微波预处理对桉木化机浆性能的影响

Effect of Microwave Pretreatment on Properties of Eucalyptus Chemical Mechanical Pulp

通过微波、水浴两种加热方式下浸渍木片吸液量的比较,探究了微波对桉木渗透性的影响,结果显示:在其它浸渍条件(NaOH质量分数4%,木片质量分数20%)相同的情况下,木片浸渍时,经微波加热后其吸液量较水浴加热显著提高,微波处理5 min即可达到水浴处理45 min的吸液量,大大提高了浸渍效率。将微波用于化学机械法制浆的预浸渍阶段,经微波处理所得纸浆二段漂白白度最高可达68.9%(ISO),较汽蒸保温提高3～6个百分点;在加拿大游离度为305 mL时,微波处理浆的抗张指数可达19 N·m/g,撕裂指数可达2.15 mN·m^2/g,耐破指数达0.8 kPa·m^2/g,分别比汽蒸处理样高3 N·m/g、0.2 mN·m^2/g和0.1 kPa·m^2/g。

The effects of microwave on the permeability of eucalyptus were studied by comparing the liquid absorption of wood chips under microwave with that under water bath.Under the same immersion conditions(NaOH 4%and mass fraction of wood chips 20%),the absorbed liquid quality of the microwave treated wood chips was significantly higher than that of the water bath.Microwave treatment for 5 minutes could reach the same absorbed liquid quality of 45 minutes in the water bath treatment,greatly improving the impregnation efficiency of wood chips.Then,microwave was used in the pre-impregnation of chemical mechanical pulping.The whiteness of the second stage bleaching pulp obtained by microwave impregnation could reach up to 68.9%(ISO),which was 3-6 percentage points higher than that of samples obtained by steaming impregnation.When the freeness of Canada was 305 mL,the tensile strength index could reach 19 N·m/g,the tear index could reach 2.15 mN·m^2/g,and the bursting index could reach 0.8 kPa·m^2/g.Furthermore,the tensile strength index was increased by 3 N·m/g on average,and the tear index was increased by about 0.2 mN·m^2/g,while the bursting index was increased by about 0.1 kPa·m^2/g.