Synthesis Of Element-benzoxazines And Thermal Properties Of The Copolymers With Epoxy Resin

Benzoxazine,as a nitrogen containing phenolic resin,has been used in many fields because of its good mechanical,flame retardancy and heat-resistant properties.At the same time,benzoxazine resin has many disadvantages,such as high curing temperature,large brittleness,low crosslinking density and poor thermal stability,which restrict its wide application.In order to get better performance of benzoxazine,this paper modified by different methods:inorganic boron,zirconium and phosphorus were introduced into the system,and boron containing benzoxazine,zirconium benzoxazine and phosphorus containing benzoxazine were successfully synthesized.(1)The boric acid ethanolamine ester(BAE)was synthesized from ethanolamine and boric acid,and then to prepare boric acid ethanolamine benzoxazine(BAE-BOZ)by reaction of ethanolamine borate with paraformaldehyde and phenol.The BAE-BOZ was solidified at high temperature,and the BAE-BOZ and epoxy resin E-51 were melted and blended with different mass ratios and cured at high temperature.The chemical structure of BAE-BOZ was analyzed by FT-IR,1H NMR and 13C NMR;The curing characteristics of BAE-BOZ were studied by DSC.The thermal stability of Poly(BAE-BOZ)was analyzed by TG.The results show that the BAE-BOZ curing peak at 218?;the boron content of BAE-BOZ reached 8.67%,under the condition of N2,Poly(BAE-BOZ)thermal decomposition temperature is 302 ?,at 426 degrees centigrade thermal decomposition rate,residual carbon 800 C rate was 58.08%,and without ethanol amine benzene boron modified the benzoxazine(E-BOZ)compared to the thermal decomposition temperature of 40?,carbon residue rate increased by 16.28%;BAE-BOZ/E-51 copolymer thermal decomposition temperature reaches 343 degrees Celsius,the thermal performance was further improved.(2)Using NaOH as catalyst,phenol and paraformaldehyde as raw materials,synthesis of salicyl alcohol(SA),boric acid as raw materials,synthesis of boric acid methyl benzene methyl ester(BSE);in BSE,aniline,phenol and formaldehyde as raw materials to synthesize methyl benzene boric acid methyl ester based benzoxazine(BSE-BOZ).The chemical structure of BSE-BOZ was analyzed by FT-IR,1H NMR.The curing characteristics of BSE-BOZ were studied by DSC.The thermal stability of boric acid benzyl oxazine polymer Poly(BSE-BOZ)was analyzed by TG The results show that the BSE-BOZ curing peak at 192?;the boron content of BSE-BOZ reached 5.92%,under the condition of N2,Poly(BSE-BOZ)thermal decomposition temperature is 315?,at 430? thermal decomposition rate,residual carbon 800 C rate was 52.12%,and without the aniline benzene boron modified the benzoxazine(AN-BOZ)compared to the thermal decomposition temperature of 35?,carbon residue rate increased by 5.28%,the thermal performance was further improved.(3)Using NaOH as catalyst,phenol and paraformaldehyde as raw materials,synthesis of 2-Hydroxybenzyl alcohol(SA),zirconyl chloride as raw materials,synthesis of zirconium methyl benzene methyl ester(ZrSE);in ZrSE,aniline,phenol and formaldehyde as raw materials to synthesize zirconium o methyl benzyl ester based benzoxazine(ZrSE-BOZ).The chemical structure of ZrSE-BOZ was analyzed by FT-IR,1H NMR;The curing characteristics of ZrSE-BOZ were studied by DSC.The thermal stability of zirconium modified benzoxazine polymer Poly(ZrSE-BOZ)was analyzed by TG The results show that the ZrSE-BOZ curing peak at 234?;the zirconium content reached 9.67%ZrSE-BOZ,under the condition of N2,Poly(ZrSE-BOZ)thermal decomposition temperature is 350?,at 425 degrees centigrade thermal decomposition rate,residual carbon 800 C rate was 54.30%,and without the aniline benzene modified zirconium the benzoxazine(AN-BOZ)compared to the thermal decomposition temperature of 45?,carbon residue rate increased by 6.28%,the thermal performance was further improved.(4)With phenol,paraformaldehyde and ethylenediamine as raw material to synthesize bicyclic diamine type benzoxazine(EDA-BOZ),followed by EDA-BOZ,9 10-,two-9-hydrogen oxa-10-p-Philippines(DOPO-10-complex oxide synthetic phosphide)synthesis at room temperature with double phosphorus intermediate DDP,and then to DDP,ethylenediamine and paraformaldehyde as raw phosphorus containing double synthesis of bicyclicbenzoxazine(DDP-BOZ).The chemical structure of DDP-BOZ was analyzed by FT-IR;curing characteristics of DDP-BOZ was studied by usingds DSC and TG.The results show that the DDP-BOZ curing peak at 250?.Under the condition of N2,Poly(DDP-BOZ)thermal decomposition temperature is 332? at 400? thermal decomposition rate.Carbon residue at 800? rate was 42.67%,and without benzene diamine type boron modified benzoxazine(EDA-BOZ)compared to the thermal decomposition temperature of 77? carbon residue rate increased from 31.84%to 42.67%;DDP-BOZ/E-51 copolymer thermal decomposition temperature reached 343? degrees of residual carbon rate from 15.2%up to 25.2%,the thermal performance can be further improved.