Fabrication of Nanocelluloses From Hemp Fibers and Their

Industrial Crops and Products 44 (2013) 192 199

Contents lists available at SciVerse ScienceDirect

Industrial Crops and Products

journa l h o me pag e: www.elsev ier .com

Fabrica s areinfor

Dasong DCivil Engineerin bridge

a r t i c l

Article history:Received 12 SeReceived in reAccepted 6 No

Keywords:Natural bersHemp bersNanocelluloseMechanical propertyInterface property

ed toed asles (nidatio011ningat thtly. T

by 3diffractogram (XRD) were used to reveal the mechanism of nanocellulose reinforcement on natural bers.FEG-SEM illustrated that the nanocellulose treatment had resulted in an effective distribution of nanocel-lulose along the stria on the surface of bers, giving rise to a signicant increase in the tensile strengthof the treated hemp bers. The XRD analysis also showed that the crystallinity index of the treated bershad increased from 55.17% to 76.39%. X-ray photoelectron spectroscopy (XPS) has been used to charac-

1. Introdu

Natural available ansteadily risiapplicationand Gassancritical discrecycling hawith the focincrease in arose muchpublicatione.g. pulp (Guand compo

The use posite mate2001). Combased bio-c

CorresponE-mail add

0926-6690/$ http://dx.doi.oterize the surface of bers and attenuated total reectance-fourier transform infrared (ATR-FTIR) wascarried out to determine the surface chemical reaction in order to elucidate the interface properties andself-modication mechanisms of the hemp bers.

2012 Published by Elsevier B.V.

ction

bers (hemp), which are rich in cellulose are abundantlyd easy to handle and process. Due to low prices and theng performance of technical and standard plastics, the

of natural bers came to a near-halt from 1940s (Bledzki, 1999; Mohanty et al., 2005). However, from 1990s, theussion about the preservation of natural resources ands led to a renewed interest concerning natural materialsus on renewable raw materials. More recently, with anenvironmental awareness, exploiting natural bers has

interest and become of importance. To date, numerouss have reported about the applications of natural bers,tirrez and del Ro, 2005), ethanol (Kreuger et al., 2011)

site (Ramires et al., 2010).of natural bers to make low cost and eco-friendly com-rials is a subject of great importance (Bismarck et al.,pared with glass ber-based composites, natural ber-omposites display several excellent advantages, e.g. low

ding author.ress: [email protected] (M. Fan).

density, renewable and low cost. However, these natural bers dis-play their drawbacks, e.g. higher polar and hydrophilic, which makenatural bers both poorly compatible with polymer and resultin the loss of mechanical properties upon atmospheric moistureadsorption (Belgacem and Gandini, 2005). Various treatments (e.g.physical treatments (Ragoubi et al., 2010), chemical treatments (Liuet al., 2007), biological treatments (Li et al., 2009)) on the nat-ural bers have been investigated by researchers to improve themechanical properties of bers.

New technologies (e.g. nanotechnology, biological technology)have also recently been employed by researchers to modify nat-ural bers and can be grouped into three approaches, namely, (1)soaking; (2) layer-by-layer deposition; and (3) sonochemical depo-sition. These approaches were mainly developed to immobilizenanoparticles on the surface of natural bers, which were used fortextiles in the nishing process. The nanotechnology-based nishtechniques give rise to new properties, e.g. anti-bacteria (Lee et al.,2003; Tarimala et al., 2006; Ilic et al., 2009), self-cleaning (Qi et al.,2007; Uddin et al., 2008; Veronovski et al., 2009), water repellent(Yu et al., 2007; Tomsic et al., 2008; Bae et al., 2009) and UV lightblocking (Wang et al., 2005; Mondal and Hu, 2007; Becheri et al.,2008) to the natural bers and enhance the performance of nalclothing product (Pasta et al., 2010). The hemp bers treated with

see front matter 2012 Published by Elsevier B.V.rg/10.1016/j.indcrop.2012.11.010tion of nanocelluloses from hemp bercement of hemp bers

ai, Mizi Fan , Philip Collinsg Department, School of Engineering and Design, Brunel University, Kingston Lane, Ux

e i n f o

ptember 2012vised form 4 November 2012vember 2012

a b s t r a c t

A novel fabrication has been employdeveloped nanocellulose was then us

The size distribution of nano-particsis (NTA). Results showed that the ox(29281 nm) and the average size (10ference under eld emission gun-scan(AFM). Mechanical testing showed thproperties of natural bers signicanmodied hemp bers were increased/ locate / indcrop

nd their application for the

, Middlesex UB8 3PH, UK

produce nanocelluloses from natural bers (hemp) and the coupling agent to modify hemp bers themselves.anocellulose) was measured by nanoparticle tracking analy-nsonication developed nanocellulose had wider size range2 nm). Morphologies of nanocellulose displayed a slight dif-

electron microscopy (FEG-SEM) and atomic force microscopye nanocellulose modication could improve the mechanicalhe modulus, tensile stress and tensile strain of nanocellulose6.13%, 72.80% and 67.89%, respectively. FEG-SEM and X-ray

D. Dai et al. / Industrial Crops and Products 44 (2013) 192 199 193

Table 1Experimental levels of NaOH and NaClO.

Experiment Addition of NaOH (%) Addition of NaClO (%)

Std 1 14 60Std 2Std 3

fungus Ophteristics anthat the ehemp bersrespectively2008) usedto modify nbiological tcessfully debers to ren

The prefabricate nalulose was distributionphologies oAFM. Mechied naturawere perfoincrease ofATR-FTIR wof natural to reveal thmechanism

2. Materia

2.1. Materi

Hemp yaHemp berLtd., UK. Dene diaminhypochloritUnsaturated

2.2. Fabrica

Hemp yaby scissors. of chopped out at 65 Cvarious sodTable 1. Yieequation:

Yield % = WW

where Wf isand Wn is th

2.3. Modic

2.3.1. DTABHemp

tained 30 mwith pH valand supporhemp bers

hemp bers were dried with vacuum oven at 70 C for 24 h andconditioned at 20 2 C and 65 2% relative humidity before uses.

2.3.2. Nanocellulose modication DTA), whraturwere

at 20

nsile

coning c

on . Su

556lengt

1 mNent a

sin a

aturyrenariouanocf dil

weie botin, t

and t, the

ers w

M

AFMf the ry in

oscopA) ws imaent

an ra

R-FT

-FTIometd wied wwas uions:

G-SE

ut 5iamet 60smal10 708 65

iostoma ulmi showed an improved acidbase charac-d resistance to moisture (Gulati and Sain, 2006); andxural strength and exural modulus of the modiedpolyester composites were improved by 21% and 12%,. Bismarck et al. (Juntaro et al., 2007; Pommet et al.,

the bacteria Gluconacetobacter xylinus strain BPR 2001atural bers (hemp bers and sisal bers). By using

echnology, nanosized bacterial cellulose has been suc-posited around natural bers, and such the adhesion ofewable polymers improved.sent work employed oxidation/ultrasonication tonocellulose from hemp bers at rst. Then, the nanocel-used as coupling agent to treat hemp bers. Size

of nanocellulose was characterized by NTA, and mor-f nanocellulose were characterized by FEG-SEM andanical properties and interfacial properties of the mod-l bers were investigated chiey. FEG-SEM and XRDrmed to reveal the mechanism of tensile strength

the bers with nanocellulose modication. XPS andere carried out to investigate the surface propertiesbers coated with unsaturated polyester with the aime mechanism of interface change and self-modications.

ls and methods

als

rns were obtained from Shanxi Greenland Textile Ltd.s were supplied by a Hemp Farm & Fiber Companyodecyltrimethylammonium bromide (DTAB), ethyl-e tetraacetic acid (EDTA), sodium hydroxide, sodiume and sodium sulde were supplied by SigmaAldrich.

polyester was obtained from CFS.

tion of nanocellulose

rns were chopped into short bers (length: 0.51 cm)Nanocellulose was prepared by the oxidation hydrolysisshort hemp bers. The oxidation hydrolysis was carried, 4 h under continuous agitation and sonication withium hydroxide and sodium hypochlorite, as shown inld of nanocellulose was worked out by the following

n

f 100 (1)

the weight of the shorted hemp yarns before hydrolysise weight of nanocellulose after oxidation.

ation of natural bers

modicationbers (1 g) were soaked in beaker (50 ml), which con-

The(30 mltempebers tioned

2.4. Te

Themountappliedof cardInstrongauge tion oftreatm

2.5. Re

Unswith stwith vtion; n20 ml o(on theinto thfor 5 m80 C, coolingthe b

2.6. AF

Thedrop oleft to dA NanCA, USple wainstrum1 Hz sc

2.7. AT

ATRSpectrout anequippof 45

condit20 C.

2.8. FE

Abodish (doven aing. A l DTAB solution 0.05% (by the weight of dried bers)ue 11. The beaker was then loosely covered with a glassted in an ultrasonic bath at 60 C for 1 h. After that, the

were washed with distilled water. Finally, the modied

a Zeiss Sup(FEG-SEM).on the surfatrical conduB modied hemp (0.5 g) bers were soaked in beakerich contained 2% nanocellulose suspension in roome for 10 min. Then, the nanocellulose modied hemp

dried with vacuum oven at 70 C for 24 h and condi- 2 C and 65 2% relative humidity before uses.

testing

ditioned individual ber was temporarily xed on theard (Fig. 1) with adhesive tape. A droplet of glue wasthe center of both sides of the hole along the lengthbject the test pieces to tensile strength test by using6 at a crosshead speed of 3 mm/min and with 25 mmh with screw grips (the capacity is 100 N with a resolu-). About 20 samples were tested for untreatment, DTABnd nanocellulose treatment.

dsorption measurements

ated polyester, which was ordered from CFS was dilutede until the volatile content was 95%. Hemp bers (0.5 g)s treatments (without modication; DTAB modica-ellulose modication) were, respectively, immersed inuted unsaturated polyester in a glass bottle. 2% catalystght of unsaturated polyester) of catalyst was then addedtle. After degassing the compounds with ultrasonic bathhe temperature was raised from room temperature tohe compounds were treated for 15 min at 80 C. After

bers were washed with distilled water, and nally,ere dried with vacuum oven at 60 C for 24 h.

was used to examine the surface of nanocellulose. Asuspension was deposited onto freshly cleaved mica and

a desiccating capsule with silica gel for a period of 12 h.e IIIa microscope (Digital Instruments, Santabarbara,

ith a multimode head was used for measurement. Sam-ged in tapping mode. Height images were recorded. The

was operated with a resonance frequency of 155 kHz,te and a spring constant of 12103 N m1.

IR

R spectra were recorded on a PerkinElmer Spectrum oneer. After resin adsorption experiment, the bers with-th nanocellulose treatment were mounted on an ATRith 3 bounce diamond crystal and an incident anglesed. The instrument was operated under the following

4000650 cm1 range; 4 cm1 resolution; 16 scans and

M

0 ml nanocellulose suspension was dropped into petriter 55 mm). Then, the suspension was dried in vacuumC. A thin nanocellulose lm was obtained after dry-l piece of the nanocellulose lm was examined withra 35 VP eld emission scanning electron microscopy

The test pieces were coated with thin layer platinumce in an Edwards S150B sputter coater to provide elec-ctivity. Following coating, samples were observed and

194 D. Dai et al. / Industrial Crops and Products 44 (2013) 192 199

men m

operated atcollected di

FEG-SEMlulose treatwith thin laobserved un

2.9. NTA

Nanoparformed usiSalisbury, Uwas introdnanocelluloscope. TheBrownian mimage analyover 22 s. Tmaximum pat 10 in the

2.10. XPS

XPS wasaluminum backgroundscans were high-resoluanalyzer paface normal10 nm. The from their n

O

C= IO

IC S

S

where IO anoxygen andsensitivity f

2.11. XRD

Raw hemlulose mod

tion dvante msed. 42 nmand 4ystal

emp

(I0 0 2I

I0 0 2 peakoth cactioetw

licate

ults

ze disFig. 1. Set-up of single ber test: (a) specimen mount and (b) test speci

10 kV using the secondary electron mode with imagesgitally.

images of hemp bers without treatment and nanocel-ment were also been taken. The test pieces were coatedyer platinum according to the above protocol and thender the same conditions as previously.

ticle tracking analysis (NTA) experiments were per-ng a digital microscope LM10 System (NanoSight,K). 1 ml of the diluted sample (concentration 0.001%)

uced into the chamber by a syringe. The particles ofse in the sample were observed using the digital micro-

video images of the movement of particles underotion were analyzed by the NTA, version 1.3 (B196)sis software (NanoSight). Each video clip was capturedhe detection threshold was xed at 100, whereas thearticle jump and minimum track length were both set

NTA software.

performed using a VG Escalab 210 system with an

diffraca D8 agraphiwere uof 0.1540 kV The cr(1959)

CI% =

wherelatticesents bof diffrangle b10 rep

3. Res

3.1. Sianode (AlK = 1486.6 eV) operating at 150 W with a pressure of 5 109 mbar. The low-resolution surveytaken with a 1 eV step and 50 eV analyzer pass energy;tion spectra were taken with a 0.1 eV step and 50 eVss energy. The angle between X-ray beam and the sur-

was kept at 0 and the depth of analysis was practicallyatomic ratio of oxygen-to-carbon (O/C) was calculatedormalized peak areas as:

C

O(2)

d IC are the normalized integrated area of the peaks for carbon, respectively SC/SO is the corrected term for theactor.

p bers, DTAB modied hemp bers and nanocel-ied hemp bers were subjected to a powder X-ray

Fig. 2 plose with vof nanocelluand 29321std 1, std 2Compared lose fabrica(the acid hacid hydrolthat oxidatThe yield o34.31% andacterized bFEG-SEM c45.45 nm todifference ticles can bcan be fouof samples.ounted on the mount (dimensions in mm).

method analysis (PXRD) respectively. For this analysis,ced Bruker AXS diffractometer, Cu point focus source,onochromator and 2D-area detector GADDS systemThe diffracted intensity of CuK radiation (wavelength) was recorded between 5 and 40 (2 angle range) at0 mA. Samples were analyzed in transmission mode.linity index (CI) was evaluated by using Segal et al.irical method as follow:

Iam)0 0 2

100 (3)

is the maximum intensity of diffraction of the (0 0 2) at a 2 angle of between 21 and 23, which repre-rystalline and amorphous materials. Iam is the intensityn of the amorphous material, which is taken at a 2een 18 and 20 where the intensity is at a minimum.s were used.

and discussion

tribution and morphologies of nanocelluloseresents the results of size distribution of nanocellu-arious treatments. According the NTA, the size rangelose for std 1, std 2 and std 3 is 31281 nm, 38278 nm

nm respectively, the average size of nanocellulose for and std 3 is 100 nm, 112 nm and 103 nm, respectively.with acid hydrolysis (Morn et al., 2008), nanocellu-ted by oxidationsonication shows wider size rangeydrolysis gives 560 nm) and higher average size (theysis gives 30.90 nm). However the NTA results discloseionsonication also can fabricate nano-scale cellulose.f nanocellulose for std 1, std 2 and std 3 are 10.72%,

42.02%, respectively (Fig. 2). Std 3 was further char-y FEG-SEM (Fig. 3(a)) and AFM (Fig. 3(b)). According toharacterization, the size of nanocellulose ranges from

168 nm. AFM image of nanocellulose shows a slightwith FEG-SEM, as shown in Fig. 3(b), not only par-e observed in this image but also rod like of bril

nd. This may be due to the difference of preparation

D. Dai et al. / Industrial Crops and Products 44 (2013) 192 199 195

nocel

3.2. Mechanbers

3.2.1. MechMechan

were summnanocelluloural bers, raw bers, tlulose modirespectivelyral bers (O

re w to th

FEG-S natubserrilla

b) cleFEG-

of tFig. 2. Size distribution and picture from NTA video of na

ical properties of nanocellulose modied natural

anical propertiesical properties of hemp bers with various treatmentsarized in Table 2. It is apparent that both DTAB andse treatment enhance the mechanical properties of nat-especially for nanocellulose treatment, compared withhe modulus, tensile stress and tensile strain of nanocel-ed hemp bers increase by 36.13%, 72.80% and 67.89%,

therefobe due

3.2.2. The

were ointerbFig. 4(bers. surface. As reported, dislocation is the weakest link in natu-uajai et al., 2004; Eder et al., 2007; Dai and Fan, 2011),

and (2) boCompared w

Fig. 3. Morphology of nanocellulose (a) by FEG-SEM (100,000) lulose (std 1, std 2 and std 3).

e conjecture the increase of mechanical properties maye repair of dislocation in the bers.

EMral bers before and after nanocellulose modication

ved with FEG-SEM. As shown in Fig. 4(a), impurity andr gap can be found on the surface of raw hemp bers.arly shows the presence of nanocellulose around theSEM micrograph shows that nanocellulose covers thehe bers with two ways, namely, (1) lling in the stria

nding the inter-bril on the surface of hemp bers.ith macro-bers from nature, nanocellulose possesses

and (b) by AFM (height image).

196 D. Dai et al. / Industrial Crops and Products 44 (2013) 192 199

Table 2Mechanical properties of modied hemp bers.

Experiment Diameter(m)

C.V. ofdiameter (%)

Modulus(GPa)

C.V. ofmodulus (%)

Tensile stressat break (MPa)

C.V. ofstress (%)

Tensile strainat break (%)

C.V. ofstrain (%)

Unmodied 696.68 9.07 2.29 5.31DTAB modi 735.29 7.65 2.47 9.98Nanocellulo 1203.85 9.25 3.84 5.92

emp bers (magnication: (a) 20,000; (b) 48,000).

higher spec2005; Stensit has a relatfor a singleWang, 2008lulose on thbers. The hand may leatage of highhydroxyl grril through elastic modcal perform(2006), lamtion could modicatiolayer, theseties of S2 laof bers.

3.2.3. XRDX-ray di

of unmodibers. An ehemp bersummarizemajor crystoccurs fromtallographicbetween 0 crystallinitylulose modis apparentincreased sion the ber

000

000

000

I002

Hemp fibers

DTAB Modified

Hemp fibers

Nanocellulose

Modified Hemp fibersCI

DTAB modified=65.95%

CIHemp fibers

=55.17%

CINanocellulose modified

=76.39% 46.76 6.75 28.29 9.39 cation 45.10 9.65 29.83 7.95 se modication 51.39 7.05 38.51 8.44

Fig. 4. FEG-SEM morphologies of untreated (a) and nanocellulose modied h

ic surface area (up to 170 m2 g1) (Samir et al., 2004,tad et al., 2008; Wagberg et al., 2008; Habibi et al., 2010),ively high elastic modulus of 78150 GPa as determined

nanocellulose bril (Guhados et al., 2005; Cheng and; Iwamoto et al., 2009). Therefore, covering of nanocel-e surface of bers will introduce new properties ontoigher specic surface area will rough the bers surfaced to a stronger interface with resin. The second advan-

3

4

5

ten

sity

(a.

u.) specic surface area is based on the high density ofoups (Stenstad et al., 2008), which will bond interb-hydrogen bonding. Moreover, the attaching of higherulus of nanocellulose may lead to a better mechani-ance for natural bers. As described by Thygesen et al.ellae with 100 nm thick existed in S2 layer, delamina-be observed in this layer. Therefore, in the process ofn, nanocellulose might penetrate into the lamellae in S2

lling will give rise to increase the mechanical proper-yer and might contribute to the dislocations reparation

ffractogram was used to investigate the crystallinityed, DTAB modied and nanocellulose modied hempxample of X-ray powder diffraction spectra from theses is given in Fig. 5. Crystallinity index analysis wasd in Table 3. It can be seen from Table 3 that thealline peak of the hemp bers with various treatments

21.77 to 22.63, which represents the cellulose crys- plane (0 0 2, Bragg reection). The minimum intensity

0 2 and 1 0 1 peaks (Iam) is from 18.52 to 19.11. The index for raw bers, DTAB modication and nanocel-ication is 55.17%, 65.95% and 76.39%, respectively. It

that after modication, crystallinity of hemp bersgnicantly. This may be due to the removal of impuritys or attributed directly to attaching nanocellulose.

1

1000

2000In

Fig. 5. X-ray dbers.

3.3. Interfa

Interfacimines the Various me

Table 3Intensity and

Samples

Raw bers DTAB modiNanocellulo

modied 0 20 30 402

I004

I101

I101

Iam

iffractogram of unmodied, DTAB and nanocellulose modied hemp

ce property of nanocellulose modied natural bers

al property of bers is the main factor, which deter-nal performance of the bers-based composites.

thods (e.g. micro-mechanical techniques (Mandell et al.,

crystallinity of modied hemp bers.

2 () Intensity(a.u)

Crystallinityindex (%)

Iam I0 0 2 Iam I0 0 2

19.11 22.63 1822 4064 55.17ed bers 18.52 21.77 1529 4491 65.95sebers

18.58 21.94 1307 5538 76.39

D. Dai et al. / Industrial Crops and Products 44 (2013) 192 199 197

Table 4Absorbed resins of raw hemp bers and modied bers.

Samples Absorbed resin (mg/0.5 g bers)

Raw bers 52.05DTAB 33.65Nanocellulose modication 72.35

1980; Gaur and Miller, 1989; Yue et al., 1995), spectroscopic tech-niques (Zadorecki and Rnnhult, 1986; Hua et al., 1987; Takaseand Shiraishi, 1989; Felix and Gatenholm, 1991), surface charac-terization (Gassan et al., 2000; Montes-Morn et al., 2001; Parket al., 2006)) have been developed for assessing interfacial property.Especially, for spectroscopic techniques, researchers always useSoxhlet extraction as pretreatment before FTIR or XPS characteriza-tion (Park and Kim, 2000; Matuana et al., 2001). In the present work,we develop a novel method without Soxhlet extraction pretreat-ment for the measurement of polyester adsorption on the surfaceof bers and the characterization of ber surface by FTIR and XPS.The adsorbed unsaturated polyester on the surface of bers withvarious treaafter nanocfrom 52.05treatment, bers to 33modicatioresult is in apaper. Namwith resins

XPS is allosic and poFig. 6 showunsaturatedvarious metelements onand C1s wefrom this gthe O/C atobers/unsaThis value indicating twith the resis 0.356 anwith the reresults of XPdeveloped cproperty of

600

O1

Fig. 6. XPS widDTAB and nan

535 530 2922902882862842822800

1000

2000

3000

4000

5000

6000

7000

8000

3 DTAB fibers/Unsaturated

polyester

C1sO1s

2 DTAB-Nanocellulose fibers

/Unsaturated polyester

1 Unsaturated polyester

4 Raw fibers/ Unsaturated

polyester

Inte

nsi

ty /

cps

Binding Energy /eV

Atomic ratio of O/C

1 0.245

2 0.272

3 0.356

4 0.349

Fig. 7. O1s and C1s narrow spectra of unsaturated polyester and bers with untreat-ment, DTAB and nanocellulose modication immersed with unsaturated polyester.

ATR-FTIR has been used extensively to investigate the surfaceof bers as well as the resin adhesion, and spectra subtraction is

in variety of situations, such as an inspection of incomingaterials, comparison of batches or samples, evaluation ofc reactionllulo

with wit

attr ATRolyew betai

can anceepord C6ver, nad emay nd Cter. T(a)) wala em1

supned 1 is

0

2

4

6

8

0

2

4

3345Region 1

a

b

of nanocellulose modified fibers

c Unsaturatted polyesteer from surface

of raw fibers

c

b

a

Region 2

360 0tments was summarized in Table 4. Table 4 shows thatellulose treatment the resin adsorption was increased

mg/0.5 g bers to 72.35 mg/0.5 g bers, but for DTABthe adsorbed resin was decreased from 52.05 mg/0.5 g.65 mg/0.5 g bers. This indicates that nanocellulosen can improve the interfacial properties of bers. Thisgreement with those discussed in 3.2.2 in this presentely, nanocellulose can increase the interface of bers.ways used to study the chemical compositions of cellu-lymeric materials as well as their chemical interactions.s XPS wide scans spectra for unsaturated polyester,

polyester coated bers, which were pretreated withhods. It can be seen that oxygen and carbon are the main

the surface of bers. High resolution of spectra at O1sre shown in Fig. 7. Atomic ratio of O/C also is calculatedure. Nanocellulose modication results in a decrease inmic ratio, which is 0.272 compared to O/C ratio for rawturated polyester or DTAB bers/unsaturated polyester.is similar with unsaturated polyester which is 0.245,hat almost all of the surface of the bers were coveredin. For DTAB treatment and raw bers, O/C atomic ratiod 0.349, respectively. These results are in agreementsin absorption measurement as illustrated above. TheS characterization indicates that the method that havean be used as novel assessment way for the interface

bers.

532.3 eV

531.5 eV

532.1 eV

531.9 eV

284.7 eV

284.8 eV

284.9 eV

284.5 eVs

Raw fiber s/U nsaturated poly este r

DTAB fibers /Unsatu rated polyes ter

DTAB-Nan ocellu lose fib ers /unsatura tedp olyese r

Unsaturate d po lyester

C1s

useful raw morganisubtrananocecoatedspectramay be

Thetra of pand raMore d(b). Asabsorbvious r(C2 anmoreo(StenstFig. 8 at C2 apolyes(Fig. 9(Tarim1380 cfurtheris assig989 cm

0.0

0.0

0.0

0.0

0.0

0.1

0.1

0.1

Ab

sorb

ance500 40 0 30 0 20 0 100 0

Binding Energy /eV

e scans spectra of unsaturated polyester and bers with untreatment,ocellulose modication immersed with unsaturated polyester.

4000

Fig. 8. ATR-FTlulose modiections, and so on. This present work employs spectra to subtract unsaturated polyester spectrum from these modied and un-modied hemps bers which are

unsaturated polyester, then compare these subtractingh raw unsaturated polyester. The differences spectrumibuted to the effect of nanocellulose.-FTIR spectra of pure unsaturated polyester (a), spec-ster subtraction from nanocellulose modied bers (b)ers (c) after resin coating were presented in Fig. 8.

ls about regions 2 and 3 were shown in Fig. 9(a) andbe seen, the subtracted spectrum b appears negative

in region 1 (from 3600 to 3345 cm1). According to pre-ts (Kondo, 1997; Singh et al., 2000), free hydroxyl groups) in cellulose were assigned around 35613358 cm1;anocellulose possesses high density of hydroxyl groupst al., 2008). The negative absorbance in spectrum (b) ofbe due to the esterication between hydroxyl groups6 of nanocellulose and carboxyl groups of unsaturatedhis can be further proved from the peak at 1426 cm1

hich is assigned with the H C H bending vibrationt al., 2006). Moreover, the appearance of peak aroundcan be clearly observed in spectrum a in Fig. 9(a) alsoport this observation. Generally, the peak at 912 cm1

with C H (in CH CH) out-of-plane bending of styrene, assigned with C H (in CH CH) out-of-plane bending

Pure unsaturated polyester

Unsaturatedpolyester from surface

Reg ion 33500 3000 2500 2000 1500 1000

Wavenumber /cm-1

IR spectra of pure unsaturated polyester, subtraction from nanocel-d bers and raw bers.

198 D. Dai et al. / Industrial Crops and Products 44 (2013) 192 199

1380

a

a Pure unsaturated polyester

b Unsaturatedpolyester from

surface of nanocellulose

modified fibers

c Unsaturatted polyesteer from

surface of raw fibers

1200

a Pure unsaturated polyester

b Unsaturatedpolyester from

surface of nanocellulose

modified fibers

c Unsaturatted polyesteer from surface of raw fibers

a

Fig. 9. ATR ed b

of unsatura2009), the less styrenepeak appeamodicatioof modiedtrum b andpolyester is

4. Conclus

Oxidatioduce nanocNTA, FEG-Scomes. Theused as coucation procconcluded a

(1) The momodierespecti

(2) Nanoceon the inter-b

(3) The cry55.17% of nano

(4) The resi50%, indicationand car

Acknowled

This reseBoard, DepaTP/5/SUS/6

References

Bae, G.Y., Min,bicity of cagent. J. Co

Becheri, A., Dof zinc oxiRes. 10, 67

Belgacem, M.Nas reinforc

Bismarck, A., Msen, G., Sp

ertiesn Che

A.K., . Poly., Wanls via aFan, Msform, Terzihe ten1.., Gatlose J., Gutral b, Milleber/nol. 3

s, G., Wle bac664., Saieating352.z, A., de mannol. 9Y., Lumbly,Flodinced wapon

2009. tton 569., S., Kobriecules

J., Pomnced pos. I., 199llulos, E., Sidustrico-pro

Yeo, S1450 1400 1350

1374

c

b

Wavenumber /cm-1

1426

(a)

1300

c

b

-FTIR spectra of pure unsaturated polyester, subtraction from nanocellulose modi

ted polyester (Rahmat and Day, 2003; Worzakowska,disappearance of 912 cm1 in spectrum indicates that

was absorbed on the surface of raw bers. However thisrs in spectrum b in Fig. 9(b), showing that nanocellulosen can increase the adhesion of styrene on the surface

bers. The appearance of peak at 975 cm1 in spec- peak at 984 cm1 in spectrum c show that unsaturated

adsorbed by both of the bers.

ions

nsonication has been successfully employed to pro-ellulose directly from natural bers (hemp bers), withEM or AFM characterizations showing consistent out-

developed nanocellulose has then successfully beenpling agent to modify hemp bers with novel modi-

esses. Specic outcomes of the self-modication can bes follows:

dulus, tensile stress and tensile strain of nanocellulosed hemp bers increased by 36.13%, 72.80% and 67.89%,vely.llulose modication resulted in two different processesber surfaces: (1) lling in the stria and (2) bonding theril on the surface of hemp bers.stallinity of modied hemp bers increased fromto 76.39%, showing the penetration and compatibilitycellulose with microstructure layers of hemp bers.n adsorption of the modied bers increased by abouticating the change of interface properties and the ester-

between hydroxyl groups at C2 and C6 of nanocelluloseboxyl groups of unsaturated polyester.

gement

arch programme is funded by the Technology Strategy

propGree

Bledzki,Prog

Cheng, Qbri

Dai, D., tran

Eder, M.on t778

Felix, J.Mcellu

Gassan, natu

Gaur, U.of a Tech

Guhadosing6642

Gulati, Dof tr347

Gutirrein thTech

Habibi, asse

Hua, L., redu

Ilic, V., SM., of co564

Iwamotomicrmol

Juntaro,enhaCom

Kondo, Tin ce

Kreugerof inand

Lee, H.J.,rtment for Business, Innovation and Skills, UK, Project/I/H0565L.

B.G., Jeong, Y.G., Lee, S.C., Jang, J.H., Koo, G.H., 2009. Superhydropho-otton fabrics treated with silica nanoparticles and water-repellentlloid Interface Sci. 337, 170175.rr, M., Lo Nostro, P., Baglioni, P., 2008. Synthesis and characterizationde nanoparticles: application to textiles as UV-absorbers. J. Nanopart.9689.., Gandini, A., 2005. The surface modication of cellulose bres for useing elements in composite materials. Compos. Interfaces 12, 4175.ohanty, A.K., Aranberri-Askargorta, I., Czapla, S., Misra, M., Hinrich-ringer, J., 2001. Surface characterization of natural bers; surface

solution oLi, Y., Pickering

posites us420426.

Liu, C.F., Sun,Chemical manhydride

Mandell, J.F., Cment of b1, 4044.

Matuana, L.M.of esterie35, 1912

Mohanty, A.K.posites: anB.R., Hinrip. 3. 1100 1000 900 800 700

966989

939

984

917

912

842

843

Wavenumber /cm-1

975

(b)

ers and raw bers in 14751340 cm1 (a) and 1300650 cm1(b).

and the water up-take behavior of modied sisal and coir bers.m. 3, 100107.Gassan, J., 1999. Composites reinforced with cellulose based bres.m. Sci. 24, 221274.g, S., 2008. A method for testing the elastic modulus of single cellulosetomic force microscopy. Compos. A: Appl. Sci. Manuf. 39, 18381843.., 2011. Investigation of the dislocation of natural bres by Fourier-

infrared spectroscopy. Vib. Spectrosc. 55, 300306.ev, N., Daniel, G., Burgert, I., 2007. The effect of (induced) dislocationssile properties of individual Norway spruce bres. Holzforschung 62,

enholm, P., 1991. The nature of adhesion in composites of modiedbers and polypropylene. J. Appl. Polym. Sci. 42, 609620.owski, V.S., Bledzki, A.K., 2000. About the surface characteristics ofres. Macromol. Mater. Eng. 283, 132139.r, B., 1989. Microbond method for determination of the shear strengthresin interface: evaluation of experimental parameters. Compos. Sci.4, 3551.an, W., Hutter, J.L., 2005. Measurement of the elastic modulus of

terial cellulose bers using atomic force microscopy. Langmuir 21,6.n, M., 2006. Fungal-modication of natural bers: a novel method

natural bers for composite reinforcement. J. Polym. Environ. 14,

el Ro, J.C., 2005. Chemical characterization of pitch deposits producedufacturing of high-quality paper pulps from hemp bers. Bioresour.6, 14451450.cia, L.A., Rojas, O.J., 2010. Cellulose canocrystals: chemistry, self-

and applications. Chem. Rev. 110, 34793500., P., Rnnhult, T., 1987. Cellulose berpolyester composites withater sensitivity (2)surface analysis. Polym. Compos. 8, 203207.jic, Z., Vodnik, V., Potkonjak, B., Jovancic, P., Nedeljkovic, J., Radetic,The inuence of silver content on antimicrobial activity and colorfabrics functionalized with Ag nanoparticles. Carbohydr. Polym. 78,

ai, W., Isogai, A., Iwata, T., 2009. Elastic modulus of single cellulosels from tunicate measured by atomic force microscopy. Biomacro-

10, 25712576.met, M., Mantalaris, A., Shaffer, M., Bismarck, A., 2007. Nanocelluloseinterfaces in truly green unidirectional bre reinforced composites.nterfaces 14, 753762.7. The assignment of IR absorption bands due to free hydroxyl groupse. Cellulose 4, 281292.pos, B., Zacchi, G., Svensson, S.-E., Bjrnsson, L., 2011. Bioconversional hemp to ethanol and methane: the benets of steam pretreatmentduction. Bioresour. Technol. 102, 34573465..Y., Jeong, S.H., 2003. Antibacterial effect of nanosized silver colloidal

n textile fabrics. J. Mar. Sci. 38, 21992204., K.L., Farrell, R.L., 2009. Analysis of green hemp bre reinforced com-

ing bag retting and white rot fungal treatments. Ind. Crops Prod. 29,

R.C., Qin, M.H., Zhang, A.P., Ren, J.L., Xu, F., Ye, J., Wu, S.B., 2007.odication of ultrasound-pretreated sugarcane bagasse with maleic

. Ind. Crops Prod. 26, 212219.hen, J.H., McGarry, F.J., 1980. A microdebonding test for in situ assess-re/matrix bond strength in composite materials. Int. J. Adhes. Adhes.

, Balatinecz, J.J., Sodhi, R.N.S., Park, C.B., 2001. Surface characterizationd cellulosic bers by XPS and FTIR spectroscopy. Wood Sci. Technol.01., Misra, M., Drzal, L.T., 2005. Natural bers, biopolymers, and biocom-

introduction. In: Mohanty, A.K., Misra, M., Drzal, L.T., Selke, S.E., Harte,chsen, G. (Eds.), Natural Fibers, Biopolymers, and Biocomposites. CRC,

D. Dai et al. / Industrial Crops and Products 44 (2013) 192 199 199

Mondal, S., Hu, J.L., 2007. A novel approach to excellent UV protecting cotton fabricwith functionalized MWNT containing water vapor permeable PU coating. J.Appl. Polym. Sci. 103, 33703376.

Montes-Morn, M.A., Martnez-Alonso, A., Tascn, J.M.D., Paiva, M.C., Bernardo, C.A.,2001. Effects of plasma oxidation on the surface and interfacial properties ofcarbon bres/polycarbonate composites. Carbon 39, 10571068.

Morn, J., Alvarez, V., Cyras, V., Vzquez, A., 2008. Extraction of cellulose and prepa-ration of nanocellulose from sisal bers. Cellulose 15, 149159.

Ouajai, S., Hodzic, A., Shanks, R.A., 2004. Morphological and grafting modication ofnatural cellulose bers. J. Appl. Polym. Sci. 94, 24562465.

Park, J.M., Quang, S.T., Hwang, B.S., DeVries, K.L., 2006. Interfacial evaluation of mod-ied jute and hemp bers/polypropylene (PP)maleic anhydride polypropylenecopolymers (PP-MAPP) composites using micromechanical technique and non-destructive acoustic emission. Compos. Sci. Technol. 66, 26862699.

Park, S.J., Kim, M.H., 2000. Effect of acidic anode treatment on carbon bers forincreasing bermatrix adhesion and its relationship to interlaminar shearstrength of composites. J. Mar. Sci. 35, 19011905.

Pasta, M., La Mantia, F., Hu, L., Deshazer, H., Cui, Y., 2010. Aqueous supercapacitorson conductive cotton. Nano Res. 3, 452458.

Pommet, M., Juntaro, J., Heng, J.Y.Y., Mantalaris, A., Lee, A.F., Wilson, K., Kalinka, G.,Shaffer, M.S.P., Bismarck, A., 2008. Surface modication of natural bers usingbacteria: depositing bacterial cellulose onto natural bers to create hierarchicalber reinforced nanocomposites. Biomacromolecules 9, 16431651.

Qi, K., Chen, X., Liu, Y., Xin, J.H., Mak, C.L., Daoud, W.A., 2007. Facile preparationof anatase/SiO2 spherical nanocomposites and their application in self-cleaningtextiles. J. Mater. Chem. 17, 35043508.

Ragoubi, M., Bienaim, D., Molina, S., George, B., Merlin, A., 2010. Impact of coronatreated hemp bres onto mechanical properties of polypropylene compositesmade thereof. Ind. Crops Prod. 31, 344349.

Rahmat, A.R., Day, R.J., 2003. Curing characteristics of unsaturated polyester/aramidreinforced composite: microwave vs. thermal energy. JTMKKHAS, 8396.

Ramires, E.C., Megiatto Jr., J.D., Gardrat, C., Castellan, A., Frollini, E., 2010. Biobasedcomposites from glyoxalphenolic resins and sisal bers. Bioresour. Technol.101, 19982006.

Samir, M.A.S.A., Alloin, F., Dufresne, A., 2005. Review of recent research into cel-lulosic whiskers, their properties and their application in nanocomposite eld.Biomacromolecules 6, 612626.

Samir, M.A.S.A., Alloin, F., Gorecki, W., Sanchez, J.Y., Dufresne, A., 2004. Nanocompos-ite polymer electrolytes based on poly(oxyethylene) and cellulose nanocrystals.J. Phys. Chem. B 108, 1084510852.

Segal, L., Creely, J.J., Martin, A.E., Conrad, C.M., 1959. An empirical method forestimating the degree of crystallinity of native cellulose using the X-ray diffrac-tometer. Text. Res. J. 29, 786794.

Singh, B., Gupta, M., Verma, A., Tyagi, O.S., 2000. FT-IR microscopic studies on cou-pling agents: treated natural bres. Polym. Int. 49, 14441451.

Stenstad, P., Andresen, M., Tanem, B.S., Stenius, P., 2008. Chemical surface modi-cations of microbrillated cellulose. Cellulose 15, 3545.

Takase, S., Shiraishi, N., 1989. Studies on composites from wood and polypropylenes.II. J. Appl. Polym. Sci. 37, 645659.

Tarimala, S., Kothari, N., Abidi, N., Hequet, E., Fralick, J., Dai, L.L., 2006. New approachto antibacterial treatment of cotton fabric with silver nanoparticle-doped silicausing solgel process. J. Appl. Polym. Sci. 101, 29382943.

Thygesen, A., Daniel, G., Lilholt, H., Thomsen, A.B., 2006. Hemp ber microstructureand use of fungal debration to obtain bers for composite materials. J. Nat.Fibers 2, 1937.

Tomsic, B., Simoncic, B., Orel, B., Cerne, L., Tavcer, P., Zorko, M., Jerman, I., Vilcnik,A., Kovac, J., 2008. Solgel coating of cellulose bres with antimicrobial andrepellent properties. J. SolGel Sci. Technol. 47, 4457.

Uddin, M.J., Cesano, F., Scarano, D., Bonino, F., Agostini, G., Spoto, G., Bordiga, S.,Zecchina, A., 2008. Cotton textile bres coated by Au/TiO2 lms: synthesis,characterization and self cleaning properties. J. Photochem. Photobiol. A 199,6472.

Veronovski, N., Rudolf, A., Smole, M., Kreze, T., Gersak, J., 2009. Self-cleaning andhandle properties of TiO2-modied textiles. Fibers Polym. 10, 551556.

Wagberg, L., Decher, G., Norgren, M., Lindstrom, T., Ankerfors, M., Axnas, K., 2008. Thebuild-up of polyelectrolyte multilayers of microbrillated cellulose and cationicpolyelectrolytes. Langmuir 24, 784795.

Wang, R.H., Xin, J.H., Tao, X.M., 2005. UV-blocking property of dumbbell-shaped ZnOcrystallites on cotton fabrics. Inorg. Chem. 44, 39263930.

Worzakowska, M., 2009. Chemical modication of unsaturated polyesters inuenceof polyesters structure on thermal and viscoelastic properties of low styrenecontent copolymers. J. Appl. Polym. Sci. 114, 720731.

Yu, M., Gu, G., Meng, W.D., Qing, F.L., 2007. Superhydrophobic cotton fabriccoating based on a complex layer of silica nanoparticles and peruoroocty-lated quaternary ammonium silane coupling agent. Appl. Surf. Sci. 253,36693673.

Yue, C.Y., Looi, H.C., Quek, M.Y., 1995. Assessment of brematrix adhesion andinterfacial properties using the pull-out test. Int. J. Adhes. Adhes. 15, 7380.

Zadorecki, P., Rnnhult, T., 1986. An ESCA study of chemical reactions on the surfacesof cellulose bers. J. Polym. Sci. A: Polym. Chem. 24, 737745.

Fabrication of nanocelluloses from hemp fibers and their application for the reinforcement of hemp fibers1 Introduction2 Materials and methods2.1 Materials2.2 Fabrication of nanocellulose2.3 Modification of natural fibers2.3.1 DTAB modification2.3.2 Nanocellulose modification

2.4 Tensile testing2.5 Resin adsorption measurements2.6 AFM2.7 ATR-FTIR2.8 FEG-SEM2.9 NTA2.10 XPS2.11 XRD

3 Results and discussion3.1 Size distribution and morphologies of nanocellulose3.2 Mechanical properties of nanocellulose modified natural fibers3.2.1 Mechanical properties3.2.2 FEG-SEM3.2.3 XRD

3.3 Interface property of nanocellulose modified natural fibers

4 ConclusionsAcknowledgementReferences