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Swelling of cotton cellulose fibres having different proportions of carboxyl groups in the H-form was studied. The carboxyl groups were introduced by carboxymethylation under different reaction conditions. By studying the swelling of modified cellulose samples (water retention value of non-dried fibre) it was shown that the concentration of sodium hydroxide was the dominant factor among the investigated...
A link is drawn between paper hornification and low temperature thermally-accelerated ageing of paper based on a review of existing research. Similarities between treatment temperature, humidity, resultant physical properties, and possible degradation mechanisms are enumerated. Hornification can be explained by irreversible intra-fibre hydrogen bonding, whereas accelerated ageing is normally attributed...
The effect of two different cellulases on the hornification phenomenon,in which drainability (Schopper–Riegler method) and mechanical propertiesdiminish when pulps are dried, was studied. The enzyme applications testedincluded a commercial enzyme named ComC (Pergalase A40 from CIBA) and alaboratory enzyme from Paenibacillus sp. strain BP-23namedCelB. Industrial never-dried Eucalyptus globulus bleachedkraft...
Solid-state 13C NMR spectroscopy was used to characterize a bleached softwood kraft pulp in the never-dried state and after cycles of drying and remoistening. Changes in NMR signal strengths indicated that growth of crystalline domains involved cocrystallization rather than accretion of cellulose from noncrystalline domains. A cluster of C-4 signals at 89.4 ppm, assigned to the interiors of crystalline...
The changes induced to paper microstructure by accelerated ageing were studied using an automated gravimetric technique based on water vapour adsorption. The technique can be used especially in applications involving the adsorption and desorption of water, such as paper recycling, hornification, ageing and aqueous conservation treatments. The logistics for the calculation of the specific surface area...
Measurements have been performed to clarify the connection between fibre–fibre joint properties and dimensional stability using laboratory sheets prepared from never-dried fibres, from heavily hornified fibres having a low molecular contact area between the fibres, and from both hornified and never-dried fibres treated with a polyelectrolyte multilayer (PEM) technique to increase the molecular contact...
Dried and never-dried chemical pulps were subjected to strong sulfuric acid hydrolysis and the dimensions of the resulting cellulose nanocrystals (CNCs) were characterized by AFM image analysis. Although the average length of CNCs was fairly similar in all samples (55–65 nm), the length distribution histograms revealed that a higher number of longer crystals and a lower number of shorter crystals...
Water-redispersible, nanofibrillated cellulose (NFC) in powder form was prepared from refined, bleached beech pulp (RBP) by carboxymethylation (c) and mechanical disintegration (m). Two routes were examined by altering the sequence of the chemical and mechanical treatment, leading to four different products: RBP-m and RBP-mc (route 1), and RBP-c and RBP-cm (route 2). The occurrence of the carboxymethylation...
NMR cryoporometry has been used for investigating the porosity changes of bleached wood pulp upon drying. This NMR method follows the same principles as thermoporosimetry, which has been used for the same purpose during the last decade and makes it possible to investigate porous material in the water-swollen state. In this study bleached softwood kraft pulp was exposed to a series of drying procedures...
Bionanocomposites of hydroxypropyl cellulose (HPC) and nanofibrillated cellulose (NFC) were prepared by solution casting. The various NFC were in form of powders and were prepared from refined, bleached beech pulp (RBP) by mechanical disintegration, optionally combined with a pre- or post mechanical carboxymethylation. Dynamic mechanical analysis (DMA) and tensile tests were performed to compare the...
Bleached acid sulphite and kraft Eucalyptus globulus pulps were subjected to treatment at high hydrostatic pressure (400 MPa during 10 min). The associated structural changes of cellulose were evaluated by X-ray scattering, solid-state NMR and infrared spectroscopy. The high pressure treatment promoted the growth of crystalline domains predominantly via lateral aggregation (cocrystallization) and,...
The textile industry is currently under pressure to decrease environmental load related to both the manufacture and the use of textiles. Material recycling may be one of many ways to accomplish such a decrease. Age-induced property changes in cotton textiles are important to understand in order to facilitate the recycling of cotton textiles. Consequently, this study investigates ultrastructural and...
This study was to determine the effect of fiber hornification on the viscosity decrease of prehydrolysis kraft-based dissolving pulp using a commercial endoglucanase-rich cellulase. Three pulp samples, namely never-dried (ND), air-dried (AD) and oven-dried (OD), were used. The results showed that the enzymatic performance in the viscosity decrease was affected by the fiber history: the ND sample showed...
The utilization of waste paper is very important for saving wood resources and reducing waste generation. Various techniques for preparing cellulose nanofibers, which is a material recently proposed for potential applications in the paper industry, have been investigated. In the present study, fine fibers were prepared using recycled pulp and a nanoengineering aqueous counter collision treatment,...
The agglomeration of cellulosic materials upon drying, often called hornification, causes a reduction of water retention, among other undesired effects. It is one of the main issues in industrial cellulose processing, especially with regard to nanocelluloses. As a consequence, high transportation and storage costs arise since nanocelluloses need to remain in aqueous suspensions unless trade-offs in...
Details on how cellulosic surfaces change under changing moisture are incomplete and even existing results are occasionally neglected. Unlike sometimes reported, water adsorption is unsuitable for surface area measurements. However, water can be utilized for assessing surface dynamics. Hygroscopic changes of pulp and bacterial cellulose were studied by dehydrating the samples in a low polarity solvent...
Recycled pulp can be used as a potential and sustainable resource for production of fermentable monosaccharides. In this work, the effects of residual lignin and thermal drying on ultrastructure, physical properties and further enzymatic digestibility of chemical pulps were investigated. The results showed that drying process (at 105 °C for 24 h) did not significantly change the functional groups...
This study analyzed the hornification properties of the old newsprint fiber and its effects on the enzymatic hydrolysis and investigated the strategy for improving the hydrolysis efficiency. The results showed both of heating and vacuum can dry the fibers and cause hornification, which resulted in a significant decrease in the pore volume and the enzymatic saccharification efficiencies. A good linear...
Hornification of cellulose is a well-known phenomenon that takes place during the drying process. Hornification involves a structural change in the cellulose that restricts the enzyme’s ability to access and saccharify the cellulose. We observed never-dried (ND), pressed (PR), and oven-dried (OD) softwood pulp during saccharification catalyzed by fluorescent labelled cellulase from Trichoderma reesei...
Recent years have witnessed an increasing interest in man-made cellulosic fibers, whose production generally requires cellulose dissolution and regeneration. Cellulosic fibers are difficult to dissolve. Thus, the recalcitrance of wood pulp can be an estimate of its reactivity. Pulp reactivity is usually assessed via complex and time-consuming laboratory simulations of the viscose process. This study...
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