research article elastic module study of the radial...

Research ArticleElastic Module Study of the Radial Section ofGuadua angustifolia Kunth Variety Bicolor

J I Cardenas1 and C Vargas-Hernaacutendez12

1 Laboratorio de Propiedades Opticas de los Materiales (POM) Universidad Nacional de ColombiaSede Manizales AA 127 Manizales Colombia

2 International Center for Nanotechnology and Advanced Materials Department of Physics and AstronomyUniversity of Texas at San Antonio TX 78249-0631 USA

Correspondence should be addressed to C Vargas-Hernandez cvargashunaleduco

Received 2 September 2013 Accepted 13 January 2014 Published 16 February 2014

Academic Editor Steve Bull

Copyright copy 2014 J I Cardenas and C Vargas-Hernandez This is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

Elastic modulus of the radial section of the Guadua angustifolia Kunth variety Bicolor was studied by technique of propagation ofacoustic waves the signal time delay in the samples was used as the control parameter The studies were carried out in the culmcross-section in radial directionThe results indicate that the elastic modulus and the propagation velocity of the longitudinal wavein each of the cross-sections varied from 25 times 107 to 16 times 109 Pa and from 1370 to 250ms for the inside and outside regionof the culm respectively This behavior is due to the inhomogeneity the water concentration the fiber density and the siliconconcentration The Raman spectroscopy analysis showed bands associated with hemicellulose cellulose (carbon-carbon bonds)hydroxides carbon and lignin Silicone polymer compounds were identified by gas chromatographymass spectroscopy

1 Introduction

The Guadua angustifolia Kunth variety Bicolor (GAKVBFigure 1(a)) has been classified by Humboldt Bonpland andKunthKart since 1806 and it is a type of vegetalmaterial of theBambusa familyThe GAKVB has been considered one of themost representative native plants of tropical forests and thereare approximately 90 genera in the world that are classifiedinto 1250 species that are distributed in the equatorial zone(51 degrees north latitude and 47 degrees south latitude andfrom sea level to 2200meters) [1] Vegetal cells of the GAKVBconsist mainly of lignin cellulose and hemicellulose whichare the most abundant biopolymers in the nature with appli-cations in traditional handicrafts architectural structuresand industries such as paper production automotives andsports and due to its density and heat capacity it is also usedin the production of charcoal [2ndash5] Currently there havebeen studies on the mixture of the GAKVB and other plantspecies with synthetic polymers to produce biodegradablecomposite materials with innovative mechanical properties[6ndash8] The GAKVB is a nonhomogeneous complex system

where the composition and structure are dynamic featuresthat depend on the age of the bambooThere is isotropy alongthe growth direction and perpendicular to it that is in theradial direction the anisotropy is presented this is due tofibers volumetric density that produces different behaviors ofthe viscoelasticity and of the crystallinity [9] Other species ofBambusae have been studied in terms of physical propertiessuch as structure composition and humidity [10ndash14] TheGAKVB is a periodical structure along the growth directionand consists of nodes and internodes (see Figure 1(a)) TheGAKVB culm consists of two basic structures a geometryof a truncated cone where the fibers are aligned in thedirection of the bamboo growth and arranged in such away that allows a significant amount of voids or saturatedwater and the other with circular geometry which form theupper and lower truncated cone (Figure 1(b)) This structureis repeated in consecutive cylinders and the vascular bundlessize decreases within the wall stem while the density of thefibers increases from base to top of the culm The culm wallis composed of parenchymal cells in the spaces between thevascular bundles and the fibers On the other hand the fibers

Hindawi Publishing CorporationAdvances in Materials Science and EngineeringVolume 2014 Article ID 935206 5 pageshttpdxdoiorg1011552014935206

2 Advances in Materials Science and Engineering

Signalsunit

Oscilloscope

(a) (b) (c) (d)

Internode

Node

PC

Sample

Data acquisition

BuzzerRadial section Wall

Figure 1 Guadua angustifolia Kunth variety Bicolor (a) nodes and internodes (b) culm and (c) experimental setup

constitute 40ndash50 of total culm tissue and 60ndash70 of theirweight [5] The culm is made up of 52 parenchyma tissue40 fibers and 8 conductive tissues these values varyaccording to the species of the bamboo For the GAKVB casethis composition is 51 40 and 9 respectively The xylem isthe principal water-conducting tissue of vascular plants andis divided in primary xylem which consists of protoxylemthat has an active stretch in its youth and the metaxylemwhich begins in the mature plant but after elongation it isstretched and is destroyed Micrographs of the GAKVB culmare shown in Figures 2(a) and 2(b) Figure 2(a) illustratesthe fibers distribution around the vascular bundles withsizes around 120120583m In the surface outside of the culmwhite dots are highlighted known as trichomes and areassociated with silica (see Figure 2(d)) [15] For orthotropicmaterials such as wood where mechanical properties inthe perpendicular directions are unique and independentthe speed of longitudinal and transverse waves in each ofthe principal axes depends on the density the direction ofpropagation and elastic constants [16] Wood is an exampleof an orthotropic material and the propagation phenomenaof ultrasonic waves are considered complex The Christoffelequation relates the elastic constants to the velocities ofultrasonic waves in an anisotropic solid as [17 18]

10038161003816100381610038161003816119862119894119895119896119897119899119894119899119895minus 120575119894119896120588V210038161003816100381610038161003816= 0 (1)

where 119862119894119895119896119897

119899119894 119899119895 120575119894119896 120588 and V are the stiffness tensor the

unit vectors in the directions 119894 and 119895 the Kronecker deltawood density and wave velocity respectively Nine constantsare obtained by solving the Christoffel equation along thethree axes of symmetry There is one longitudinal wave andtwo transverse waves in each of the principal axes which arerelated to material density and wave velocity by 119862

119894119894= V2119894119894120588

the density of the culm is obtained by volumetric methods[19 20] The GAKVB is hygroscopic and an anisotropicporous structure whose mechanical properties depend onhumidity The sonic pulse method is nondestructive and

integrity of the material affected is also inexpensive and canbe implemented by a simple technology The transmission ofultrasonic waves depends on the compression and stretchingof chemical bonds of materials being widely used in theidentification of mechanical properties in different types ofmetallic and nonmetallic materials among others [19 21]For frequencies from 20 to 200KHz the sonic pulses arenot affected by the nonhomogeneity of the materials andthe distribution of the acoustic wave beam has a sphericalwavefront whose center is at the emitter-detector [20] Whenthe two devices transmitter and receptor are placed oppositeto each other the sound wave will travel the shortest distanceand speed depends essentially on the mechanical propertiesof the material The sound wave loses energy and amplitudedue to the fact that plant materials are not perfectly elasticthis scattering occurs at the borders of the emitter-sample-receptor as well as on reflection and interference generatedthere and that should be taken into account for the determi-nation of the mechanical parameters

In this work elastic modulus of the radial section of theGuadua angustifolia Kunth variety Bicolor was studied bytechnique of propagation of acoustic waves the signal timedelay in the samples was used as control parameter Thestudies were carried out in the culm cross-section in radialdirection

2 Experimental Details

Figure 1(c) illustrates the experimental setup consisting of awave generator (Agilent 33220A) that sends a sinusoidal pulseevery 20ms to the piezoelectric buzzer which is coupled tothe system via an impedance bridge circuit (119885

119868 119885119874) The

pulse amplitude was 8Vpp with an excitation pulse width of675 120583s and a data acquisition time of 2 120583s The signal passesthrough the sample and is sent to a phase-sensitive lock-inamplifier and subsequently processed in the PC using thesoftware of Labview 85 The wave velocity (V

119898) through the

Advances in Materials Science and Engineering 3

Outer

Gro

wth

dire

ctio

n

Inner

15mm

(a)

Inside

Outside1mm

(b)

Vascular bundles

Fibers34120583m

126120583m

550120583m

200120583m

(c)

Trichomes-silica 50120583m

(d)

Figure 2 Micrographs of the GAKVB culm (a) radial section (b) distribution of vascular bundles (c) fibers and vascular bundles and (d)Trichomes silica in the surface of the GAKVB

material is obtained from the sample length (119871119898) and delay

time (119905119877) according to the following equation

V119898= ℎ119871119898

119905119877

(2)

119905119877is obtained from the phase difference between the two

signals the reference signal and the signal obtained in thedetector and it is corrected by 119905

119877= 119905119898minus119905119868 where 119905

119898and 119905119868are

the time measured in the detector and the instrumental timedelay respectively and ℎ is the instrumental correction due tothe coupling impedances (119885

119868119885119874) In the first approximation

the longitudinal 11986222

elastic constant in a radial direction isobtained by

11986222= 120588V2119898 (3)

The GAKVB samples that have been used for measure-ments were obtained by cutting sections from the center tooutside in radial direction with dimensions of 15mm thick-ness and 4 cm2 surface area see Figure 2(a)Themicrographsand the elemental quantification of the silicon concentrationwere obtained with an environmental scanning electronmicroscopy (ESEM) Philips XL-30TMP equipped with astandard probe (EDAX) The Raman spectra were recordedwith a LabRam HR-800 Confocal Microscope (Horiba JobinYvon) using a 473 nm blue laser The gas chromatogra-phymass spectroscopy (GCMS) was performed with Agi-lent Technologies 6580 Series I with mass spectroscopy

1100

1000

900

800

700

600

500

400

300

20

200

30 40

40

50 60

60

70 80

80

90 100

100

20

0

40

60

80

100

Den

sity

(kg

m3)

Outside

Outside

Inside

Inside

Radial section ()

Hum

idity

()

Radial section ()

Figure 3Density and humidity content of theGAKVBas a functionof radial section percentage of the GAKVB

detection (MSD Insert 5975B Agilent Technologies) andwithcolumn (HP-INNOWAX Polyethylene Glycol Capillary)

3 Results and Discussion

The density 120588 for each of the different regions of the cross-section of GAKVB samples shown in Figure 3 has valueswhich are between 380 and 1030 kgm3 and are of the same


20

200

0 40

40

60

60

80

80

100

100

600

400

200

800

1000

1200

1400

Outside

Outside

Inside

Inside

Radial section ()

Velo

city

(ms

)

Elas

ticity

mod

ule (

Pa)

Radial section ()

00

18

16

14

12

10

08

06

04

02

times109

Figure 4 Elasticity modulus and velocity of the GAKVB asa function of radial section percentage

600400 800 1000 1200 1400 1600

Hemicellulose

Inte

nsity

(au

)

Outside

Inside

Commercial cellulose

Si-O-Si C-H Lignin

SiO2

Raman shift (cmminus1)

Figure 5 The Raman spectra of different radial sections of theGAKVB as well as commercial cellulose

order of magnitude compared with other plant materialsthat have been reported [6 22] The behavior of 120588 is dueto the concentration of silicon and has been associated withnonuniform distribution through the wall of the microfibersand metaxylem and phloem ducts and these channels aresites where water molecules are more likely to be trappedThe vascular bundles shown in SEM micrographs (seeFigure 2(c)) have an average diameter of about 120120583m anaverage density of 22 per mm2 and a maximum at a radialposition of 20 of the thickness of the bamboo with respectto the outside surface The above results agree with thoseobtained in the humidity curve (inset Figure 3) indicatingthat there is a greater accumulation of water in a regionbetween 60 and 100 measured from the outside surfaceof the bamboo Sound velocity and the elastic modulusof the GAKVB were obtained by (2) and (3) respectively

The velocity of wave propagation was obtained between250ms and 1370ms (inset Figure 4) these values agreewith those reported for other plant species [23] As the wavepropagates perpendicularly to the fibers the velocity takes themaximum value when these fibers are closer together thatis in 20 of the radial position measured from the outsidesurfaceThe elastic modulus119862

22is shown in Figure 4 and the

values obtained are comparable with those reported in theliterature by using nanoindentation techniques [16] In themeasurements carried out on the time delay of the signal thefibers were oriented perpendicular to the contact surface ofthe detector The behavior of 119862

22on the outside wall of the

GAKVB has been associated with a higher content of siliconwithin the structure and contributes to the high rigidity andimpermeability of the outside surface as evidenced by thebehavior of the relative humidity The highest concentrationof water is associated with nonuniform distribution throughthe wall of the microfibers and tubes (metaxylem andphloem) and acquires a maximum value at a depth of 20measured from the inside of the bamboo wall At this depththe11986222module acquires aminimum value because the water

produces a plasticizing effect associated with the tendency forwater molecules located in these regions to allow themobilityof the polymer chains Vibrational spectroscopy has beenwidely used because it provides information about the localstructural features of inorganic solids The Raman spectrawere obtained in the range 400ndash1650 cmminus1 at room tempera-ture In Figure 5 spectra of the commercial cellulose aswell asthe different sections in radial direction (outside middle andinside) of the GAKVB are shown The peaks are associatedwith cellulose phases hemicellulose lignin and silicates[24ndash26] The bands around 530 830 and 1366 cmminus1 areassigned to hemicellulose phase The peak around 1584 cmminus1

is associated with lignin The silicates (SiO2 830 cmminus1) and

the CndashH compounds are increased in the outside region ofthe GAKVB The Raman spectra indicate that hemicellulosephases and silicates have proportions higher in the outsidethan in the inside region

4 Conclusions

The sound pulse technique indicated that the elastic modulus11986222

and the velocity of wave propagation of the Guaduaangustifolia Kunth variety Bicolor varied between 25 times 107

and 16 times 109 Pa and 250 and 1370ms respectively 120588 valuesare between 380 and 1030 kgm3 and are due to the radialdistribution of the vascular bundles The behavior of 119862

22is

due to the concentration of silicon and water present in thestructure as well as inhomogeneous distribution across thewall of the microfibers metaxylem and phloem conduitsand acquires a minimum value because the water producesa plasticizing effect associated with the tendency for watermolecules located in these regions allowing mobility of thepolymer chains In the outside region of the GAKVB thehighest concentration of silicon is due to the compounds ofsilicates


Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

The authors wish to acknowledge the helpful suggestions ofthe reviewer and the editor of the journal

References

[1] A Londono ldquoA decade of observations of aGuadua angustifoliaplantation in Colombiardquo The Journal of the American BambooSociety vol 12 no 1 pp 37ndash42 1998

[2] A C Sekhar B S Rawat and R K Bhartari ldquoStrength ofbamboos Bambusa nutansrdquo Indian Forester vol 88 no 1 pp67ndash73 1962

[3] F Hugot and G Cazaurang ldquoMechanicalproperties of anextruded wood plastic composite analytical modelingrdquo Journalof Wood Chemistry and Technology vol 28 no 4 pp 283ndash2952008

[4] M M Zawlocki Characterization of wood-plastic composites bydissipated energy [MS thesis] Department of Civil and Envi-ronmental Engineering Washington State University 2003

[5] J O Brito M T Filho and A L B Salgado ldquoProducao ecaracterizacao do carvao vegetal de especies e variedades debamburdquo Revista IPEF (Atual Scientia Forestalis) no 36 pp 13ndash17 1987

[6] C-J LinM-J Tsai and S-YWang ldquoNondestructive evaluationtechniques for assessing dynamic modulus of elasticity of mosobamboo (Phyllosachys edulis) laminardquo Journal of Wood Sciencevol 52 no 4 pp 342ndash347 2006

[7] T Y Lo H Z Cui and H C Leung ldquoThe effect of fiber densityon strength capacity of bamboordquo Materials Letters vol 58 no21 pp 2595ndash2598 2004

[8] Y Hu T Nakao T Nakai J Gu and F Wang ldquoVibrationalproperties of wood plastic plywoodrdquo Journal of Wood Sciencevol 51 no 1 pp 13ndash17 2005

[9] S Amada Y Ichikawa TMunekata Y Nagase andH ShimizuldquoFiber texture and mechanical graded structure of bamboordquoComposites B vol 28 no 1-2 pp 13ndash20 1997

[10] J A Gutierrez ldquoStructural adequacy of traditional bamboohousing in Latin-Americardquo Tech Rep 321-98-519 LaboratorioNacional de Materiales y Modelos Estructurales Universidadde Costa Rica San Pedro Costa Rica 1999

[11] O A Arce-Villalobos Fundamentals of the design of bamboostructures [PhD thesis] Eindhoven University of TechnologyHolland The Netherlands 1993

[12] J J A Janssen Bamboo in building structures [PhD thesis]Technical University of Eindhoven Holland The Netherlands1981

[13] J J A Janssen Mechanical Properties of Bamboo vol 37 ofForestry Sciences Series Kluwer Academic Dordrecht TheNetherlands 1991

[14] Z B Espiloy ldquoEffect of age on the physico-mechanical prop-erties of some Philippine bamboos bamboos in Asia and thePacificrdquo in Proceedings of the 4th International Bamboo Work-shop pp 180ndash182 IDRCFAOUNDP FAO BangkokThailandNovember 1994

[15] M Montiel V M Jimenez and E Guevara ldquoUltrastructuredel bambu Guadua angustifolia var bicolor (Poaceae Bambu-soideae) presente en Costa Ricardquo Revista de Biologia Tropicalvol 54 no 2 pp 13ndash19 2006

[16] L Zou H Jin W-Y Lu and X Li ldquoNanoscale structural andmechanical characterization of the cell wall of bamboo fibersrdquoMaterials Science amp Engineering C vol 29 no 4 pp 1375ndash13792009

[17] R F S Hearmon An Introduction to Applied AnisotropicElasticity Oxford University Press Oxford UK 1961

[18] S Dahmen H Ketata M H Ben Ghozlen and B HostenldquoElastic constants measurement of anisotropic Olivier woodplates using air-coupled transducers generated Lamb wave andultrasonic bulk waverdquo Ultrasonics vol 50 no 4-5 pp 502ndash5072010

[19] S S Chauhan and J C FWalker ldquoVariations in acoustic velocityand density with age and their interrelationships in radiatapinerdquo Forest Ecology andManagement vol 229 no 1ndash3 pp 388ndash394 2006

[20] L Acuna M R Diez and M Casado ldquoLos ultrasonidos y lacalidad de la madera estructural aplicacion a Pinus pinasterAitrdquo Boletin del CIDEU no 2 pp 7ndash26 2006

[21] R Saggin and J N Coupland ldquoNon-contact ultrasonic mea-surements in food materialsrdquo Food Research International vol34 no 10 pp 865ndash870 2001


[23] M Hasegawa and Y Sasaki ldquoAcoustoelastic birefringence effectin wood III ultrasonic stress determination of wood by acous-toelastic birefringence methodrdquo Journal of Wood Science vol50 no 2 pp 108ndash114 2004

[24] V P Zakaznova-Herzog W J Malfait F Herzog and WE Halter ldquoQuantitative Raman spectroscopy principles andapplication to potassium silicate glassesrdquo Journal of Non-Crystalline Solids vol 353 no 44ndash46 pp 4015ndash4028 2007

[25] K Ishimaru T Hata P Bronsveld and Y Imamura ldquoMicro-structural study of carbonized wood after cell wall sectioningrdquoJournal of Materials Science vol 42 no 8 pp 2662ndash2668 2007

[26] S Andersson R Serimaa T Paakkari P Saranpaa and EPesonen ldquoCrystallinity of wood and the size of cellulosecrystallites in Norway spruce (Picea abies)rdquo Journal of WoodScience vol 49 no 6 pp 531ndash537 2003

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

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Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

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NanoparticlesJournal of



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Biomaterials


NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

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CrystallographyJournal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research



MetallurgyJournal of


BioMed Research International

MaterialsJournal of


Nano

materials


Journal ofNanomaterials


Signalsunit

Oscilloscope

(a) (b) (c) (d)

Internode

Node

PC

Sample

Data acquisition

BuzzerRadial section Wall

Figure 1 Guadua angustifolia Kunth variety Bicolor (a) nodes and internodes (b) culm and (c) experimental setup

constitute 40ndash50 of total culm tissue and 60ndash70 of theirweight [5] The culm is made up of 52 parenchyma tissue40 fibers and 8 conductive tissues these values varyaccording to the species of the bamboo For the GAKVB casethis composition is 51 40 and 9 respectively The xylem isthe principal water-conducting tissue of vascular plants andis divided in primary xylem which consists of protoxylemthat has an active stretch in its youth and the metaxylemwhich begins in the mature plant but after elongation it isstretched and is destroyed Micrographs of the GAKVB culmare shown in Figures 2(a) and 2(b) Figure 2(a) illustratesthe fibers distribution around the vascular bundles withsizes around 120120583m In the surface outside of the culmwhite dots are highlighted known as trichomes and areassociated with silica (see Figure 2(d)) [15] For orthotropicmaterials such as wood where mechanical properties inthe perpendicular directions are unique and independentthe speed of longitudinal and transverse waves in each ofthe principal axes depends on the density the direction ofpropagation and elastic constants [16] Wood is an exampleof an orthotropic material and the propagation phenomenaof ultrasonic waves are considered complex The Christoffelequation relates the elastic constants to the velocities ofultrasonic waves in an anisotropic solid as [17 18]

10038161003816100381610038161003816119862119894119895119896119897119899119894119899119895minus 120575119894119896120588V210038161003816100381610038161003816= 0 (1)

where 119862119894119895119896119897

119899119894 119899119895 120575119894119896 120588 and V are the stiffness tensor the

unit vectors in the directions 119894 and 119895 the Kronecker deltawood density and wave velocity respectively Nine constantsare obtained by solving the Christoffel equation along thethree axes of symmetry There is one longitudinal wave andtwo transverse waves in each of the principal axes which arerelated to material density and wave velocity by 119862

119894119894= V2119894119894120588

the density of the culm is obtained by volumetric methods[19 20] The GAKVB is hygroscopic and an anisotropicporous structure whose mechanical properties depend onhumidity The sonic pulse method is nondestructive and

integrity of the material affected is also inexpensive and canbe implemented by a simple technology The transmission ofultrasonic waves depends on the compression and stretchingof chemical bonds of materials being widely used in theidentification of mechanical properties in different types ofmetallic and nonmetallic materials among others [19 21]For frequencies from 20 to 200KHz the sonic pulses arenot affected by the nonhomogeneity of the materials andthe distribution of the acoustic wave beam has a sphericalwavefront whose center is at the emitter-detector [20] Whenthe two devices transmitter and receptor are placed oppositeto each other the sound wave will travel the shortest distanceand speed depends essentially on the mechanical propertiesof the material The sound wave loses energy and amplitudedue to the fact that plant materials are not perfectly elasticthis scattering occurs at the borders of the emitter-sample-receptor as well as on reflection and interference generatedthere and that should be taken into account for the determi-nation of the mechanical parameters

In this work elastic modulus of the radial section of theGuadua angustifolia Kunth variety Bicolor was studied bytechnique of propagation of acoustic waves the signal timedelay in the samples was used as control parameter Thestudies were carried out in the culm cross-section in radialdirection

2 Experimental Details

Figure 1(c) illustrates the experimental setup consisting of awave generator (Agilent 33220A) that sends a sinusoidal pulseevery 20ms to the piezoelectric buzzer which is coupled tothe system via an impedance bridge circuit (119885

119868 119885119874) The

pulse amplitude was 8Vpp with an excitation pulse width of675 120583s and a data acquisition time of 2 120583s The signal passesthrough the sample and is sent to a phase-sensitive lock-inamplifier and subsequently processed in the PC using thesoftware of Labview 85 The wave velocity (V

119898) through the


Outer

Gro

wth

dire

ctio

n

Inner

15mm

(a)

Inside

Outside1mm

(b)

Vascular bundles

Fibers34120583m

126120583m

550120583m

200120583m

(c)


(d)




V119898= ℎ119871119898

119905119877

(2)



119877= 119905119898minus119905119868 where 119905

119898and 119905119868are





11986222= 120588V2119898 (3)


1100

1000

900

800

700

600

500

400

300

20

200

30 40

40

50 60

60

70 80

80

90 100

100

20

0

40

60

80

100

Den

sity

(kg

m3)

Outside

Outside

Inside

Inside

Radial section ()

Hum

idity

()

Radial section ()






20

200

0 40

40

60

60

80

80

100

100

600

400

200

800

1000

1200

1400

Outside

Outside

Inside

Inside

Radial section ()

Velo

city

(ms

)

Elas

ticity

mod

ule (

Pa)

Radial section ()

00

18

16

14

12

10

08

06

04

02

times109


600400 800 1000 1200 1400 1600

Hemicellulose

Inte

nsity

(au

)

Outside

Inside


Si-O-Si C-H Lignin

SiO2












4 Conclusions




22is





Acknowledgments


References


































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




Outer

Gro

wth

dire

ctio

n

Inner

15mm

(a)

Inside

Outside1mm

(b)

Vascular bundles

Fibers34120583m

126120583m

550120583m

200120583m

(c)


(d)




V119898= ℎ119871119898

119905119877

(2)



119877= 119905119898minus119905119868 where 119905

119898and 119905119868are





11986222= 120588V2119898 (3)


1100

1000

900

800

700

600

500

400

300

20

200

30 40

40

50 60

60

70 80

80

90 100

100

20

0

40

60

80

100

Den

sity

(kg

m3)

Outside

Outside

Inside

Inside

Radial section ()

Hum

idity

()

Radial section ()






20

200

0 40

40

60

60

80

80

100

100

600

400

200

800

1000

1200

1400

Outside

Outside

Inside

Inside

Radial section ()

Velo

city

(ms

)

Elas

ticity

mod

ule (

Pa)

Radial section ()

00

18

16

14

12

10

08

06

04

02

times109


600400 800 1000 1200 1400 1600

Hemicellulose

Inte

nsity

(au

)

Outside

Inside


Si-O-Si C-H Lignin

SiO2












4 Conclusions




22is





Acknowledgments


References


































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




20

200

0 40

40

60

60

80

80

100

100

600

400

200

800

1000

1200

1400

Outside

Outside

Inside

Inside

Radial section ()

Velo

city

(ms

)

Elas

ticity

mod

ule (

Pa)

Radial section ()

00

18

16

14

12

10

08

06

04

02

times109


600400 800 1000 1200 1400 1600

Hemicellulose

Inte

nsity

(au

)

Outside

Inside


Si-O-Si C-H Lignin

SiO2












4 Conclusions




22is





Acknowledgments


References


































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials






Acknowledgments


References


































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials










CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



research article elastic module study of the radial...

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