华南湿地松EMCC制浆过程中木素结构的变化(英文)

Structural Changes of Lignin During EMCC Pulping of Pinus Elliottii in Southern China

以华南湿地松为原料制备卡伯值为 16～ 32的常规硫酸盐浆和深化脱木素的改良硫酸盐 (EMCC)浆 .从木材和纸浆中分离木素 ,利用13C_NMR和31P_NMR技术表征木素样品的结构 ,研究制浆过程中木素结构的变化 .结果表明 ,从木材和纸浆中分离出来的木素结构是不同的 ;制浆方法影响纸浆残余木素的结构特征 ,包括脂肪羟基、酚羟基和羧基含量 ,β_O_4结构和缩合结构含量 .对常规硫酸盐浆和改良硫酸盐浆 ,卡伯值较低的纸浆残余木素脂肪羟基和 β_O_4结构含量较低 ,酚羟基、羧基和缩合结构含量较高 .当卡伯值相同时 ,EMCC木素的脂肪羟基和酚羟基含量较低 ,β_O_4结构和羧基含量较高 。

Conventional and simulated EMCC  kraft pulps with Kappa numbers from 16 to 32 were produced from Pinus elliottii wood chips in southern China. Lignins from the wood and these pulps were isolated and structurally characterized by using quantitative 13 C_NMR and 31 P_NMR spectroscopy. This study examined the structural changes in lignin of the wood and pulp samples. Studies indicated that lignins from wood and various Kappa pulps were structurally different. And pulping procedures influenced the structural features of residual lignin of pulps including the content of aliphatic and phenolic hydroxyl groups, β_O_4 structures, carboxylic acid groups, and condensed lignin units. For both conventional and EMCC  pulps, the residual lignin with lower Kappa numbers had lower contents of aliphatic hydroxyl groups and β_O_4 structures and higher contents of carboxylic acid groups, phenolic OH, and condensed structures. Comparison between conventional and EMCC  residual lignins with similar Kappa numbers indicated that EMCC  lignins had a lower content of aliphatic OH and phenolic OH groups, a higher content of β_O_4 structures and carboxylic OH groups, and a comparable content of condensed structures.