Studies on mechanism of phase transformation of carboxylated poly(phenylene oxide) and polystyrene blend by Fourier transform infrared spectrometry

The thermally-induced phase transformation behaviors of carboxylated poly(phenylene oxide)(CPPO)/polystyrene(PS), and PPO/PS blends were studied by using a difference-spectrum method of Fourier Transform Infrared Spectrometry (FTIR). The difference intensities(μ) and vibration frequency shifts(Δν) of the characteristic infrared absorption bands in both CPPO/PS and PPO/PS increased with raising temperature. A linear temperature dependence in the band frequency vs. temperature plots was observed for PPO/PS system, while three slopes corresponding to the three temperature ranges: below 190°C, 190°–215°C, and above 220°C, appeared in frequency-temperature curves for the CPPO/PS blend. These temperature ranges are consistent with the UCST area, the miscible area and the LCST area obtained by our previous works. The mechanism of phase transformation of CPPO/PS was discussed.