Preparation And Properties Of Fly Ash/coal Gangue-LLDPE Composite Sheet

As a big energy country,China emits more than 4 billion tons of solid waste every year,but the comprehensive utilization rate is less than60%.These large amounts of industrial solid waste not only occupy the land,but also pollute the environment,which is in urgent need of development and utilization.Most of the existing industrial solid waste utilization technologies are concentrated in the fields of cement,brick making and civil engineering.The products have low added value and are difficult to be transported and popularized in a large range.The combination of fly ash,coal gangue and high molecular polymer to prepare organic-inorganic composite materials,so as to reduce production cost and improve product performance not only conforms to the development concept of innovation,coordination,green,open and sharing in China,but also meets the development requirements of the national "14th Five-Year Plan".Organic-inorganic composite materials are new materials widely used in various fields of residents' life and industrial and agricultural production.How to prepare industrial solid waste into organic-inorganic composite materials with high added value is the direction of current researchers' efforts.Therefore,this paper mainly carries out the following research:(1)With coal gangue and linear low density polyethylene(LLDPE)as the experimental material,with double screw extruder composite was prepared by melt blending coal gangue-LLDPE,key is investigated and the coal gangue particle size for multiple ligands hot melt fluidity and composite density,hardness,bending strength and impact strength index,the results show that coal gangue particle size decreases,and its composite materials melt mass flow rate showed a trend of decrease,but the fine particles of coal gangue,is beneficial to increase the flexural strength and impact strength of the composite,especially the impact strength;The increase of gangue content will significantly reduce the mass flow rate of composite melt.However,the increase of gangue content can improve the density and hardness of the composite,and the bending strength of the composite increases with the increase of gangue content.On the contrary,coal gangue will increase the brittleness of composite materials,that is,the ability to resist impact decreases.When the content of coal gangue in 150-mesh sieve is 75%,the composite material density is 1.62 g /cm3,hardness is 66(HD),bending strength and impact strength are 18.25 MPa and 10.91 k J /m2,respectively.(2)With fly ash and linear low density polyethylene(LLDPE)as the experimental materials,use of plate vulcanizing machine hot press molding preparation composite materials,the author and the process parameters such as time,dosage of fly ash cooling method for composite material such as density,hardness,thickness,bending strength and bending modulus of indicators,and its mechanism through SEM,TGA and DSC analysis.The results show that under the experimental conditions of 500 g total material,80% fly ash content and 180 ? hot pressing temperature,the flexural strength and flexural modulus of the composite are 17.7 MPa and 3406.8MPa.In addition,when 20 mesh stainless steel mesh is added to prepare fly ash(80% content)-LLDPE composite material,the bending strength and bending modulus are 20.6 MPa and 3866.3 MPa,respectively,increasing by16.4% and 13.5%,respectively.The corresponding composite material density is 1.7 g/cm3,and the thickness is 7.5 mm.TGA shows that the addition of fly ash can improve the thermal stability of the composites.DSC experimental data show that the content of fly ash does not significantly change the melting temperature of the composites,but the addition of fly ash makes the crystallization peak temperature of the composites move to the direction of high temperature,that is,the crystallization temperature of the composites increases.(3)The high content(90%)composite sheet was prepared by hot pressing of coal gangue particles.The influence of coal gangue particle size on the properties of composite materials was studied,and the composites with better properties were obtained by optimizing the process parameters.The results show that when the coal gangue particle size range is 20?60 mesh,the composite strength is better,the density of the composite material is 1.97g/cm3,the Shore hardness is 71(HD),the bending strength is 13.52 MPa,the bending modulus is 3721.9 MPa.When 20 mesh stainless steel mesh is added to prepare high content gangue(20?60 mesh)-LLDPE composite material,the bending strength and bending modulus are 15.2 MPa and 4226.6 MPa,respectively,increasing by 12.4% and 13.6%,respectively,and the corresponding density of composite material sheet is 2.1 g/cm3.Shore hardness is 71(HD).DSC shows that the particle size of coal gangue has no obvious effect on the melting temperature and crystallization temperature of the composites,but the melting temperature increases compared with that of pure PE.TGA shows that the addition of coal gangue is beneficial to enhance the thermal stability of the composites,but with the decrease of coal gangue particle size,the decomposition temperature of the composites decreases,that is,the thermal stability decreases.