Polyvinyl Butyral with Different Acetalization Degrees: Synthesis and Solubility Parameters

In the research described here polyvinyl butyral (PVB) samples with mass acetalization degrees of 84.4%, 70.4%, 58.8%, 40.3% and number-average molecular weights (Mn) of 29300 ∼ 36100 g mol−1 were synthesized using p-toluenesulfonic acid as a catalyst. The PVB samples were characterized by gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and differential thermogravimetric analysis (DTGA). Furthermore, the solubility parameters of the PVB with different acetalization degrees were determined by the Hansen Solubility Parameter in Practice (HSPiP) software, turbidimetric titration and group contribution methods. The results showed that the total solubility parameter (δt) and two of the solubility parameter components (polar solubility parameter δp and hydrogen bonding solubility parameter δh) increased linearly with the decrease of the acetalization degree of the PVB, while the change of δd (dispersion solubility parameter) was not obvious. The correlation between the solubility parameters and acetalization degree of PVB was established. The solubility parameters obtained in this paper can be used to predict the affinity of PVB with solvents or additives, which is convenient for solvent selection and formulation design.