ABSTRACT The possibilities of the preparation of filled PVC and PVC with a high content of wood particles were investigated by avoiding the deterioration of the mechanical and hydroscopical properties of the resulting material. It was... more
ABSTRACT
The possibilities of the preparation of filled PVC and PVC with a high content of wood particles were investigated by avoiding the deterioration of the mechanical and hydroscopical properties of the resulting material. It was found that the portion of the wood particles that can be added as filler in the PVC with regard to the extrudability and properties of the resulting material depends mainly on the homogenization of the mixture and on the modification of the wood particles. The addition of 15% wood filler in the PVC does not cause the decrease of the impact strength by 38 % and the application of wood fiber decreases the flexure strength by 21 %. The addition of 50 % wood filler decreases the extrudability and resistance against water. The flexure strength is decreased by 25 -70 %, the impact strength by 20 -50 % according to the conditions of extrusion and geometry of the wood particles (Tables 1 and 2ň. The modification of the wood particles and the intensive homogenization on a calender at the temperatures 120 - 130°C made it possible to prepare samples of PVC with a content of wood particles higher than 200 %. The impact strength of this material was in the range of 50 -80 MPa, thus higher than the unfilled PVC. The modification of the wood particles decreases the negative effect of the filler on the resistance of the filled PVC against water. For the improvement of the properties of materials based on the wood particles and thermoplastics it is possible to use the modification of the particles by means of thermosetting coatings, by sizing and hydrophobic agents, by transformation without changing the degree of polymerization, by grafting and by the combination of the indicated procedures.
The possibilities of the preparation of filled PVC and PVC with a high content of wood particles were investigated by avoiding the deterioration of the mechanical and hydroscopical properties of the resulting material. It was found that the portion of the wood particles that can be added as filler in the PVC with regard to the extrudability and properties of the resulting material depends mainly on the homogenization of the mixture and on the modification of the wood particles. The addition of 15% wood filler in the PVC does not cause the decrease of the impact strength by 38 % and the application of wood fiber decreases the flexure strength by 21 %. The addition of 50 % wood filler decreases the extrudability and resistance against water. The flexure strength is decreased by 25 -70 %, the impact strength by 20 -50 % according to the conditions of extrusion and geometry of the wood particles (Tables 1 and 2ň. The modification of the wood particles and the intensive homogenization on a calender at the temperatures 120 - 130°C made it possible to prepare samples of PVC with a content of wood particles higher than 200 %. The impact strength of this material was in the range of 50 -80 MPa, thus higher than the unfilled PVC. The modification of the wood particles decreases the negative effect of the filler on the resistance of the filled PVC against water. For the improvement of the properties of materials based on the wood particles and thermoplastics it is possible to use the modification of the particles by means of thermosetting coatings, by sizing and hydrophobic agents, by transformation without changing the degree of polymerization, by grafting and by the combination of the indicated procedures.
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n study of degradation products of paper, LC methods were tested for determination of some saccharides in water extracts of paper. Saccharides were analyzed by ion-exchange and partition chromatography with differential refractive index... more
n study of degradation products of paper, LC methods were tested for determination of some saccharides in water extracts of paper. Saccharides were analyzed by ion-exchange and partition chromatography with differential refractive index detection and on-line preconcentration, and by RP-HPLC with fluorescence detection based on pre-column derivatization with dansylhydrazine. The limits of determination for sugars (cellobiose, D-arabinose, D-fructose, D-galactose, D-glucose, D-lactose, D-mannose, D-xylose and methyl D-glucopyranoside) were evaluated by all the tested methods. The degradation products of paper after accelerated ageing for 0-30 days at 98 degrees C were estimated. The presence of some saccharides (D-mannose, D-fructose, D-arabinose and D-xylose) above the limits of determination was proved. Their concentrations depend on the type of paper modification and the ageing time.
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Nová metóda a multifunkčné zariadenie pre tryskové nanášanie konzervačných látok a sústav na báze vody na papierové listy, súbory listov a knihy. The new method and multifunctional device for jet application of conservation substances and mixtures based on water onto paper sheets, sheet files and...more
Determination of the pH value of the paper is a very specific phenomenon, especially the surface pH measurement. In the case of heritage objects, such as archival documents, books, artworks on paper carriers, is a determination of real pH... more
Determination of the pH value of the paper is a very specific phenomenon, especially the surface pH measurement. In the case of heritage objects, such as archival documents, books, artworks on paper carriers, is a determination of real pH value in the whole structure (in cross section) of paper very important, because of the mechanism of degradation and thus the rate of degradation of the paper components at a given point in the paper structure depends on the pH value in the environment. This paper is aimed to show the possibilities of using modified papers by acid–base indicator, in the field of measurement of pH value of paper in the cross section of the paper. A calibration series of acidic samples neutralizing by magnesium bicarbonate of different concentrations was created. It was found that the indicator changed in the desired area, pH value 6–8, and it was observed gradual color change. The color parameters were measured and the most correlated parameter with pH value was fou...
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Cellulose materials and related bioresources have been the first-line tools of defense of human health against COVID-19. The alfa cellulose, wood cellulose, and multilayer composite face masks have been used by billions, simultaneously... more
Cellulose materials and related bioresources have been the first-line tools of defense of human health against COVID-19. The alfa cellulose, wood cellulose, and multilayer composite face masks have been used by billions, simultaneously with millions of tons of cellulosic bioresources-based medical specialty, hygiene, and packaging products used to deal with the global disaster. This editorial considers recently available facts and disputes some statements that have appeared in the media during the year 2020 concerning properties and the risks of the masks. According to recent findings, the carbon dioxide concentration increases by 2.3 to 4.3 times inside of the mask, compared to ambient air, and therefore we suppose that there will be also a concentration increase of larger chemical compounds, toxins, volatile organic compounds (VOC), and particles. These quantities should be measured, and the data used in further research aimed at quality improvement.
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The surface pH is a critical factor in the quality and longevity of materials and products. Traditional fast colorimetric pH detection-based tests such as water quality control or pregnancy tests, when results are determined by the naked... more
The surface pH is a critical factor in the quality and longevity of materials and products. Traditional fast colorimetric pH detection-based tests such as water quality control or pregnancy tests, when results are determined by the naked eye, cannot provide quantitative values. Using standard pH papers, paper-printed comparison charts, or colorimetric microfluidic paper-based analytical devices is not suitable for such technological applications and quality management systems (QMSs) where the particular tested material should contain a suitable indicator in situ, in its structure, either before or after the process, the technology or the apparatus that are being tested. This paper describes a method based on the combination of impregnation of a tested material with a pH indicator in situ, its exposure to a process of technology whose impact on pH value is to be tested, colorimetric pH measurement, and approximation of pH value using derived pH characteristic parameters (pH-CPs) base...
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In this paper a development of an information system for an identification of fiber materials is discussed. Identification of fiber materials using ISO, STN or TAPPI standard is usually performed on the base of color hue. It strongly... more
In this paper a development of an information system for an identification of fiber materials is discussed. Identification of fiber materials using ISO, STN or TAPPI standard is usually performed on the base of color hue. It strongly depends on the skills of a technician to distinguish samples of wood materials. It is a lack of objectivity what makes these standards disadvantageous [1]. In this paper we propose an automatic procedure for evaluation of fiber materials from color images. In the procedure fibers are extracted from color images by means of fundamental image processing routines. We present linear and quadratic discrimination on the base of the Helmholtz color system that includes information about hue. We review the automatic identification on a classification experiment with four types of wood fibers.
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ABSTRACT
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The quality of the processes of stabilization of paper and other lignocellulosics using deacidification and strengthening has been evaluated mostly by measuring kinetic relationships between physico-mechanical properties and ageing time.... more
The quality of the processes of stabilization of paper and other lignocellulosics using deacidification and strengthening has been evaluated mostly by measuring kinetic relationships between physico-mechanical properties and ageing time. The evaluation, comparison and optimizing of the modification processes can be promoted through improving knowledge on relevant characteristic parameters for efficiency measurement of stabilization process. In the present work, few parameters, such as integral S - the integral of coefficient of stabilisation, I-k - the ratio of rate degradation constants of treated and control samples, I-t1/2 - the relative half-life and I-tTC - the technological critical life-time, are applied in the various processes of modification. The methods and parameters tested could be used for measurement, comparison, development and optimizing of the modification processes as well as for the development of standards for communication and testing in the field of chemical t...
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The water retention value (WRV) as a measure of the capability of cellulose fibres to retain water (swelling of fibres) was evaluated during accelerated ageing of acidic wood pulp newspaper containing 20% chemical fibres. It has been... more
The water retention value (WRV) as a measure of the capability of cellulose fibres to retain water (swelling of fibres) was evaluated during accelerated ageing of acidic wood pulp newspaper containing 20% chemical fibres. It has been found that the WRV considerably decreases with accelerated ageing. Relations between the WRV properties and the mechanical properties of paper have also been evaluated. The characterization of samples by mercury microporosimetry has shown that the cumulative column of the pores increases with the period of ageing. On the other hand, the average radius of the pores, as well as their specific surface, decreases. This supports the process of hornification, which occurs during accelerated ageing of paper, as the small pores get smaller and the larger ones get even larger as a result of shrinkage of fibres. When considering accelerated ageing, hornification of fibres as one of the outcomes of fibre brittleness has to be taken into account.
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Organic acids are spontaneously generated in significant concentrations during natural ageing of all cellulose-based papers, the alkaline ones included. The present study reviews the paper degradation research devoted to the... more
Organic acids are spontaneously generated in significant concentrations during natural ageing of all cellulose-based papers, the alkaline ones included. The present study reviews the paper degradation research devoted to the identification and determination of the role ...
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Research Interests: Chemistry, Analytical Chemistry, Chromatography, Mass Spectrometry, Medicine, and 15 moreAdsorption, TIME, Sampling, Identification, Solid Phase Extraction, Technique, Gas Chromatography, Sample, Time Factors, Reproducibility of Results, End, Time, Sampling Technique, Volatile organic compound, and Paper
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Research Interests: Materials Engineering, Chemical Engineering, Materials Science, Chemistry, Kinetics, and 10 morePOlymer degradation and stability, Cellulose, Viscometry, Gel Permeation Chromatography, Polymer Degradation, Electricity Industry, Chemical Properties, Reaction Mechanism, Depolymerization, and Newsprint
The damage to historical documents and books caused by the acidic character of paper is often manifested as a complete loss of their mechanical properties. Deacidification and restoration of archived paper objects require knowledge of the... more
The damage to historical documents and books caused by the acidic character of paper is often manifested as a complete loss of their mechanical properties. Deacidification and restoration of archived paper objects require knowledge of the long-term behaviour of paper before and after repair actions. Our study was focused on the investigation of mechanical properties (tensile strength, stretch, tensile index,
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... State Forest Products Research Institute, Lamafcskä l, 844 11 Bratislava, Czechoslovakia andGabriela KatuScäkovä Pulp and Paper Research Institute, Lamafcskä 3, 815 20 Bratislava, Czechoslovakia Keywords ... The CIELAB in industrial... more
... State Forest Products Research Institute, Lamafcskä l, 844 11 Bratislava, Czechoslovakia andGabriela KatuScäkovä Pulp and Paper Research Institute, Lamafcskä 3, 815 20 Bratislava, Czechoslovakia Keywords ... The CIELAB in industrial routine. Hung. Sei. Instruments 52,1-8. ...
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Whatman cellulose impregnated with calcium and magnesium carbonates was oxidized and chemiluminescence accompanying this oxidation has been measured. It was shown that magnesium ions in deacidified cellulose pulp promote the light... more
Whatman cellulose impregnated with calcium and magnesium carbonates was oxidized and chemiluminescence accompanying this oxidation has been measured. It was shown that magnesium ions in deacidified cellulose pulp promote the light emission significantly. On the other hand, acid papers give the more pronounced light signals at temperatures close to ambient. The relation between chemiluminescence runs and paper degradation has been implicated, with an attempt to extrapolate half-lives of paper samples to conditions close to ambient. To cite this article: J. Rychlý et al., C. R. Chimie 9 (2006).
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During natural ageing, paper undergoes colour changes and becomes brittle. It is mainly due to the degradation of cellulose, the main component of paper fibres. From the viewpoint of conservation/protection of paper-based information... more
During natural ageing, paper undergoes colour changes and becomes brittle. It is mainly due to the degradation of cellulose, the main component of paper fibres. From the viewpoint of conservation/protection of paper-based information carriers, as well as of the utilisation of secondary fibres, knowledge of the impact of a decrease of the degree of polymerisation (DP) of cellulose on mechanical properties of paper becomes of key importance. In this paper, correlations between the decrease of DP of cellulose and the loss of paper folding endurance (FE) using three model samples (pure cellulose, groundwood pulp paper, and degraded groundwood pulp paper) at accelerated ageing were investigated. The existence of such correlations between DP and FE is supported by experimental results; the correlations are linear for pure cellulose and groundwood pulp paper ageing, while exponential correlation was observed in case of degraded groundwood pulp paper. The results indicate that the rate of p...
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The title compound, C7H5N5, was designed and synthesized as a potential antitumour agent. The molecules are located on crystallographic mirror planes. The electron-accepting 6-cyano group has no effect on the π-electron cloud of the... more
The title compound, C7H5N5, was designed and synthesized as a potential antitumour agent. The molecules are located on crystallographic mirror planes. The electron-accepting 6-cyano group has no effect on the π-electron cloud of the heterocyclic system. The molecular packing is governed by C—H...N intermolecular hydrogen bonds, which link the molecules into chains running along the c axis.