Abstract:
p-Propargyloxyphenyl side groups were grafted to the backbone of novolac-type cyanate ester (NCE) by diazo coupling reaction to obtain a new novolac resin (PPANC) with cyanate ester and propargyloxyphenyl side groups. The resins were characterized by
1H-NMR, FT-IR and UV-Vis. The thermal cure reaction of PPANC was studied by differential scanning calorimetry (DSC) and
in situ monitoring Fourier-transition infrared. Furthermore, quartz fabrics (QF) reinforced PPANC composites were also molded using hot-press process. The thermal stability of the resins and the mechanical and dielectric properties of the composites were also studied. The results showed that the propargyloxyphenyl side groups in the prepared PPANC could promote the curing reaction of cyanate ester groups attached on NCE as facilitated by the acidic hydrogen of the terminal alkynyl groups. The curing temperature of the NCE resins decreased with the introduction of the propargyloxyphenyl groups, and further decreased with increase of the propargyloxyphenyl content. The thermal stability of the cured PPANC resins in nitrogen decreased with increase of the propargyloxyphenyl content. However, the temperature at 5% mass loss of the cured PPANC resins retained higher than 400 °C. The PPANC resin with a moderate propargyloxyphenyl content was reinforced by QF to form the composite which showed higher mechanical properties and lower dielectric properties than those of the composites of NCE and PPANC matrices. The flexural strength and modulus, and interlayer shear strength (
SILS) of the QF/PPANC composite could reach about 612 MPa, 26 GPa and 52 MPa, respectively. The glass transition temperature of the QF/PPANC composites and QF/NCE composite were higher than 350 ℃. The dielectric constant and dissipation of the QF/PPANC composites were lower than 3.6 and 0.004, respectively. These values are lower than those of the QF/NCE composite in the frequency range of 1~10
6 Hz.