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INFLUÊNCIA DE DIFERENTES COMBINAÇÕES DE LÂMINAS DE Eucalyptus saligna E Pinus taeda EM PAINÉIS ESTRUTURAIS LVL / THE INFLUENCE OF DIFFERENT COMBINATIONS OF Eucalyptus saligna AND Pinus taeda VENEERS IN LVL STRUCTURAL PANELSMüller, Marcos Theodoro 29 May 2009 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This research aimed at investigating the influence of the positioning of Eucalyptus saligna and Pinus taeda wood veneers on the layers composing the Laminated Veneer Lumber (LVL) structural panels. The panels were manufactured in six different combinations of five veneers of 3,2 mm, glued with phenol-formaldehyde, resulting in treatments constituted of wood of the same species or with a composition of the two wood types. The evaluation of the proposed combinations was performed under the characterization of physical properties (moisture content, density, water absortion, thickness swelling and volumetric expansion) and mechanical properties verified in flatwise and edgewise static bending (modulus of elasticity, stress at the proportional limit and modulus of rupture). The quality of the adhesive wood bonding
was evaluated through the glue line shear strength by compression loading and the percentage of wood failure. Wood bonding tests were done with wood of the same
species and wood of two studied types. The results obtained indicated that, in most situations, the different positionings of the veneers with larger density (in the outer, intermediate and inner layers) influenced the mechanical properties of the panels. The influence detected was varied, especially for MOE and MOR when comparing the flatwise and edgewise experimented positions. In certain positions, in the layers
of the LVL compositions, the presence of eucalypt veneers resulted in stiffness and strength increases. In dry shear the resistances of the joints were shown to be
equivalent; after boiling, the joints in eucalypt veneers presented larger strength. The percentage of wood failure was above 80% (in eucalypt veneers) and above 90% (in
pine and mixed veneers) and maintained stable after boiling, indicating good gluing
quality for all the tested wood bondings. However, it was verified that the adhesive
wood bonding of eucalypt and pine was shown more reliable than the bonding
between eucalypt veneers. Therefore, the treatments formed by interposed veneers
of eucalypt and pine presented a better combination of performance and reliability for
the properties of stiffness, strength and adherence. / Investigou-se a influência do posicionamento de lâminas de madeira de Eucalyptus saligna e Pinus taeda nas camadas componentes de painéis estruturais Laminated Veneer Lumber (LVL). Os painéis foram manufaturados em seis diferentes
combinações de cinco lâminas de 3,2 mm de espessura, coladas com adesivo fenolformaldeído, resultando em tratamentos constituídos de madeira de uma mesma
espécie e outros com mistura de madeira das duas espécies. A avaliação das combinações propostas foi realizada mediante a caracterização de propriedades físicas (teor de umidade, massa específica, absorção de água, inchamento em
espessura e expansão volumétrica) e propriedades mecânicas, verificadas em ensaios de flexão estática flatwise e edgewise (módulo de elasticidade, tensão no limite proporcional e módulo de ruptura). A qualidade da colagem foi avaliada por
meio da resistência ao cisalhamento na linha de cola por ensaio de compressão e do percentual de falha na madeira. Foram testadas colagens de madeira de mesma espécie e entre madeiras das duas espécies estudadas. Os resultados obtidos indicaram que, na maior parte das vezes, os diferentes posicionamentos das lâminas de maior massa específica (nas camadas externas, intermediárias e de miolo)
influíram nas propriedades mecânicas dos painéis. A influência constatada mostrouse variada, em especial para MOE e MOR, quando comparados os valores para as posições de ensaio flatwise e edgewise. Em determinadas posições, nas camadas
das composições LVL, a presença de lâminas de eucalipto resultou em aumentos de rigidez e resistência. Em cisalhamento a seco, as resistências das juntas se mostraram equivalentes; entretanto, após fervura, as juntas entre lâminas de eucalipto apresentaram maior resistência. Os percentuais de falha na madeira foram superiores a 80% (entre lâminas de eucalipto) e a 90% (entre lâminas de pinus e em juntas mistas) e se mantiveram estáveis após a fervura, indicando boa qualidade de adesão para todas as colagens testadas. Entretanto, a colagem entre eucalipto e
pinus mostrou-se mais confiável que a colagem entre lâminas de eucalipto. Contudo, os tratamentos formados por lâminas intercaladas de eucalipto e pinus apresentaram uma melhor combinação de performance e confiabilidade para as
propriedades de rigidez, resistência e aderência.
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Dimensionsstabile und pilzresistente Furnierwerkstoffe durch Zellwandmodifizierung mit niedermolekularem Phenol-Formaldehyd / Dimensional stable and fungal decay resistant veneer-based composites via cell wall modification with low-molecular-weight phenol formaldehydeBicke, Sascha 16 September 2019 (has links)
No description available.
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Assessing wood failure in plywood by deep learning/semantic segmentationFerreira Oliveira, Ramon 09 December 2022 (has links)
The current method for estimating wood failure is highly subjective. Various techniques have been proposed to improve the current protocol, but none have succeeded. This research aims to use deep learning/semantic segmentation using SegNet architecture to estimate wood failure in four types of three-ply plywood from mechanical shear strength specimens. We trained and tested our approach on custom and commercial plywood with bio-based and phenol-formaldehyde adhesives. Shear specimens were prepared and tested. Photographs of 255 shear bonded areas were taken. Forty photographs were used to solicit visual estimates from five human evaluators, and the remaining photographs were used to train the machine learning models. Twelve models were trained with the combination of four image sizes and three dataset splits. In comparison to visual estimates, the model trained on 512 × 512 image size with 90/10 dataset split had a mean absolute error (MAE) of 6%, which was the best among the literature.
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Enhancement of Phenol Formaldehyde Adhesive with Crystalline Nano CelluloseEkstrand, Johan January 2019 (has links)
Abstract The wood industries to this day use almost exclusively petroleum derived adhesives that are based mainly on the reaction of formaldehyde with urea, melamine or phenol. These adhesives have low cost and good adjustable properties which makes it hard for bio-based alternatives to compete. Phenol formaldehyde (PF), as an example of a synthetic adhesive, has been in use for over 100 years. In some parts of the world, legislation around formaldehyde is changing, and there is an increasingly voluntary awareness about the toxicity and unsustainability of formaldehyde. Industries realize that raw materials from oil is unstainable. The latter is currently a driving factor behind research on alternatives to amino based adhesives. Also, consumer interest in healthy and sustainable products, such as emitting less formaldehyde indoors, increases the need for bio based adhesives. Cellulose contained in plant cell walls is a renewable, abundant and nontoxic resource. During the last decades, many innovations have been achieved around cellulose and this trend does not seem to be slowing down. Cellulose shows excellent mechanical properties, high strength, high elastic modulus as well as having a low density. Research about cellulose reinforced adhesives has been increased the last years. This thesis studied the enhancement of phenol formaldehyde adhesive with Crystalline Nano Cellulose (CNC) at 5wt% and 10wt% loading levels for producing plywood boards. Indecisive results when using CNC higher than 3wt%, especially with PF resin, have been reported by other authors. In this thesis, European standards were applied. EN 314 was applied to test the panels shear strength. Three (3) treatment classes were selected, indoor room condition as well as pre-treatments 5.1.1 and 5.1.3. Other properties measured were modulus of elasticity, thickness swelling, formaldehyde emissions. Results showed a shear strength increase for all pre-treatment classes. 10wt% CNC mixture with phenol formaldehyde in water bath, pre-treatment (5.1.1) for 24h showed the highest increase in shear strength (+73,9%). The 10 wt% CNC mixture panels also showed the highest wood fibre failure of all panel types produced. A decrease in MOE has been observed with 10 wt% CNC compared to the 5 wt% CNC panels. Formaldehyde emissions tests were inconclusive, but since less PF was used, there was a general reduction in emissions. The 5 wt% CNC panels were superior in terms of modulus of elasticity and swelling and also showed improved shear strength.
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Novas estruturas fotônicas: I – Auto-organização de estruturas 1D de Te; II – Biopolímeros e plásticos reutilizados multifuncionais / New photonic structures: I – Self assembly of 1D Te structures; II – Multifunctional biopolymers and reused plasticsSilva, Robson Rosa da [UNESP] 23 May 2016 (has links)
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Previous issue date: 2016-05-23 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Nanoestruturas unidimensionais de telúrio (Te1D) na forma de whiskers, fios e hélices foram preparados com facilidade por uma síntese em etapa única na presença de solução aquosa de Pluronic® F68 à baixas temperaturas (< 100 °C) e pressão ambiente. A forma das nanoestruturas puderam ser controladas de acordo com a cinética da reação. Estruturas empacotadas de nanowhiskers e nanofios de Te foram obtidas via auto-organização em interface líquido-líquido e pela técnica de drop-cast em substrato de Si/SiO2. Estruturas híbridas 1D foram obtidas utilizando nanoestruturas Te1D como molde de sacrifício para anexar nanopartículas metálicas ou mesmo produzir nanoestruturas 1D metálicas. Por exemplo, nanoestruturas híbridas 1D foram preparadas decorando nanofios de Te com nanopartículas de Ag em solução aquosa de poli(vinilpirrolidona). Nanoestruturas 1D de Au com forma de nódulos foram preparados por deslocamento galvânico de íons Au3+ em uma mistura de nanohélices de Te, ácido ascórbico e solução aquosa de poli(vinilpirrolidona). Além disso, nanohélices de Te foram funcionalizadas com uma camada resina resorcinol-formaldeído em condições brandas de síntese. A resina de resorcinol-formaldeído é uma via intermédia para explorar a deposição de compostos opticamente ativos tais como nanopartículas de hidroxicarbonato de Tb3+ ou nanopartículas de Au. Para aplicações práticas é essencial que estas nanoestruturas possam ser suportadas em filmes rígidos ou flexíveis de alta qualidade óptica. Filmes de polímeros naturais puros e filmes híbridos de sol-gel epóxi foram avaliados como potenciais matrizes hospedeiras para luminóforos. A fabricação de híbridos é baseada na incorporação de 3-glicidoxipropiltrimetoxissilano na solução homogênea de polímero natural com posterior secagem sobre uma superfície plana. Particularmente, filmes flexíveis de fibroína da seda e acetato de celulose e os seus híbridos derivados exibiram excelentes propriedades ópticas para hospedar compostos opticamente ativos. Por exemplo, compostos de Eu3+ emissores na região do vermelho e corantes fluorescentes foram incorporados em matriz pura de polímero e híbridos epóxi e suas propriedades ópticas foram investigadas. Laser de corantes por feedback distribuído (DFB) foram fabricados dopando grades de difração de fibroína de seda com Rodamina 6G. Devido a sua capacidade de replicar superfícies padronizadas com resolução nanométrica, grades de fibroina da seda dopadas com corante foram depositadas contra a grade de difração de uma mídia de disco compacto comercial. Lasers modificados de DFB baseados em filmes de fibroina contendo nanopartículas espalhadoras de luz de SiO2 e Ag aleatoriamente distribuídas na grade de fibroina demonstraram aumento da intensidade do laser, além de estreitamento da largura do pico de emissão. Filmes híbridos flexíveis e transparentes (> 85%) de fibroina da seda e acetato de celulose modificados com função epóxi e contendo compostos fluorescentes na região do vermelho como complexos β-dicetonato de Eu3+ e nanopartículas de YVO4:Eu3+ em baixa proporção relativa mássica (<5%) foram preparados. De maneira geral, o resultado são filmes homogêneos com funções epoxi e/ou alcoxissilano não hidrolisados disponíveis para outras modificações químicas. Devido a matéria-prima limitada de polímeros naturais para uma alta demanda de fabricação de dispositivos ópticos, é igualmente importante desenvolver materiais com base na reutilização de polímeros sintéticos. Filmes finos de poliestireno foram concebidos por dissolução de poliestireno expandido (EPS) recuperado de resíduos em D-limoneno, um solvente verde proveniente de óleos cítricos. Filmes transparentes dopados com complexos β-dicetonato de Eu3+ demonstraram excelente transparência e aptos para uso em guias de luz. Estes resultados são motivadores para a) a engenharia de nanoestruturas 1D com propriedades ópticas sintonizáveis bem como, b) desenvolvimento de híbridos flexíveis e transparentes baseados em híbridos de polímeros naturais com alta funcionalidade química ou polímeros sintéticos reciclados como potenciais matrizes hospedeiras ópticas almejadas em aplicações fotônicas. / One-dimensional Te nanostructures (Te1D) in the shape of whiskers, wires and helices were prepared by a facile one-pot synthesis in the presence of aqueous Pluronic® F68 solution at low temperatures (< 100 ºC) and ambient pressure. The shape of Te1D nanostructures could be manuvered according with the reaction kinectics. We evaluate some techniques to assemble Te1D nanostructures on the pursuit for complex nanoarchitectures. Bundles of Te nanowhiskers and nanowires were achieved by self-assembly in liquid-liquid interface or by drop-cast technique in Si/SiO2 substrates. 1D hybrid structures have been conceived by using Te1D nanostructures as sacrificial template to attach metallic nanoparticles or even produce metallic 1D nanostructures. For example, 1D hybrid nanostructures were easily prepared by decorating Te nanowires with Ag nanoparticles in aqueous solution of poly(vinylpyrrolidone). Au 1D nanostructures with nodular-like shape were prepared by galvanic displacement of Au3+ ions in a mixture of Te nanohelices, ascorbic acid and an aqueous solution of poly(vinylpyrrolidone). Furthermore, Te1D nanohelices were functionalized with a layer of resorcinol-formaldehyde resin at mild synthesis conditions. The RF resin allowed us to fashion an intermediate pathway to explore the deposition of optically active compounds like Tb3+ hydroxylcarbonate or Au nanoparticles. Seeking practical applications, these nanostructures should be hosted over rigid or flexible films possessing excellent optical properties. Pure natural polymers and epoxy sol-gel hybrids films were evaluated as potential host for luminophors. The fabrication of epoxy hybrids is based on the incorporation of 3-glycidoxypropyltrimethoxysiloxane on the homogenous solution of natural polymer with subsequent casting over flat surface. Particularly, flexible silk fibroin and cellulose acetate films and their derivative hybrids displayed excellent optical properties to host optically active compounds. For instance, red emitting Eu3+ compounds and fluorescent dyes were hosted on pure natural polymer and hybrid films and the optical features of the luminescent films were investigated thoroughly. Distributed feedback dye-lasers were fabricated by doping silk fibroin diffraction gratings with Rhodamine 6G. Owing its ability to mimic patterned surfaces at nanoscale resolution, dye-doped SF gratings were fabricated using replica-casting patterning against a commercial blank digital versatile disc as template. A modified DFB Laser based on SF films with Ag or SiO2 light scattering particles randomly distributed on the grating unveiled an enhancement of laser intensity withal narrowing of emission peak linewidth. Flexible and highly transparent SF- and CA-epoxy hybrids (> 85%) containing red fluorescent Eu3+ b-diketonate complex and YVO4:Eu3+ nanoparticles at low relative content (< 5 wt%) were tailored. In general, the outcome is homogeneous films with epoxy and/or unhydrolized alkoxysilane functions available for further chemical modification.
Owing the limited feedstock of natural polymers for high demanding production of optical devices, it is equally important develop materials based on the reuse of synthetic polymers. Thin films of polystyrene were conceived by dissolving waste-recovered expanded-polystyrene (EPS) in D-limonene, a green solvent from citrus oil. Transparent EPS films doped with Eu3+ b-diketonate complex displayed excellent transparency and light waveguiding, These assertions provide a framework that motivates the research on a) engineering of 1D hybrids nanostructures with tunable optical properties and b) flexible natural polymer/epoxy hybrid with enhanced functionality or plastic recycled as potential optical hosts sought in photonic applications. / FAPESP: 2013/12367-6
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Painéis tecnológico do Eucalyptus benthamii para produção de painéis de partículas orientadas (OSB) / Tecnology potencial of Eucalyptus benthamii wood for orientes strand boards painels (OSB)Martarello, Larissa Pasa 30 May 2014 (has links)
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Previous issue date: 2014-05-30 / The present study aimed to evaluate technically the
feasibility of production of oriented strand board (OSB) of
Eucalyptus benthamii Maiden et Cambage 13 years of age
through different levels of resin and compositions of particles
between the layers of the mattress. Therefore, the
characterization of density and dimensional stability of solid wood
by NBR 7190 (1997) was performed. The experimental design for
the study on the OSB consisted of 8 treatments with four different
compositions between the layers (30:40:30 , 20:60:20 , 25:50:20
and 100%) and two percentages resin (4 and 6%). Three panels
were produced by treatment with dimensions of 49 x 42 x 1.5 cm,
which were subjected to a cycle of hot pressing temperature 180
°C, pressure of 40 kgf/cm2 for a time of 8 minutes. The
technological tests on panels were made according to the
procedures of ASTM D1037 (1996) and DIN 52362 (1982). The
statistical analysis used was a Factorial Analysis and Tukey Test
at 95% probability, as well as the comparison with the minimum
values specified in the standard CSA 0437 (1993). The results for
the physical properties of solid wood, it has been density of 0.53
g/cm3 with mean value and the realization of high dimensional
stability of the parts analyzed. Regarding physical properties of
the panels, it was found that the average density was 0.63 g/cm3
and swells for 2 hours and 24 hours were 12,35 % and 34,43 %,
respectively , which overcomes the maximum setting of 10 % to
24 hours of immersion in the standard CSA 0437 (1993). For
mechanical testing bending strength uniformity were observed
values of rupture and elastic modulus in the direction parallel
module, however, in perpendicular direction, an increase of the
values of strength and stiffness as it increased the amount of
particles in the inner layer of the mattress. For internal bond,
there was a strong influence of the increase in the percentage of
resin, with an average value of 0.36 MPa, thus, only treatments
with 6% resin reached the minimum values established by the
referenced standard. The results of this study indicate that
Eucalyptus benthamii can be an alternative for the production of
oriented strand board (OSB), through adjustments to be made in
the production process / O presente estudo teve por objetivo avaliar tecnicamente
a viabilidade da produção de painéis OSB a partir de toras de
Eucalyptus benthamii com 13 anos de idade por meio de
diferentes teores de resina e composições de partículas entre as
camadas do colchão. Para tanto, foi realizada a caracterização
da massa específica e da estabilidade dimensional da madeira
sólida por meio da NBR 7190(1997). O delineamento
experimental para o estudo relativo aos painéis OSB foi
composto por 8 tratamentos, com 4 diferentes composições entre
as camadas (30:40:30, 20:60:20, 25:50:20 e 100%) e duas
porcentagens de resina (4 e 6%). Foram produzidos 3 painéis por
tratamento com dimensões de 49 X 42 X 1,5 cm, os quais foram
submetidos a um ciclo de prensagem à quente de 180oC de
temperatura, 40 kgf/cm2 de pressão por um tempo de 8 minutos.
Os ensaios tecnológicos dos painéis foram feitos de acordo com
os procedimentos da ASTM D1037 (1996) e da DIN 52362
(1982). A análise estatística adotada foi a Análise Fatorial e
Teste de Tukey a 95% de probabilidade, bem como a
comparação com os valores mínimos especificados na norma
CSA 0437 (1993). Como resultado para as propriedades físicas
da madeira sólida, tem-se a massa específica aparente básica
com 0,53 g/cm3 de valor médio e a constatação da alta
instabilidade dimensional das peças analisadas. Quanto às
propriedades físicas dos painéis, constatou-se que a massa
específica média foi de 0,63 g/cm3 e os inchamentos para 2
horas e 24 horas foram de 12,35% e 34,43%, respectivamente, o
que supera o parâmetro máximo de 10% para 24 horas de
imersão pela norma CSA 0437 (1993). Para os ensaios
mecânicos de flexão estática, observou-se uma homogeneidade
dos valores de módulo de ruptura e de módulo de elasticidade no
sentido paralelo, no entanto, no sentido perpendicular, houve um
aumento nos valores de resistência e rigidez à medida que se
aumentava a quantidade de partículas na camada interna do
colchão. Para ligação interna, verificou-se uma forte influência do
aumento da porcentagem de resina nos resultados
apresentados, com valor médio de 0,36 MPa, assim, somente os
tratamentos com 6% de resina atingiram os valores mínimos
estabelecidos pela norma referenciada. Os resultados deste
estudo indicam que a madeira de Eucalyptus benthamii pode ser
uma alternativa para a produção de painéis de partículas
orientadas (OSB), mediante ajustes a serem realizados no
processo produtivo
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Entwicklung eines naturnahen Bindemittels aus nachwachsenden Rohstoffen auf Proteinbasis zur Herstellung von Mitteldichten Faserplatten / Development of a near-natural protein based bonding agent for the production of medium density fibreboardsSchöpper, Christian 15 March 2006 (has links)
No description available.
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