Side-chain motion of components in wood samples partially non-crystallized using NaOH-water solution

Wood samples (Picea jezoensis Carr.) were treated with solutions of aqueous NaOH (0-0.20 concentration fraction) and each treated samples evaluated by dynamic mechanical analyses (DMA). NaOH treatment was shown to affect the interactions between microfibrils and the surrounding matrix and, in particular, the dynamics of methylol groups in the microfibrils. The former is not dependent on the degree of crystallization but rather on the eluviation of the matrix. The latter depends on the degree of crystallization. Alkali treatment induces changes in the polymer domains as a result of matrix eluviation. This decreases the dynamics of methylol groups at NaOH concentrations less than 0.11. On the other hand, alkali treatment causes non-crystallization at concentrations greater than 0.11, which quantitatively increases the flexibility of methylol groups. Crystallinity decreased, and main-chain dynamics increased, following treatment with highly concentrated NaOH solutions. The dynamics of lignin also increased due to weakened interactions with microfibrils due to non-crystallization.