eng k49 materiais de origem vegetal aplicados na construção celularfibres 151.pdf · materiais...
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Celular Fibres
ENG K49 Materiais de origem vegetal aplicados na construo
Ricardo Fernandes Carvalho
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Materiais Fitogneos
Materiais fitogneos (de origem vegetal) Lignocelulsicos - conhecidos por fitomassa, porque eles so produzidos atravs da fotossntese;
"biobased", baseado em tecidos biolgicos. As fontes incluem: madeiras, resduos (agrcolas e agroindustrial), fibras vegetais, plantas aquticas, gramneas e outras substncias vegetais.
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As fibras naturais so substncias compostas principalmente por celulose, hemiceluloses (polioses) e lignina. As fibrilas de celulose so unidas naturalmente por uma macromolcula natural fenlica, a lignina, a qual est comumente presente nas paredes celulares das fibras vegetais, da o nome lignocelulsicos, com exceo para o lnter do algodo, que no contm lignina.
Materiais Fitogneos3
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Por serem fontes renovveis de recursos naturais,vm sendo convertidas atravs de processos deextrao, fermentao e pirlise em produtosqumicos, como insumos industriais e energiadesde a antigidade.
Vrios estudos e pesquisas vm sendodesenvolvidos com os materiais lignocelulsicos,visando o aproveitamento de culturas e resduosvegetais para a obteno de combustveis,fertilizantes ou matria-prima para as indstrias.
Materiais Fitogneos4
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Os materiais lignocelulsicos so constitudos principalmente de clulas esclerenquimtica chamadas de fibras, de clulas parenquimticas chamadas de medula (material no fibroso) e de clulas epidrmicas. Os materiais lignocelulsicos provenientes de fibras vegetais so classificadas de acordo com sua origem nas plantas:
Materiais Fitogneos5
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Materiais Lignocelulsicos
Fibras de tecido vivo (floema) dos caules, ou das partes internas das cascas, em feixes, tambm chamadas fibras moles para uso txtil;
Fibras de folhas, que correm no sentido do comprimento das folhas de monocotiledneas, tambm referidas como fibras duras;
Fibras de cabelos de sementes, principalmente algodo; constituindo as principais fontes de fibras vegetais.
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Existem cerca de 250.000 espcies de plantas superiores, mas menos de 0,1% so comercialmente importantes como fontes de fibras.
O estudo de materiais lignocelulsicos tem atrado grande interesse na indstria de polmeros, devido a sua utilizao como material de reforo em matrizes polimricas no desenvolvimento de novos materiais ou compsitos.
Materiais Lignocelulsicos7
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Celulose, as hemiceluloses (polioses), a lignina
extrativos orgnicos e inorgnicos Substncias de baixa massa molar chamados comumente (sais minerais - cinzas).
Variaes da proporo depende: diferenas genticas dentre as espcies, Tecidos especializados dentro das plantas e condies de crescimento e
Condies climticas e do solo.
Principais componentes8
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Componentes dos Materiais Lignocelulsicos
Extrativos
Substncias Orgnicas
Cinzas
Substncias Inorgnicas
Substncias de baixa massa molar
Lignina
Celulose Polioses
Polissacardeos
Substncias Macromoleculares
Materiais Lignocelulsicos
Principais componentes9
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Polssacardeos: celulose e hemiceluloses
Compostos aromticos: lignina
Compostos inorgnicos: sais extrativos: leos essncias, resinas (gomas), cinzas
Taninos, acares, etc.
Principais componentes10
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Celullarwall
Carbo-hydrate
CellulosesHemi-
celluloses
LigninAsh and
extractives
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Cellulose
Molecules are randomly oriented and have a tendency to form intra and intermolecular hydrogen bonds. The molecular chains pack in layers that are held together by weak
van der Waals forces. H2O interactions
X-ray diffraction experiments indicate that crystalline cellulose
Type of cellulose Crystalline and noncrystalline Accessible and nonaccessible
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Cellulose
Cellulose I or native cellulose has a space group symmetry where a = 16.34 and b = 15.72
Cellulose II is obtained by mercerization and regeneration of native cellulose
Cellulose III is formed by treatment of cellulose I with liquid ammonia at about 80C followed by evaporation of the ammonia.
Cellulose IV is formed by heating cellulose III in glycerol at 260C
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Principais componentes14
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Composio qumica aproximada de bagao integral, fibras e medula de vrias regies geogrficas (%)
Origem Tipo -Celulose Lignina Polioses Cinzas
EUA integral 36,8 21,3 29,4 2,9 (Louisana) fibra 38,7 20,7 30,0 2,0
medula 32,3 21,3 29,9 4,6 integral 34,9 22,3 31,8 2,3
Filipinas fibra 41,2 21,8 31,2 1,2 medula 34,9 22,5 33,2 2,6 integral 30,1 18,1 29,6 3,9
Porto Rico fibra 40,2 19,8 31,6 1,2 medula 32,6 18,8 31,9 3,2
frica do Sul integral --- 22,1 24,1 1,6 integral 36,5 - 38,8 27,6 - 28,4 19,4 - 21,6 1,3 - 2,0
Hava fibra 41,9 - 43,3 25,8 - 27,3 20,0 - 22,0 0,6 - 0,8 medula 33,1 - 36,4 27,6- 28,8 19,3 - 21,5 1,8 - 2,4 integral 38,3 20,7 25,2 2,6
Cuba fibra 40,4 19,5 25,1 1,4 medula --- 21,7 26,0 5,5
Brasil integral --- 20,3 27,8 1,6 (So Paulo) fibra --- 20,8 26,7 0,8
medula --- 20,2 28,5 3,0
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De acordo com a parte do vegetal de onde se originam as fibras vegetais comumente comercializadas podem ser agrupadas da seguinte maneira: 1) Sementes: algodo e pina (kapok). 2) Lber (floema): juta, linho, cnhamo, rami, papoula
de So-Francisco (Kenaf), crotalria e guaxima (malva).
3) Folha: sisal, abac, henequem, rfia, piaava e curau.
4) Fruto: babau (pericarpo) , coco (pericarpo) e bucha.
5) Caule: bamb, palhas de cereais, bagao de cana.
Materiais Lignocelulsicos16
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Indstria Automotiva 46.000 t/ano (23 kg/carro)
Construo Civil Indstria Moveleira Indstria Eletro/Eletrnica Indstria de Embalagens Indstria Farmacutica e Veterinria
Materiais Lignocelulsicos17
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0
10000
20000
30000
40000
50000
60000
70000
80000
1986 1988 1990 1992 1994 1996 1998 2000 2002 2004Anos
To
n
Consumo de Fibras Lignocelulsicasna Indstria Automobilstica Alem18
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0
20000
40000
60000
80000
100000
120000
140000
1980 1985 1990 1995 2000 2005 2010Anos
To
n Europa
Total
Consumo Total de Fibras Lignocelulsicaspela Indstria Automotiva Europia19
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Fibras Naturais Cultivada Mundialmente (%)
6414
10
8 2 2 JutaLinhoKenafSisalRamiHempCoco
Produo Proporcional20
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A01 EichhornAnsell21
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2900000
630000
470000
38000098000 72000
Juta
Linho
Kenaf
Sisal
Rami
Hemp
Coco
Fibras cultivadas no Mundo com usos Automobilsticos (%)22
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A00 Vincentshort technical note - Applied Composite Materials 7: 269271, 2000.
A UNIFIED NOMENCLATURE FOR PLANT FIBRES FOR INDUSTRIAL USE
The major cell type is sclerenchyma which has very thick lignified cell walls and is often associated with conducting tissue
Cell Wall Structure Fibres Celullose: cellulose is produced from rosette-shaped enzymes as microfibrils 5 nm in diameter. the small microfibrils to is fused into larger microfibrils about 20 nm in diameter.
Hemicellulose is a polysaccharide somewhat less perfectly crystalline than cellulose
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A00 Vincentshort technical note - Applied Composite Materials 7: 269271, 2000.
A UNIFIED NOMENCLATURE FOR PLANT FIBRES FOR INDUSTRIAL USE
Fibre Bundles Tissue: sclerenchyma textile fibre the use of special words such as technical, elementary or primary for fibre bundles should be avoided as confusing
Non-Structural Fibres Fibres found in association with fruit and seeds are not assembled into bundles, are very long and thin and have the cellulose microfibrils wound around the fibre rather than parallel to the longitudinal axis cotton.
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Cells in Wood
Cell Walls the middle lamella, and
the primary cell wall of the adjacent cell: largely random orientation of cellulose microfibrils.
S1 layer: 50 to 70 S2 layer: 5 to 30 S3 layer: >to 70 Pits: cell walls are
modified to allow communication and transport between the cells in the living plant.
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A08 Beakou26
A vegetal fiber extracted
from the Rhectophyllum
camerunense
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Chemical composition of the cell wall of scots pine27
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GEOMETRY
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MSc10 Oliveira, AMRiclS
Dimenses da fibro-clula (de) largura (di) dimetro do lmen (L) comprimento
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MSc10 Oliveira, AMRiclS
IRK, ndice Rukel para
qualificao de fibras para a produo de papel
Coeficiente de enfeltramento Coeficiente de forma
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MSc10 Oliveira, AMRiclS
Coeficiente de flexibilidade e propriedades da fibra tcnica
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Optical Microscope32
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SEM
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Scanning Electron Microscopy (SEM)34
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tHitachi SU-70 Schottky (SEM)35
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A09 Satyanarayanacr
oss
-se
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ns
of
fib
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(aa
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ba
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;(c
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)
ba
ga
sse
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ag
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nb
ars
wit
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ale
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A12 Davies
The secondary cell walls of plant fibres (the S2 layer) are composed of highly crystalline cellulose fibrils spirally wound in a matrix of amorphous hemi cellulose and lignin.
The fibres are roughly circular and exhibit a large lumen, with a wall thickness around 2 m.
The small outer diameter of these fibres - 510m.
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A09 Elenga
SEM micrograph of the bottom layer of raffia textilis fiber. Note the honeycomb-like pattern
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A08 Beakou
This thicknessof metal as wellas theapplication of asuitable voltageof the electronbeam arenecessary toprevent thefibers frombeing damagedunder the actionof thebombardmentof electronsduringobservation.
Scanning electron microscopy of the RC fiber. (a) Cross-section of the fiber (x212). (b) Individual fiber cell (x312). (c) Reinforcement of the cell wall inside the lumen (x1850). (d) Longitudinal section showing microfibrils(x1150).
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A07 SatyanarayanaKG
Scanning electron micrographics of longitudinal sections of curauas fibers.
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A07 SatyanarayanaKG
Scanning electron micrographics of fracture of curauas fibers
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A14 Raj
The specimens were coated with platinum layer to avoidelectron beam charging effects during examination
The surface morphology was examined in the longitudinal direction
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A09 DePaoli
Scanning electron microscope (JEOL JSM6360LV) at an acceleration voltage of 25 kV.
The samples were coated with gold
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File Equipam. Kv Magf DW Probe Detec Obs
A12 Davies 8 x300 -x500
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A09 Satyanarayana
15 x500 -x18000
A09 ElengaA08 Beakou T220 Jeol 520 Fine layer of gold of
70 nm thickness is deposited
A07 SatyanarayanaKG
Philips Model XL-30 scanning electronmicroscope (SEM)
20 100x -x500
11,5-13,1
5.0 SE
A14 Raj HITACHI ModelS3000H
3 100x -x500
16 29 SE
A09 DePaoli JEOL JSM6360LV 25 x750 The samples were coated with gold
A08 Silva Shimadzu SSX-550 20 x240-x500 17 5.3 SE
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TEM
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Schematic of a transmission electron
microscope (TEM).46
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A08 Beakou
Transmission electron microscopy of the RC fiber. (a) Consecutive layers (x16,400). (b) Layer stacking (x16,400). (c) Warty sub-layer (x7660). Reinforcement by a small cell (x10,900).
A) and B) represents the consecutive layers of the cell wall and their stratification for mechanical modelling. It is noted that only the S1, S2 and S3 sub-layers of the secondary wall have thicknesses
The primary layer P being very thin is not distinguishable from the lignin-rich middle lamella M
C) presence of a warty sub-layer inside the S3 sub-layer.
D) a smaller triangular elementary fiber is locally inserted during growth to rigidify the fiber.
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CHEMICAL CONTENT
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Analytical Procedures
Contend of Protocol Sampling Procedure, Extraction, Sample Preparation, Apparatus, Reagents and Materials, Procedures, Report, Precision, Additional Information
Procedures Ash Content (ASTM D-1102-84) Preparation of Holocellulose (Chlorite Holocellulose) Preparation of Alpha-Cellulose (Determination of Hemicelluloses)
Preparation of Klason Lignin Determination of Methoxyl Groups Determination of Acetyl by Gas Liquid Chromatography
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Analytical Procedures
Information should accompany each chemical analysis: Source of the wood
Geographic location Part of the tree sampled Date sample was taken
Sampling Different anatomical parts Degree of biological deterioration, if any Sample size Drying method applied
Analytical procedure used Calculations and reporting technique
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FIBERS PROPERTIES
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Materials Properties
Density Thermal Electrical and Magnetic
Optical
Chemical Atomic
Radiological
Manufacturing Environmental Mechanical
Acoustical
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DENSITY
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=M.V-1
Density or specific weight. The dimensionless quantity
Relative density or specific gravity The ratio of the density of the material to that of a standard material, usually water at 25oC.
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Experimental, =M.V-1
Homogeneous materials
The mass is measured with a balance The volume may be measured
Directly (from the geometry of the object) or By displacement of a fluid (graduated cylinder). Or, by the mass of a fluid displaced.
Archimedes
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Density of liquid water at 1 atm pressure56
Temp Density H2O
(oC) (g/cm3)
-30 984
-20 994
-10 998
0 1.000
4 1.000
10 1.000
15 999
20 998
22 998
25 997
30 996
40 992,2
60 983,2
80 971,8
100 958,4
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Experimental, =M.V-1
Heterogeneous materials Non-compact materials
Bulk density is the mass divided by bulk volume. Voids fraction: Air, even gaseous, or water. Dimension and access of voids.
H2O, He2, Mg.
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Gas pycnometry
A gas pycnometer is also sometimes referred to as a helium pycnometer
Measure the volume of solids, porous or non-porous, monolithic, powdered, granular or in some way comminuted,
Employing method of gas displacement and the volume : pressure relationship known as Boyle's Law.
Helium therefore is most often prescribed as the measurement gas, Small size, it is also inert and the most
ideal gas. Alternatives: Dry air, N2 e CO2
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Gas pycnometry
Vs is the sample volume, Vc is the volume of the empty sample chamber, known from a prior calibration step,
Vr is the volume of the reference volume, again known from a prior calibration step,
P1 is the first pressure, in the sample chamber only
P2 is the second (lower) pressure after expansion of the gas into the combined volumes of sample chamber and reference chamber.
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He P1
Vr
HeP2
Vc
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DOI: 10.1021/ja060474j
He pycnometry was used to estimate the actual space in the material accessible to the He gas. Measurements were run on an AccuPyc 1330 gas pycnometer (Micromeritics)
give an average of three independent measurements Each sample was measured several times (10 runs in each determination) to achieve stable results
The total porosity of the materials studied (P(He), %) was calculated as the space fraction in a sample accessible to the helium gas
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A13 Zauer
Pycnometry according to DIN 66137-2 (2004)
PI, Initial pressure PF, Final pressure VS, volume of sample chamber
VR, volume of reference chamber
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Protocol
Gas pycnometer must be calibrated using certified calibration spheres in accordance with the exact bulk volume of the sample for accurate measurements.
The sample should be dried to remove moisture. In air or vacuum (depending on sample) Put on diseccator
Equipment preparation Warm up at least 30 minutes Several cycles of pressurization depressurization are necessary The blank measurement (volume of the empty cell) takes about 1 minute
Weigh the mass of the empty cell using the analytical balance (accuracy 0.1 [mg]) and carefully write down the result WC [g]
With the spatula add a sufficient amount of powder into the cell (1-5 g) Carefully write down the result WT [g] The mass of the powder is calculated WP=WT-WC
Put the cell with the powder in the instrument, and close it Start analisys Once the measurement is finished and saved, remove the powder from
the cell, wash it with water and ethanol and dry at 60 [C]
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