Preparation And Characterization On Thermal Properties Of Based On The Bifunctional Benzoxazine Resin

As a novel phenolic type thermoset, polybenzoxazine have not only the advantageousproperties of conventional phenolic resins but also other interesting advantages such as heatresistance, superior electronic properties, low water absorption, low surface energy andexcellent dimensional stability. The disadvantages of the typical polybenzoxazines are thehigh temperature needed for complete curing, the low crosslinking density and the brittlenessof the cured materials that can sometimes limit their potential applications.In this paper, being improving the crosslinking density, heat resistance and the flameretardancy, the group of polymerizable, rigid or phosphorus structure were incorporatedinto benzoxazines.1. Nine benzoxazines with a methoxy, allyl or DOPO structure, respectively, weresuccessfully synthesized by a one-pot procedure. using the4-methoxy phenol,2-allyl-phenol, ortho-diallyl bisphenol A,10-(2,5-Dihydroxyphenyl)-10H-9-oxa-10-phospha-phenantbrene-10-oxide(ODOPB) as a source of phenol,4,4’-Diaminodiphenyl-methane,4,4’-diaminodiphenylsulfone,4,4’-diamino diphenylether, methylamine as as a sourceof primary amine, paraformaldehyde as a source of aldehyde. The novel materials werecharacterized by FTIR and1H NMR.2. Nine corresponding polybenzoxazine were prepared. Their thermal stability were studiedusing the TG analysis. The results show that: The introduction of allyl can effectivelyincrease the cross-linking density of the cured materials; The higher the content of allyl inbenzoxazines were, the better thermal stability of benzoxazine resins were; Td5%ofPBoz-07and PBoz-05were as high as398℃,384℃; when phenol sources were thesame, the thermal stability of benzoxazine resins is4,4’-diaminod phenylsulfone≥4,4’-Diaminodiphenylmethane>4,4’-diaminodiphenylether; With4,4’-diaminodiphenyl-ether as a source of primary amine, thermal stability of benzoxazine resins is ODOPB>4-methoxy phenol≈2-allylphenol> ortho-diallyl bisphenol A.3. The curing behavior of benzoxazine was investigated by FT-IR and DSC using Boz-01as an example; The results showed that, after curing at100℃/1h、120/1h、140℃/1h、160℃/1h、180℃/1h、200℃/1h、220℃/1h、240℃/1h, benzoxazine polymerizdcompletely.Thermal stability of benzoxazine resins in nitrogen atmosphere or air atmospherewere tested by TG. The TG curve showed the thermal stability under air atmosphere of PBoz-01was good. Td5%of P Boz-01under air atmosphere and nitrogen atmospherewere346℃and342℃, respectively.4. Two kinds of Benzoxazine/epoxy resin E-51composite: Boz-01/epoxy resin E-51composite and ODP-Boz/epoxy resin E-51composite were prepared. Effects of the contentof epoxy resin on the thermal stability of composite resin were investigated. The results show:With the content of epoxy resin increasing, the thermal stability of composite resins increasefirst and then decrease; the optimum content of epoxy resin are different for differentcomposite resins; the optimum content of epoxy resin of Boz-01/epoxy resin E-51compositeand ODP-Boz/epoxy resin E-51composite were50%and20%, respectively.