液化工艺对沙柳材液化产物流变性的影响

Effects of Liquefaction Process on Rheological Properties of Salix psammophila Timber

研究沙柳(Salix psammophila)液化工艺因子(液化时间、液化温度和催化剂98%浓硫酸用量)与液化产物流变特性的关系,为液化产物在管道内流通提供理论依据。单因素试验结果表明:(1)沙柳液化产物动力黏度受液化率和液化产物状态双重影响,随液化工艺因子水平呈先减小后增大变化,在液化时间80 min、液化温度150℃、催化剂用量6%时液化产物动力黏度最小值0.16 Pa·s。(2)液化产物剪切应力随液化工艺因子水平呈先增大后减小变化,在液化时间80 min、液化温度160℃、催化剂用量4%时剪切应力获最大值;液化产物储能模量(G’)、损耗模量(G")和复数黏度(η^(*))随液化工艺因子水平呈先增大后减小变化,在液化时间70 min、液化温度160℃、催化剂用量4%时G’和损G"获最大值;G’和损G"随角频率增加而增大,η^(*)随角频率增加而减小。(3)优化工艺条件下液化产物非牛顿指数n值0.91,表现出假塑性流体性质;液化产物黏流活化能随剪切速率增大而减小,黏流活化能依赖于温度和剪切速率。沙柳液化产物流变性能受液化工艺因子影响,剪切应力、储能模量、损耗模量和复数黏度存在最佳工艺条件。

The relationship between the Salix liquefaction process factors(i. e.,the time,temperature,and catalyst dosage)and the rheological properties was studied in this paper. The results showed that the dynamic viscosity of the Salix liquefaction products was affected by both the liquefaction rate and the state of the liquefaction products,it first decreased and then increased with the level of the liquefaction factor,when the time was 80 min,the temperature was 150°C,and the catalyst dosage was 6%,the minimum dynamic viscosity was 0. 16 Pa·s. The shear strength of the Salix liquefaction products increased first and then decreased with the process factors,the shear stress reached the maximum value when the time was 80 min,the temperature was 160℃,and the catalyst dosage was 4%. The storage modulus(G’),loss modulus(G"),and complex viscosity(η^(*))first increased and then decrease with the process factors,G’ and loss G" got the maximum values when the time was 70 min,the temperature was 160℃,and the catalyst dosage was 4%;the G’ and loss G" increased with the increase of the angular frequency,and the η^(*) decreased with the angular frequency increasing. The non-Newtonian index n value under the optimized process conditions was 0. 91,showing the properties of the pseudoplastic fluid,the viscous flow activation energy depended not only on the temperature but also the shear rate,and it decreased with the shear rate increasing. The rheological properties of the Salix liquefaction products were affected by the liquefaction process,and there were optimal conditions for the shear stress,storage modulus,loss modulus,and complex viscosity.