Study On Phenolic Foams Modified By Dicyandiamide And Phosphorylated Polyvinyl Alcohol

The phenolic foams(PF)have attracted attention remarkably by the excellent fire resistance.However,there are some shortcomings of phenolic foams.This article has focused on the poor strength and easily broken feature of phenolic foams.We have selected three modifying agents,dicyandiamide(DICY),phosphorylated polyvinyl alcohol(PPVA)and diatomite,to modify phenolic foams.The resin are characterized by Fourier transform infrared Spectrum(FT-IR),which show the incorporation of dicyandiamide(DICY) and phosphorylated polyvinyl alcohol(PPVA) into the phenolic resin.we have carried out compression strength test,impact strength test,pulverzation rate test,scan electron microscopy(SEM),thermogravimetic analysis and limit oxygen index(LOI)test of the phenolic foams.This article has three expermimental parts.The first part is the phenolic foams modified by dicyandiamide.In this research,we select dicyandiamide as chemical modifying agent,which used to synthesize resin with phenol and formaldehyde together,and the resin has been characterized by FT-IR.The foams have been prepared from the resin.The results of the tests have showed that the compression strength is0.046 MPa,the impact strength is 3.35kJ/m2,the pulverzation rate is 2.13%,and the LOI is above 40%,relatively,the values of phenolic foams are 0.033 MPa,2.1kJ/m2,6%and36%.The flammaility has improved,and the strength has also reinforced obviously.The SEM show no more inhomogeneous or breaken cells in modified foams.The second part is the phenolic foams modified by PPVA.We use Polyvinyl alcohol(PVA) and phosphoric acid to synthesize PPVA,then we use it to prepare modified resin,which is characterized by FT-IR.Then we prepare the modified foams from the resin.The foams have been tested by some ways.The results show that the compression strength is 0.056 MPa,the impact strength is 3.50kJ/m2,the pulverzation rate is 2.8%,and the LOI is above 42%.The performance of the foams have been improved obviously.The pictures magnified 200 times from SEM show that the uniform and smaller cells in the foams,and the breaken cells has reduced.What's more,we have used diatomite to reinforce the foams.In this research,wo use diatomite as physical touhening agent into phenolic resin,which foaming into phenolic foams.As the incorporation of diatomite,the performance of phenolic foams have improved.The compresssion strength is 0.063 MPa,impact strength is 4.0kJ/m2,pulverzation rate is 3,4%.The strength have improved obviously.And there is no decline in LOI,which means the flammability have not been destruct.Morever,the pictures of SEM show the incorporation into foams,the disc and column of diatomite among cells.