Note on the glass transition temperature of Poly(vinylphenol)

Critical overview of literature data on the glass transition temperature Tg of poly(4-vinylphenol) PVPh revealed a large scatter of values ranging between 53 and 194 °C, which can only partially be attributed to molecular-mass effect. The reason could be seen in residual moisture and/or solvent in samples subjected to insufficient or even no drying. Based on selected two thirds of literature data, a regression equation is proposed for the dependence of Tg on 1/Mn. Two samples of commercial PVPh (Mn 11,500; Mw 22,100) and (Mn 19,700; Mw 40,900) were studied by DSC, ATR-FTIR, and SEC methods. A procedure of preparing well defined samples is proposed: PVPh vacuum-dried at 140 °C for 24 h is dissolved in tetrahydrofuran and precipitated in hexane. The precipitate is vacuum-dried at 40 °C for 24 h, weighed into a pierced DSC pan. After final vacuum drying at 140 °C for 24 h, the sample is analyzed. The PVPh samples treated in this way showed Tg of 175.0 °C and 179.6 °C, respectively.