value of impact toughness of HDPE/3wt%nano-CaCO3 composites is 14.05KJ/m2,increased by 27.61%than HDPE,OMMT can improve the composite yield strength and the maximum value of yield strength of HDPE/3wt%OMMT composite is up to 26.04MPa,increased by 7.87%than HDPE.Vicat softening temperature test analysis showed that with OMMT or nano-CaCO3 dosage increases,HDPE/OMMT,HDPE/CaCO3 nano-composites heat resistance are improved.Finally,structure and properties of HDPE/OMMT/CaCO3 nano-composits with 2%content of OMMT and 3%content of CaCO3 were discussed.the influence of compatibility agent was also discussed.XRD results showed HDPE-g-MAH not only more effectively promotes forming intercalated structure of HDPE/OMMT/CaCO3 nano-composites,but also promote the improvement of HDPE crystallinity.SEM results revealed that HDPE-g-MAH and SEBS-g-MAH can promote dispersion of OMMT,nano-CaCO3 particles and improve OMMT,CaCO3 particles and HDPE interface compatibility.PE2m3ca7s has the best impact toughness;PE2m3ca7h has maximum yield strength of 27.67MPa,increased by 14.72%compared with pure HDPE.It is because the synergistic strengthening effect of OMMT particles and CaCO3 particles under the action of HDPE-g-MAH.Vicat softening temperature tests showed that adding HDPE-g-MAH can improve heat resistance of the composites,while adding SEBS-g-MAH decrease heat resistance of the composites.EWF parameter analysis reveals that OMMT and CaCO3 particles have a synergistic toughening effect,PE2m3ca7h has maximum the basic work of fracture we,PE2m3ca7s has maximum non-essential work of fracture βwp,the former mainly attributed to the HDPE-g-MAH improve the dispersibility of the inorganic particles and the compatibility with HDPE,the later mainly attributed to the elastic SEBS-g-MAH coated with inorganic particles,forming coated structure.Coated structure is conducive to plastic deformation of composite during stretching. |
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