Biological Characterization of Panels Manufactured from Recycled Particleboards using Different Adhesives

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1 PEERREVIEWED ARTICLE Biologil Chrteriztion of Pnels Mnuftured from Reyled Prtilebords using Different Adhesives Ali Shlbfn,, * Jn T. Benthien, b nd Henrik Lerhe Trnsforming wste or reyled mterils into vluedded produts is of high priority tody. Wood plsti omposites (WPCs) show high potentil for the use of reyled mterils in mking durble omposites. The pplibility of WPC pnels produed from reyled mterils (ultrlight fom ore prtilebords) for exterior building pplition ws tested using wooddestroying bsidiomyetes. The results showed tht the pnels were fully resistnt ginst Coniophor puten (Cp) nd Gloeophyllum trbeum (Gt), but not very resistnt ginst Pleurotus ostretus (Po). The dey suseptibility index of Poexposed speimens showed tht the polystyrenebonded (PS) smples were more resistnt thn solid beeh wood smples tht were used s referenes, followed by melmineure formldehydebonded smples. A omprison with the referene smples lso showed tht the pnel density hd signifint influene on the pnel s resistne ginst bsidiomyetes. The higher the pnel density, the more resistne will be hieved in the pnel. Keyword: WPCs; Reyled mterils; Bsidiomyetes; Outdoor pplition Contt informtion: : Deprtment of Wood nd Pper Siene nd Tehnology, Fulty of Nturl Resoures nd Mrine Sienes, Trbit Modres University, Tehrn, Irn, b: Thünen Institute of Wood Reserh, Hmburg, Germny, : Hmburg University, Fulty of Nturl Sienes, Centre of Wood Sienes, Mehnil Wood Tehnology, Hmburg, Germny; * Corresponding uthor: li.shlbfn@modres..ir INTRODUCTION Using prodution wstes is of eonomi nd eologil importne in the prtilebord industry, s it ombines the hne to t in highly ompetitive mrket with n lmost perfeted tehnology. Wste trimmings nd prodution rejets from prtilebord produtions re usully burned for power genertion or further proessed nd used gin s ore lyer mteril (Irle nd Brbu 2010). A new tehnology to produe lightweight fom ore prtilebord hs been developed reently, derived from the onventionl prodution line of prtilebord (Luedtke 2011). The produed ultrlight pnels (< 400 kg/m³) onsist of resinted wood prtiles for the fing nd expnded polystyrene fom in the ore lyer (Shlbfn et l. 2012). An dditionl innovtive hrteristi of this ultrlight prtilebord is tht its ontinuous mnufturing ours in onestep proess, whih mkes it possible to produe fom ore pnels using onventionl doublebelt press. However, in ontrst to ommon prtilebord prodution, wste trimmings nd prodution rejets from ultrlight fom ore prtilebords nnot be diretly reyled beuse the thermoplsti fom mteril would lnd in the surfe lyers nd ould omplite the proess. Wood plsti omposites (WPCs) were introdued to the mrket in the 1990s. A WPC is homogeneous mteril omprised primrily of wood prtiles, thermoplsti polymer, nd, depending on the intended use, vrious dditives (Wolott 2003; Segerholm Shlbfn et l. (2016). Biologil hr. WPCs, BioResoures 11(2),

2 PEERREVIEWED ARTICLE et l. 2012; Rhmn et l. 2013). This tehnology shows good potentil for using wste or reyled wood nd polymers to mke durble omposites, whih in turn re potentilly reylble (Rowell et l. 1991). The use of wste s rw mteril for WPC prodution hs been investigted by number of uthors (Rowell et l. 1991; Chhrmhli et l. 2008; Poletto et l. 2011). The fom ore lyer of the reyled ultrlight pnels n be possible mteril for WPC prodution, sine it hs thermoplsti nture. Shlbfn et l. (2013) hve shown tht produing durble nd wterresistnt WPC pnels is possible using dryblended residues of ultrlight fom ore prtilebords. The min pplition of WPC produts is for outdoor use (e.g., deking nd fening), nd the produts n thus be infeted by wooddegrding fungi. Hene, resistne ginst destrutive bsidiomyetes is one of the most importnt hrteristis for WPC produts (Yp et l. 1990). The risk of fungl influx n be lso hnged when the wood ontent is vried (Kruse nd Gellerih 2014). Benthien et l. (2012) ompred the fungl dey resistne of wood with WPC nd found tht WPC pnels re more durble thn wood smples. Curling nd Murphy (2002) reommend the use of dey suseptibility index (DSI) to ompre dey tests rried out in different lbortories, periods nd onditions, or to ompre smples of different sizes nd densities. Defoirdt et l. (2010) mentioned tht ompring the biologil durbility of WPC usge tests tht were developed for wood or woodbsed pnels is only justified if their moisture behvior is similr. Severl publitions reommend moistening method for WPC pnels to hieve minimum level of moisture ontent for fungl ttk (Rowell 2007; Kim et l. 2008; Defoirdt et l. 2010). In this study, fltpressed WPC pnels mde of milled fom ore prtilebords residues were hrterized regrding their resistne ginst biologil degrdtion by investigting the smples mss loss nd dey suseptibility index (DSI) fter fungl dey. Melmine ure formldehyde (MUF)bonded prtile mterils were used s referene mteril. The effets of wood flour (WF) ontent nd binder type were studied. Before testing, smples were lehed by immersion in wter ording to EN 84 (1997). It ws the im of this study to evlute the durbility of WPC mteril with respet to moisture resistnt prtilebsed pnel mteril. EXPERIMENTAL Pnel Prodution Two types of pnels, both mnuftured from reyled prtilebords but differing in dhesive, either polystyrene (PS) or MUF, were ompred in this study. The press temperture nd speifi pressure were set t 210 C nd 1 N/mm 2, respetively. The hot pressing time ws 400 s for rehing to the desired nominl thikness of 10 mm. At the end of the pressing yle, ooling of the pnels ws performed under pressure (inside the press) by internl ooling of the press pltes for the next 400 s to reh the mbient temperture. More detils regrding the pnel prodution proess is explined by Shlbfn et l. (2013). Composite pnels ontining PS were produed in three steps, following previous studies (Shlbfn et l. 2012, 2013b). Step one ws the prodution of fom ore prtilebords tht onsisted of softwood prtiles (sprue nd pine) for the surfe lyers, whih inluded ure formldehyde resin (UF) nd mmonium sulfte (AS) s dditives, nd expndble polystyrene beds (Sunpor GmbH, Austri) in the ore lyer. Seond, the Shlbfn et l. (2016). Biologil hr. WPCs, BioResoures 11(2),

3 PEERREVIEWED ARTICLE fom ore prtilebords were rushed into powder blend (minly between 0.1 nd 0.5 mm), nd, third, the WPC pnels were produed from the powder blend. In this study, the omposite pnels were produed without dding oupling gent or further ompounding with the extruder, s Shlbfn et l. (2013) showed tht suh prmeters hd no positive or signifint effet on the pnel properties. PS plyed role s n dhesive in the omposite pnels beuse of its thermoplsti nture. The ontents of PS s dhesive in the finl mixtures were 12% nd 24% bsed on the oven dry mss of the reyled wood prtiles. Both types were nmed ording to the dhesive mounts, s PS12 nd PS24, respetively. Composite pnels with trget density of 1000 kg/m³ nd trget thikness of 10 mm were produed from the rushed powder blend. The seond type of dhesive, used s referene, ws MUF. Composite pnels ontining MUF were lso produed in three steps, whih were s similr s possible to the steps of the omposite pnels ontining PS to ensure the mximum omprbility. Step one ws the prodution of prtilebords using softwood prtiles, UF nd AS, ording to Shlbfn et l. (2012) but without PS fom ore. Step two onsisted of rushing of the prtilebords to powder blend. Step three, the prodution of omposite pnels from the powder blend, ws rried out ording to Shlbfn et l. (2013), but with n dditionl sprying of MUF into the powder blend. The powder blends were mixed with 12% (MUF12) nd 24% (MUF24) MUF resin bsed on the oven dry mss of the wood prtiles. The dhesive ws spryed onto the prtile furnish tumbling in rotting drumtype blender using ompressed ir spry hed. The MUF resin lled Prefere 10H116 ws supplied from Dyne Austri GmbH (Krems, Austri). The pnel density nd thikness were kept onstnt t 750 kg/m 3 nd 10 mm, respetively. A higher pnel density thn 750 kg/m 3 ws hrd to hieve s the prtile mt moisture ontent rehed levels tht were not mngeble in the se of high resin ontent smples. Three pnels were produed from eh pnel vrition. Three smples of eh replite (resulting in n = 9) were rndomly seleted nd tested. Tble 1 shows the omposition of the produed WPC pnels. Tble 1. Composition of the WPC Pnels Smple Wood ontent (%) Adhesive ontent (%) Adhesive type * Pnel density (kg/m 3 ) Repetitions PS PS PS PS MUF MUF MUF MUF *PS: Polystyrene; MUF: Melmine ure formldehyde Test Speimen Preprtion Testing methods for the hrteriztion of WPC pnels re desribed in the EN (2012). Composite pnels were ut into test speimens with dimensions of 250 x 50 x 10 mm³ for the flexurl tests nd 50 x 50 x 10 mm³ for ll other tests. Surfe lyers of test speimens were not further proessed. Prior to testing, speimens were onditioned t 65% reltive humidity nd 20 C for two weeks to reh equilibrium moisture ontent (EMC). Shlbfn et l. (2016). Biologil hr. WPCs, BioResoures 11(2),

4 PEERREVIEWED ARTICLE Biologil properties The resistne ginst wooddestroying bsidiomyetes in the form of loss of mss nd the dey suseptibility index (DSI) ws determined by testing ording to ENV (2002) with modifitions ording to EN (2012) nd n ging proedure ording to EN 84 (1997). The DSI is lulted using following eqution, DSI(%) = T S 100 (1) where T is loss in mss of n individul test speimen (%) nd S is loss in mss of the pproprite set of size ontrol speimens (%). Loss in mss ws lulted s the perentge of the entire initil test speimen mss minus the mss of its dhesive (12 or 24 wt%). The ging proedure of preonditioning, whih ws performed to ensure optiml growth onditions for Coniophor puten (Cp) nd Gloeophyllum trbeum (Gt), ws unneessry for Pleurotus ostretus (Po) beuse test speimens hd to be embedded into wterimpregnted vermiulite nywy. A totl of 30 test speimens per omposite pnel type (PS24, PS12, MUF24, nd MUF12) were spred over five test groups (Cp, Gt, Po, moisture ontent hek, nd wetting hek), eh with six test speimens. Twentyfour ontrol speimens onsisting of Sots pine spwood (Pinus sylvestris) were spred over four test groups (virulene ontrol nd size ontrol of the test fungi Cp nd Gt, whih uses dey of brown rot type), eh with six test speimens. Twelve ontrol speimens onsisting of beeh (Fgus sylvti) were spred over two test groups (virulene ontrol nd size ontrol of the test fungus Po, whih uses white rot type of dey), eh with six test speimens. Physiomehnil properties Flexurl strength nd flexurl modulus of elstiity (three point bending test) were determined ording to EN 310 (1993) using 200mm support spn with rosshed speed of 5 mm/min. Internl bond strength (tensile strength perpendiulr) of the test piees ws lso determined ording to EN 319 (1993). Squre test piees of 50*50 mm 2 for IB were prepred from eh of the pnel replites (n = 15). Density ws determined by testing 45 test speimens per omposite pnel type, whih were lter used for testing resistne ginst fungl ttk, ording to EN 323 (1993). Five smples of eh replite (resulting in n = 15) were rndomly seleted nd mehnilly tested. Tble 2. Test Speifitions Test Stndrd type Smple size (mm) Repetitions Density EN x 50 x Biologil properties ENV x 50 x Thikness swelling EN x 50 x 10 9 Internl bond strength EN x 50 x Bending properties EN x 50 x Wter bsorption nd thikness swelling were determined fter 24, 48, nd 672 h of wter immersion by testing nine test speimens per omposite pnel type ording to EN 317 (1993). Wter bsorption is shown s the perentge of the entire initil test Shlbfn et l. (2016). Biologil hr. WPCs, BioResoures 11(2),

5 PEERREVIEWED ARTICLE speimen mss nd not s the perentge of only the initil mss of the wood prt. Detiled informtion for testing speifitions is shown in Tble 2. Sttistil Anlysis To evlute the signifine of differenes mong men vlues of PS24, PS12, MUF24, nd MUF12, singleftor nlysis of vrine (ANOVA) nd Tukey honest signifint differene (HSD) test were onduted using the nlysis tool of SAS JMP (SAS Cmpus Drive, Cry, USA). The null hypothesis, no effet, ws epted if the pvlue exeeded the = 0.05 signifine level. RESULTS AND DISCUSSION Biologil Properties Aording to ENV (2002), the loss in mss of the virulene ontrol nd size ontrol speimens re the bsis for ny further pprisl of test speimen results regrding the resistne ginst wooddestroying bsidiomyetes. An overview of the results for the ontrol speimens is presented in Tble 3. Men losses in mss of virulene ontrol nd size ontrol speimens within eh test fungus group were lwys similr nd therefore indited low influene of the differene in form between virulene ontrol (50 x 25 x 15 mm³) nd size ontrol speimens (50 x 50 x 10 mm³). For virulene ontrol speimens, ording to ENV (2002), minimum loss in mss of 20% is required fter 16 weeks of fungl ttk exposure to ept the fungi test results s vlid. This minimum level ws exeeded by Cp (25.77%) nd Gt (31.07%) but not by Po (14.94%). Filed virulene ontrol limits of Po were lso reported by Brishke et l. (2014) s result of strin wekness. However, in this study, even the Po results were onsidered further, tking into ount tht this test fungus led only to reltively low mss loss. Men mss losses of size ontrol speimens, lso inluding Po results, were used to lulte the DSI. Tble 3. Biologil Properties of Virulene Control nd Size Control Speimens Loss in mss (%) Coniophor puten Gloeophyllum trbeum Pleurotus ostretus Sots pine spwood Beeh Virulene Virulene Size ontrol ontrol ontrol Size ontrol MV * SD * MV SD MV SD MV SD *MV: men vlue; SD: stndrd devition An overview of the biologil properties of the test speimens is given in Tble 4. Regrding the mss loss results, fungi using brown rot dey, Cp nd Gt, led to mss loss lerly under 3%. The fungus using white rot dey, Po, led to mss loss of more thn 3% in ll test speimens. The high mss loss used by Po ws unexpeted beuse of the filed virulene ontrol limit nd the low shre of hrdwood in the omposite pnels. Shmidt (2006) showed tht whiterot fungi suh s Po prefer hrdwoods, wheres brownrot fungi like Cp nd Gt grow better on softwoods. Köse et l. (2011) erlier lso reported findings similr to those reported here (Po fungi hve preferene to grow on softwood). Shlbfn et l. (2016). Biologil hr. WPCs, BioResoures 11(2),

6 PEERREVIEWED ARTICLE Köse et l. (2011) showed tht in se of Po, the mss loss of prtilebord nd fiberbord is higher thn tht of Gt. The results my be due to the proessing onditions of wood nd woodbsed pnels. Wood strutures nd their ompositions n be hnged during the prodution proess of woodbsed pnels; hene, different biologil hrteristis were hieved. Deng et l. (2006) lso stted tht the proess onditions n signifintly ontribute to the mold resistne of fiberbord. The lowest mss loss vlues (%) for Po were obtined for the PS24 (3.55%) followed by the PS12 (4.02%). The pnel types MUF24 nd MUF12 hd mss loss of 21.01% nd 16.9%, respetively. For Po, there were sttistilly signifint differenes in mss losses between PS nd MUF omposites. The higher shre of dhesive in the MUF24 speimens my hve led to their higher mss loss used by Po then for the MUF12 speimens. This ws unexpeted beuse higher shre of dhesives (t MUF24) should result in inresed moisture resistne of the speimens nd, ordingly, lower funglindued mss losses (beuse of the protetive effet of wter bsorption). However, beuse of the high stndrd devition of the mss losses of MUF speimens (Po), suh results were not signifint nd it ould not be onluded tht testing hrteristis used the results. Tble 4. Biologil Properties of Test Speimens Loss in mss (%) Coniophor puten Gloeophyllum trbeum Pleurotus ostretus PS12 PS24 MUF12 MUF24 MV * SD * HG * MV SD HG MV SD HG MV SD HG b ,b b b Dey Suseptibility Index () Coniophor puten Fully resistnt Fully resistnt Fully resistnt Fully resistnt Gloeophyllum trbeum Fully resistnt Fully resistnt Fully resistnt Fully resistnt Pleurotus b b ostretus * MV: men vlue; SD: stndrd devition; HG: homogeneous group (Within row, groups with the sme letter re not sttistilly different; α = 0.05) In ordne with ENV (2002), the DSI ws only lulted if the men mss losses were greter thn 3%, nd the rest were designted s fully resistnt to ttk by woodrotting bsidiomyetes. Thus, only DSIs for Po speimens were lulted to llow omprison between test speimens (omposites) nd size ontrol speimens (beeh). The PS omposites with DSI below 100 (PS24 t nd PS12 t 26.78) were more resistnt thn beeh, wheres the MUF speimens with DSI bove 100 (MUF24 t nd MUF12 t ) were less resistnt thn beeh (Tble 4). Higher resistne of the PS speimens ompred to those of the MUF nd beeh speimens my hve resulted from the inherent nture of the polymer nd possible hemil tion tking ple in the reyled PS smples. Shlbfn et l. (2016). Biologil hr. WPCs, BioResoures 11(2),

7 PEERREVIEWED ARTICLE PhysioMehnil Properties An overview of the hieved mehnil properties is given in Tble 5. Mny of the PS smples filed during the perpendiulr tensile strength tests (internl bond strength) beuse of the filure t the dhesive joint between the test speimen nd the test bloks. The wekest point in the rrngement of internl bond strength tests ws the dhesive joint in 14 out of 15 PS24 smples nd 4 out of 15 PS12 smples (PS24: 1.50 N/mm² nd PS12: 1.50 N/mm²). This showed tht the results obtined for the PS smples were pproximtely the perpendiulr tensile strength of the dhesive joint. The ft tht 14 PS24 nd only 4 PS12 speimens were too strong for IB mesurements permit the ssumption tht the true tensile strength perpendiulr to PS24 ws higher thn those of PS12, without inditing the preise mount. However, this problem in estimting the perpendiulr tensile strength of strong omposites lso rose when using nother type of dhesive, polyurethne dhesive, for fixing speimens on the plywood test bloks. Tking the dhesive problems into ount, it ould be generlized tht PS speimens (1.50 N/mm²) hd higher perpendiulr tensile strength thn MUF speimens (MUF24 t 1.44 N/mm² nd MUF12 t 1.05 N/mm²). Moreover, it ws likely tht for both mterils PS omposites nd MUF omposites higher dhesive shre (PS or MUF) led to higher perpendiulr tensile strength. A rnking similr to tht for internl bond strength ws observed for the flexurl properties; PS24 lwys hd the highest men vlues, followed by PS12, MUF24, nd MUF12. Signifint differenes were observed for both the MOE nd the MOR between the orresponding speimens of PS nd MUF smples. Aordingly, higher dhesive shre (PS or MUF) led to inresed flexurl properties (MOE nd MOR). The higher flexurl properties of the PS smples ourred beuse of the nerly 30% higher pnel density ompred with those of MUF pnels. Flexurl properties in wood nd woodbsed omposites re funtion of its density (Kretshmnn 2010). On the other hnd, redution of polymer ontent (from 24% to 12%) results in redued binding between the wood flours nd, dversely, leds to the lowering of flexurl properties (Sndi et l. 2001). In WPC pnels with high WF ontent (> 50%), polymer ts s n dhesive to bond wood flour together. Redution of the polymer mount leds to the wek bonding of wood flour nd onsequently redues bending properties (Shlbfn et l. 2013). Tble 5. Mehnil Properties of Test Speimens PS12 PS24 MUF12 MUF24 MV SD HG MV SD HG MV SD HG MV SD HG Internl bond :b b Flexurl test MOE b b MOR b MV: men vlue; SD: stndrd devition; HG: homogeneous group (Within row, groups with the sme letter re not sttistilly different; α = 0.05) An overview of the hieved physil properties is given in Tble 6. Signifint differenes between the densities of PS nd MUF speimens were generlly expeted beuse of their different trget densities. However, in ontrst to the density of MUF speimens (MUF24: 751 kg/m³ nd MUF12: 732 kg/m³), whih differed in smll rnge round their trget density (750 kg/m³), the density of PS speimens (PS24: 1,114 kg/m³ nd PS12: 1,072 kg/m³) signifintly differed from one nother nd were lerly bove the Shlbfn et l. (2016). Biologil hr. WPCs, BioResoures 11(2),

8 Wter bsorption (%) PEERREVIEWED ARTICLE trget density of PS speimens (1,000 kg/m³). The density ws higher for smples with higher dhesive ontent (PS24 nd MUF24). This n be explined by the higher ompressibility of the smples with higher mounts of dhesives (PS nd MUF). However, these density differenes were very likely result of mnul spreding. Tble 6. Physil Properties of Test Speimens PS12 PS24 MUF12 MUF24 MV SD HG MV SD HG MV SD HG MV SD HG Density (kg/m 3 ) b Wter bsorption (%) 24 h immersion 48 h immersion 672 h immersion b b d b Thikness swelling (%) 24 h immersion 48 h immersion 672 h immersion d d b b b MV: men vlue; SD: stndrd devition; HG: homogeneous group (Within row, groups with the sme letter re not sttistilly different; α = 0.05) Rnkings of wter bsorption were unhnged during the whole period (672 h) of wter immersion; PS24 lwys hd the lowest men vlues, followed by PS12, MUF24, nd MUF12 (Fig. 1). Thus, the PS speimens hd lower wter bsorptions thn the MUF speimens, nd speimens with high shre of dhesive hd lower vlues thn those with low dhesive shre. At the end of the tretment, fter 672 h of immersion in wter, sttistilly signifint differenes existed between ll tested mterils. 100 PS24 PS12 MUF24 MUF Durtion of wter immersion (h) Fig. 1. Wter bsorption of test speimens (men vlues nd stndrd devition) Wter bsorption (WA) ws influened by the pnel density. Higher pnel density ws orrelted with lower WA. It is diffiult for wter moleules to permete smples with higher density. The sme ws true when the mount of dhesive shre ws inresed (Yp Shlbfn et l. (2016). Biologil hr. WPCs, BioResoures 11(2),

9 Thikness swelling (%) PEERREVIEWED ARTICLE et l. 1990; Shlbfn et l. 2013). A good orreltion (R 2 =83%) ws found between the mount of wter bsorption nd mss loss for the white rot dey (Po), implying tht the penetrtion of fungus myelium into the speimens followed similr pttern s the penetrtion of wter moleules (Bri et l. 2014). Suh orreltion ws not observed for the Cp nd Gt fungi. Thikness swelling (TS) vlues fter longterm immersion (672 h) re presented in Fig. 2. Another rnking ws observed for TS ompred to WA; PS24 hd the lowest men vlues, followed by MUF24, MUF12, nd PS12. It ws striking tht the MUF speimens, whih hd higher wter bsorptions thn PS speimens, showed thikness swellings in between nd not higher thn those of PS speimens. This ould hve been used by the lower density of MUF24 nd MUF12, whih re ssoited with higher mount of hollow spes in the omposite nd ould prtilly llow wter bsorption without swelling. It ws lso onluded tht the MUF dhesive hd better overing nd binding effet on wood flour thn did the PS dhesive. This ws ttributed to the deresed swelling of wood prts in the MUF speimens. It ws onluded tht minimum mount (24%) of dhesive for reyled WPC pnels ws neessry to hieve omprble physil properties. However, higher shre of dhesive lso led to lower thikness swelling. 25 PS24 PS12 MUF24 MUF Durtion of wter immersion (h) Fig. 2. Thikness swelling of test speimens (men vlues nd stndrd devitions) CONCLUSIONS 1. The study showed tht utiliztion of reyled nd wste mterils in the vluedded nd durble WPC pnel for outdoor pplitions ws possible. 2. WPC nd referene pnels were fully resistnt to ttk by woodrotting of Cp nd Gt, while the pnels were not resistnt ginst Po. 3. The dey suseptibility index (DSI) of Po speimens showed tht the PS smples were more resistnt thn beeh wood, followed by MUF smples. Suh trends n be explined by the higher density of PS omposites. 4. The mehnil properties (MOE, MOR, nd IB) were rised t higher pnel density nd the performne rnking with this regrd ws PS24 > PS12 > MUF24 > MUF12. Shlbfn et l. (2016). Biologil hr. WPCs, BioResoures 11(2),

10 PEERREVIEWED ARTICLE 5. Physil properties (WA nd TS) showed tht the mount of dhesive ontent should be t lest 24% to hieve durble pnel for outdoor pplition. 6. As finl onlusion, it n be sid tht the reyled WPC pnels were produed without oupling gent nd even extr ompounding proess (s they re too ostly), whih hs good potentil to be used for exterior pplition. ACKNOWLEDGMENTS The uthors would like to knowledge the finnil support provided by Trbit Modres University, Irn. The uthors would lso like to express their sinere ppreition to Nikolos Chlkiopoulos nd Mrie T. Lenz for their ssistne in the experimentl proedure. Dr. Christin Heinemnn (Dyne Austri GmbH, Austri) is knowledged for kindly supplying MUF. REFERENCES CITED Bri, E., Tghiyri, H. R., Shmidt, O., Ghorbni, A., nd Aghbbei, H. (2014). Effets of nnoly on biologil resistne of woodplsti omposite ginst five wooddeteriorting fungi, Mders Cien. Tenol. 17(1), DOI: /S X Benthien, J. T., Thoemen, H., Mikowski, S., nd Lenz, M. T. (2012). Resistne of fltpressed woodplsti omposites to fungl dey: Effets of wood flour ontent, density, nd mnufturing tehnology, Wood Fiber Si. 44(4), Brishke, C., Welzbher, C. R., Gellerih, A., Bollmus, S., Humr, M., Plshkies, K., Sheiding, W., Alfredsen, G., Aker, J. V., nd Windt, I. D. (2014). Wood nturl durbility testing under lbortory onditions: results from roundrobin test, Eur. J. Wood Prod. 72(1), DOI: /s Chhrmhli, M., Tjvidi, M., nd Kzemi, N. S. (2008). Mehnil properties of wood plsti omposite pnels mde from wste fiberbord nd prtilebord, Polym. Compos. 29(6), DOI: /p Curling, S. F., nd Murphy, R. J. (2002). The use of the Dey Suseptibility Index (DSI) in the evlution of biologil durbility tests of wood bsed bord mterils, Eur. J. Wood Prod. 60(2): DOI /s Defoirdt, N., Grdin, S., Bulke, J. V. D., nd Aker, J. V. (2010). Moisture dynmis of WPC nd the impt on fungl testing, Int. Biodeter. Biodegr. 64(1), DOI: /j.ibiod Deng, J., Yng, D. Q., nd Geng, X. (2006). Effet of proess prmeters on fungl resistne of MDF pnels, Forest Prod. J. 56(3), EN 84 (1997). Wood preservtives. Aelerted geing of treted wood prior to biologil testing. Lehing proedure, Europen Committee for Stndrdiztion, Brussels, Belgium. EN (2012). Composites mde from ellulosebsed mterils nd thermoplstis (usully lled woodpolymer omposites (WPC) or nturl fibre omposites (NFC)) Prt 1: Test methods for hrteriztion of ompounds nd produts, Europen Committee for Stndrdiztion, Brussels, Belgium. Shlbfn et l. (2016). Biologil hr. WPCs, BioResoures 11(2),

11 PEERREVIEWED ARTICLE ENV (2002). Durbility of wood nd woodbsed produts Woodbsed pnels Method of test for determining the resistne ginst wooddestroying bsidiomyetes, Europen Committee for Stndrdiztion, Brussels, Belgium. EN 310 (1993). Woodbsed pnels Determintion of modulus of elstiity in bending nd of bending strength, Europen Committee for Stndrdiztion, Brussels, Belgium. EN 317 (1993). Prtilebords nd fibrebords Determintion of swelling in thikness fter immersion in wter, Europen Committee for Stndrdiztion, Brussels, Belgium. EN 319 (1993). Prtilebords nd fibrebords Determintion of tensile strength perpendiulr to the plne of the bord, Europen Committee for Stndrdiztion, Brussels, Belgium. EN 323 (1993). Woodbsed pnels Determintion of density, Europen Committee for Stndrdiztion, Brussels, Belgium. Kretshmnn, D. E. (2010). Mehnil properties of wood, in: Wood Hndbook Wood s n Engineering Mteril, Generl Tehnil Report FPLGTR190, Forest Produts Lbortory, Mdison, WI. 5_15_46. Irle, M., nd Brbu, M. C. (2010). Woodbsed pnel tehnology, in: Woodbsed Pnels An Introdution for Speilists, H. Thoemen, M. Irle, nd M. Sernek (eds.), Brunel University Press, London, UK, pp 194. Kim, J. W., Hrper, D. P., nd Tylor, A. M. (2008). Effet of wood speies on wter sorption nd durbility of wood plsti omposites, Wood Fiber Si. 40(4), Köse, C., Terzi, E., Büyüksri, Ü., Avi, E., Ayrilmiş, N., Krtl, S. N., nd Immur, Y. (2011). Prtilebord nd MDF pnels mde from mixture of wood nd pineones: Resistne to dey fungi nd termites under lbortory onditions, BioResoures 6(2), DOI: /biores Kruse, A., nd Gellerih, A. (2014). Evluting durbility of thermoplsti wood omposites ginst bsidiomyetes nd development of suitble test design, Wood Mter. Si. Eng. 9(3), DOI: / Luedtke, J. (2011). Entwiklung und Evluierung eines Konzepts für die Kontinuierlihe Herstellung von Leihtbupltten mit Polymerbsiertem Kern und Holzwerkstoffdeklgen, disserttion, Hmburg University, Germny. Poletto, M., Dettenborn, J., Zeni, M., nd Ztter, A. J. (2011). Chrteriztion of omposites bsed on expnded polystyrene wstes nd wood flour, Wste Mnge. 31(4), DOI: /j.wsmn Rhmn, M. R., Li, J. C. H., Hmdn, S., Ahmed, A. S., Bini, R., nd Sleh, S. F. (2013). Combined styrene/mma/nnoly rosslinker effet on woodpolymer omposites (WPCs), BioResoures 8(3), DOI: /biores Rowell, R. M. (2007). Chllenges in biomss Thermoplsti omposites, J. Polym. Environ. 15(4), DOI: /s Rowell, R. M., Youngquist, J. A., nd MNtt, D. (1991). Composite from reyled mterils, in: Proeedings of the 25th Interntionl Prtilebord/Composite Mterils Symposium, Pullmn, WA, pp Sndi, A. R., Hunt, J. F., nd Culfield, D. F. (2001). High fiberlow mtrix omposites: Kenf fiber/polypropylene, in: Proeedings of the 6th Interntionl Conferene on WoodfiberPlsti Composites, Mdison, WI, pp Shlbfn et l. (2016). Biologil hr. WPCs, BioResoures 11(2),

12 PEERREVIEWED ARTICLE Shmidt, O. (2006). Wood nd Tree Fungi: Biology, Dmge, Protetion, nd Use, Springer, Berlin, Germny. Segerholm, B. K., Ibh, R. E., nd Westin, M. (2012). Moisture sorption, biologil durbility, nd mehnil performne of WPC ontining modified wood nd polylttes, BioResoures 7(4), DOI: /biores Shlbfn, A., Welling, J., nd Luedtke, J. (2012). Effet of proessing prmeters on mehnil properties of lightweight fom ore sndwih pnels, Wood Mter. Si. Eng. 7(2), DOI: / Shlbfn, A., Benthien, J. T., Welling, J., nd Brbu, M. C. (2013). Flt pressed wood plsti omposites mde of milled fom ore prtilebord residues, Eur. J. Wood Prod. 71(6), DOI: /s Shlbfn, A., Luedtke, J., Welling, J., nd Fruehwld, A. (2013b). Physiomehnil properties of ultrlightweight fom ore prtilebords: Different ore densities, Holzforshung 67(2), DOI: /hf Wolott, M. P. (2003). Formultion nd proess development of fltpressed wood polyethylene omposites, Forest Prod. J. 53(9), Yp, M. G. S., Chi, L. H. L., nd Teoh, S. H. (1990). Woodpolymer omposites from tropil hrdwoods I. WPC properties, J. Wood Chem. Tehnol. 10(1), 119. DOI: / Artile submitted: Jnury 30, 2016; Peer review ompleted: Mrh 18, 2016; Revised version reeived nd epted: April 7, 2016; Published: April 19, DOI: /biores Shlbfn et l. (2016). Biologil hr. WPCs, BioResoures 11(2),