Synthesis And Properties Of Phthalonitrile Blends

In this paper, a series of phthalonitriles were successfully synthesized via the nucleophilic displacement reaction in which the monomers were classified into three categories: bisphenol-based phthalonitriles prepared from bisphenol(bisphenol A, bisphenol Af, bisphenol Ap and bisphenol Z) and 4-nitrophthalonitrile, triphenol-based phthalonitriles prepared from triphenol and 4-nitrophthalonitrile, and bisphenol-based phthalonitriles containing multiple ether linkages prepared from bisphenol(bisphenol A and bisphenol Af),4,4'-difluoro diphenylmethanone and 4-nitrophthalonitrile. The corresponding phthalonitriles above were named BPAPh, BPAfPh, BPApPh, BPZPh, TPPh, CMEBPAPh and CMEBPAfPh and the structures of products were confirmed by Fourier transform infrared (FT-IR) and 1H nuclear magnetic resonance(1H NMR). A series of phthalonitrile blends were prepared from 4-(4-aminophenoxy) phthalonitrile (APNPh) and the above phthalonitriles by directly powder-mixing, in which the APNPh was used as catalyst. Various kinds of phthalonitrile/benzoxazine blends were obtained by mixing phthalonitriles and benzoxazines in melt state. Differential scanning calorimetry (DSC) was used to study their curing behaviors, thermogravimetric analysis (TGA) and dynamic mechanical thermal analysis(DMA) were adopted to study their thermal stability and thermomechanical properties after the blends were cured. Moreover, FT-IR, DMA and TGA were employed to investigate the influence of ?-ray on anti-radiation performance.For phthalonitrile blends, the thermal properties were greatly affected by the structure of monomer and curing procedure. When the post-cured temperature was 280 ?,the glass transition temperature (Tg) of BPAPh,BPAfPh,BPApPh and BPZPh were 311,307, 314 and 315 ?, respectively. When the post-cured temperature was 350 ?, the Tg of BPAfPh and BPApPh were 358 and 369 ?, the Tg of BPAPh and BPZPh were going up to the higher temperature than 380 ?. The reason is mainly ascribed to the hindrance of the strong polar and rigid group on the formation of the more compact cross-linked network at the higher temperature. Owning to the existence of C-F bond, the bisphenol Af-based phthalonitrile resin displayed the highest thermal stability. With the increase of functional group, the Tg was higher than 380 ? even though the post-cured temperature was 280 ?, the reason is due to the higher cross-linked network density. The incorporation of flexible ether linkages have improved their processabilities and mechanical properties while maintained good thermal properties. Under the 100 kGy dosages of the y-ray, the structures, thermal stabilities and thermomechanical properties have not showed significant changes.The phthalonitrile/benzoxazine blends was chosen as the objects in order to investigate the effects of blends proportion and the type of phthalonitrile on the thermal properties of blends. The results showed that the addition of phthalonitrile have dramatically increased the Tg and thermal stability and, the thermal properties increased with the rise of phthalonitrile content. It is also found that the Tg and thermal stability of the resins are related to the chain lengt of the phthalonitrile, the types of side groups linked to the main chain and the number of functional group. Among these influencing factors, the number of functional group ranked the highest. When the mass fraction of TPPh was 0, 10, 20 and 30%, the Tg were 164, 201,258 and 278 ?, T5 were 336, 363, 381 and 395 ?, Yc were 32.3, 52.4, 59.2 and 65.3,respectively.