Preparation And Properties Of HDPE/Modified Inorganic Nano Particle Composites

High-density polyethylene(HDPE)as a copolymer thermoplastic polyolefin,with superior chemical stability,low temperature resistance,wear resistance,electrical insulation properties,as well as excellent mechanical strength and easy processing and molding and other characteristics,widely used in plastic packaging,building materials,automotive materials and other fields,but HDPE in practical applications with heat aging resistance,insufficient weather resistance,low hardness,weak impact resistance,volatility,poor air permeability and other defects,so it is particularly important to have a oriented functional modification to expand its application field Nanoparticles with functional characteristics can be used as HDPE fillers,and inorganic nanoparticles can improve the strength,rigidity,heat resistance and processing fluidity of polymer composites while improving the toughness of the matrix,thereby improving the cost performance of HDPE composites.In this paper,HDPE is used as the matrix,sodium sulfate(Na₂SO₄),calcium sulfate whisker(CSW)and barium sulfate(Ba SO₄)are used as fillers,and silane coupling agent KH570 is used as modifier.Sexual HDPE/inorganic nanoparticle composites.The effects of different contents of Na₂SO₄,CSW and Ba SO₄ on the mechanical properties,crystallization properties and thermal stability of HDPE/inorganic nanoparticle composites were analyzed by mechanical property test,thermogravimetric analysis(TG)and differential calorimetric analysis(DSC).The crystallization behavior and thermal decomposition behavior of HDPE/inorganic nanoparticle composites were analyzed by non-isothermal crystallization kinetics and thermal degradation kinetic model equations.At the same time,the service life of HDPE/inorganic nanoparticle composites was discussed,and the rmooxidative aging performance of HDPE/inorganic nanoparticle composites was studied by means of thermooxidative aging treatment,and the law of thermooxidative aging performance of HDPE/inorganic nanoparticle composites was explored,and its main conclusions are as follows:(1)It is found that the mechanical properties of HDPE/inorganic nanoparticle composites show a trend of increasing first and then decreasing.When the contents of Na₂SO₄,CSW and Ba SO₄ were 10%,20%and 10%,respectively,the tensile strength and flexural strength increased by 7.56%and 39.51%,9.58%and 31.65%,15.9%and18.8%respectively compared with pure HDPE.In comparison,it was found that the tensile strength and bending strength of Ba SO₄ and Na₂SO₄ with 10%content increased the most,and the comprehensive mechanical properties were improved to Ba SO₄>Na₂SO₄>CSW.(2)Systematic analysis of the crystallization properties of HDPE/inorganic nanoparticle composites found that Na₂SO₄,CSW,Ba SO₄ filled HDPE all belong to heterogeneous crystallization,and the crystallization behavior satisfies three stages:crystallization nucleation stage,grain growth stage and relatively slow crystallization stage.Secondary crystallization;with the increase of filler content in the composites,the crystallization rates of HDPE/Na₂SO₄ composites and HDPE/CSW composites increased,and the crystallization rates of HDPE/Ba SO₄ composites decreased.In order to further study the non-isothermal crystallization of HDPE/inorganic nanoparticle composites with different contents(Na₂SO₄,CSW,Ba SO₄)at different cooling rates(10K/min,15K/min,20K/min,25K/min,30K/min)Influence of behavior,combined with Jeziorny equation model and Mo Zhishen equation model to explore non-isothermal crystallization behavior,it is found that the cooling rate of HDPE/inorganic nanoparticle composites is positively correlated with the crystallization rate.With the increase of filler content,HDPE/Na₂SO₄ composites,HDPE/CSW composites and HDPE/Ba SO₄composites Avrami index(n)and non-isothermal crystallization rate(Z_C)increase first and then decrease,n are 2.0-4.0,2.0-3.0,2.0-4.0,namely HDPE/Na₂SO₄composites The crystal growth mode of HDPE/Ba SO₄ composites is the mixed growth of two-dimensional platelets and three-dimensional spherulites,and the HDPE/CSW composites are two-dimensional platelet growth;Na₂SO₄,CSW,Ba SO₄ filled HDPE/inorganic nanoparticle composites correspond to Z_C respectively.are0.96,0.92,0.94,and the effect of improving the crystallization performance is Na₂SO₄>Ba SO₄>CSW.The non-isothermal crystallization kinetic parameters obtained by the Mo Zhishen equation also confirmed that nanofillers are beneficial to improve the crystallization stability,crystallization rate and crystallinity of HDPE/inorganic nanoparticle composites,and there are various crystal growths in Na₂SO₄ and Ba SO₄systems Ways coexist,CSW is a single growth.(3)Analysis of the TG of the HDPE/inorganic nanoparticle composite material found that the thermal degradation of the HDPE/inorganic nanoparticle composite material was first-order degradation.The thermal stability of the material decreases gradually,and the degree of influence of inorganic nanoparticles on the thermal stability of HDPE/inorganic nanoparticle composites is Na₂SO₄42SO₄ composites,HDPE/CSW composites and HDPE/Ba SO₄ composites during thermal degradation is lower than that of pure HDPE,and the energy required for HDPE/inorganic nanoparticle composites in thermal degradation is reduced;The thermal degradation mechanism of HDPE/inorganic nanoparticle composites according to the-Redfern equation varies with different fillers.The thermal degradation mechanism function of HDPE/Na₂SO₄ composites and HDPE/Ba SO₄ composites is g(a)=[-ln(1-?)]^3/4,reaction order=3/4,thermal degradation mechanism is random nucleation and subsequent growth reaction;HDPE/CSW composites satisfy thermal degradation mechanism function as g(?)=[1-(1-?)]^1/1,the reaction order is 1,and the thermal degradation mechanism belongs to the phase boundary reaction(one-dimensional).(4)Through mechanical property testing,thermogravimetric analysis(TG),differential calorimetric thermal analysis(DSC),non-isothermal crystallization kinetic model and thermal degradation kinetic model(Kissinger equation,Flynn-Wall-Ozawa equation,Coast-Redfern equation Eq.)and other characterization methods to analyze the thermo-oxidative aging properties of HDPE/inorganic nanoparticle composites,and explore the thermo-oxidative aging of HDPE/inorganic nanoparticle composites under antioxidant 1010 and different thermo-oxidative aging times(0d-50d).The study found that with the increase of thermal oxygen aging time,the mechanical properties,crystallization properties and thermal stability of HDPE/inorganic nanoparticle composites decreased,and the failure mode of the composite system was the internal cracking of HDPE/inorganic nanoparticle composites.As a result,the anti-thermal oxidation aging effect is CSW>Na₂SO₄>Ba SO₄;and after adding antioxidant 1010,under the same aging time,the HDPE/inorganic nanoparticle composite material improves thermal stability,mechanical properties,crystallization rate and crystallinity,The crystal elongation mode of the matrix HDPE has changed.The crystallization mechanism of HDPE/Na₂SO₄ composite and HDPE/Ba SO₄ composite is a single two-dimensional platelet growth,and the HDPE/CSW composite is a mixed growth of one-dimensional and two-dimensional platelets,but the composite system The thermal degradation mechanism did not change with the addition of antioxidants.