Materials and Design 51 (2013) 751–755

Contents lists available at SciVerse ScienceDirect

Materials and Design

journal homepage: www.elsevier .com/locate /matdes

Technical Report

Effect of waste melamine impregnated paper on properties of orientedstrand board

0261-3069/$ - see front matter � 2013 Elsevier Ltd. All rights reserved.http://dx.doi.org/10.1016/j.matdes.2013.04.052

⇑ Corresponding author. Tel.: +90 462 377 3127; fax: +90 462 325 5588.E-mail address: adonmez@ktu.edu.tr (A. Dönmez Çavdar).

Ayfer Dönmez Çavdar a,⇑, Hüsnü Yel b, Hülya Kalaycıoglu c, Salim Hiziroglu d

a Department of Interior Architecture, Karadeniz Technical University, 61080 Trabzon, Turkeyb Department of Forest Industry Engineering, Artvin Coruh University, 08000 Artvin, Turkeyc Department of Forest Industry Engineering, Karadeniz Technical University, 61080 Trabzon, Turkeyd Department of Natural Resource Ecology & Management, Oklahoma State University, Stillwater, OK 74078-6013, United States

a r t i c l e i n f o a b s t r a c t

Article history:Received 25 February 2013Accepted 15 April 2013Available online 24 April 2013

The objective of this study is to evaluate some of the properties of oriented strand board (OSB) panelsmanufactured using waste melamine impregnated paper (WMIP) as filler. Shredded WMIP particles wereused up to 50% with increment of 10% based on oven-dry wood weight in the core layer of experimentalpanels made from poplar (Populous euro� Americana) strands sprayed with urea formaldehyde as binder.A total of twelve three-layer panels with the dimensions of 40 cm by 40 cm by 1.0 cm having an averagetarget density of 0.55 g/cm3 were manufactured. Mechanical and physical properties including modulusof elasticity, modulus of rupture, internal bond strength, thickness swelling, and water absorption of thesamples were determined according to EN 310, EN 319 and EN 317 standards, respectively. Based on theresults of this work, the bending properties and internal bond strength values of the samples improvedwith increasing WMIP amount in the panels. In addition, thickness swelling and water absorption char-acteristics of the samples having WMIP content were lower than those of the control panels. It appearsthat WMIP could have potential to be utilized in OSB without any adverse influence on their strengthproperties.

� 2013 Elsevier Ltd. All rights reserved.

1. Introduction

Most of interior wood based panels such as particleboard andmedium-density fiberboard (MDF) are generally used as substratefor thin overlays various laminating applications. Approximately70% of laminating applications are made by using melamineimpregnated papers. In the impregnation process, a-cellulose pa-per is thoroughly immersed in the resin solution, compressed be-tween rollers, and then dried in air draft tunnel oven at thetemperature range from 70 to 120 �C using flow rate of 10 m/s.Melamine formaldehyde (MF) resins are generally used as a bindergiving an advantage of excellent water resistance to the panels [1].Therefore, melamine impregnated paper is one of the most widelyused materials to manufacture furniture units, laboratory benchesand other various indoor applications [2].

Today, concepts of waste management have substantially in-creased due to limited natural resources and increasing populationof the world. Especially these concepts are leading search forrenewable chemical resources, and converting waste into rawmaterials to be used for value-added products [3–5]. Regardingto solid wastes, polymer waste has become a serious issue globallyand also caused depletion of petroleum resources. To manage poly-

mer waste, most preferred solutions are the minimization of waste,reuse of materials in the same application and recycling in anotherimplementation [6].

Wood based panel industry widely uses the thermosetting poly-mer as adhesive. Certain amount of waste inevitable and createsproblem along the production line. Both impregnations processingand laminating on surface of panels also create substantial amountof waste during the manufacturing. This waste is usually burnedsimilar to the other waste material as energy resource. It is factthat melamine based resins are relatively more expensive thanother wood adhesives and wood materials [7]. Therefore melamineimpregnated paper wastes are required to be evaluated in moreefficient applications. Some of the studies reported that amountof dry melamine impregnated paper waste is adding up to400 tons/year for a typical medium sized paper impregnating plant[6]. Consequently, the residual waste of MF resin- impregnated pa-pers could be considered as a potential resource as a binder inmanufacturing of different types of wood based panels.

Several studies related to recycling of the waste melamineimpregnated (WMIP) have been carried out [6,8–10]. Fur et al.[8] reused WMIP in powder form ranging from 17% to 11% basedon dry wood weight as an adhesive for particleboard and as mela-mine substitute during the formulation and preparation of liquidmelamine urea formaldehyde (MUF) resins. They found that inter-nal bond strength of the particleboard manufactured using directly

Table 1Experimental schedule for OSB panel manufacture.

Panel type WMIP loading (%) Resin content (%) wood wt.

Face layers Core layer Face layers Core layer

WMIP1 – 10 14 8WMIP2 – 20 14 7WMIP3 – 30 14 6WMIP4 – 40 14 5WMIP5 – 50 14 4Control – – 14 9

752 A. Dönmez Çavdar et al. / Materials and Design 51 (2013) 751–755

WMIP powder satisfied relevant standards requirements. They alsoreported that WMIP could be used directly as a binder in particle-board manufacture, and indirectly during preparation of MUF resinadhesives. In another study, Alplar and Winkler [9] investigated ef-fect of recycling dried impregnated decorative paper in particle-board production. The results of this study indicated that addingjust 20% of impregnated décor paper waste into the raw materialcould produce particleboard even without using an adhesive.Ayrılmıs� [10] also studied on recycling resin impregnated decora-tive and overlay paper as a binder in manufacture of light MDF.It was reported that the dimensional stability and mechanicalproperties of the light MDF panels improved by adding hammer-milled WMIP. Currently there is little or no information on utiliza-tion of WMIP as filler or binder in oriented strand board (OSB). It isa fact that melamine and phenol formaldehyde resins which arevery expensive and durable compared to urea formaldehyde whichare excellent binders for OSB [11].

The objective of this study was to evaluate the mechanical andthe physical properties including modulus of rupture (MOR), mod-ulus of elasticity (MOE), internal bond (IB) strength, water absorp-tion (WA), thickness swelling (TS) of OSB panels manufactured byusing WMIP as a filler and a binder.

Table 2Mechanical properties of OSB panel made by adding WMIP.

Panel type MOR (N/mm2) MOE (N/mm2) IB (N/mm2)

WIMP1 Mean 16.37(AB) 6448.59(B) 0.41(B)SD 0.87 264.77 0.06

WIMP2 Mean 16.86 (AB) 6472.23(B) 0.43(B)SD 1.71 195.99 0.03

WIMP3 Mean 17.68(A) 6957.73(A) 0.53(A)SD 1.21 545.21 0.06

WIMP4 Mean 17.72(A) 7038.77(A) 0.58(A)SD 0.74 127.67 0.09

WIMP5 Mean 13.63(C) 5792.73(C) 0.37(BC)SD 1.57 195.76 0.05

Control Mean 15.35(B) 6417.51(B) 0.28(C)SD 1.39 489.94 0.11

SD: Standard deviation.

2. Materials and methods

Low quality poplar (Populus euro � americana) trees with anaverage age of 10 years old were locally harvested. After logs werecut into 15 cm long sections they were reduced into strandsemploying a laboratory Hildebrand flaker. Typical strand size was80 mm by 10 mm by 0.7 mm. In the next step raw material wasdried to 3% moisture content in a laboratory oven.

Melamine impregnated paper was supplied by Kastamonu Inte-grated Wood Industry and Trade Company from their waste prod-uct line. The impregnated paper consists of 50% melamine resin,3.5% Al2O3, 1% hardener/wetting agent, and 6% moisture with theexception of raw paper. WMIP was shredded into small particleshaving an average dimension of 0.3 mm by 2 mm. Six types of threelayer panels having WMIP ranging from 10% to 50% at increments of10% were used in the core layer. Face layers of the samples weremade of 100% poplar strand with 14% urea formaldehyde adhesiveas binder. All panels with dimensions of 40 cm by 40 cm by 1.0 cmwere manufactured. Hand formed mats having strands oriented at90� to core layer of the panels were compressed in a computer con-trolled hot press using a pressure of 26.5 kg/cm2 and a temperatureof 150 �C for 8 min. Each panel was conditioned in a climate roomwith a temperature of 20 �C and a relative humidity of 65% untilthey reach equilibrium moisture content before test samples werecut based on European Standards. MOE, MOR, and IB strength ofthe specimens were determined on an Instron Testing MachineModel 5569 having 5000 kg capacity load cell based on EN 310[12] and EN 319 [13], respectively. Physical properties, namely, TSand WA of the panels were also evaluated using EN 317 [14].

A total of 12 panels including control samples at an average tar-get density of 0.55 g/cm3 were manufactured for the experimental.Table 1 displays sampling schedule. 10 mm by 10 mm samplesfrom each type of panels were cut and they were split in core layerto evaluate interaction between WMIP and strands employingscanning electron microscope (SEM). Micrographs were taken fromthe surface of each sample on JEOL EVO LS 10 at a magnification of100�.

Duncan’s mean separation test and analysis of variance withANOVA in SPSS 13.0 software was used for statistical analysis ofmechanical properties of the specimens. Physical properties char-acteristics of the panels were also evaluated with repeated mea-sures analysis of variance.

3. Results and discussion

3.1. Mechanical Properties

Bending properties of the sample with WMIP and control sam-ples are presented in Table 2. MOR and MOE values of the samplesimproved with increasing content of the WMIP in core layer. Dun-can’s mean separation test results are also shown by letters in Ta-ble 2.

When the amount of the WMIP in the samples increased up to40 wt.%, the MOR and MOE of the samples also increased by 15%and 10% compared to those of control panels, respectively. The rea-son of the increment above is that the melamine content also in-creased by the increment of WMIP in the core layer of OSB panel.It is known that melamine resins improve overall properties inwood based panel properties since melamine content significantlyaffects resin properties and glue bond quality [1,15]. Also, MF res-ins form stronger wood-to-wood bonds than that of urea formalde-hyde resins. The bond quality among wood strands improved dueto the increase of WMIP content in the OSB.

In previous studies, it has been shown that WMIP has improvedstrength properties and bond quality in wood based panels [3,8–10]. For example, Alplar and Winkler [9] and Ayrılmıs� [10] reportedthat flexural properties of wood based panels such as particleboardand light MDF increased by adding up to 20 wt.% WMIP into ureaformaldehyde.

When 50 wt.% WMIP was used in core layer of the panels, theirbending properties of slightly decreased (Fig. 1). This might be re-lated to the decrement of wood strands. In our study, WMIP wasused not only as a binder combined with UF resin but also as araw material instead of wood strands in core layer of OSB. The den-sity of samples decreased owing to lowered wood strands, andtherefore bending properties of samples also decreased. It is knownthat strength properties of wood and wood composites are directlyproportional to density [16,17].

(a)

(b)Fig. 1. Bending properties of the samples: (a) MOR and (b) MOE.

A. Dönmez Çavdar et al. / Materials and Design 51 (2013) 751–755 753

Internal bond (IB) strength of the samples resulted in similartrend of improvement to those of the bending properties withthe increment of WMIP content in core layer as illustrated inFig. 2. IB strengths of the samples including up to 40% WMIP in-creased by 107% as compared to those of control samples. Severalauthors have reported in [9] and [10]. IB strengths of WBPs (parti-cleboard and light MDF) have improved by 33% and 53%, respec-tively, as compared to those of control samples when theamounts of WMIP increased up to 20 wt.% in UF resin. A possiblereason for this improvement can be explained that WMIP includes50–60% melamine resin which improves IB quality between thestrands [8,18]. Melamine resin has resistance to hydrolysis, andprovides stable bonds [19]. As WMIP content increases in theOSB, melamine resin content becomes higher than urea formalde-hyde content. It is known that IB quality of melamine resin is high-

Fig. 2. Internal bond strength of the samples.

er than that of urea resin. In previous study [8], it was observedthat WMIP improved IB strength of particleboard. Also WMIPwas a stronger bond among the wood strands with compared tocontrol samples as can be observed from the microphotographs ta-ken on SEM in Fig. 3.

When IB strengths of the OSB samples are compared to EN 300[20] standard requirements (OSB1: › 0.28 N/mm2; OSB2 and OSB3:› 0.32 N/mm2; OSB4: › 45 N/mm2), it was observed that all paneltypes of samples satisfy OSB/1 requirements while WMIP1, WMIP2and WMIP5 panel types satisfy OSB/2 and OSB/3 requirements, andWMIP3 and WMIP4 panel types satisfy OSB/4 as well OSB/2 andOSB/3.

Table 3 summarizes analysis of variance (ANOVA) of the test re-sults for mechanical properties of OSB panels made having WMIP.The variance analysis showed that adding of WMIP had significanteffect on mechanical properties of the panels (P < 0.0001).

3.2. Physical properties

Thickness swelling (TS) and WA of OSB samples produced byhaving WMIP at 2 h and 24 h are shown in Figs. 4 and 5. The lowestTS and WA rates were determined for panel types WMIP4 andWMIP5, respectively. TS and WA values of the samples signifi-

Fig. 3. The Scanning electron microscope (SEM) microphotographs of fracturedsurface samples of control panels (a) and WMIP4 panel type (b).

Table 3Analysis of variance (ANOVA) test results for mechanical properties of OSB panelmade by adding WMIP.

Mechanicalproperties

Source Sum ofsquares

df Meansquare

F Sig.

Modulus ofrupture

Betweengroups

61.24 5 12.25 7.29 0.000

Withingroups

40.35 24 1.68

Total 101.59 29

Modulus ofelasticity

Betweengroups

5037648.53 5 1007529.71 12.57 0.000

Withingroups

1923595.74 24 80149.82

Total 6961244.28 29

Internal bondstrength

Betweengroups

0.29 5 0.06 11.16 0.000

Withingroups

0.13 24 0.01

Total 0.42 29

Fig. 4. Effect of WMIP using as a function of water immersion time on thicknessswelling of the samples.

Fig. 5. Effect of WMIP using as a function of water immersion time on waterabsorption of the samples.

Table 4Analysis of variance (general linear model) test results for physical properties of OSBpanel made by adding WMIP.

Physical properties Source Sum ofsquares

df Meansquare

F Sig.

Thickness swelling WMIP usingrate

667.20 5 133.44 44.19 0.000

Error 72.47 24 3.02Water absorption WMIP using

rate1314.63 5 262.93 12.11 0.000

Error 521.04 24 21.71

754 A. Dönmez Çavdar et al. / Materials and Design 51 (2013) 751–755

cantly decreased by the increment of WMIP content, moreover, inpanel type of WMIP5, the WA values improved while the mechan-ical properties adversely affected. This would be due to high mel-amine content in WMIP. Melamine resin is distinguished fromurea formaldehyde resin by its higher moisture resistance [1].Therefore melamine resin content in the WMIP improved physicalproperties of OSB panels with compared to control samples. TS andWA of samples for 24 h were improved by 44–50% and 16–22%respectively with compared to control samples when amount ofWMIP increased up to 40–50 wt.% in core layer of OSB samples.

According to EN 300 [20] standard, TS rate for 24 h in waterimmersion is minimum requirement <20%, all of specimens TSrates for 24 h except for control specimens are satisfied.

Table 4 summarizes analysis of variance (general linear model)test results for physical properties of OSB panel made by addingWMIP. The variance analysis showed that adding WMIP had signif-icant effect on physical properties of the panels (P < 0.0001).

4. Conclusions

This study evaluated effect on mechanical and physical proper-ties of OSB samples manufactured using waste melamine impreg-nated papers in their core layer. The results showed that addingWMIP into the core layer improved mechanical and physical prop-erties of the panels. In addition, WMIP can be mixed with strandsup to 40% in core layer of OSB. Therefore, amount of wood strandsand the percentage of urea formaldehyde can be decreased by add-ing WMIP. In conclusion, WMIP may have potential filler and bin-der to be utilized in OSB panels with positive impact on theirmechanical and physical properties.

Acknowledgement

The authors would like to thank to Kastamonu Integrated WoodIndustry and Trade Company for supplying melamine impregnatedpapers.

References

[1] Pizzi A. Melamine-formaldehyde resins. In: Pizzi A, Mittal KL, editors.Handbook of adhesive technology. NewYork: Marcel Dekker; 2003. p. 635–80.

[2] Varga M, Alplar T, Nemeth G. General waste handling and recycling inparticleboard production. Manag Environ Qual Int J 2004;15(5):509–20.

[3] Ono H, Yamada T, Hatan Y, Motohashi K. Adhesives from waste paper bymeans of phenolation. J Adhes 1996;59(1–4):135–45.

[4] Ramakrisnan PS. Increasing population and declining biological resources inthe context of global change and globalization. J Biosci 2001;26(4):465–79.

[5] Ljungberg LY. Materials selection and design for development of sustainableproducts. Mater Des 2007;28(2):466–79.

[6] Thomas R, Vijayan P, Thomas S. Recycling of thermosetting polymers: theirblends and composites. In: Fainleib A, Grigoryeva O, editors. Recentdevelopments in polymer recycling kerala. Transworld Research Network;2011. p. 121–53.

[7] Orr L. Wood Adhesives: a market opportunity study. p. 23. <http://soynewuses.org/wp-content/uploads/pdf/final_WoodAdhesivesMarketOpportunity.pdf>; 2013 [accessed 03.01.13].

A. Dönmez Çavdar et al. / Materials and Design 51 (2013) 751–755 755

[8] Fur XL, Galhac M, Zanetti M, Pizzi A. Recycling melamine-impregnated paperwaste as board adhesives. Holz Roh Werkst 2004;62:419–23.

[9] Alplar T, Winkler A. Recycling of impregnated décor paper in particleboard.Acta Silva Lign Hung Int J 2006;2:113–6.

[10] Ayrılmıs� N. Enhancement of dimensional stability and mechanical propertiesof light MDF by adding melamine resin impregnated paper waste. Int J AdhesAdhes 2012;33:45–9.

[11] Sulaiman O, Salim N, Hashim R, Yusof LHM, Razak W, Yunus NYM, et al.Evaluation on the suitability of some adhesives for laminated veneer lumberfrom oil palm trunks. Mater Des 2009;30(9):3572–80.

[12] EN 310. Wood based panels, determination of modulus of elasticity in bendingand bending strength. Brussels (Belgium): European Committee forStandardization; 1999.

[13] EN 319. Particleboards and fiberboards, determination of tensile strengthperpendicular to plane of the board. Brussels (Belgium): European Committeefor Standardization; 1999.

[14] EN 317. Particleboards and fiberboards, determination of swelling in thicknessafter immersion. Brussels (Belgium): European Committee for Standardization;1999.

[15] Hse CY, Fu F, Pan H. Melamine-modified urea formaldehyde resin for bondingparticleboards. Forest Prod J 2008;58(4):56–61.

[16] Higgins ED. The strength of bonded wood strand composites. Thesis in thefaculty of harvesting and wood sci. Canada: Univ. of British Columbia; 1990. p.298.

[17] Vick CB. Adhesive bonding of wood materials. In: Wood handbook—wood asan engineering material. Madison (WI): Forest Products Laboratory; 1999. p.463.

[18] Nemli G, Usta M. Influences of some manufacturing factors on the importantquality properties of melamine-impregnated papers. Build Environ2004;39:567–70.

[19] Maloney T. Modern particleboard and dry process fiber manufacturing. SanFrancisco: Miller Freeman Inc.; 1993.

[20] EN 300. Oriented Strand Boards (OSB) – definitions, classification andspecification. Brussels (Belgium): European Committee for Standardization;2006.