The Effect of Consistency and Freeness on the Yield Stress of Chemical Pulp Fibre Suspensions

BioResources

Hui Zhang¹  Abbas Nikbakht²  James Olson³  Jiulong Sha³  Chen Wang⁴ 

[1] Canada;China;Jiangsu Provincial Key Lab of Pulp and Paper Science and Technology, Nanjing Forestry University, Nanjing, China;Pulp and Paper Centre, The University of British Columbia, 2385 East Mall, Vancouver, British Columbia, V6T 1Z4, Canada;

关键词: Rheology;    Yield stress;    PFI mill;    Freeness;    Pulp fibre suspensions;   

DOI  :  10.15376/biores.10.3.4287-4299

来源: DOAJ

【 摘 要 】

To study the influence of mechanical treatments on the yield stress of chemical pulp suspensions, a traditional rheometer, coupled with local velocity measurements (ultrasonic Doppler velocimetry), was used to measure the yield stress of two types of commercial chemical pulp suspensions with different freeness values at mass concentrations (consistencies) ranging from 0.5 to 1.5%. Over the range of consistencies tested, the yield stress was found to depend on the consistency through a power law relationship for all tested samples. Moreover, the results showed that as the freeness decreased, the yield stress of hardwood suspensions increased to a maximum value then decreased. This variation in yield stress was also observed in softwood suspensions with mass concentrations above 1%. However, when the consistency was lower than 0.75%, the yield stress of softwood suspensions increased with decreasing freeness.This behaviour can be understood based on the underlying fibre properties of fibrillation, curl, and stiffness, suggesting that fibre morphology plays a significant role on the yield stress of pulp suspensions over the concentration range studied.

【 授权许可】

Unknown