Study On The Preparation And Properties Of PS Microcellular Foam

Microcellular foam is a new type of polymer material with small cell size(less than 100 ?m)and high cell density(more than 108 cell/cm3).The microcellular foam both reduces the amount of materials and greatly improves the performance of the materials.Microcellular foam have been applied in high precision areas such as computer,aerospace and biomedical applications.Polystyrene materials are widely used and in great demand.However,Polystyrene material is brittle and has low impact strength and poor heat resistance.Ordinary PS foam has large cell size,and there are also some problems such as bubble hole rupture and low impact strength.In order to improve the performance of PS materials,the microcellular foaming process is applied to the preparation of PS foam material.The microstructure of microcellular foam is poorly controlled,and the relationship between microstructure and material properties is less studied.In this paper,studied the effect of nano-SiO2 particles and process parameters on microstructure of PS microcellular foam,and explored the relationship between the properties and microstructure of PS microcellular foam.Firstly,pure PS and PS/SiO2-1%,PS/SiO2-3%,PS/SiO2-5%materials were prepared by single screw extruder.The microstructure,infrared spectrum,rheological properties and thermodynamic properties of the four materials were compared and analyzed.The result showed that when the content of SiO2 was less than 3%,SiO2 particles were evenly distributed in the PS matrix and tangled with PS molecular chain.The viscoelasticity of PS/SiO2 composite was increased with the increase of SiO2 addition,and the viscoelasticity of PS/SiO2-3%was higher than that of pure PS and PS/SiO2-1%.And when the content of SiO2 was 5%,due to the large amount of SiO2 reuniting in the PS matrix.,the molecular chain structure of PS was destroyed and the viscoelasticity of PS/SiO2-5%material is lower than that of the other three materials.With the increase of Si02 content,the absorption peak intensity of Si-O-Si at 1106cm-1 gradually increased.Then the PS microcellular foam was prepared by batch foaming.The influence of nano-SiO2 and foaming process parameters on the microstructure of PS microcellular foam was systematically studied,and the influence mechanism was also revealed.The results showed that nano-SiO2 particles were added to the PS matrix,and the nano-SiO2 particles acted as nucleating agents,reducing the cell size and improving the cell density of PS microcellular foam.The cells of PS/SiO2-3%foam sample.were fine and evenly distributed.The nucleation effect of nanoparticles was weakened and the uniformity of cell decreased due to the agglomeration of nano-SiO2 in PS/SiO2-5%foam sample.When the foaming temperature was in the range of 110??140 ?,the expansion ratio and cell size increased with the increase of foaming temperature.The foaming temperature had a significant effect on expansion ratio.When the foaming pressure was in the range of 10MPa-25MPa,with the increase of foaming pressure,the cell density and expansion ratio increased,and the cell size decreased.The foaming pressure had a significant effect on cell size and cell density.Finally,according to the influence of process conditions on the microstructure of PS microcellular foam,adjust foaming process condition.PS microcellular foam of different microstructure were prepared,and the effects of microstructure of PS microcellular foam on compression and thermal conductivity were investigated.The result showed that The thermal conductivity of PS foam decreases linearly with the increase of expansion ratio.the foam with similar expansion ratio,the smaller the cell size,the lower the radiant heat conductivity of the material and the smaller the thermal conductivity.The static compression test was performed on PS microcellular foam of different microstructure.The results showed that the foam with similar cell size,the smaller the expansion ratio,the larger the compression strength of the material.And the foam with similar expansion ratio,the smaller the cell size,the greater the compression strength of the material.The thermal conductivity of PS microcellular foam with different microforms was tested.The results showed that the thermal conductivity of PS foam decreased linearly with the increase of expansion ratio.The foam with similar expansion ratio,the smaller the cell size,the smaller the thermal conductivity.