Preparation And Properties Of Almond Shell/High Density Polyethylene Composites

Almond shell(Als)is a kind of food by-product with a large output In the 2015/16 season,global almond production totaled 1 million tons,and shells accounted for 35%-70%,about 38.5 million-770 tons.Usually these shell are directly discarded or incinerated,which not only pollutes the environment but also wastes resources.The purpose of this paper is to develop the composite materials reinforced with high density polyethylene(HDPE)from almond shell,and then prepare flame retardant composites,so as to avoid wasting resources and reduce environmental pollution.Firstly,X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS)and Fourier transform infrared spectroscopy(FTIR)were used to analyze the physical and chemical properties of almond shell.The effect of almond shell size,its ratio to plyethylene and preparation method on the properties of Als/HDPE composites were studied.Poplar veneer was used to enhance its mechanical properties.based on the pore structure of almond shell,it is considered to prepare flame retardant Als/HDPE composite with the emulsification treatment(FRW).The research results provide a new way to make a full use of almond shell,which benefit to reduce biomass resource waste and environmental pollution.(1)Almond shell is full of pores with different sizes.The diameter of large pores was 300-500?m and small pore was 40-60?m.It remains elements of C,O,N,Si.Its main chemical constituent is cellulose,hemicellulose and lignin The extract content of almond shell was tested.The content of alkali extractives was the highest,followed by benzene alcohol,hot water and cold water.In the analysis of the benzene alcohol extracties of almond,it was found that it mainly contained 16 organic compounds,such as cycloalkanes,esters,alkenes and benzene compounds.Main weightlessness peak at 335?.Cellulose fiber belongs to cellulose I type and crystallization is 32.88%.(2)Preparation of Als/HDPE composites:The ratio of almond shell to high-density polyethylene and its preparation method have significant effects on the properties of composites.When Als:HDPE is 6:4 the composites shows higher performance and dynamic mechanical properties than 7:3.The particle size of almond shell has little effect on the mechanical properties of the composite,but it has great water absorption,density and dynamic mechanical properties.With the decrease in particle size,the water absorption,density and dynamics of the Als/HDPE composites decrease either.The mechanical properties are all reduced.Compared with the mold forming method,the composite material prepared by extrusion has higher mechanical properties and higher density.The composites prepared by mold process have higher specific strength and specific stiffness,but the water absorption properties of the materials are also higher than those of the extruded composites.The mechanical properties of the composites were improved after Als/HDPE composites was laminatedd with veneer.Its surface bonding strength was 0.74 MPa.No renting occurred after soaking for 3 hours at 63?.(3)Preparation and properties of flame-retardant Als/HDPE composites:Flame retardant composites were prepared by immersing Alsl/HDPE composite in in fire retardant solution FRW with 5%-25%solid contend.The flame retardant properties were investigated by means of cone calorimeter(CONE)and limiting oxygen index(LOI).The analysis results show that the higher the flame retardant addition,the better the flame retardant performance of the Als/HDPE composite.However,the change from 15%to 25%is not significant.The suitable usage of FRW was 15%,and at this level the comprehensive mechanical properties of Als/HDPE composite are good.With the increase of FRW content,the limiting oxygen index of Als/HDPE composites increased.The oxygen index of Als/HDPE composite without FRW was 24.2%.When 5%,15%,25%flame retardant was added,Als/HDPE composite showed the oxygen index of 25.7%,26.5%,and 27.1%,respectively.Compared with poplar powder/HDPE composites,the composites prepared from almond shell have higher flame retardant properties.