Study On Synthesis, Polymerization And Performance Of Novel Benzoxazine Derivatives

Benzoxazine is a kind of N,O compounds prepared by the condensation reaction of phenolic compounds,amines and formaldehyde by Mannich reaction.Benzoxazines have the advantages of easily available raw materials and low viscosity,no strong catalyst is needed for curing,and no by-products produced when curing,near-zero shrinkage,benzoxazines have overcome the problem of the phenolic resin of curing process in the release of small molecules and many other shortcomings.Polybenzoxazine has a good thermal properties,mechanical properties and dielectric properties and high residual carbon rate.In the construction,electronics,flame retardant industry and other fields,benzoxazines have a wide range of applications.In recent years,with the electronics and other fields of science and technology continue to move forward,the performance of benzoxazine put forward higher and higher requirements.The benzoxazine with high Tg and high flame retardancy and good thermal stability has become a hotspot in the field of benzoxazine.In order to prepare high Tg and high flame retardant,good thermal stability of benzoxazine,benzoxazine can be modified.There are two main ways to modify benzoxazine:one way is to prepare new monomers by molecular design;the other is by blending or copolymerizing with other resins,macromolecules and the like.In this paper,different functional groups were introduced into the benzoxazine by molecular design.A series of benzoxazines were synthesized.The main contents and results were as follows:1.Two kinds of monoxazine benzoxazines were synthesized by using different phenol derivatives(p-hydroxybenzaldehyde and phenol)with n-butylamine and formaldehyde as raw materials.The structure of two monoxazine benzoxazine precursors was characterized by Fourier transform infrared spectroscopy(FTIR),proton nuclear magnetic resonance spectroscopy ~1H-NMR.The curing process of two kinds of benzoxazine precursors was studied by differential scanning calorimetry(DSC),The thermal properties of the two benzoxazines after curing were characterized by thermogravimetric analyzer(TGA).Two kinds of monoxazine benzoxazine have two peaks in the curing process,respectively,corresponding to the benzoxazine evaporation endothermic peak and the ring opening polymerization exothermic peak;with p-hydroxybenzaldehyde as phenol source benzoxazine thermal curing peak temperature is far less than with phenol for the phenol source synthesis of benzoxazine thermoset exothermic peak temperature,peak position was moved forward,the aldehyde promoted the thermal curing of benzoxazine during the curing process,reducing the benzoxazine ring opening polymerization temperature;with"phenol"for the phenol source synthesis of benzoxazine has a high thermal stability and residual carbon rate,the 5%and10%of the weight loss temperature were 292?and 340?,and the char yield at 800?is up to 42%.2,Another two kinds of monoxazine benzoxazines were synthesized by using allyl amine and formaldehyde as raw materials,and different phenol derivatives(p-hydroxybenzaldehyde and p-cresol).The structure of two monoxazine benzoxazine precursors was characterized by Fourier transform infrared spectroscopy(FTIR),proton nuclear magnetic resonance spectroscopy ~1H-NMR.The curing process of two kinds of benzoxazine precursors was studied by differential scanning calorimetry(DSC).The thermal properties of the two benzoxazines after curing were characterized by thermogravimetric analyzer(TGA).Two kinds of monoxazine benzoxazine have two peaks in the curing process,respectively,corresponding to the benzoxazine evaporation endothermic peak and exothermic peak,The exothermic peak is the addition of polymerization of allyl double bond and the ring opening polymerization of benzoxazine;with p-hydroxybenzaldehyde as phenol source benzoxazine thermal curing peak temperature is far less than with p-cresol for the phenol source synthesis of benzoxazine thermoset exothermic peak temperature,peak position was moved forward,the aldehyde promoted the thermal curing of benzoxazine during the curing process,reducing the benzoxazine ring opening polymerization temperature;The polybenzoxazine prepared from p-hydroxybenzaldehyde showed higher thermal stability and residual carbon rate,The 5%and 10%of the weight loss temperature were 302?and 360?,and the char yield at 800? is up to 46.4%.3,Two bicyclo-benzoxazine was synthesized by using 1,6-Diaminohexane and formaldehyde as raw materials,and different phenol derivatives(p-hydroxybenzaldehyde and p-cresol).The structure of two bicyclo-benzoxazine precursors was characterized by Fourier transform infrared spectroscopy(FTIR),proton nuclear magnetic resonance spectroscopy~1H-NMR.The curing process of two kinds of benzoxazine precursors was studied by differential scanning calorimetry(DSC).The thermal properties of the two benzoxazines after curing were characterized by thermogravimetric analyzer(TGA).Two kinds of bicyclo-benzoxazine have two peaks in the curing process,respectively,corresponding to the benzoxazine melting endothermic peak and the ring opening polymerization exothermic peak;with p-hydroxybenzaldehyde as phenol source benzoxazine thermal curing peak temperature is far less than with p-cresol for the phenol source synthesis of benzoxazine thermoset exothermic peak temperature,peak position was moved forward,the aldehyde promoted the thermal curing of benzoxazine during the curing process,reducing the benzoxazine ring opening polymerization temperature;The polybenzoxazine prepared from p-hydroxybenzaldehyde showed higher thermal stability and residual carbon rate,The 5%and 10% of the weight loss temperature were 355?and 410?,and the char yield at 800?is up to 52%.4?BOZ-DOPO was synthesized by using benzoxazine BOZ-4 and DOPO as raw materials.The structure of BOZ-DOPO precursors was characterized by Fourier transform infrared spectroscopy(FTIR)and LC-MS.The curing process of BOZ-DOPO precursors was studied by differential scanning calorimetry(DSC).The thermal properties of the BOZ-DOPO after curing were characterized by thermogravimetric analyzer(TGA).benzoxazine BOZ-DOPO have two peaks in the curing process,respectively,corresponding to the benzoxazine melting endothermic peak and the ring opening polymerization exothermic peak;With the increase of temperature,BOZ-DOPO started to take the polymerization of the ring opening,and the initial exothermic polymerization temperature is 170?,and the exothermic peak of BOZ-DOPO is observed at the temperature of 216?;The addition of DOPO group can improve the thermal properties of benzoxazine,compared with BOZ-4,BOZ-DOPO has a high thermal stability and residual carbon rate,the 5%and 10%of the weight loss temperature were 308?and 332?,and the char yield at 800? is up to 32%.