The study of rheological properties and microstructure of carboxylated nanocellulose as influenced by level of carboxylation
The study of rheological properties and microstructure of carboxylated nanocellulose as influenced by level of carboxylation
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DOI：
10.1016/j.foodhyd.2021.106985
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发表时间：
2021-12
影响因子：
10.7
通讯作者：
Rui Qu;Yong Wang;Dong Li;Lijun Wang
中科院分区：
文献类型：
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作者：
Rui Qu;Yong Wang;Dong Li;Lijun Wang
本文采用TEMPO-高碘酸盐氧化法制备了羧化纳米纤维素，通过调节次氯酸钠（NaClO）浓度来控制羧化程度。研究了羧化程度对羧化纳米纤维素分散液流变行为和微观结构的影响。结果表明，当NaClO浓度为2 mmol/g时，纳米纤维素分散体呈溶胶状态，储能模量（G′）和损耗模量（G″）较低。但当NaClO浓度较高（6-12 mmol/g）时，纳米纤维素分散体呈凝胶状，当NaClO浓度为4 mmol/g时，纳米纤维素分散体达到临界状态（G ′和G ″值相近）。随着NaClO浓度的增加，纳米纤维素分散液的G ′和G ″均先增大后减小。当NaClO浓度控制在8 mmol/g时，得到的模量最高，分形维数（Df）也很高，显示出致密的网络结构。大振幅振荡剪切（LAOS）结果表明，纳米纤维素分散体呈现Ⅰ型（应变变稀），但也有Ⅲ型（弱应变超调）的趋势。采用傅里叶变换流变学、切比雪夫系数和李萨如曲线分析了纳米纤维素分散体的非线性行为，表明纳米纤维素分散体的非线性行为与其网络结构之间存在相关性。该研究为纳米纤维素分散液的性能调控提供了一定的指导。
In this work, carboxylated nanocellulose had been prepared by using TEMPO-periodate oxidized reaction, in which the level of carboxylation was controlled by adjusting sodium hypochlorite (NaClO) concentration. The effects of the level of carboxylation on the rheological behavior and microstructure for the carboxylated nanocellulose dispersion had been investigated. It indicated that the nanocellulose dispersion exhibited sol state with low storage (G′) and loss (G″) modulus when NaClO concentration controlled to 2 mmol/g. But nanocellulose dispersion presented a form of gel at high NaClO concentration (6–12 mmol/g) and a critical state (similar values ofG′andG″) was obtained with the NaClO concentration of 4 mmol/g. In addition, both theG′andG″of nanocellulose dispersion were increased and then decreased with the increase of NaClO concentration. The highest modulus obtained when NaClO concentration controlled to 8 mmol/g, and a high fractal dimension (Df) was also obtained at this concentration, indicating a compact network structure. The large amplitude oscillation shear (LAOS) suggested that nanocellulose dispersion exhibitedⅠbehavior (strain thinning) but had a trend ofIIIbehavior (weak strain overshoot). The Fourier transform rheology, Chebyshev coefficient, and Lissajous curves were used to analyze the nonlinear behavior, implying a correlation between the nonlinear behavior and the network structure of the nanocellulose dispersion. This work would provide some guidance for regulating the properties of nanocellulose dispersion.