回用过程对二次纤维聚集态结构和成纸性能的影响

The effect of recycling process on aggregation state and physical properties of eucalyptus cellulose fiber

采用XRD、FT-IR以及NMR研究了桉木纤维经多次回用后聚集态结构的变化规律,进一步研究了聚集态结构改变对成纸性能的影响。结果表明:随着回用次数的增加,纤维素的结晶度增大,002面微晶尺寸随着回用次数的增加而增加,红外结晶指数增大并且和结晶度有很好的一致性;而NMR研究计算得到的结晶度明显小于XRD计算得到的结晶度,可能对于13CNMR,只有晶区内的部分才看做结晶区;回用后抗张指数和耐破指数减少,经过5次回用后抗张指数和耐破指数分别下降了61.61%、10.57%,撕裂指数先增大后减小,5次回用后,下降了33.07%。由于回用导致纤维聚集态结构中的晶区和非晶区的比例发生了变化,这种聚集态结构的变化最终导致了成纸性能的衰变。

The changing regularity of the aggregation state of eucalyptus fiber during recycling was studied by XRD, FT-IR, and NMR. Furthermore, the influence of the state of aggregation on physical properties were studied. The results show that with increased numbers of recycling cycles, the crystallinity of cellulose increases, the average width of crystallite in 002 also increases. Infrared crystallization index and the crystallinity calculated by XRD have very good consistency. The crystallinity calculated by NMR is smaller than that by XRD, which maybe because only the part in the crystallites can appear as crystalline by NMR spectra. Tensile index and burst index decreased with the increase of times of the reuse, tensile index tall by 61.61% and burst index fall by 10.57%, tearing index first increases then decreases in reuse process, and fall by 33.07% after five times of reuse. The change in ratio of crystalline region to amorphous region can lead to the decay of paper physical performance.