粉丹竹SCMP木素结构及其在漂白和老化时的变化

Lignin Structure of Bamboo Bambusa chungii SCMP and Its Change During Bleaching and Aging

为了探寻化学机械浆可漂性和白度稳定性差的原因,采用核磁共振波谱分别对粉丹竹磺化化学机械浆(SCMP)及其漂白浆、漂后老化浆中的木素结构进行了分析.结果表明:SCMP中的对羟苯基型木素结构含量较高,紫丁香基结构的酚羟基主要以醚键形式存在,在木素结构中每100个苯环中有20个为缩合结构,导致粉丹竹SCMP的可漂性差;在过氧化氢漂白和漂白浆老化过程中,木素样品中总酚羟基含量分别减少了30.7%和38.4%,羧基的含量分别增加了53.2%和55.3%;木素结构中烷基芳基醚键和α-烷基醚键发生了断裂,γ-烷基醚键则比较稳定;同时木素侧链发生断裂,引入共轭COOR基团,如Ar-CHO和Ar-COOH等,从而导致漂白浆白度较低和稳定性较差.

In order to expose the causes of the poor bleachability and brightness stability of the sulfonated chemimachenical pulp（SCMP） from bamboo Bambusa chungii,NMR spectroscopy was used to analyze the structures of lignin samples of SCMP,bleached SCMP（BSCMP） and aged BSCMP.The results show that the SCMP of bamboo Bambusa chungii is of poor bleachability not only because the SCMP lignin has a high content of p-hydroxyl-phenyl unit,the phenolic hydroxyl groups of syringyl unit in the SCMP mainly exist in the form of ether bond,but also because there are 20 condensed units in per 100 aromatic units in the lignin.Moreover,it is found that,during the bleaching and the aging,the total contents of phenolic hydroxyl groups in lignin samples decrease by 30.7% and 38.4%,respectively,while those of carboxylic hydroxyl groups increase respectively by 53.2% and 55.3%,that Alk-O-Arand α-OAlk ether bonds in lignin samples are cleaved,while γ-OAlk ether bond is stable,and that the linkage of the side chain in lignin samples is simultaneously cleaved to form conjugated bonds such as Ar-CHO and Ar-COOH,thus reducing the brightness and the brightness stability of the pulp.