RESINAS EPOXI Y BENZOXAZINAS FOSFORADAS Y SILILADAS RETARDANTES A LA LLAMA

M. SPONTÓN

Universitat Rovira I Virgili

Lugar: Tarragona; Año: 2009 p. 205

978-84-691-9480-5

LIBRO PUBLICADO A PARTIR DE LOS CONTENIDOS DE LA TESIS DOCTORAL - During the last decades much work has been concentrated on developing new flame-retardant materials with high performance for applications such as, electronic and aerospace industries. These must exhibit high glass transition temperature, low internal stress, good adhesion, low constant dielectric, low toxicity and high flame retardancy. The bromine-containing epoxy, are found among the most used polymers in the manufacture of electronic devices. However, the bromine-containing advanced epoxy resin release hydrogen bromide, dibenzo-p-dioxin and dibenzo-furan during combustion, which cause corrosion and toxicity. The concept of sustainable development requires fire retardant technologies to be developed, which have minimum impact on health and the environment. The incorporation of phosphorus or silicon functionality in the polymeric structure is recognized as one of the most efficient ways to obtain an environmentally friendly flame retardant system. The general objective of this work has been the development of new fire retardant thermosettings systems, keeping the material properties and environmentally friendly, The goals is to improve the good properties of some standard materials, phenolic and epoxy resins, but introducing the non inflammability character by means of new ignifugation systems, alternative to the classic halogenated systems. We propose the synthesis and characterization of new types of flame retardant systems - phosphorus- and/or silicon containing in the structure of epoxy resins and polybenzoxazines and we evaluated their properties. We synthesized the diglycidyl ether of (2,5-dihydroxyphenyl)diphenyl phosphine oxide (Gly-P) and we investigated its thermal behaviour and reactivity. We examined the incorporation of different amounts of phosphorus into the epoxy resin by curing the Gly-P/DGEBA system with DDM. Also, phosphorus and silicon-containing epoxy resins were prepared from (2,5-dihydroxyphenyl) diphenyl phosphine oxide (Gly-P), diglycidyloxy methylphenyl silane (Gly-Si) and 1,4-bis(glycidyloxidimethyl silyl)-benzene (BGDMSB) as epoxy monomers and diaminodiphenylmethane (DDM) , bis(3-aminophenyl)methyl phosphine oxide (BAMPO) and bis(4-aminophenoxy)dimethyl silane (APDS) as curing agents. Epoxy resins with different phosphorus and silicon content were obtained. Their thermal, dynamic mechanical and flame retardant properties were evaluated. The high Limiting oxygen index (LOI) values confirmed that epoxy resins heteroatom-containing are effective flame retardants, but a synergistic efficiency of phosphorus and silicon on flame retardation was not observed.Moreover, in this work, a the phosphoru was incorporated into the structure of the benzoxazine in the form of phenylphosphine oxide thus a diamine-based benzoxazine was obtained using a three-step synthetic method from the aromatic diamine and 2-hydroxybenzaldehyde as starting materials. Curing kinetics was investigated by non-isothermal differential scanning calorimetry (DSC) at different heating rates and by FTIR spectroscopy. The curing of mixtures of bis(m-aminophenyl)methylphosphine oxide based benzoxazine and glycidylether or benzoxazine of bisphenol A has been studied. In all samples the molar ratio of benzoxazine monomers or the benzoxazine-epoxy system was varied to achieve different phosphorus content. The phosphorus-containing polybenzoxazines have been characterized by dynamic mechanical and thermogravimetric analysis. Limiting oxygen index values indicate good flame retardant properties. Another alternative to incorporate phosphorus or silicon in benzoxazine-epoxy systems have been by copolymerisation of the benzoxazine of bisfenol A with Gly-P and Gly-Si. In all samples the molar ratio of the benzoxazine-epoxy system was varied to achieve different phosphorus or silicon content. Their thermal, dynamomechanical and flame retardant properties were evaluated. The high limiting oxygen index values confirmed that the phosphorus-containing benzoxazine-epoxy resins are effective flame retardants, but no efficiency of silicon on flame retardation was observed.