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Industrial Crops and Products 33 (2011) 683–689

Contents lists available at ScienceDirect

Industrial Crops and Products

journa l homepage: www.e lsev ier .com/ locate / indcrop

ovel, binder-free fiber reinforced composites based on a renewable resourcerom the reed-like plant Typha sp.

ünter Wuzellaa, Arunjunaj Raj Mahendrana, Thorsten Bätgeb, Sandra Jurya, Andreas Kandelbauerb,c,∗

WOOD Carinthian Competence Center, Kompetenzzentrum Holz GmbH, Klagenfurterstrasse 87-89, A-9300 St. Veit an der Glan, AustriaDepartment of Wood Science and Technology, University of Natural Resources and Life Sciences, Peter Jordan Strasse 82, A-1190 Vienna, AustriaSchool of Applied Chemistry, Reutlingen University, Alteburgstrasse 150, D-72762 Reutlingen, Germany

r t i c l e i n f o

rticle history:eceived 18 November 2010eceived in revised form 4 January 2011ccepted 5 January 2011vailable online 31 January 2011

eywords:enewable resources

a b s t r a c t

The aim of this paper is to demonstrate for the first time the technological potential of novel, totallybio-based, binder-free vegetable fiber-composites based on the reed-like plant Typha sp. Binder-freevegetable fiberboards based on Cattails were prepared and their mechanical (flexural modulus of elas-ticity, flexural strength and water absorption) and surface textural properties were determined. Theinfluence of press time and panel density on the properties was investigated. In contrast to currentlyknown natural fiber composites based on hemp, flax, kenaf or the like annual plants which all requireup to 30 wt% of suitable bonding resins, the typha based composites were prepared completely without

ypha sp.atural fiber reinforced compositesattailsechnological propertiesurface roughness

the addition of any extraneous glue and showed good mechanical performance that clearly exceeded theperformance of other natural fiber composites containing low percentages of phenolic binder (15%). Ofspecial interest were the superior surface properties of the typha based panels. Despite the coarse natureof the raw fiber material and the rough texture of the typha based fiber mats, binder-free typha panelsshowed excellent surface smoothness which makes this novel composite material highly interesting forlight-weight applications with high surface quality standards, for example, as powder-coated elements

rnitu

for the automotive and fu

. Introduction

Cattails make up the genus Typha of the family Typhaceae,hich grow in wetlands throughout the world and are commonly

lso known as bulrush or raupo (Fig. 1). The genus consists of 10pecies (Typha latifolia, Typha angustifolia, Typha domingensis, Typhaapensis, etc.) which occur commonly in wet soil, marshes, swamps,nd shallow fresh and brackish waters, throughout the world. Cat-ails can grow three or more meters in height. The linear cattaileaves are thick, ribbon-like structures which have a spongy cross-ection because of the presence of air channels. The subterraneantem (Fig. 2a) arises from thick creeping rhizomes and similar tohe leaves, the stem has a spongy cross-section (Fig. 2b) exhibiting

ir channels. The significance of the morphological architecture ofhis cross-sectional view is obvious: one is immediately remindedf light-weight sandwich panel structures which are currently find-ng increasing scientific and industrial attention (Stoll et al., 2006).

∗ Corresponding author at: School of Applied Chemistry, Reutlingen University,lteburgstrasse 150, D-72762 Reutlingen, Germany. Tel.: +49 (0) 7121 271 2009;

ax: +49 (0) 7121 271 90 2009.E-mail address: andreas.kandelbauer@reutlingen-university.de

A. Kandelbauer).

926-6690/$ – see front matter © 2011 Elsevier B.V. All rights reserved.oi:10.1016/j.indcrop.2011.01.008

re industries.© 2011 Elsevier B.V. All rights reserved.

However, so far Typha sp. has not yet been explored in the contextof composite materials but it is nevertheless of widespread use inother areas. For example, cattails are used in water treatment plantsto naturally treat and purify water without addition of chemicalsor use of expensive water cleaning systems. More generally, phy-toremediation is currently one of the major applications of Typhaand numerous studies describe the elimination of pollutants likeheavy metals (Chandra and Yadav, 2010) or nitrogen compounds(Matheson and Sukias, 2010; O’Luanaigh et al., 2010).

In contrast, another potential field of application for Typha sp.fibers, namely as a natural fiber for composite reinforcement hasnot yet been described in the literature. While so far, the potential offlax, hemp, kenaf, sisal, etc. as reinforcing vegetable fibers has beeninvestigated by many researchers (John and Thomas, 2008; Saheband Jog, 1999), the reed-like plant Typha sp. has not yet drawn muchattention for composites production.

In the present contribution, for the first time the technologicalproperties of composites made of vegetable fibers from Typha sp.as reinforcement in 3D-shaped and flat composites are described.

Since these composites were prepared totally without addition ofany binder system, some constituents of the cattails are requiredto act as an intrinsic natural binder. Research papers in the pastwere concerned with the analysis of the composition of differentspecies of cattail (Gallardo-Williams et al., 2002; Shode et al., 2002;

684 G. Wuzella et al. / Industrial Crops an

MKaipwpeab

2

2

wK

2

ifntafi

Fig. 1. Cattails (Typha latifolia).

cManus et al., 2002; Ruangrungsi et al., 1987; Clopton and Vonorff, 1945); however, none so far was focussed on the self-gluingspects of this materials in particular and hence there is only littlendication on what actually happens in the hot-press during com-osite formation. After the synthetic binder resin-free compositesere hot pressed in a compression moulding process at differentress times panels of different densities were obtained. The influ-nce of press times and densities on the properties was investigatednd the technological panel properties were compared to variousinder-containing fiberboards.

. Materials and methods

.1. Vegetable fibers

For the composites the broad leaved cattail species T. latifoliaas used. Staple fibers of T. latifolia were delivered from Naporolima Dämmstoff GmbH, Moosdorf, Austria.

.2. Manufacturing of composites

The manufacturing of fiber mats composed of typha fibersnvolved opening of the typha fiber bundles on a carding machine

ollowed by layering the fibers to a fiber felt with the SPIKE tech-ology which is a combination of traditional air-laid and cardingechnology (Andersen, 2005). Subsequently, fiber mats with anrea weight of 1.200 g/m2 were produced by needle-punching theber felts.

Fig. 2. Cattail stem: (a) longitudinal

d Products 33 (2011) 683–689

The binder-free typha mats were compression moulded to pan-els at a constant press temperature of 160 ◦C and at a constantpressure of 80 bar. Panels of different densities were obtained bypressing typha mats of comparable area weights to panels of vary-ing thicknesses. To this end, during hot pressing of the mats, panelthickness was adjusted by using metal spacer plates of definedthickness which were inserted between the two press plates. Afterthe pressing the actual panel density was determined by weighingthe panel and dividing the measured weight by the panel volumewhich was calculated from the measured panel length, width, andthickness. Due to the fiber preparation process, the fiber mats aswell as the moulded composites are anisotropic in their mechan-ical behaviour. Hence, for flexural strength measurements samplespecimens were taken both in parallel and perpendicular to thedirection of the production line and mechanically tested for eachdirection separately. Additionally, fiber mats with more isotropicbehaviour were produced by cross-wise pressing two mats topanels resulting in panels with more homogenous behaviour. Toestimate the influence of temperature on the performance, thebinder-free typha mats were pressed for seven different presstimes, t1 = 5 min, t2 = 15 min, t3 = 30 min, t4 = 45 min, t5 = 60 min,t6 = 120 min, and t7 = 180 min.

The mechanical and surface properties of the typha panelswere compared to the performance of panels prepared from purekenaf, flax, hemp, coco and mixtures of kenaf/flax, hemp/flax, andwood/flax fiber mats. These fiber panels could not be producedwithout addition of significant amounts of binder resin which wasa polymeric phenol–formaldehyde or an aqueous acrylic resin. Theexact procedures for obtaining these reference fiberboards are pub-lished elsewhere (Kandelbauer et al., submitted for publication;Wuzella et al., 2010a,b; Wuzella, 2006).

2.3. Technological properties of composites

As technological properties the flexural strength, the flexuralmodulus of elasticity (MOE) and the water absorption of eachmoulded composite were measured. The flexural properties weremeasured according to the standard DIN EN 310 and the waterabsorption according to the standard DIN 52351.

3. Results and discussion

3.1. Binder-free typha based panels

The surface color of the pressed panels varied from light brownto very dark brown. This is shown in Fig. 3(For interpretation of thereferences to color in this text, the reader is referred to the web ver-sion of the article.).All the panels shown in the figure were pressed

and (b) cross-sectional view.

G. Wuzella et al. / Industrial Crops and Products 33 (2011) 683–689 685

Fa

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sofdpsbdqmtatbhbcseosupwiessptttnodegspftiai

different amounts of a phenolic glue (PF) for comparison. Again,the mechanical performance of the purely vegetable fiber basedcomposite is in general lower when compared to any of the otherconventional composites where high amounts of PF resin (30%)were used for the binding. However, it is still remarkable that in

ig. 3. Panels produced from Typha vegetable fibers without additional binder resinnd with the effect of density on surface color.

nder the same pressing conditions, that is, they were all pressed at60 ◦C for 15 min. Hence the reason for this color change could notave been simple differences in the charring of heat-sensitive com-ounds resulting from differences in temperature load between thehown specimens.

However, the panels depicted in Fig. 3 varied in their final den-ity, low density panels being on the left, high density panels beingn the right hand side. Upon comparison of the obtained valuesor the densities of the manufactured boards it is evident that aark color only appeared when panels of higher densities wereroduced whereas the surface color of panels of rather low den-ities were always light brown. Hence, the darkening effect mighte connected with an increased amount of a component liquefieduring the pressing process which of course is present in largeruantities directly in contact with the hot press plates when moreaterial is pressed to a denser panel. This liquefied component con-

ributed strongly to the observed, pronounced surface smoothnessnd lead to good embedding of the vegetable fibers (see below, Sec-ion 3.3 and Fig. 12a); it might also comprise the natural intrinsicinder material since it was observed that the darker materials ofigher density also showed higher mechanical performance (seeelow Section 3.2). However, it remains yet unclear what exactlyauses the gluing effect. In order to get a first idea on the rea-ons for the self-gluing effect of typha vegetable fibers, preliminaryxtraction experiments were performed. While Soxhlett extractionf the typha fibers with n-hexane overnight did not result in anyignificant extractives enrichment in the organic phase, polar sol-ble compounds could be removed with water and subsequentlyrecipitated to form a brownish powder. After the fiber materialas subjected to Soxhlett extraction with water for 24 h, compos-

te panels were pressed from the treated fibers. Pressing of thextracted material yielded a composite that although of some con-istency did not show sufficient mechanical strength to performtandardized tests. Hence, it was hypothesized that a main pro-ortion of the leachable compound might contribute significantlyo the observed fiber bonding. To gain further preliminary insight,he extract was analyzed by attenuated total reflectance Fourierransform infrared spectroscopy (ATR FTIR) and differential scan-ing calorimetry (DSC). However, the comparisons of the spectraf the dark areas of the composite surfaces and the brownish pow-er did not give conclusive results so far. Similarly, although somexothermal enthalpy changes were observed in the DSC thermo-rams, further systematic studies on the potential causes of theelf-gluing capacity of typha fibers are required and currently inrogress. Similarly, the reasons for the darkening need still to be

urther studied in detail since the darkening may have some nega-ive impact on potential uses of typha based composites. However,n typical automotive or furniture applications the visual appear-nce of the crude panels is of less importance since as productionntermediates they are usually surface finished.

Fig. 4. Flexural MOE of binder-free typha panels with different densities (diamonds)and linear regression of flexural MOE on density (solid line).

3.2. Mechanical performance of binder-free typha composites

Binder-free typha mats were pressed at a constant press temper-ature at various press times to obtain panels of different densities.The results of both measured flexural properties are shown inFigs. 4 and 5 respectively.

Both flexural properties, the flexural MOE (Fig. 4) and the flexu-ral strength (Fig. 5), depend on the density of the binder-free typhapanels regardless of the chosen press time. The higher the densityof the panel is the higher are the flexural properties. The flexuralMOE increases linearly and the flexural strength increases expo-nentially as the panel density increases (see solid line of regressionin Figs. 4 and 5).

A similar tendency for the flexural properties was found also forthe mechanical behaviour of fiberboards derived from a flax/kenaffiber mixture that was bond together with an acrylic resin. Thecorresponding data are shown in Figs. 6 and 7. It is evident uponcomparison of the different kinds of composites that although theoverall tendencies are similar, the acrylic resin bonded materialwas much stronger mechanically; however, when typha basedcomposites of high final densities are prepared their mechanicalperformance is of comparable order of magnitude although there isno additional binder material added. Table 2 shows some mechan-ical characteristics for further composites which are based on two

Fig. 5. Flexural strength of binder-free typha panels with different densities (dia-monds) and linear regression of flexural strength on density (solid line).

686 G. Wuzella et al. / Industrial Crops and Products 33 (2011) 683–689

Fig. 6. Flexural strength of moulded composites based on a flax/kenaf (50/50) mix-ture bonded with two different contents of acrylic binder resin as function of densityand tested in two orthogonal directions. Full circles, 25% acrylic resin, measurementitdp

ttflflc3srtcTfporrupb

rot

F(trsmp

Fig. 8. Water absorption of binder-free typha panels with press time = 15 min (dia-monds) and linear regression of water absorption on density (solid line).

Table 1Slope k, intercept d, and coefficient of determination R2 of linear regressions of waterabsorption on the density of binder-free typha panels, one linear regression for eachof seven press times.

Press time (min)a kb dc R2d

5 −717.9 881 0.97915 −277 397.1 0.99830 −393.9 500.2 0.97245 −317.5 432.9 0.91260 −280.6 376.4 0.997

120 −352 416.6 0.980180 −291.3 361.2 0.997

n production direction; open circles, 25% acrylic resin, measurement perpendicularo the production direction; full triangles, 15% acrylic resin, measurement in pro-uction direction; open circles, 15% acrylic resin, measurement perpendicular to theroduction direction.

he cases where suboptimal amounts of PF binder are employed, theypha based compounds performed clearly much better in terms ofexural MOE than any of the other composites and with respect toexural strength were still competitive. In the case of the wood/flaxomposite, the binder-free typha material was even better than the0% PF containing wood/flax panel. These findings indicate that theelf-gluing performance of typha based materials is indeed quiteemarkable and suggests that upon small addition of glue easilyhe mechanical performance of conventionally bound materialsan be obtained with using cattail as a natural fiber reinforcement.his was shown for a completely bio-based binder resin derivedrom linseed oil in a study published elsewhere (Wuzella et al., inreparation). Upon addition of only 10% of an epoxidized linseedil binder, typha composites were obtained that were clearly supe-ior in their mechanical performance than conventional ones thatequired up to 30% of PF or acrylic binder. It should be noted thatpon substitution of conventional composites by typha based com-osites the consumption and usage of environmentally harmful

inder resins may significantly be reduced.

Besides the mechanical properties, the performance withespect to water uptake is also of importance. The water absorptionf binder-free typha panels depended on both process parame-ers, on the press time as well as on the panel density. The water

ig. 7. Flexural modulus of elasticity of moulded composites based on a flax/kenaf50/50) mixture bonded with two different contents of acrylic binder resin as func-ion of density and tested in two orthogonal directions. Full circles, 25% acrylicesin, measurement in production direction; open circles, 25% acrylic resin, mea-urement perpendicular to the production direction; full triangles, 15% acrylic resin,easurement in production direction; open circles, 15% acrylic resin, measurement

erpendicular to the production direction.

a Press time of binder-free typha mats.b Slope of linear regression: water absorption = k *panel density + d.c Intercept of linear regression: water absorption = k *panel density + d.d Coefficient of determination.

absorption of panels with the same press time decreased linearlyas the panel density increased (see Fig. 8, with linear regression forpress time = 15 min). Hence, for panels with the same press time alinear regression on the panel densities was calculated (results ofregression for each of the seven press times in Table 1).

For an arbitrary panel density the water absorption as afunction of press time was calculated by using linear regres-sion (see Fig. 9, with the water absorption calculated for panelswith density = 1 g/cm3). Such density normalized water absorption

Fig. 9. Water absorption of binder-free typha panels calculated for panel den-sity = 1 g/cm3 using regression equations for different press times in Table 1(diamonds) and logarithmic regression of calculated water absorption on press time(solid line).

G. Wuzella et al. / Industrial Crops an

Fig. 10. Fibermat Typha.

dr

3

ra(fflpm

powder coated kenaf panel (see Fig. 12c) than a native kenaf panel.

TSp

Fig. 11. Fibermat coco.

ecreases logarithmic as the press time increases (see solid line ofegression in Fig. 9).

.3. Surface smoothness of typha based panels

Typha mats prior to the hot pressing (Fig. 10) have a veryough surface appearance; the single fibers are very coarse andppear quite similar to fibers and fiber mats made of coconut fibers

Fig. 11). In contrast, the physical appearance of fiber mats maderom flax or hemp is much smoother because these fibers are finer,uffier and more flexible. It was found earlier (Wuzella et al., inreparation) that panels produced from coco fiber have a muchore in-homogenous surface texture than panels based on hemp

able 2urface roughness expressed in roughness parameters Ra and Rt , flexural modulus of elashenolic (PF) binder resin in comparison to the binder-free produced Typha based panels (

Fiber mixture Binder Resin content (%) Ra

Kenaf (100%) PF 15 25.27 ± 2.18PF 30 24.00 ± 4.88

Flax (100%) PF 15 12.89 ± 1.18PF 30 13.37 ± 0.36

Hemp (100%) PF 15 20.90 ± 2.19PF 30 20.72 ± 1.63

Coco (100%) PF 15 32.57 ± 2.87PF 30 34.2 ± 1.94

Kenaf/flax (50/50) PF 15 22.08 ± 2.02PF 30 22.85 ± 2.30

Hemp/flax (50/50) PF 15 15.93 ± 0.98PF 30 12.83 ± 1.81

Wood/flax (75/25) PF 15 17.86 ± 2.27PF 30 17.14 ± 1.61

Typha – 0 4.96 ± 0.51

d Products 33 (2011) 683–689 687

or flax fiber mats and upon surface finishing with a powder coating,consequently, yield much less satisfactory results in terms of sur-face smoothness than the latter. From the roughness parameters Ra

and Rt for different types of fiberboards which are given in Table 2this becomes quite obvious.

While Ra describes roughness as an average across the ridges,holes and edges, the core roughness depth, Rt, yields informationon the order of magnitude of the deepness of pores and cavities.Coco fiber mats containing high amounts of a PF binder resin leadto the highest overall values for Ra and Rt whereas the smoothestboards were obtained with pure flax or flax/hemp (50:50) mix-tures (Wuzella et al., in preparation). The best panel (flax/hemp)was about the factor 3 smoother than the worst one (coco based)in terms of Rt.

Since typha and coco mats are very much alike with respectto coarseness of fibers and fibermat surface texture, it would beexpected then, that panels produced from typha fibers should alsolead to a similar, highly pronounced surface roughness and henceto a rather inhomogeneous surface appearance.

However, after the hot pressing the typha panels all showedvery smooth and closed surfaces without pores or distinct cavities.As apparent from the infinite focus micrograph in Fig. 12a, whichshows an area segment of approximately 1 mm2 of a typical, hot-pressed typha based fiberboard panel, no single fibers stick out, nodistinct surface features are visible and the overall appearance ofthe surface is homogenous, defect-free and uniform. This good sur-face quality is also evident from the values for Ra and Rt for thetypha based board in Table 2, which are by far the lowest valuesof all the boards compared. The surface of a typical coconut fiberpanel is much rougher and contains many pores and even with pan-els made of flax, hemp or kenaf fibers their surface quality is muchinferior in comparison to the pressed typha panels. Fig. 12b depictsa typical surface profile of a kenaf based hot-pressed fiber-board.In this case, the influence of single fibers on the surface texturecan be clearly seen; obviously upon heating and pressing the lique-fied binder resin sinks in and settles during bonding of the middlefiber layers towards the bulk of the composite board. The fiberslocated on the surface are by then not anymore sufficiently cov-ered by the PF resin and become exposed to the surface causing theobserved pronounced roughness texture. In contrast, when pan-els are pressed from typha mats this is not observed (see Fig. 12a).Surprisingly, the surface quality and the roughness profile of anunfinished typha board resemble more that of a surface finished,

This finding was very surprising and unexpected and holdsgreat promises for a potential future use of typha based compos-ite materials where the surface quality plays an important role.One such potential application would be for example the manu-

ticity (MOE) and flexural strength of various natural fiber composite bonded withall values in the table were obtained from panels of the same density (� = 1 g cm−3)).

Rt Flexural MOE (MPa) Flexural strength (MPa)

289.04 ± 35.73 932.5 ± 1190 22.5 ± 14.0300.23 ± 74.51 4343 ± 1064.5 53.8 ± 12.1136.45 ± 11.07 574 ± 230 17.4 ± 3.2159.49 ± 12.00 4839 ± 886.5 47.5 ± 13.5259.77 ± 50.24 2276.5 ± 230 37.9 ± 9.0260.20 ± 39.80 6186.5 ± 500 73.3 ± 4.5351.82 ± 41.85 n.d. n.d.444.64 ± 11.98 2049.5 ± 696.5 44.4 ± 9.1294.70 ± 39.15 1488.5 ± 792.5 29.3 ± 5.3256.44 ± 45.71 5877.5 ± 884.5 50.3 ± 13.1175.98 ± 8.37 1420 ± 518.5 20.4 ± 7.4174.99 ± 14.25 5524 ± 601 67.1 ± 7.3237.80 ± 54.57 n.d. n.d.219.25 ± 24.95 1202 ± 149 15.1 ± 0.9100.98 ± 10.00 3100 ± 92 21 ± 2

688 G. Wuzella et al. / Industrial Crops and Products 33 (2011) 683–689

ha pan

fiahiwmbtrlifoB

ss2ecpmocptr

tmbfir(s2bpfiw

Fig. 12. Infinite focus micrograph of (a) binder-free typ

acturing of constructive and decorative parts for the automotivendustry where light-weight panels based on renewable resourcesre very attractive, especially when they are good substrates forigh-quality surface finishes. As another example, such compos-

tes could also be successful new materials in the furniture industry,here high quality surface issues and design aspects play an evenore important role than in the automotive sector. Here, typha

ased composites could possibly represent an interesting alterna-ive material to wood fiber based materials because of their lowereproduction circles and indeed favorable surface roughness. Theatter feature is especially of interest when innovative novel coat-ng technologies such as powder coating technology is targeted ator ecologically and environmentally sustainable surface finishingf such materials (Kandelbauer et al., submitted for publication;auch et al., 2007).

Natural fiber based composites have recently been shown to beuccessfully coated using powder technology (Kandelbauer et al.,ubmitted for publication; Wuzella et al., 2010a,b; Jocham et al.,011) and here, the surface features of the substrates play anxtremely important role. The novel typha based composites dis-ussed and described for the first time in the present study couldotentially provide another constructive panel element which isade from natural fibers and is solely and completely based

n renewable resources with much better suitability for furtheroating processes than the previously described natural fiber com-osites. Studies on the effects of various processing parameters inhe powder coating of typha based composite materials are cur-ently in progress and will be published separately.

Compared to other natural-fiber based composite materials,he completely binder-free Typha panels show slightly inferior

echanical behaviour, especially when compared with wood-fiberased panels. Velázques and coworkers investigated binder-freeberboards from steam exploded Miscanthus sinensis. The bestesults were 6.07 MPa for MOE, 48 MPa for modulus of ruptureMOR), 2.8 MPa for internal bond (IB) strength, 4% of thicknesswelling (TS), and only 8% for water absorption (Velásquez et al.,

003). Widsten and coworkers investigated binder-free wood-fiberased boards produced using a biotechnologically modified wetrocess, employing laccase-enzyme activated tannin and woodbers. The hardboards (thickness 4–4.5 mm, density 920 kg m−3)ith the best performance had an internal bond (IB) strength of

el, (b) kenaf panel, and (c) powder coated kenaf panel.

1.39 MPa, a modulus of rupture (MOR) of 39.5 MPa, a modulusof elasticity (MOE) of 41,900 MPa and a thickness swelling (TS)of 45.0% (Widsten et al., 2009). The slightly inferior mechanicalperformance of binder-free typha based panels in comparison totheir flax, hemp, wood or kenaf based, synthetic resin bondedcounterparts described in this study, can be compensated for byaddition of small supplementary amounts of binder resins which bythemselves again may be solely based on bio-renewable resources.Experiments performed with typha derived vegetable fibers thatwere bonded with minor amounts (10%, w/w) epoxidized linseedoil showed that already by using only a 50–30% of the amounts ofsynthetic resin that were used to bond the traditional compositesdiscussed for comparison in the present contribution, the mechani-cal performance of typha based composites can be boosted to aboutthe same level of technological performance (Wuzella et al., inpreparation). Furthermore, as also shown in the present article, canthe mechanical strength also be increased by increasing the densityof the fiberboard.

4. Conclusion

In this contribution, for the first time technological proper-ties of “green” composites are described that were prepared fromvegetable fibers from Typha sp. Binder-free Typha based compos-ites where only the naturally-occurring constituents of cattailsacted as a binder were mechanically tested. The flexural MOE, theflexural strength and the water absorption of binder-free typhapanels were measured and the influence of press time and paneldensity on these properties was investigated. It was found thatthe mechanical properties due to self-gluing are remarkable, andeven more surprisingly it was found that the surface proper-ties of the novel composites are extraordinary good. Binder-free,cattails-based composites have a great potential as novel “green”composites for uses in the automotive and the furniture industries.

Acknowledgement

This project was funded by the Austrian Research PromotionAgency (FFG) which is gratefully acknowledged.

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