Preparation And Properties Of Dielectric Cyanate Ester Adhesive With Excellent Flame Retardant

Cyanate ester resins(CEs)possess high-performances in terms of excellent dielectric characteristics,good adhesive properties,flame resistance,high glass transition temperatures,good thermal stability,and so on.Thus they have been treated as the key fundamental material in many cutting-edge fields in terms of structural aerospace composites,electrical i nformation storage,electronic insulation,and so on.However,the self-catalyzed reactive process of CEs needs a high temperature(>Tg)and a relatively long time,which are insupportable for most electronic parts and components.At the same time,unreact ed —OCN in polycyanurate is harmful to dielectric properties.On the other hand,CEs do not have suitable fireproof features,while fascinating flame retardancy of modern materials has been increasingly required.Therefore,the preparation of cyanate adhesive with favorable curing characteristic,outstanding dielectric characteristics and preeminent flame resistance has drawn lots of attentions in past decades.In this article,4,4'-(Hexafluoroiso-propylidene)Diphenol(BPAF),Bisphenol-AF epoxy resin(DGEBHF)and 10-(2,5-Dihydroxyphenyl)-10-H-9-oxa-10-phospha-phenantbrene-10-oxide(DOPO-HQ)were introduced to cure 2,2-Bis(4-cyanato-phenyl)propane(BACY),novel dielectric and flame retardant adhesive of BACY was obtained,and their properties were characterized in detail.A novel dielectric and flame retardant adhesive of BACY was prepared by employing BPAF as modifier.The curing efficiency of BPAF/BACY was evaluated by means of gelation time(GT),differential scanning calorimetry(DSC)and Fourier translation infrared spectroscopy analysis(FT-IR).It was found that the curing properties of BACY adhesive were obviously improved by BPAF.Besides,BPAF/BACY adhesive owned outstanding properties including excellent curing characteristics,high shear stre ngth,remarkable dielectric properties,high flame resistance and thermal stability in contrast to BACY,4,4'-(1-Methylethylidene)Bisphenol(BPA)/BACY and nonylphenol(No P)/BACY adhesive.Moreover,the properties of BPAF/BACY adhesive modified by different proportions of BPAF were studied in detail.It was shown that the optimal proportion of BPAF/BACY was 15/85 by mass,the dielectric constant(Dk)was 2.68,and tangent of dielectric loss angle(Df)was 0.0081,and the limited oxygen index(LOI)was 35.8%.DGEBHF was employed to cure BACY,and a dielectric and flexible adhesive was obtained.Its' properties were studied in detail and compared with Bisphenol-A epoxy resin(DGEBA)/BACY adhesive.The curing characteristics of DGEBHF/BACY was evaluated by GT,DSC and FT-IR.It was found that GT was decreased obviously as the concentration of DGEBHF increased.The properties of two kinds of adhesives were analyzed carefully,it was showed that cured DGEBHF/BACY adhesive was more outstanding than DGEBA/BACY at the same conditions.Moreover,the best concentration of DGEBHF/BACY was 15/85,and under that restriction,Dk = 2.95,Df = 0.0099,LOI = 26.1%.However,for DGEBA/BACY adhesive,Dk = 3.04,Df = 0.0105,LOI = 25.2% under same conditions.A novel phosphorus-containing,dielectric and flame retardant cyanate adhesive was prepared by using DOPO-HQ and BACY as materials.The curing behavior of DOPO-HQ/BACY adhesive was analyzed by GT,DSC and FTIR.It was revealed that the curing temperature and time were evidently decreased when DOPO-HQ was employed.According to DEA,dielectric properties was improved by DOPO-HQ,Dk = 2.69 and Df = 0.007 when DOPO-HQ/BACY = 10/90 by mass.The results evaluated by LOI and UL-94 presented that flame resistance of copolymer was improved by DOPO-HQ,LOI was 29.7% and UL-94 was V-1 when the content of DOPO-HQ/BACY was 5/95,LOI was 33.1% and UL-94 was V-0 when the content was 10/90 by mass.Finally,the mechanical and thermal properties of DOPO-HQ/BACY were characterized in detail.