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Posouzení trvanlivosti vybraných druhů dřev pro obchodovatelný výrobek
Sion, Matěj
In this thesis, the problem of the resistance of terrace boards to biological degradation. The following woods were chosen for the experiment: 1) Garapa (Apuleia leiocarpa Vog.) → is a representative of tropical woods and at the same time a species required by customers. 2) Mulberry (Morus) → a possible alternative in future years. 3) Acetylated European alder wood (Alnus glutinosa) → a possible alternative, when this method of modification appears to be very effective. The selected woods were tested according to the ČSN EN 350 standard for resistance to the wood decay fungi of white rot (Trametes versicolor) and brown rot (Gloeophyllum trabeu) and Coniophora puteana). The second part of this thesis was the determination of the total content of extractive substances (ES), phenolic substances (FS), carbohydrates (C), and pH values of aqueous leachate selected wood species. All samples were tested and compared with each other. The wood of the mulberry tree was evaluated and as to how these properties change along the radius of the trunk. The selected woods have been found to be suitable for decking. Weight losses (white and brown rot) were in negative values, so the fungi were not able to attack the wood and it was classified in durability class 1 "very durable". From the point of view of chemical composition, it was found that the most chemical substances are contained in the wood of the mulberry tree, garapa, and the least acetylated alder. In the case of the mulberry tree, it was also found that the amount of chemical substances varies depending on the position along the stem radius. The high resistance of garapa and mulberry to wood-rotting fungi is mainly caused by the content of chemical substances. The resistance of acetylated alder was due to the acetylation process.
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Analýza množství extraktivních látek a barvy dřeva dubu zimního
Holčák, Martin
This thesis assesses the experimental findings of the total content of extractives and of the shared content of phenolic substances in wood extracts of the Sessile oak (Quercus petraea) from four different locations in the southern region Pfälzer Wald in the Rheinland-Pfalz Federal Republic of Germany. Moreover, the thesis measures the wood colour in CIE Lab besides focusing only on chemical analysis. The theoretical part outlines general facts about the macroscopic and microscopic structure of the wood (Quercus pertaea). Also, it discusses in detail the issue of colour and chemical composition of wood with a focus on accompanying components. The chapter Methodics describes the process of the entire experiment for the possibility of repeatability of the measurement. The results of this work show mean values of the parameters of the colour L* = 66,7; a* = 7,0; b* = 20,8. Dependence on the total content of the extracts in the wood of the Sessile Oak is not statistically evaluated for these values. The total average content of extracts in wood is assessed at 6,7 % and the content of phenolic substances represents 3,4 %. It is detected that the own colour of wood and also the content of extractives may be affected by the location of growth or even by the position itself within the trunk radius.
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Porovnání účinnosti metod extrakce tropických dřev na základě analýzy získaného extraktu a jeho vlivu na dřevokazné houby
Přibylová, Zdeňka
The thesis compares the efficiency of two extraction methods: using the FexIKA apparatus and using ultrasound. To compare the extraction methods, extracts from merbau (Intsia bijuga O.Ktze.) and jatoba (Hymenaea courbaril L.) were created. These tropical woods were ground and extracted. From the extracts, three concentrations of protective substances were created. The protective substances were tested to determine the content of extractive compounds and polyphenolic compounds. The obtained protective substances were impregnated into the wood of common beech (Fagus sylvatica L.) and pine (Pinus sylvestris L.). The impregnated beech and pine samples were tested to determine the protective effectiveness against Trametes versicolor L. and Coniophora puteana P. Karst. From the acquired data, the loss of mass of the wood was assessed. The results showed that only samples impregnated with the protective substance with concentration of 3 showed adequate protection. Analysis of the protective substances showed a higher yield when using FexIKA on Merbau wood. Jatoba wood extraction showed a slightly higher yield when extracting using ultrasound. In general, the samples impregnated with extracts obtained using FexIKA showed lower mass loss than samples impregnated with extracts obtained using ultrasound.
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Využití extraktivních látek tropických dřev pro zvýšení přirozené trvanlivosti buku
Přibylová, Zdeňka
This Bachelor thesis focuses on evaluating antimycotic activity of extractive compounds acquired using the FexIKA extraction apparatus. Merbau (Intsia bijuga O.Ktze.) and jatoba (Hymenaea courbaril L.) were used as the sampled material. The extractive compounds were obtained from ground samples of the tropical woods. Then, the beech wood was impregnated with the compounds. A rapid durability test of vulnerability against Trametes versicolor L. was performed. From the data acquired, the weight loss of the impregnated samples and reference samples was evaluated. The results show that the extractive compounds procured from Merbau wood in the highest concentration were able to increase the natural durability of beech from class 5, i.e. not durable, to class 1 - very durable. Impregnation with extractives from Jatoba in the highest concentration level increased the durability from class 5 to class 2, i.e. durable.
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Influence of wood structure on wood properties of tropical species
Baar, Jan
The presented thesis is focused on aesthetical and acoustic properties of tropical wood. The discussed tropical species are utilized in Europe mainly for their unusual appearance and colour in joinery and furniture production. The irreplacable acoustic properties like low internal friction predestine specific species for production of musical instruments. The colour of six selected tropical species - jatoba (Hymenea courbaril L.), massaranduba (Manilkara bidentata A. Chev.), muiracatiara (Astronium graveolens Jacq.), angelim amargoso (Vatairea spp.), angelim pedra (Hymenolobium spp.) and angelim vermelho (Dinizia excelsa Ducke) - were analyzed and expressed in CIEL*a*b* colour space. Subsequently the samples were exposed to artificial sunlight and the light-induced discolouration rate and progress was evaluated. The colour change was rapid in zhe first hours of exposure and all species showed a similar trend in lightness (L*) change - initial darkening replaced by gradual fading. The change in chromatic parameters (a* and b*) change was specific for individual species and probably related to the chemical composition of the extractives. The overall discolouration of lighter coloured wood samples is more distinctive. The extractive content of tropical species is usually high and determines wood colour. The wood of African Padauk (Pterocarpus soyauxii Taub) and Jatoba (Hymenaea courbaril L.) was extracted in a mixture of methanol, water and acetone. The total extractives and total phenolic content was measured. Extractive content was related to colour parameters and above all to lightness in both species. The increase in extractive content leads to a lighter and more yellow colouration of Jatoba wood while African Padauk was darker with a higher amount of extractives. In Jatoba, a positive correlation was found between extractive content and the rate of discolouration. The extractives are responsible for intensive discolouration of tropical woods in contrast to light coloured woods from the temperate zone, where the yellowing is primarily caused by lignin photodegradation. The sound velocity was measured by ultrasound and resonance longitudinal method in heartwood of doussie (Afzelia bipindensis), merbau (Intsia bijuga), wengé (Millettia stuhlmannii Taub.), muiracatiara (Astronium graveolens Jacq.) and zebrano (Microberlinia brazzavillensis). The sound velocity was not related to the density in any case. Although anatomical structural characteristics as fiber length or ray ratio positively influenced it. With longer fibers and slender rays the sound velocity increased. Other acoustic properties like dynamic young modulus of elasticity, specific modulus of elasticity, internal friction and acoustic conversion efficiency (ACE) were determined and were related to measured anatomical features. The differences in composition of wood tissue of individual species were the main source of departure between the assessed relationships. The wood with longer fibers and lower frequency of rays reached lower values of internal friction. The stiffness of wood characterized by the dynamic modulus of elasticity was correlated with fiber and ray tissue. A higher volume of fibers influenced the stiffness positively, while ray volume had the opposite effect on stiffness. Positive effects of fiber length and ray ratio were found for dynamic modulus of elasticity and for acoustic conversion efficiency as well. Both values increased with longer fibers and higher ray ratio. The sound velocity is the basis of some nondestructive techniques for determination of wood mechanical properties. The comparison of density and three dynamic moduli of elasticity (longitudinal and flexural resonance method and ultrasound method) in prediction of mechanical properties was carried out. The density was evaluated as a poor predictor when the samples are not straight-grained and defect free. The interlocked grain often occurred in tropical species and its presence influences the mechanical properties of wood but not wood density. The dynamic moduli of elasticity showed strong correlation with the static modulus of elasticity. Among nondestructive techniques, the weakest correlation was found for the ultrasound method, which is probably partially explained by different measuring mechanism. The prediction of the modulus of rupture is less accurate when the dynamic modulus of elasticity is compared with the static modulus of elasticity; however, it was still good in comparison with the density model.
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Vztah mezi trvanlivostí jádrového dřeva akátu (Robinia pseudoacacia) a jeho přirozenou barvou
Dobrovolný, Jakub
This bachelor thesis deals with a finding off a relationship between the durability of acacia heartwood against wood decaying fungi varicoloured bracket (Trametes versicolor) and its natural color. Durability of wood was determined as a percentage of body weight loss compared to the original sample. It has been analyzed a dependence of the natural color of the acacia wood and a share of extractive substances that have a main influence to durability of wood. The theoretical part describes all the problems related to this topic. In second part, the measured values are processed statistically evaluated and compared with literature.
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Vliv stanoviště na množství extraktivních látek dřeva akátu
Bachan, Tomáš
This thesis, which is performed as an experiment, deals with dependence of locations on the amount of extractive substances in the heartwood, sapwood and bark of acacia (Robinia pseudoacacia L.) across radius of the trunk. Thesis also aims to determine at what part of the trunk is situated most of extractive substances. Furthermore is evaluated, if the amount of extractive substances is depending on the height of the trunk, at altitudes from 0 m and 1.3 m from which the samples were taken. A final point is to compar according to the cardinal directions. In the theoretical part is described the issue of extractive substances and chemical composition of acacia. The second part presents the measured values from taked and extracted samples and their statistical evaluation.
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