Preparation And Application Of Polycyclic Phosphonate Of 4-tert-butylphenol-formaldehyde Resin

Flame retardants(FRs) can improve ?re performance of polymers to meet the requirement in electrical engineering and the electronic, transportation, and building industries. Traditionally, halogenated compounds are used as economic and effective FRs. However, their applications are limited because of the toxic, corrosive, and halogenated gases along with the combustion. In recent studies, organophosphorus flame retardants are proved to be notably effective in extending flame retardancy for polymers. Their combustion products are innocuous or less toxic to the environment, and their dosage is less than that of inorganic FRs in polymer. Based on this, a novel polycyclic phosphonate phenolic resin was synthesized and utilized to modify epoxy resin and unsaturated polyester.4-Tert-butylphenol-formaldehyde resin was firstly synthesized from p-tert-butylphenol and formaldehyde with the catalyst of Amerlyst-15. Then, a novel polycyclic phosphonate resin was successfully synthesized by reacting phosphoric dichloride with p-substituted phenol formaldehyde resins using the high speed dispersion homogenizer. The results indicated that using high speed dispersion homogenizer as the reactor can not only shorten the reaction time, but also accelerate the cyclizative condensation in good yield. The structural investigation confirmed the formation of polycyclic phosphonate oligomers by Fourier transform infrared spectroscopy(FTIR) and nuclear magnetic resonance spectroscopy(1H NMR, 31 P NMR).The phosphorus content of polycyclic phosphonate of 4-tert-butylphenol-formaldehyde resin was determined by ammonium phosphomolybdate precipitation. The highest phosphorus yield of the product was obtained when the phosphoric dichloride reacted with p-substituted phenol formaldehyde resins under ice water bath condition. The optimum ratio of p-tert-butylphenol and formaldehyde for synthesizing p-substituted phenol formaldehyde resins is 1:0.8. The resulting polycyclic phosphonate of 4-tert-butylphenol-formaldehyde resin was further used to modify epoxy resin and unsaturated polyester.The demands for ?ame retardant epoxy resins(EP) and unsaturated polyesters(UPR) are extremely strong because of their wide application in adhesives, coatings and advanced composites in aerospace and electronic industries. The most effective way to improve their ?ame retardancy is to add flame retardant. In our work, the thermal stability and degradation behavior of the modified EP and modified UPR were measured with thermal gravimetric analysis(TGA) measurements both in N2 and air atmosphere. Combined with the LOI data analysis, we come to the conclusion that EP shows best thermal stability with 15 wt% of polycyclic phosphonate of 4-tert-butylphenol-formaldehyde resin; UPR shows best thermal stability with 10 wt% of polycyclic phosphonate of 4-tert-butylphenol-formaldehyde resin.Phosphorus-containing compounds often degrade at relative low temperature due to the weak bonds of phosphonate. They form a surface layer of char rather than yielding CO or CO2 during the process of decomposition. The carbon layer can hinder the transfer of mass and heat during a fire, which can provide polymer composites with flame-retardant property.