• 펄프종이기술
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• 제47권6호
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• pp.5-21
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• 2015

The common production methods of nanocellulosic (cellulosic nanofibrils, CNF) materials from wood are being reviewed, together with large scale applications and particularly papermaking applications. The high energy demand for producing CNF has been one particular problem, which has been addressed over the years and can now be considered solved. Another problem was the clogging of homogenizers/microfluidizers, and the different routes to decrease the energy demand. The clogging tendency, related to the flocculation tendency of fibres is discussed in some detail. The most common methods to decrease the energy demand are TEMPO-oxidation, carboxymethylation and mechanical/enzymatic pre-treatments in the order of increased energy demand for delamination. The rheology characteristics of CNF materials, i.e. the high shear viscosity, shear thinning and the thixotropic properties are being illuminated. CNF materials are strength adjuvants that enhance the relative bonded area in paper sheets and, hence increase the sheet density and give an increased strength of the paper, particularly for chemical pulps. At the same time papers obtain a lower light scattering, higher hygroexpansion and decreased air permeability, similar to the effects of beating pulps. The negative effects on drainage by CNF materials must be alleviated through the appropriate use of microparticulate drainage aids. The use of CNF in films and coatings is interesting because CNF films and coatings can provide paper/board with good oxygen barrier properties, particularly at low relative humidities. Some other high volume applications such as concrete, oil recovery applications, automotive body applications and plastic packaging are also briefly discussed.

• 펄프종이기술
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• 제48권1호
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• pp.5-18
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• 2016

Electron microscopy is an important investigation and analytical method for the morphological characterization of various cellulosic materials, such as micro-crystalline cellulose (MCC), microfibrillated cellulose (MFC), nanofibrillated cellulose (NFC), and cellulose nanocrystals (CNC). However, more accurate morphological analysis requires high-quality micrographs acquired from the proper use of an electron microscope and associated sample preparation methods. Understanding the interaction of electron and matter as well as the importance of sample preparation methods, including drying and staining methods, enables the production of high quality images with adequate information on the nanocellulosic materials. This paper provides a brief overview of the micro and nano structural analysis of cellulose, as investigated using transmission and scanning electron microscopy.