Scale of Homogeneous Mixing in Miscible Blends of Organosolv Lignin Esters with Poly(ε-caprolactone)

초록

Organosolv lignin (OSL) esters (side-chain carbon number, n = 3, 4, and 5) have been demonstrated to be miscible with poly(epsilon-caprolactone) (PCL) on a scale (20-30 nm) for detecting glass transition temperature (Tg) by differential scanning calorimetry (Polym. J. 2009, 41(3), 219-227). Further precise quantification of homogeneity was conducted for the OSL propionate (OSL-Pr, n = 3)/PCL and OSL butyrate (OSL-Bu, n = 4)/PCL blends by means of dynamic mechanical analysis (DMA) and solid-state nuclear magnetic resonance (NMR). DMA revealed a composition-dependent Tg for these blend samples, which implies the attainment of an intimate mixing of the ingredients on a scale of 15 nm. From the measurements of proton spin-lattice relaxation times (T1H) using solid-state NMR, the blends were estimated to be substantially homogeneous on a scale of 6 nm. But the equalization of the T1H for the components of OSL-Pr/PCL was not remarkable; that is, the constituents of OSL-Pr/PCL were relatively imperfectly miscible with each other.

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