Synthesis And Characterization Of Adamantane-Containing High Performance Resins

Two novel adamantane-containing epoxy compound 1,3-bis (4-hydroxyphenyl) adamantane diglycidyl ether (DGEBAD) and phthalonitrile compound 1,3-bis (4-hydroxyphenyl) adamantane bisphthalonitrile (ABPh) were synthesized respectively from the 1,3-bis (4-hydroxyphenyl) adamantane (BHPA) and epichlorohydrin (ECH) or 4-nitrophthalonitrile, which were then thermally cured with 4,4’-diaminodiphenyl methane (DDM). The two structures were confirmed by FT-IR and NMR spectra, MS and EA. The rates of production were respectively 53.6% and 49.1%.The epoxy value characterized by hydrochloric-acetone titration method was 0.39-0.41 and the rheology property was also characterized by rotational rheometer. The curing process confirmed by DSC method was 100℃/1h+150℃/3h+180℃/2h. Dynamic thermal-mechanical analysis (DMA) data showed that Tg values of the cured DGEBAD/DDM resin were increased compared with the cured E51/DDM resin because of the rigid adamantyl group was incorporated into the backbones. According to the thermogravimetric analysis (TGA), the DGEBAD/DDM system exhibited higer thermal stability, and the water absorption of the DGEBAD/DDM system was decreased by 47.4% compared with the DGEBA/DDM system. Moreover, the dielectric constant of the DGEBAD/DDM was 4.17 when f=10MHz, and was decreased by 12.4% compared with the DGEBA/DDM.The melting point of the adamantane-containing bisphthalonitrile resin characterized by DSC analysis was 188.4℃, differed by 50-60℃ from the initial curing reaction temperature. Therefore the processing window was enlarged when introduced the adamantyl group into backbones. The cure reaction achieved with dramatically accelerated with 3wt% of DDM and got gelation in 11mins. The DMA and TGA characterization of the cured resin showed excellent thermal-mechanical property with Tg=363℃ and thermal-oxidation stability with weight retention of 95% T5%=490℃, and the char yield of the cured resin was 71.2% at 1000℃. ABPh resin and GFRP composite was prepared by using the combined process of wet method and dry method. The Tg of the result laminate can reach 405℃ and the water absorption is only 1.2%. The ABPh/glass fiber composites possessed excellent chemical resistance. And the cured ABPh resins carbonized at different temperatures exhibited good electrical conductivity because of the conjugated macrocyclic structure.Combined with the characterization results of the DGEBAD resin and the ABPh resin, we have found that the properties of the cured resins were dramatically enhanced because of the introduction of the adamantane group. It is mainly because the adamantyl-group is a symmetrically and rigidly aliphatic cyclic alkane.