Rheological properties of nanocellulose suspensions: effects of fibril/particle dimensions and surface characteristics
Rheological properties of nanocellulose suspensions: effects of fibril/particle dimensions and surface characteristics
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DOI：
10.1007/s10570-017-1283-0
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发表时间：
2017-06-01
期刊：
影响因子：
5.7
通讯作者：
Rigdahl, Mikael
中科院分区：
文献类型：
--
作者：
Moberg, Tobias;Sahlin, Karin;Rigdahl, Mikael
比较了基于三种不同纳米纤维素的水悬浮液的流变性能。一个系统是通过酸水解（从而产生结晶纳米纤维素，CNC）和其他两个从机械剪切，但来自不同的来源，并进行不同的预处理。在后两者中，一种被认为是相当典型的纤维素纳米原纤维（CNF）悬浮液，而另一种是CNF和CNC之间的一种中间体。所有三种纳米纤维素元素在尺寸上不同，这从透射电子显微镜和原子力显微镜可以看出。关于原纤维/颗粒的长度，三种纳米纤维素形成三个不同的组，其长度在200 nm和略大于800 nm之间。三种纤维素元素也进行了TEMPO介导的氧化，产生类似的羧酸盐含量在三个系统。此外，TEMPO氧化元素接枝聚（乙二醇）（PEG）。接枝PEG的量为约35重量%。在室温下测定未改性的、TEMPO氧化的和接枝的纳米纤维素的悬浮液的剪切粘度、储能模量和损耗模量，并且悬浮液的固体含量在0.7和2.0重量%之间变化。得出的结论是，取决于纤维素元素的尺寸和它们的表面特性的悬浮液之间的流变性能变化显着。在这种情况下，颗粒的长度（或纵横比）起着非常重要的作用。
The rheological properties of aqueous suspensions based on three different nanocelluloses were compared. One system was obtained via acid hydrolysis (thus yielding crystalline nanocellulose, CNC) and the other two from mechanical shearing, but from different origins and subjected to different pretreatments. Of the latter two, one was considered to be a rather typical cellulose nanofibril (CNF) suspension whereas the other was a kind of intermediate between CNF and CNC. All three nanocellulose elements differed in dimensions as evident from transmission electron microscopy and atomic force microscopy. With regard to the length of the fibrils/particles, the three nanocelluloses formed three distinct groups with lengths between 200 and slightly more than 800 nm. The three cellulosic elements were also subjected to a TEMPO-mediated oxidation yielding a similar carboxylate content in the three systems. Furthermore, the TEMPO-oxidized elements were grafted with poly(ethylene glycol) (PEG). The amount of grafted PEG was about 35 wt%. The shear viscosity, the storage modulus and the loss modulus of suspensions of the unmodified, the TEMPO-oxidized and the grafted nanocelluloses were determined at room temperature and the solids content of the suspensions was varied between 0.7 and 2.0 wt%. It was concluded that the rheological properties varied significantly between the suspensions depending on the dimensions of the cellulosic elements and their surface characteristics. In this context, the length (or the aspect ratio) of the particles played a very important role.