浆浓及助留助滤剂对桉木浆纤维悬浮液屈服应力的影响

Influence of the Pulp Consistency and Addition of Retention and Drainage Aids on the Yield Stress of Eucalyptus Pulp Fiber Suspension

中文关键词:  桉木浆  纤维悬浮液  屈服应力  阳离子聚丙烯酰胺  阳离子淀粉

Key Words:eucalyptus pulp  fiber suspension  yield stress  CPAM  cationic starch

中文摘要:

      纸浆纤维悬浮液的屈服应力（τy）是纸浆流体力学的关键流变参数。研究了桉木漂白硫酸盐浆（BKP）的浆浓（Cm）以及分别添加阳离子聚丙烯酰胺（CPAM）和阳离子淀粉对其纤维悬浮液屈服应力的影响。结果表明，在稳态剪切条件下，桉木BKP纤维悬浮液屈服应力随浆浓的升高而迅速增大，两者符合指数关系，即τy=aCbm（a=3.20，b=2.62）；添加CPAM或阳离子淀粉后，两者仍满足该指数关系，但添加CPAM后，a值减小、b值增大，而添加阳离子淀粉后，a和b值均在原来的基础上上下浮动。浆浓一定的桉木BKP，其屈服应力随CPAM添加量的增加，先增大后减小，但仍大于不添加CPAM桉木BKP纤维悬浮液的屈服应力；当浆浓为4.0%、添加约0.6%（相对于绝干浆质量，下同）的CPAM时，其屈服应力增幅最多，达30%；随着阳离子淀粉添加量的增加，屈服应力先增大后减小，当添加约为2.5%的阳离子淀粉、浆浓4.0%时，桉木BKP纤维悬浮液屈服应力下降最多，降低了约25.4%。

Abstract:

      The yield stress （τy） of pulp fiber suspension is a key rheological parameter. The influence of consistency （Cm） of eucalyptus bleached kraft pulp， the amounts of addition of CPAM or cationic starch on τy of the eucalyptus pulp fiber suspension was studied. The results showed that， in the steady state shear condition， the τy of eucalyptus pulp fiber suspension increased rapidly with the increase of Cm， their relationship was accorded with the exponential relation τy=aCbm（a=3.20， b=2.62）. After adding CPAM or cationic starch to eucalyptus pulp fiber suspension， the exponential relation was still satisfied， but the values of a and b changed. After adding CPAM， a would decrease， and b would go up. After adding cationic starch， both a and b floated up and down on the original basis. For eucalyptus pulp fiber suspension with certain Cm， the τy would first increase then decrease with the increase of CPAM addition, but the τy was still stronger than the τy of blank pulp fiber suspension. The τy of eucalyptus pulp fiber suspensions increased by up to 30% when Cm was 4.0% and the CPAM addition amount was about 0.6%. With the addition of cationic starch， the τy of eucalyptus pulp fiber suspension increased first then decreased. When the amount of cationic starch was about 2.5% and Cm was 4.0%， the τy of eucalyptus pulp fiber suspension decreased by 25.4%.