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Seman B.,Katedra chemie a chemickych technologii | Geffert A.,Katedra chemie a chemickych technologii
Acta Facultatis Xylologiae | Year: 2014

This work deals with common sulphate cooking of heartwood (oak) and sapwood (beech) and their influence on the sulphate cooking process. Sulphate pulp from beech, oak and from the mixture of both was prepared under the same conditions. In the prepared unbleached pulp were observed the characteristics of sulphate batch. Part of the pulp was bleached by sodium chlorate. The unbleached and bleached pulps were determined the selected mechanical features, optical features and dimensional characteristics of the pulps. In common sulphate batch of different wood species occurs to the influence of each other. It is caused by differences in characteristics between the heartwood and sapwood. Different wood structure affects the rate of penetration of the cooking liquor into the chips. Then it is reflected in the manufacturing process of bad impregnating of the chips by cooking liquor. These results are the lower yields, increased volume of rejects, tearing the paper in the pulp machine and worse optical features of pulps.


In this study the changes of selected characteristics of poplar (Populus tremula L.) cellulose after hydrothermal treatment were described. Water prehydrolysis was applied on the wood samples at temperature 200°C and four different durations (30, 60, 120 and 240 min). Non-treated wood sample and samples of solid residues after water prehydrolysis were analysed by means of gel permeation chromatography (GPC) and Fourier Transform Infrared (FTIR) spectroscopy. It was observed that the degree of polymerization and molecular weight distribution (MWD) of cellulose decreased and the crystallinity ratio of cellulose (Total Crystallinity Index and Lateral Order Index) relatively increased with duration of hydrothermal treatment.


Cabalova I.,Katedra chemie a chemickych technologii | Kacik F.,Katedra chemie a chemickych technologii | Briskarova A.,Katedra chemie a chemickych technologii
Acta Facultatis Xylologiae | Year: 2013

Ageing of paper is a serious problem for library and archival documents. Durability and longevity of these documents depends on the quality used paper. The reason is the process of paper ageing and its degradation that affected polysaccharide chain of cellulose macromolecules. Acid catalysed hydrolysis is an important factor causing the decrease in paper strength properties. Molecular weight of celluloses from samples of various papers from historical books (3 samples from 18th century, 3 samples from 19th century and 1 sample from 21stcentury) were studied by gel permeation chromatography (GPC) and breaking length of papers according to standard STN 50 0340. Correlation between the breaking length of paper and the degree of polymerization of cellulose chains has not been confirmed. The reason may be due to different materials from which were made the papers, pulp production methods and conditions which were exposed these books (light, heat, humidity). The lowest breaking length and the highest degree of polymerization (DP) were measured by paper from the year of 1763.


Halajova L.,Katedra chemie a chemickych technologii | Kacik F.,Katedra chemie a chemickych technologii
Acta Facultatis Xylologiae | Year: 2011

Degradation of cellulose changes its physical, mechanical and chemical properties and has an influence on longevity of the paper. Degree of polymerization is the main factor that changes in aging of paper and has an impact on the properties of paper and cellulose. In this paper there are described alterations of degree of polymerization (DP) and molecular weight distribution (MWD) in the recycling process of hardwood bleached sulphate pulps after the thermal loading at the temperature of 150 °C during 24 hours. The molecular weight distribution was determined by the method of gel permeation chromatography (GPC) of cellulose tricarbanilates (CTC). The cellulose chains were cleaved to shorter ones and the degree of polymerization decreased at the recycling treatment.


Halajova L.,Katedra chemie a chemickych technologii | Kucerova V.,Katedra chemie a chemickych technologii
Acta Facultatis Xylologiae | Year: 2011

In paper there are described alterations of degrees of polymerization (DP), polydispersity (PD) and distribution of molecular weights from recycling hardwood bleached sulphate pulps after the thermal loading with temperature 150 °C during 24 hours. Pulp fibres were dried in recycling process by temperature 120 °C. The distributions of molecular weight were determined by method of gel permeation chromatography (GPC). The cellulose chains cleavages to shorter and the degree of polymerization and polydispersity decreased at the recycling treatment.

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