Preparation And Properties Of Benzoxazine Based On 2-Allyl Phenol/4,4’- Diaminodiphenyl Sulfone

Benzoxazines, which can be synthesized from amines, phenols and formaldehyde, are a class of nitrogen- and oxygen-containing heterocyclic compounds, and can be polymerized into polybenzoxazines with excellent combination properties. Thus, they are widely used in aerospace, electronic and automotive industry and other fields. As the development of science and technology, the demands on properties of polybenzoxaine are hsrah. In this paper, a new type of benzoxazines is synthesized, which contains rigid sulfone and active allyl groups, and the resulted polybenzoxazine possesses excellent properties, such as high hardness, high glass transition temperature, and good thermal stability. In addition, a siloxane was introduced into benzoxazine molecule, and the performance of the benzoxazine was improved. The main research works are as follows:(1) The 3,3’-phenysulfuryl-bis(3,4-dihydro-8-allyl-2H-1,3-benzoxazine)(o AP-dds) was synthesized via a solution method using o-allyl-phenol, 4,4’-diamino diphenyl sulfone and formaldehyde. The chemical structure of o AP-dds was confirmed by Fourier transform infrared(FTIR) spectroscopy, 1H and 13 C nuclear magnetic resonance(NMR) spectroscopy, and elemental analysis. The thermally activated polymerization behaviors of o AP-dds were studied by FTIR, solid-state 13 C NMR, and differential scanning calorimetry(DSC). The dynamic mechanical properties of the polybenzoxazine(Po AP-dds) were studied by dynamic mechanical analysis(DMA). The DSC results show that only one exothermic peak is shown on the DSC curve, and the polymerization peak temperature is 281°C and the exothermic heat is 157.5J/g. FTIR spectra show that the intensities of the peaks related to the oxazine ring decrease gradually and some absorption peaks disappear in the polymerization reaction. At the same time, the intensities of the peaks related to allylic groups also decrease. It is show that both oxazine ring and allylic group are involved in the polymerization. The storage modulus of the Po AP-dds is 3.18 GPa at 25°C, and the glass transition temperature of the Po AP-dds is 193°C. Thermal degradation behaviors of Po AP-dds were studied by thermogravimetry(TG) and FTIR, and the char yield is 40.0% at 800°C in nitrogen.(2) In inert atmosphere, the hydrosilylation of o AP-dds was performed using 1,1,3,3-tetra-methyldisiloxane(TMDS) in the presence of platinium(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex solution in xylene(approximately 2% Pt). The structure of the hydrosilylation product(PTMDS-PP-dds) was confirmed by FTIR and NMR. The curing behavior of the PTMDS-PP-dds was studied by DSC, and the dynamic mechanical properties and thermal stabilities of CR-PTMDS-PP-dds were studied by DMA and TG, respectively. The DSC results show that the polymerization peak temperature is 274°C and the exothermic heat is 93.6J/g, indicating that the peak temperature is close to that of the o AP-dds and the exothermic heat is lower than that of o AP-dds. The storage modulus of CR-PTMDS-PP-dds is 2.42 GPa which is lower than that of Po AP-dds.The glass transition temperature of CR-PTMDS-PP-dds is 238°C, which is higher than that of Po AP-dds. The char yield of CR-PTMDS-PP-dds is 34.1% at 800°C in nitrogen.(3) To improve the properties of Po AP-dds, o AP-dds/polysulfone(PSU) blends were prepared. The curing behaviors of o AP-dds/PSU were investigated using DSC, and the morphology of the Po AP-dds/PSU blends was observed using scanning electron microscopy(SEM). The dynamic mechanical properties of Po AP-dds/PSU blends were studied by DMA. The results show that exothermic peak temperature of o AP-dds/PSU blends are lower than that of Po AP-dds and the storage modulus of the Po AP-dds/PSU blends are lower than that of Po AP-dds. The SEM results show that the compatibility of Po AP-dds and PSU is poor.