Study On The Preparation And Properties Of Ceramifiable Phenolic Foam

Phenolic foam is a kind of excellent thermal insulation material with excellent properties such as low thermal conductivity,high oxygen index,low smoke and low density.However,the traditional phenolic foam meets the fire will be carbonized,resulting in powder.Ceramifiable phenolic foam is a kind of fire resistance insulation material,it has excellent performance of traditional phenolic foam at room temperature,and in high temperature combustion can quickly generate ceramic layer that can prevent phenolic foam from being burned through and maintain a certain degree of mechanical strength,effectively overcome the problem of phenolic foam collapsed after burning.This paper discussed the formulation and process of preparing pure phenolic foams.Then,TiB₂ inorganic ceramic filler and low melting point B₂O₃ flux were added to study the effects of TiB₂ powder content on mechanical strength,thermal conductivity and thermal properties of ceramifiable phenolic foam before and after pyrolysis.The effects of the ratio of B₂O₃ and TiB₂ on the ceramifiable properties and thermal properties of phenolic foams at different temperatures were studied.The mechanism of ceramicization of phenolic foams was also analyzed.The main contents of this paper are as follows:?1?Single factor experiment method was used to study the effect of the optimum curing temperature,the amount of surfactant,foaming agent and curing agent on the properties of phenolic foam.The results showed that the phenolic foams prepared by curing temperature of 60⁷0?,8 wt%surfactant,6¹2 wt%foaming agent and10²0 wt%curing agent of hydrochloric acid:p-toluenesulfonic acid=1:2 displayed better overall performance.The micro-structure of phenolic foams were observed by scanning electron microscopy?SEM?.The pore size of the foams increased with the increase of the amount of foaming agent,and the mechanical properties decreased gradually.With the increase of the amount of curing agent,the pore size decreased and mechanical properties rose,but the cells appeared more holes and expansion ratio was low.?2?TiB₂/ceramifiable phenolic foam was prepared by adding TiB₂ powder to the foam.The results showed that TiB₂ can increase the thermal conductivity and mechanical strength before and after pyrolysis.When the content of TiB₂ powder was50 wt%,ceramifiable phenolic foam had the best ceramic effect at high temperature,and the compressive strength after heat treatment at 1000?was up to 0.18MPa.The results of FTIR and thermogravimetric analysis showed that TiB₂ could not be introduced into molecular chains and could not improve the pyrolysis peak temperature of phenolic foam,but it could greatly increase the residue yields of phenolic foam.When the amount of TiB₂ powder was 50 wt%,the residue yields of TiB₂/phenolic foam was 78.91%,which was 21.98%higher than that of pure phenolic foam.?3?Adding low melting point B₂O₃ could improve the mechanical strength of ceramifiable phenolic foam at low temperature.The results of FTIR and thermogravimetric analysis showed that some B atoms reacted with phenolic hydroxyl groups to form boron ester bond and B-O coordination bond.B₂O₃ powder melted into liquid phase to promote the ceramicization of TiB₂ and pyrolysis gas,and improved the thermal properties of phenolic foam.When the amount of B₂O₃ was 20wt%and the dosage of TiB₂ was 30 wt%,the pyrolysis peak temperature of ceramifiable phenolic foam was 501?,and the residue yields of phenolic foam was86.35%.The maximum compressive strength of B₂O₃-TiB₂/ceramifiable phenolic foam after ablation at 600?was 0.15MPa,and the maximum compressive strength after ablation at 1000?was 0.22MPa.