Research On The Systhesis And Properties Of Benzoxazine Resins

Benzoxazine resin is a kind of heterocycle thermosetting resin,which carries on the excellent properties of phenolic,such as thermal properties,flame resistence and eletrical performance.and other comprehensive performance,and in some areas it is expected to replace traditional phenolic resin,polyster,epoxy,cyanate ester,polyimide and other materials.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.Due to the benzoxazine has the shortcoming of high glass temperature and high brittleness,for its shortcoming,In this papper,a series of low glass temperature benzoxazine was synthesized by using the flexible molecule design of benzoxazine,and continue to study through modification.The main results of this paper are as follows:?1?Allyl-Benzoxazine?BZ?withdoublebondwassythesizedbybutyl parahydroxy-benzoate formaldehyde,and allyl amine,then phosphorous-containing benzoxazine?DOPO-BZ?is obtained by Allyl-Benzoxazine BZ and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide?DOPO?.The structures of BZ and DOPO-BZ are characterizedusingFouriertransforminfraredspectroscopy?FTIR?,liquid chromatograph-mass spectroscopy?LC-MS?,nuclear magnetic resonance?NMR?,and the curing behavior of the products and the structure of the polymer are characterized by differential scanning calorimetry?DSC?.The results reveal that BZ shows a two-step curing at high temperature,namely ring-opening raction of BZ and polrmerization of double bond afterwards;DOPO-BZ presents a one-step curing,introduction of DOPO exerts a remarkable influence on the curing progress.Both of the polymers PBZ and P?DOPO-BZ?do not exist a glass transition temperature?Tg?.TGA shows that the thermostability of PBZ is significantly improved with the introduction of huge rigid phosphorous-containing DOPO,the char yield?Y_C?increase about 15%at 800°C.?2?The synthesis of benzoxazine with double long aliphatic chain was synthesized by moleculardesign.TheNonyl-phenol,longaliphaticchain?Dodecyl-Amine,Tetradecyl-amine,1-Hexadecyl-amine and Octadecyl-amine?and paraformaldehyde was synthesized double long aliphatic chain benzoxazine with solventless.The structures of product was characterized by ¹H nuclear magnetic resonance?¹H-NMR?and Fourier transform infrared spectroscopy?FT-IR?.The curing behavior of benzoxazine monomers at different curing temperature were monitored by DSC and FT-IR.The initial temperature of oxazine ring opening was aroud 180°C,and the peak temperature of curing reaction was ahout 241-261°C.The termal curing reaction completes at 240°C.At the same time,DSC was tested the thermal properties of benzoxazine,the results showed that polybenzoxazine has low temperature of the glass transition temperature?Tg?,Tg were in the range-39°C to-19°C.Thermal properties of the polybenzoxazines were studied by thermogravimetric analysis?TGA?,found that the PBZ-C₁₂?PBZ-C₁₄?PBZ-C₁₆ and PBZ-C₁₈ had high maximum decomposition temperature about 450⁰C,and char yield?Yc?was 15.09%?14.39%?12.09%?10.51%respectively,it is showed that they have good thermal stability.Through the contact angle test,it is found that the double long aliphatic chain benzoxazine has hydrophobic property,and with the increase of the aliphatic chain,the contact angle increases and the surface energy decreases.?3?Polyether-amine benzoxazine?A-BZ?was obtained with Nonyl-phenol,polyether amine D-400 and paraformaldehyde without solvent.The structures of A-BZ was characterized by ¹H nuclear magnetic resonance?¹H-NMR?and Fourier transform infrared spectroscopy?FT-IR?.The A-BZ and epoxy resin?E-44?according to the mass ratio of 1?0.9?1?1?1?1.1?1?1.2?1?1.3 blends,after heating polymerization obtain the PA-BZ₁,PA-BZ₂,PA-BZ₃,PA-BZ₄,PA-BZ₅.According to the DMA test PA-BZ₁,PA-BZ₂,PA-BZ₃,PA-BZ₄,PA-BZ₅ found:at below zero centigrade,the storage modulus reached as high as2520MPa,but when 25°C,storage modulus reach the maximum value about1.60GPa.The glass transition temperature?Tg?,Tg were in the range 55°C to 61°C.The curing process of blends ploymer were discussed by DSC,found that with the content of epoxy resin?E-44?decreased,the maximum curing ring opening temperature was increased.Thermal properties of the polybenzoxazines were studied by thermogravimetric analysis?TGA?,found that PA-BZ?PA-BZ₁?PA-BZ₂?PA-BZ₃?PA-BZ₄?PA-BZ₅ had high maximum decomposition temperature about 450⁰C,and char yield?Yc?were 9.76%?6.95%?6.99%?7.11%?7.24%?9.17%,it is showed that they have good thermal stability.