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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Madeiras do agreste para uso em habitação / Wood of the agreste for use in house

Nascimento, Maria Fátima do 22 April 1998 (has links)
A dissertação enfoca as possibilidades e desenvolvimento de estudos das espécies de madeiras do Nordeste do Brasil para uso em habitação. Desenvolveu-se um breve estudo antropológico para reconhecimento da região. No Brasil, os maiores centros de estudos das espécies de madeira estão localizados da região sul e sudeste, desta forma foi feito um estudo tecnológico e a caracterização de uma das espécies de madeira do agreste do NE - Mimosa Caesalpiniaefolia Benth - Sabiá. Os resultados obtidos de caracterização anatômica, mecânica e física, foram bastante satisfatórias. Foram abordadas: resistência à compressão paralela e normal às fibras, tração paralela e normal às fibras, cisalhamento, fendilhamento. No âmbito de caracterização física foram analisados a retratibilidade e densidade. Microscopicamente, foi analisado as lâminas para obtenção de resultados no que tange as fibras, raios e vasos. Através destes estudos, conclui-se que a espécie em questão, tem possibilidades positivas para aplicação na habitação, bem como no uso da construção civil. Deduziu-se ainda que as espécies de madeira do agreste do NE, podem ter melhor proveito, a partir de evolução e apoio técnico, incluindo a possibilidade de reflorestamento. / In Brazil, the biggest study centers of wood species are located in the south and southeast regions. A brief study to reconnaissance of the area has been done. This dissertation discusses the possibilities and the development of wood species studies in the brazilian northeast with the purpose of being used in habitation. A technological study to characterize one of the wood species from the northeast rural area (dry area) - Mimosa Caesalpiniaefolia Benth - Sabiá, has been developed. The results obtained from the anatomical, mechanical and physical characterizations have been very satisfactory. What has been analyzed: strength to parallel and normal compression to the fibers, parallel and normal tension to the fibers, sheer and clefting. Concerning the physical characterization, the retractility and the density were analyzed. Microscopically, the plates used in order to obtain results concerning the fibers, rays and vases, were analyzed. It was possible to conclude from these studies that the species in question have positive possibilities to be applied to habitation, as well as to civil construction usage. Furthermore, we could also conclude that the wood species from the northeast agreste could be better used if there are evolution and technical support, including the possibility of reforestation.
2

Madeiras do agreste para uso em habitação / Wood of the agreste for use in house

Maria Fátima do Nascimento 22 April 1998 (has links)
A dissertação enfoca as possibilidades e desenvolvimento de estudos das espécies de madeiras do Nordeste do Brasil para uso em habitação. Desenvolveu-se um breve estudo antropológico para reconhecimento da região. No Brasil, os maiores centros de estudos das espécies de madeira estão localizados da região sul e sudeste, desta forma foi feito um estudo tecnológico e a caracterização de uma das espécies de madeira do agreste do NE - Mimosa Caesalpiniaefolia Benth - Sabiá. Os resultados obtidos de caracterização anatômica, mecânica e física, foram bastante satisfatórias. Foram abordadas: resistência à compressão paralela e normal às fibras, tração paralela e normal às fibras, cisalhamento, fendilhamento. No âmbito de caracterização física foram analisados a retratibilidade e densidade. Microscopicamente, foi analisado as lâminas para obtenção de resultados no que tange as fibras, raios e vasos. Através destes estudos, conclui-se que a espécie em questão, tem possibilidades positivas para aplicação na habitação, bem como no uso da construção civil. Deduziu-se ainda que as espécies de madeira do agreste do NE, podem ter melhor proveito, a partir de evolução e apoio técnico, incluindo a possibilidade de reflorestamento. / In Brazil, the biggest study centers of wood species are located in the south and southeast regions. A brief study to reconnaissance of the area has been done. This dissertation discusses the possibilities and the development of wood species studies in the brazilian northeast with the purpose of being used in habitation. A technological study to characterize one of the wood species from the northeast rural area (dry area) - Mimosa Caesalpiniaefolia Benth - Sabiá, has been developed. The results obtained from the anatomical, mechanical and physical characterizations have been very satisfactory. What has been analyzed: strength to parallel and normal compression to the fibers, parallel and normal tension to the fibers, sheer and clefting. Concerning the physical characterization, the retractility and the density were analyzed. Microscopically, the plates used in order to obtain results concerning the fibers, rays and vases, were analyzed. It was possible to conclude from these studies that the species in question have positive possibilities to be applied to habitation, as well as to civil construction usage. Furthermore, we could also conclude that the wood species from the northeast agreste could be better used if there are evolution and technical support, including the possibility of reforestation.
3

Development of production of Lentinula edodes (Shiitake mushrooms) on inoculated logs of a range of tree species

Aji, Irwan Mahakam Lesmono January 2009 (has links)
Shiitake (Lentinula edodes (Berkeley) Pegler) produces an edible mushroom that has been cultivated for centuries in China, Korea, Japan, Singapore, Thailand and other Asian countries. Shiitake mushrooms grow naturally on decaying wood of hardwood trees and have traditionally been grown on short lengths of freshly-cut logs. Until now, there has been no serious exploration of the potential for Australian forest owners to utilise small logs of native or plantation forest species for shiitake mushroom production, such as eucalypt (Eucalyptus spp.). / Logs of six tree species were harvested from farm forestry plantations in Victoria and inoculated with shiitake infected dowels imported from the United States. Over the course of the next 18 months the logs were soaked four times to initiate fruiting. The fresh mushrooms were harvested and weighed to allow a comparison between log species and size. A sample of the mushrooms from each log species produced in the 2nd and 3rd fruiting were tested for their protein and fibre content. / Quercus robur was the most productive species. Over the course of the trial (four frutings) the oak logs produced almost 1 kilogram of fresh mushrooms per log which was significantly more than E. cladocalyx (527 g/log) and Alnus glutinosa (465 g/log) and Eucalyptus nitens (389 g/log) which were all, in turn, significantly more productive than Populus sp. (140 g/log) and Acacia melanoxyon (98 g/log). Larger logs produced more fruit although this may have been related to the greater number of inoculations. The protein and fibre content of mushrooms produced from shining gum logs was slightly lower than that from the oak logs but greater than that from alder. Sugar gum mushrooms had the lowest protein content. / The research suggests that there is potential to use eucalypt logs thinned from young fast-grown farm plantations as the basis for a log-based shiitake industry although more work is required to test the marketability of eucalypt grown shiitake and the economic viability of small scale production units.
4

Development of production of Lentinula edodes (Shiitake mushrooms) on inoculated logs of a range of tree species

Aji, Irwan Mahakam Lesmono January 2009 (has links)
Shiitake (Lentinula edodes (Berkeley) Pegler) produces an edible mushroom that has been cultivated for centuries in China, Korea, Japan, Singapore, Thailand and other Asian countries. Shiitake mushrooms grow naturally on decaying wood of hardwood trees and have traditionally been grown on short lengths of freshly-cut logs. Until now, there has been no serious exploration of the potential for Australian forest owners to utilise small logs of native or plantation forest species for shiitake mushroom production, such as eucalypt (Eucalyptus spp.). / Logs of six tree species were harvested from farm forestry plantations in Victoria and inoculated with shiitake infected dowels imported from the United States. Over the course of the next 18 months the logs were soaked four times to initiate fruiting. The fresh mushrooms were harvested and weighed to allow a comparison between log species and size. A sample of the mushrooms from each log species produced in the 2nd and 3rd fruiting were tested for their protein and fibre content. / Quercus robur was the most productive species. Over the course of the trial (four frutings) the oak logs produced almost 1 kilogram of fresh mushrooms per log which was significantly more than E. cladocalyx (527 g/log) and Alnus glutinosa (465 g/log) and Eucalyptus nitens (389 g/log) which were all, in turn, significantly more productive than Populus sp. (140 g/log) and Acacia melanoxyon (98 g/log). Larger logs produced more fruit although this may have been related to the greater number of inoculations. The protein and fibre content of mushrooms produced from shining gum logs was slightly lower than that from the oak logs but greater than that from alder. Sugar gum mushrooms had the lowest protein content. / The research suggests that there is potential to use eucalypt logs thinned from young fast-grown farm plantations as the basis for a log-based shiitake industry although more work is required to test the marketability of eucalypt grown shiitake and the economic viability of small scale production units.
5

Seleção de especies arboreas tropicais prioritarias para a conservação : o caso da Estação Ecologica de Caetetus

Stella, Andre 09 February 2002 (has links)
Orientador : Paulo Yoshio Kageyama / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-02T09:14:25Z (GMT). No. of bitstreams: 1 Stella_Andre_M.pdf: 10711050 bytes, checksum: 297037a1994968f5793c631d00f8e345 (MD5) Previous issue date: 2002 / Resumo: Foi testada uma metodologia de seleção de espécies arbóreas tropicais prioritárias para a conservação. O estudo foi conduzido na Estação Ecológica de Caetetus, uma unidade de conservação de proteção integral, administrada pelo Instituto Florestal, no estado de São Paulo. Foram definidos critérios de pontuação e foi usado o método dos algoritmos para a classificação das espécies em ordem de importância para a conservação. A partir de um total de 214 espécies lenhosas conhecidas, cinco prioritárias foram selecionadas para estudos posteriores: Myroxilum peruiferum; Euterpe edulis; Chorisia speciosa; Hymenaea courbaril e Jacaratia spinosa. As populações destas espécies foram investigadas in situ procurando-se realizar um levantamento preliminar da distribuição de indivíduos adultos e da regeneração; quatro espécies apresentaram densidade entre baixa e média (até 10 árvores/ha), enquanto que E. edulis mostrou-se em alta densidade somente em áreas muito úmidas; duas espécies apresentaram exigências a fatores limitantes (umidade e luz); foi concluído que as amostragens foram insuficientes e que um esforço amostral de 2 ha pode ser pequeno para aquelas espécies. A análise do sistema dos algoritmos, bem como a da seleção e uso dos critérios revelou pontos fortes e pontos fracos da metodologia, tendo sido concluído que a metodologia pode ser útil para a seleção de espécies arbóreas tropicais para diferentes fins; foi sugerido que o estudo seja continuado, de forma a corrigir suas eventuais falhas / Abstract: An algorithmic method, composed of 17 criteria, was tested in order to do the assessment of priority wood species for conservationists' purposes in tropical areas. The research was conduced in a semi-deciduous seasonal forest, inside the 'Caetetus' Ecological Station, a protected area located in the countryside of São Paulo state, BraziL All the tree species were classified in order of importance for the conservation of the genetic resources of the forest. From a survey of 214 tree species, five were selected for further research: Myroxilum peruiferum; Euterpe edulis; Chorisia speciosa; Hymenaea courbaril and Jacaratia spinosa. A preliminary survey of their regeneration and adults population was conduced; the results pointed that two of them have specific environmental requirements (moisture or light); four of them occur in low to medium density (< 10 tree/ha); and showed the needing of higher sampling efforts. The algorithmic systematic and the selection of the criteria was discussed, pointing some strong and other weak points of the method; it was concluded that this analyses could be used for the assessment of tropical wood species; and it was suggested that the weaker points should be corrected in a further research / Mestrado / Mestre em Biologia Vegetal
6

Evaluation of five hardwood species from Zambia to produce fuel pellets for cooking purposes : Study with a single pellet press including pellet production, post production testing and X-ray examinations / Utvärdering av fem lövträslag från Zambia för att producera bränslepellets för matlagningsändamål : Studie med en enpetarpress inklusive pelletstillverkning, efterproduktionsprovning och röntgenundersökningar

Silvennoinen, Annika January 2023 (has links)
81% of the population in sub-Saharan Africa relies on charcoal and firewood to cover their energy needs for cooking. In Africa charcoal is usually produced by burning tree in a traditional kilns and then the food is cooked with a carbon-fired stoves indoors. All that links to three problems; deforestation, health issues and overpopulation, all of which can be reduced with a pellet cooking stove. Zambia in sub-Saharan Africa consumes charcoal equivalent to 6,089,000 tons of firewood each year. The total consumption of firewood being 13,967,000 tons per year. That leads to harvesting rate between 250,000 and 300,000 hectares each year making Zambia having one of the world’s fastest deforestation rates. Deforestation can be reduced by using the energy from the wood more efficient. In charcoal production and heating with charcoal about 72-86% of the produced energy is released to the atmosphere resulting the efficiency rate of only 14-28%. In comparison pellet production efficiency rate is 70-83%. Therefore if fuel pellets are used for cooking purposes energy instead of charcoal efficiency increases by 42-69% leading to lower need of wood material to cover equal energy demand. In this study five hardwood species and a softwood reference material from Zambia has been evaluated for fuel pellet production purposes. Evaluated hardwood species are Umsafwa, Umupundu, Umusamba, Umwenge and Umutondo. Reference material is already in use for pellet production in Zambia. Evaluation includes pellet production in a single pellet press, post production testing and X-ray examinations for tree different moisture contents; 8%, 10% and 12%. Pellet production includes friction energy, maximal friction energy and compression energy measurements. Post production testing includes density and hardness testing as well as X-ray examinations that indicate the amount of produced ash in the combustion process. High compression energy means higher energy cost in production so low compression energy is a desired property. Umupundu was the only wood species whose moisture content had no effect on the amount of compression energy. Umsamba and Umutondo gave the lowest and Umupundu and Umsafwa the highest compression energies of the tested hardwood pellets. Almost all of the friction energies of the tested materials were close to one another. The biggest exception was Umsafwa with 8% moisture content which had 38% higher friction energy than the reference material on average in this study. The values of the friction energy are low compared with other studies but within the reasonable limits compared with the reference material. A clear linear relationship was found between the friction energy and Fmax, so the friction energy directly implies the magnitude of the force of Fmax. A high hardness value is desirable because high hardness links directly to pellets high durability. All hardwood species tested were harder than the reference material. Ash significantly shortens the service life of the pellet stove, therefore it is desirable to produce as little ash as possible. Umsafwa and Unwenge has the lowest amount of metals that indicates the smallest amount of ash formed when burning pellets. Umsafwa with MC of 12% and Umwenge with MC of 10% are the best mix based on this study. / 81% av befolkningen i Afrika söder om Sahara är beroende av träkol och ved för att täcka sitt energibehov för matlagning. I Afrika produceras träkol vanligtvis genom att träden bränns i en traditionell ugn och sedan tillagas maten med en koleldad spis inomhus. Det leder till tre problem; avskogning, hälsoproblem och överbefolkning, allt detta kan minskas med en pellets spis. I Zambia förbrukar träkol motsvarande 6 089 000 ton ved varje år, och den totala förbrukningen av ved är 13 967 000 ton per år. Det leder till en avverkningstakt på mellan 250 000 och 300 000 hektar varje år vilket gör att Zambia har en av världens snabbaste avskogningshastigheter. Avskogningen kan minskas genom att energin från veden används mer effektivt. Vid produktion och användning av träkol frigörs cirka 72-86% av den producerade energin till atmosfären, vilket resulterar i en användningsgrad på endast 14-28%. Vid pelletstillverkning är motsvarande värde mycket högre, 70-83%. Om bränslepellets används istället för kol för matlagningsändamål ökar därför energieffektiviteten med 42-69%, vilket leder till lägre behov av trämaterial för att täcka lika energibehov. I denna studie har fem lövträslag och ett referensmaterial av barrträd från Zambia utvärderats för produktion av bränslepellets. De utvärderade lövträslag är Umsafwa, Umupundu, Umusamba, Umwenge och Umutondo. Referensmaterialet används redan för pelletstillverkning i Zambia. Utvärderingen inkluderar pelletsproduktion i enpetarpress, efterproduktionstestning och röntgenundersökningar för trädens olika fukthalter; 8%, 10% och 12%. Pelletsproduktion omfattar friktionsenergi, maximal friktionsenergi och mätningar av kompressionsenergi. Testning efter produktion inkluderar densitets- och hårdhetstestning samt röntgenundersökningar som indikerar mängden producerad aska i förbränningsprocessen. Hög kompressionsenergi innebär högre energikostnad i produktionen alltså låg kompressionsenergi är en önskad egenskap. Umupundu var det enda träslag vars fukthalt inte hade någon effekt på mängden kompressionsenergi. Umsamba och Umutondo gav de lägsta och Umupundu och Umsafwa de högsta kompressionsenergierna av de testade lövträpellets. Nästan alla friktionsenergier för de testade materialen låg nära varandra. Det största undantaget var Umsafwa med 8% fukthalt som hade 38% högre friktionsenergi än referensmaterialet i genomsnitt i denna studie. Värdena på friktionsenergierna är låga jämfört med andra studier men inom de tillåtna gränserna jämfört med referensmaterialet. Ett tydligt linjärt beroende hittades mellan friktionsenergin och Fmax, således friktionsenergin antyder direkt storleken på kraften hos Fmax. Ett högt hårdhetsvärde är önskvärt eftersom det kopplas direkt positivt till pellets hållbarhet. Alla lövträslag som testades var hårdare än referensmaterialet. Ask förkortar pelletskaminens livslängd avsevärt, därför är det önskvärt att producera så lite aska som möjligt. Umsafwa och Unwenge har den lägsta mängden metaller som anger den minsta mängd aska som bildas vid förbränning av pellets. Umsafwa med MC på 12% och Umwenge med MC på 10% är den bästa mixen baserat på denna studie.
7

Industrial Requirements for Cross-Laminated Timber Manufacturing

Torneport, Matilda January 2021 (has links)
Wood is a valuable sustainable material that meets the requirements for structural application. Cross-laminated timber (CLT) is a wood-based product that is mainly used in the building industry. Due to the rapid global market increase, a number of new CLT plants are emerging worldwide and thereby a need for standardisation is more than ever. There is no existing harmonised standard for CLT and it means a diversity between manufacturers, CLT products and its layup, which may in turn affects the properties of available CLT in the market. Therefore, this study was performed through literature study and internet-based interviews from five manufacturer in Sweden and Central Europe, to provide more information regarding the industrial requirements for CLT production. Three specific objectives of this study were: (1) wood and adhesive types in CLT production, (2) wood strength classes for CLT production, (3) important requirements for CLT producers and existing standards.   Literature review and interviews showed that spruce (Picea abies L. Karst.) in combination with polyurethane (PUR) adhesive is the most commonly used materials in Europe for CLT production, which are approved by EN 16351 (2021). Other wood species, e.g., pine, poplar and birch can be used or are already used in a minor extent. Strength classes for lamellas in CLT are often C24, but timbers with lower strength grades are possible. Some manufacturer use combinations of different strength graded timber and in this small scale study different strength graded timber was in generally the biggest diversity between manufactures. Only a few material properties such as modulus of elasticity, modulus of rupture, compression and shear strength are listed in EN 16351 (2021) and EN 338 (2016), as the factors for quality measurements of the CLT products. This study, however, showed that the critical material properties for the most interviewed CLT producers are merely modulus of elasticity and rarely modulus of rupture.
8

Factors Affecting the Corrosivity of Pulping Liquors

Hazlewood, Patrick Evan 11 April 2006 (has links)
Increased equipment failures and the resultant increase in unplanned downtime as the result of process optimization programs continue to plague pulp mills. The failures are a result of a lack of understanding of corrosion in the different pulping liquors, specifically the parameters responsible for its adjustment such as the role and identification of inorganic and organic species. The current work investigates the role of inorganic species, namely sodium hydroxide and sodium sulfide, on liquor corrosivity at a range of process conditions beyond those currently experienced in literature. The role of sulfur species, in the activation of corrosion and the ability of hydroxide to passivate carbon steel A516-Gr70, is evaluated with gravimetric and electrochemical methods. The impact of wood chip weathering on process corrosion was also evaluated. Results were used to identify black liquor components, depending on the wood species, which play a significant role in the activation and inhibition of corrosion for carbon steel A516-Gr70 process equipment. Further, the effect of black liquor oxidation on liquor corrosivity was evaluated. Corrosion and stress corrosion cracking performance of selected materials provided information on classes of materials that may be reliably used in aggressive pulping environments.
9

Caractérisation et valorisation des substances extractibles de cinq essences camerounaises majeures de l'industrie du bois : Ayous, Moabi, Movingui, Padouk et Tali / Characterization and valorization of extractives substances of five cameroonians species of major wood industry : Ayous, Moabi, Movingui, Padouk and Tali

Saha Tchinda, Jean-Bosco 29 October 2015 (has links)
Au cours de ce travail, le taux d’extractibles de cinq essences camerounaises a été évalué par la technique d’extraction accélérée ASE 200 et au Soxhlet. Le taux d’extractibles varie de 4,4 à 17,7%. Le screening des extraits a révélé la présence de polyphénols, de saponines, de flavonoïdes, de stérols et de terpènes. Les phénols totaux contenus dans les extraits ont été évalués par la méthode de Folin–Ciocalteu en utilisant l’acide gallique comme standard. La teneur varie de 16,5 à 165,83 mg éq acide gallique / g d’extrait. Le dosage des tannins condensés par la méthode colorimétrique a permis de montrer que ces derniers varient de 0,15 à 23,61 g cyanidin équivalents / 100 g de matière sèche. L’identification des composés contenus dans les extraits par GC-MS a permis d’identifier de l’homopterocarpine et de la pterocarpine dans les extraits de padouk. Les extraits de tali contiennent de la catéchine, l’acide gallique et du pyrogallole. L’acide gallique, le squalène et les triterpènes sont les composés majoritairement identifiés dans les extraits de movingui. La durabilité naturelle des bois a été évaluée par la norme européenne EN 350-1, 1994. Il ressort que les pertes de masse deviennent plus importantes lorsque les éprouvettes de bois ont été extraites. La perte de masse des éprouvettes non extraites varie de 0,1 à 59% (le hêtre a été pris comme référence). Les essais d’inhibition de croissances sur les champignons de pourriture ont montré qu’à des concentrations de 250 ppm, nos extraits étaient fongistatiques et qu’à des concentrations de 500 ppm certains extrait étaient fongicides (extrait de tali). L’évaluation des propriétés antioxydante et colorante des extraits pour envisager de potentielles applications industrielles a été effectuée. Le pouvoir antioxydant des extraits a été évalué par la méthode d’inhibition du linoléate de méthyle induite par l’azobisisobutyronitrile (AIBN). Les résultats obtenus sont satisfaisants car l’activité antioxydante varie de 10 à 86%. Le pouvoir anti-radicalaire des extraits a été évalué en utilisant le radical 2,2-diphényl-1-picrylhydrazyl (DPPH.). Les concentrations nécessaires pour consommer 50% du radical varie de 2,7 à 60,5 mg/L. La capacité des extraits aqueux et alcalins à teindre les fibres naturelles et artificielles a été évaluée. La mesure de la coloration prise par les fibres s’est faite à l’aide d’un colorimètre Datacolor D65°10. Les résultats montrent que ces extraits donnent une coloration jaune avec les extraits de movingui et une coloration rouge avec les extraits de padouk. L’utilisation des extraits pour inhiber la croissance bactérienne a montré que les extraits étaient bactériostatiques pour les concentrations testées / In this work, the accelerated technical ASE 200 and Soxhelet was used to evaluate the amount of extractives contained in five Cameroonian wood species. The amount of extractives ranged from 4.4 to 17.7% with respect to oven-dry matter. Phytochemical screening of the extractives revealed the presence of polyphenols, saponins, flavonoïds, sterols and terpenes. The total phenolic content of the extracts was measured by the Folin-Ciocalteu method using gallic acid as standard. The phenolic content ranged from 16.5 to 165.83 mg eq gallic acid/g of extract. The condensed tannins, evaluated by colorimetric method, ranged from 0.15 to 23.61 g cyanidin equivalents/100 g of dry matter. GC-MS identified the homopterocarpine and pterocarpin as major compound in extracts of padouk. Catechin, gallic acid and pyrogallole were the major compounds found in the extracts of tali. Extracts of movingui consisted mainly of diterpenes and several compounds not readily identifiable. Gallic acid, squalene and triterpenes were the predominant compounds identified in the extracts of movingui. The natural durability of wood was evaluated using the European Standard EN 350-1. Mass losses increased when the wood samples were extracted. Mass losses of non-extracted samples ranged from 0.1 to 59% (with beech taken as a reference). The effect of extractives on fungal growth showed that at 250 ppm concentrations, the extracts were fungistatic and that at 500 ppm concentrations, the extracts of tali were fungicidal.Valorization of the extractives in the food and the textile industries was attempted. In food, the antioxidant activity of the extracts by inhibition of methyl linoleate induced by AIBN was evaluated. The results obtained were satisfactory because all the extracts showed antioxidant activity which varied from 10 to 86%. Then the anti-radical capacity of our extracts was assessed by the DPPH method. The concentration necessary to consume 50% of DPPH varied from 2.7 to 60.5 mg/L. Aqueous and alkaline extracts were used to dye natural and artificial fibers. The coloration taken by the fibers was measured using a Datacolor D65°10 apparatus. These extracts gave a yellow color with extracts of movingui and a red color with extracts of padouk. The effect of extractives on bacteria growth showed that the extracts were bacteriostatic at the tests concentrations
10

Wood/Polymeric Isocyanate Resin Interactions: Species dependence

Das, Sudipto 28 September 2005 (has links)
The performance of polymeric diphenylmethane diisocyanate (PMDI) resin is known to be highly dependent on the wood species. This species dependence may be due to differences in: cure chemistry, interphase morphology, or both of these factors. This study addresses aspects of the cure chemistry and interphase morphology of wood/PMDI bondlines; specifically these effects are compared using two woods: yellow-poplar and southern pine. In this study, the cure chemistry of wood-PMDI system was analyzed with solid state NMR (SSNMR) using wood samples cured with doubly labeled (15N,13C) PMDI resin. The kinetics of PMDI cure in the presence of wood was analyzed with differential scanning calorimetry. Thermogravimetric analysis was used to analyze the effect of resin impregnation on the degradation patterns of wood. The wood-PMDI bond morphology was probed with dynamic and static (creep) mechanical analyses in both dry and plasticized conditions. The effect of resin on wood polymer relaxations was quantitatively analyzed by both the time-temperature superposition principle and the Kohlrausch-Williams-Watts equation. The presence of a small but statistically significant species effect was observed on both the cure chemistry and bond morphology of wood-PMDI system at low cure temperatures. The cure of PMDI resin was found to be significantly faster in pine relative to corresponding poplar samples. Resin impregnation showed a significant species dependent effect on the wood mechanical properties; the resinated pine samples showed increase in compliance while the corresponding poplar samples became stiffer. The in situ lignin relaxation was studied with both dynamic and static modes, using plasticized wood samples. Results showed that the lignin relaxation was slightly affected by resin impregnation in both woods, but the effect was relatively larger in pine. Static experiments of dry wood samples showed a significant reduction in the interchain interactions of wood polymers in pine samples, exclusively. Investigation of plasticized pine samples, which focuses on the in situ lignin relaxations, showed only minor changes with resin impregnation. This led us to hypothesize that the large changes observed in dry samples, were due to the in situ amorphous polysaccharides. The wood-PMDI interactions were significantly reduced upon acetylation of wood. This study also discusses three new and highly sensitive methods for the analysis of wood-resin interactions. / Ph. D.

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