eng k49 materiais de origem vegetal aplicados na construção celularfibres 151.pdf · materiais...

Celular Fibres

ENG K49 Materiais de origem vegetal aplicados na construo

Ricardo Fernandes Carvalho

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

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.


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 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

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

Componentes dos Materiais Lignocelulsicos

Extrativos

Substncias Orgnicas

Cinzas

Substncias Inorgnicas

Substncias de baixa massa molar

Lignina

Celulose Polioses

Polissacardeos

Substncias Macromoleculares

Materiais Lignocelulsicos


Polssacardeos: celulose e hemiceluloses

Compostos aromticos: lignina

Compostos inorgnicos: sais extrativos: leos essncias, resinas (gomas), cinzas

Taninos, acares, etc.


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Celullarwall

Carbo-hydrate

CellulosesHemi-

celluloses

LigninAsh and

extractives

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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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.


Indstria Automotiva 46.000 t/ano (23 kg/carro)

Construo Civil Indstria Moveleira Indstria Eletro/Eletrnica Indstria de Embalagens Indstria Farmacutica e Veterinria


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

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

Fibras Naturais Cultivada Mundialmente (%)

6414

10

8 2 2 JutaLinhoKenafSisalRamiHempCoco

Produo Proporcional20

A01 EichhornAnsell21

2900000

630000

470000

38000098000 72000

Juta

Linho

Kenaf

Sisal

Rami

Hemp

Coco

Fibras cultivadas no Mundo com usos Automobilsticos (%)22

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

Chemical composition of the cell wall of scots pine27

GEOMETRY

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MSc10 Oliveira, AMRiclS

Dimenses da fibro-clula (de) largura (di) dimetro do lmen (L) comprimento

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IRK, ndice Rukel para

qualificao de fibras para a produo de papel

Coeficiente de enfeltramento Coeficiente de forma

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Coeficiente de flexibilidade e propriedades da fibra tcnica

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Optical Microscope32

SEM

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Scanning Electron Microscopy (SEM)34

tHitachi SU-70 Schottky (SEM)35

A09 Satyanarayanacr

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36

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

38

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).

39

A07 SatyanarayanaKG

Scanning electron micrographics of longitudinal sections of curauas fibers.

40

A07 SatyanarayanaKG

Scanning electron micrographics of fracture of curauas fibers

41

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

42

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

26

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

45

Schematic of a transmission electron

microscope (TEM).46

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

51

Materials Properties

Density Thermal Electrical and Magnetic

Optical

Chemical Atomic

Radiological

Manufacturing Environmental Mechanical

Acoustical

52

DENSITY

53

=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.

54

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

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

58

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

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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