Polysilazane As A New Foaming Agent To Prepare High Performance Epoxy Foam

Epoxy foam can be applied in many important areas such as aviation,aerospace,deep diving,machinery manufacturing and architecture because of its excellent temperature resistance,adhesion,mechanical properties and good processing properties.However,the research of epoxy foam started relatively late.The application of epoxy foam is limited due to the flaw of preparation method.Among the preparation method,adding hollow microsphere and physical foaming both exihibit obvious defects,but chemical foaming is relative good with which a large amount of gas can be generated via smiple process.Such advantage determined that chemical foaming is the best choice of preparing low density,high performance epoxy foam.However,chemical foaming agents used these days exihibit poor performance.In this paper,polysilazane(PSN2)was used as novel chemical foaming agent to prepare epoxy foam.The structure and property of epoxy foam were characterized.Moreover,the applications of such epoxy foam were investigated based on its structure and property.It is amied to preparing low density,high performance epoxy foam via simple process with novel chemical foaming agent PSN2.The main work and results are summarized as follows.1.Epoxy foam were prepared via two-step batch process with PSN2 as foaming agent,triethylenetetramine(TETA)as hardener,emulsifier OP-10 as surfactant.The morphology,density,porosity and mechanical property of foam were characterized.The result shows that the apparent density and compressive strength of foam decrease with the content rise of PSN2 when the the content of PSN2 were adjusted from 2.5 to 7.5 wt.%.The apparent density and compressive strength of foam were 0.151 to 0.321 g/cm~3 and 2.53 to 7.39 MPa,respectively,which was much better than other reported epoxy foam with similar density.2.The influence of TETA content and OP-10 content on morphology,density,porosity and mechanical property of Epoxy foam were investigated.Considering testing result,when the content of PSN2 was 5 wt.%,the morphology and property can be optimized via increasing the content of TETA in the range from 10 wt.%to 15 wt.%.When the content of PSN2 was 2.5 wt.%,the property of epoxy can be optimized via the introduction of OP-10.The optimum content of OP-10 is 1 wt.%.3.The chemical structure of PSN2 were characterized with NMR and FTIR.The foaming mechism of as-prepared epoxy foam were analyzed with related reports and the structure of PSN2.The Si-N and Si-H of PSN2 can react with hydroxyl groups generated by the oxirane ring opening reaction and TETA,respectively to generate gas.4.The epoxy foam were tried to used as foam adhesive and heat resistance,insulation material.The foam adhered aluminium alloy concentric tubes exihibits relatively high shear strength below 100?.Moreover,epoxy foam also exihibited execellent heat resistance and low thermal conductivity according to TGA and thermal conductivity test,which implied that the as-prepared epoxy foam is a potential heat resistance and insulation material.