Fabrication Of Carbon Foams With High Mechanical Properties Derived From Sucrose/polyacrylamide Hydrogel

With various preparation process and diversity of carbonsource,carbon foams show a number of significant physical propertiesand can be widely applied in many fields,such as high temperature thermal control materials,adsorption materials,and electrode materials,aerospace and so on.Based on the current research of low-cost sucrose-based carbon foam,this paper proposes a novel idea using sucrose/acrylamide hydrogel as carbon precursor and sodium dodecyl sulfate?SDS?as blowing agent.By the heating polymerization,carbon foams with high char yield and uniform pores is prepared.Besides,the mechanism of the synthesis of carbon foams is studied.This paper discusses the effects of process parameters on the structure and establishes a relationship between pore structure and properties.Firstly,this paper studies the mechanism of the synthesis of sucrose/acrylamide hydrogel-based carbon foams.The process of preparation on the physical foaming and thermal polymerization process is also discussed.The results show that the foam can be uniformly sized in foaming system under the modified function of the SDS?less than 100?m?;with the increasing speed of the foam,the foam volume and viscosity of the foaming system significantly improved;when the foaming speed is 1500r/min,the foam has a uniform size and most stable performance.Thermal polymerization of sucrose/acrylamide hydrogel leads to high char yield of carbon foam?27.87³1.09wt.%?.With the increase of sucrose content,thermal polymerization degree tends to saturation,which relates the acrylamide hydrogel.Higher thermal polymerization degree is beneficial to increase the orderdegree of carbon foams.Secondly,this paper studies the effects of component content?sucrose and SDS?on the pore structure of carbon foams,and establishes a relationship between pore structure and its density and porosity.The results show thatthe pore size can be controlled within the range of 5.92²3.48?m;with the increase of sucrose content and SDS,carbon foam pore size decreases,pore size distribution tends to be concentrated,resulting in thechange ofdensity?0.17⁰.93 g/cm³?andporosity?53.57%⁹1.49%?.With the increase of sucrose content,density of carbon foams increase and then decreases,which depends on the pore wall structure formed during thermal polymerization;at 2wt.%of SDS content,the highest porosity of carbon foam is obtained for the best foaming ability.The paper also studies the effects of component content?sucrose and SDS?on the properties of carbon foams,and establishes the relationship between pore structure and its various properties.The results show that the carbon foams has the smallest pore size and pore walls thickest dimension at 55wt%sucrose contents and 3wt%SDS,leading to the largest mechanical strength 107.97 MPa;carbon foams with the density of 0.79 g/cm³ performs the maximum energy absorption per unit volume of23.52 MJ·m^-3.Besides,the conductivity of carbon foam shows a linear relationship with its density.The maximum conductivity of carbon foams?70.79 S/cm?is obtained at the highest density?0.93 g/cm³?since its high order degree.The amount of carbon residue retains about 30wt.%after isothermal oxidation at 450 ^oC air conditions,which showes good antioxidant capacity of carbon foams.