羧甲基化取代度和干燥温度对二次纤维角质化的影响

Effects of Carboxymethyl Substitution Degree and Drying Temperature on the Hornification of Secondary Fiber

通过改变羧甲基取代度和干燥温度,研究了羧甲基化处理和干燥温度与二次纤维角质化的关系。结果表明:羧甲基化后浆料的润涨性能得到改善,保水值和羧基含量都高于原浆,但是保水值和羧基含量并不是随着取代度的增加而增加,在低温干燥范围内,羧甲基对角质化的影响起到主要作用,低取代度浆料的增强效果最好。60℃的干燥温度下,低取代度浆料抄造的纸页抗张指数相对原浆提高了148.89%,80℃的干燥温度下,低取代度浆料的抗张指数相对于原浆提高了28.83%;洗涤后浆料的强度性能得到明显提高,可能和后洗涤使得纸页成型处于离子化状态,从而极大的缓解了二次纤维的衰变有关;2次抄纸后低取代度浆料相对于2次抄纸后的原浆抗张、耐破和撕裂指数增加了28.82%,124.07%,55.03%,表明羧甲基化处理的浆料能有效缓解纤维角质化;不同取代度浆料的XRD谱图表明羧甲基化处理并没有改变纤维的结晶形态,只是减小了结晶度,有利于再润胀。

Through the change of carboxymethyl substitution degree and the drying temperature, the relationship of carboxymethylation, drying temperature and honification of secondary fiber was studied. The results show that the swelling ability and the degree of honification decreased in these types of modified cellulosic fibre. But water retention value and carboxyl content didn＇ t increase with growing substitution degree of carboxymethylation. Under low drying temperature, carboxymethylation was found to play a significant role during honification. Drying at 60%, tensile index of low substitution degree sheets increased by 148.89% , drying at 80℃ , tensile index of low substitu- tion degree sheets increased by 28.83% as compared to the virgin pulp. After washing the strength performance improved obviously relative to the virgin pulp, which may be related to ionization state of carboxyl group. Tensile index, burst index, and tearing index of low substitution degree sheets increased by 28.82% , 124.07% ,55.03% , showing that the processing of carboxymethylation can effectively relieve fiber hornification; Fiber crystal morphology did＇ t change during carboxymethylation, but the crystallinity reduced,which is favorable for fiber reswelling.