The present study was conducted to investigate the possibility of using PVA-glued laminated panels in place of conventional kitchen countertops namely 32 mm thick MDF and 38 mm thick particleboard. Three types of glued laminated panels were manufactured by laminating two 16 mm thick MDFs, two 16 mm thick particleboards,
and three 12 mm thick particleboards at a pressure of 3 MPa , a temperature of 25 0C and variable pressing times of 20, 30, and 40 minutes. Bending and shear strengths, water absorption, and thickness swelling of the laminates were measured and compared with a 32 mm thick MDF and 38 mm thick particleboard. The results indicated that the glued laminated panels remained more dimensionally stable compared to the conventional kitchen countertops. Particleboard laminates had improved bending and shear strengths compared to 38 mm thick particleboard. The results of this study demonstrated that PVA-glued laminated panels could be used as kitchen countertops.Istraživanje prikazano u radu provedeno je s ciljem ispitivanja mogućnosti uporabe lamelirane ploče lijepljene PVA ljepilom umjesto konvencionalnih kuhinjskih radnih ploča,MDF ploča debljine 32mm i iverica debljine 38 mm. Tri tipa lijepljenih lameliranih ploča proizvedena su od dvije MDF ploče debljine 16 mm, dvije ploče
iverice debljine 16 mm i tri ploče iverice debljine 12 mm pri tlaku prešanja 3 MPa i temperaturi 25 oC, uz promjenjivo vrijeme prešanja od 20, 30 i 40 minuta. Mjerene su čvrstoća savijanja i čvrstoća smicanja, apsorbcija vode te debljinsko bubrenje lamelirane ploče i uspoređeno sa svojstvima MDF ploče debljine 32 mm i iverice debljine 38 mm. Rezultati su pokazali da su lijepljene lamelirane ploče dimenzionalno stabilnije od konvencionalnih kuhinjskih
ploča. Lamelirana ploča od iverice imala je bolju čvrstoću savijanja i smicanja od ploče iverice od 38 mm. Rezultati istraživanja pokazuju mogućnost uporabe lameliranih ploča lijepljenih PVA ljepilom za kuhinjske radne ploče

Asghar Tarmian

Kambiz Pourtahmasi

Mazdak Mojarradi

English

Hrčak - Portal of scientific journals of Croatia

Kambiz Pourtahmasi, Asghar Tarmian, Mazdak Mojarradi1Glued laminated panelsas kitchen countertopsLijepljene lamelirane plo~e kao radne plo~eu kuhinjiPreliminary paper • Prethodno priop}enjeReceived – prispjelo: 2. 10. 2006.Accepted – prihva}eno: 12. 3. 2007.UDK: 630*832.284; 630*836.1ABSTRACT • The present study was conducted to investigate the possibility of using PVA-glued laminated panels inplace of conventional kitchen countertops namely 32 mm thick MDF and 38 mm thick particleboard. Three types ofglued laminated panels were manufactured by laminating two 16 mm thick MDFs, two 16 mm thick particleboards,and three 12 mm thick particleboards at a pressure of 3 MPa , a temperature of 25 0C and variable pressing times of20, 30, and 40 minutes. Bending and shear strengths, water absorption, and thickness swelling of the laminates weremeasured and compared with a 32 mm thick MDF and 38 mm thick particleboard. The results indicated that the gluedlaminated panels remained more dimensionally stable compared to the conventional kitchen countertops. Particlebo-ard laminates had improved bending and shear strengths compared to 38 mm thick particleboard. The results of thisstudy demonstrated that PVA-glued laminated panels could be used as kitchen countertops.Key words: 32 mm thick MDF, 38 mm thick particleboard, glued laminated panel, kitchen countertopSA@ETAK • Istra`ivanje prikazano u radu provedeno je s ciljem ispitivanja mogu}nosti uporabe lamelirane plo~elijepljene PVA ljepilom umjesto konvencionalnih kuhinjskih radnih plo~a, MDF plo~a debljine 32 mm i iverica deb-ljine 38 mm. Tri tipa lijepljenih lameliranih plo~a proizvedena su od dvije MDF plo~e debljine 16 mm, dvije plo~eiverice debljine 16 mm i tri plo~e iverice debljine 12 mm pri tlaku pre{anja 3 MPa i temperaturi 25 0C, uz promjenji-vo vrijeme pre{anja od 20, 30 i 40 minuta. Mjerene su ~vrsto}a savijanja i ~vrsto}a smicanja, apsorbcija vode tedebljinsko bubrenje lamelirane plo~e i uspore|eno sa svojstvima MDF plo~e debljine 32 mm i iverice debljine 38mm. Rezultati su pokazali da su lijepljene lamelirane plo~e dimenzionalno stabilnije od konvencionalnih kuhinjskihplo~a. Lamelirana plo~a od iverice imala je bolju ~vrsto}u savijanja i smicanja od plo~e iverice od 38 mm. Rezulta-ti istra`ivanja pokazuju mogu}nost uporabe lameliranih plo~a lijepljenih PVA ljepilom za kuhinjske radne plo~e.Klju~ne rije~i: MDF plo~a debljine 32 mm, plo~a iverica debljine 32 mm, lijepljena lamelirana plo~a, kuhinjskaradna plo~a1 INTRODUCTION1. UVODIn kitchen cabinet industry, 38 mm thick particle-board and 32 mm thick medium density fiberboard(MDF) are the primary raw materials for the fabricationof kitchen countertops, i.e. kitchen worktops. However,due to the lack of thick panels, PVA-glued laminatedpanels are widely used by some cabinet industries tomanufacture kitchen countertops. Glued laminated pa-nels used for kitchen worktops refer to two or more la-yers of thin particleboards or MDFs laminated togetherto obtain the nominal 38 mm or 32 mm thicknesses.The materials are processed in a manner similar toDRVNA INDUSTRIJA 58 (1) 13-17 (2007) 13..... Pourtahmasi, Tarmian, Mojarradi: Glued Laminated Panels as Kitchen Countertops1The authors are assistant professor, Ph.D. student and graduated student, respectively in Wood Science and Technology Department, Faculty ofNatural Resources, University of Tehran, Karaj, Iran.1Autori su profesor, doktorand i diplomant u Zavodu za znanost o drvu i drvnu tehnologiju, Fakultet prirodnih resursa, Sveu~ili{te u Teheranu,Karaj, Iran.wood-based sandwich panels, structural composites(SCLs), and glued laminated timbers (glulams). Manyauthors have studied the characteristics of these struc-tural panels (Kawasaki et al. 1999; Aydin et al. 2004)but very few studies have been conducted regardingglued laminated panel fabrication (McNatt et al. 1984).Most of kitchen cabinet industries use cold-settingpoly (vinyl acetate) resin to fabricate glued laminatedcountertops. However, it is well known that PVA gluehas limited water resistance (Pizzi 1983) and is not gene-rally recommended for joints subjected to high tempera-ture or high humidity (Sellers et al. 1988). In addition,Uysal et al. (2005) reported that PVA adhesive was un-suitable for the fabrication of laminated veneer lumber(LVL) used in wet conditions. They also reported thatshear strength of the PVA-bonded LVL panels was lessthan that of UF or PF-bonded LVL panels.Countertops are the most important parts of thekitchen cabinet requiring desired dimensional stabilityas well as adequate strength. Although the glued lami-nated countertops are laminated with a moisture resi-stance overlay, such as high pressure laminate (HPL),they may suffer lack of resistance to water due to PVAapplication. Therefore, this study was undertaken toevaluate the possibility of using PVA-glued laminatedpanels for kitchen countertops.2 MATERIALS AND METHODS2. MATERIJAL I METODE2.1 Materials2.1. Materijali12 and 16 mm thick particleboards, and 16 mmthick MDF with mean densities of 0.61, 0.76, and 0.65g cm-3 were selected to fabricate PVA-glued laminatedpanels. 38 mm thick particleboards and 32 mm thickMDFs with mean densities of 0.61 and 0.71 g cm-3 wereused as control panels for comparison. Physical andmechanical properties of control panels are given in Ta-ble 1. The panels were provided from Oraman WoodIndustrial Co.PVA adhesive with a pH value of 4.52, solid con-tent of 28% and viscosity of 0.42 cp provided fromShomal Adhesive Co. was used in the construction oflaminated panels.2.2 Glued laminated panel fabrication2.2. Proizvodnja lamelirane plo~eFor producing glued laminated panels, PVA wasapplied by uniformly brushing approximately 240 g m-2on each laminate. Then, two 16 mm thick particlebo-ards, two 16 mm thick medium density fiberboards, andthree 12 mm thick particleboards were assembled to-gether. The dimensions of the laminated panels were500 × 500 mm. For gluing with cold-setting adhesives,such as PVA, extended assembly time may be requiredto ensure adequate adhesive wetting before pressure isapplied (Sellers et al. 1985). Therefore, the pressurewas applied approximately 10 minutes after adhesiveapplication. The laminas were cold-pressed at 25 0Cand 3 MPa for 20, 30, and 40 minutes. The glued lami-nated panels were subsequently conditioned at 65 % re-lative humidity and 20 0C for about 2 weeks.2.3 Physical and mechanical testing2.3. Ispitivanje fizikalnih i mehani~kih svojstavaTest specimens were cut from each laminated pa-nel according to DIN 68763 specification. The dimen-sions of the specimens to test bending strength, shearstrength, and thickness swelling and water absorptionafter 24h immersion were 250 × 50, 50 × 50, 20 × 20and 20 × 20 mm, respectively. The bending and shearstrengths, thickness swelling and water absorption ofthe laminates were measured according to DIN 52362,ASTM D 1037, and DIN 52364 specifications, respec-tively.Data were analyzed using analysis of variance.Standard deviations were also computed from the dataand are shown as error bars in each corresponding figu-re.3 RESULTS AND DISCUSSION3. REZULTATI I RASPRAVA3.1 Bending strength3.1. ^vrsto}a savijanjaThe results indicate that bending strength of allparticleboard laminates, except 12 mm thick particle-board laminate, increases with increasing of the presstime from 20 min to 30 min, and then remains approxi-mately constant (Fig. 1). The MDF laminates have hi-gher bending strength than particleboard laminates dueto greater bond line strength caused by lower penetra-tion of PVA glue into the MDF structure. However, thebending strength of 12 mm thick particleboard laminatefabricated at 30 min was abnormally high. This abnor-mal behavior can be explained by the fact that PVAglue cures completely within 30 min but excessivepress time destroys the laminate structure, resulting inlower bending strength. Another explanation for thisbehavior is considered to be overpenetration of adhesi-ve into laminate structure during increased press time.It appeared that bending strength of the MDF laminateincreased with increase in the press time. All laminatedpanels, except laminated 12 mm thick particleboard fa-bricated at 20 minutes, had higher bending strengthsthan the 38 mm thick particleboard. Bending strengthof the 32 mm thick MDF was higher than that of theglued laminated MDF (Table 1 and Fig. 1).3.2 Shear strength3.2. ^vrsto}a na smikIt can be seen from Fig. 2 that glued laminatedMDF had higher shear strength than glued laminatedparticleboard. The results also showed that shear stren-gth of the laminated 16 mm thick particleboard was hi-gher than that of laminated 12 mm thick particleboard.As it can be observed from Table 1 and Fig. 2, the parti-cleboard laminates have higher mean values of shearstrength compared to the 38 mm thick particleboard. Inaddition, shear strength of the MDF laminate was hi-14 DRVNA INDUSTRIJA 58 (1) 13-17 (2007)Pourtahmasi, Tarmian, Mojarradi: Glued Laminated Panels as Kitchen Countertops ......gher than that of the control panel 32 mm thick MDF. Apositive relationship between press time and shearstrength of the MDF laminate was observed, whereasshear strength of the 12 mm thick particleboard lamina-te increased at first and then decreased as the press timeincreased.DRVNA INDUSTRIJA 58 (1) 13-17 (2007) 15..... Pourtahmasi, Tarmian, Mojarradi: Glued Laminated Panels as Kitchen CountertopsTable 1 Physical and mechanical properties of control panelsTablica 1. Fizikalna i mehani~ka svojstva kontrolnih plo~aPanel typeVrsta plo~eBending strength^vrsto}a savijanjaMPaShear strength^vrsto}a na smikMPaWater absorptionApsorpcija vode%Thickness swellingDebljinsko bubrenje%38 mm thick particleboardiverica debljine 38 mm9.72 (0.47) 1.2 (0.08) 105.17 (3.44) 25.93 (0.61)32 mm thick MDFMDF debljine 32 mm38.08 (0.72) 2.88 (0.28) 65.85 (8.2) 24.6 (0.67)*Values in parentheses are standard deviations. (Vrijednosti u zagradi standardne su devijacije.)Figure 1 Bending strength of glued laminated panels,  – laminated 12 mm thick particleboard,  – laminated 16 mm thickparticleboard,  – laminated 16 mm thick MDFSlika 1. ^vrsto}a savijanja lijepljenih lameliranih plo~a,  – lamelirana plo~a od iverice debljine 12 mm,  – lamelirana plo~aod iverice debljine 16 mm,  – lamelirana plo~a od MDF plo~a debljine 16 mmFigure 2 Shear strength of glued laminated panels,  – laminated 12 mm thick particleboard,  laminated 16 mm thick parti-cleboard,  – laminated 16 mm thick MDFSlika 2. ^vrsto}a na smik lijepljenih lameliranih plo~a,  – lamelirana plo~a od iverice debljine 12 mm,  – lamelirana plo~aod iverice debljine 16 mm,  – lamelirana plo~a od MDF plo~a debljine 16 mm3.3 Water absorption3.3. Apsorpcija vodeAs shown in Fig 3, the glued laminated MDF ishigher water resistant than the glued laminated particle-board. The MDF laminate showed a different behaviorin comparison with the particleboard laminate. In con-trast to the particleboard laminate, a positive relation-ship between press time and water resistance of theMDF laminate was observed. This may be attributed tocomplete curing of PVA adhesive due to the increasedpress time. The negative relationship between presstime and water resistance of particleboard laminatesmay be due to collapse in the laminate structure. Despi-te low water resistance of the PVA adhesive, water ab-sorption content of the glued laminated panels was lo-wer compared to control panels, 32 mm thick MDF and38 mm thick particleboard (see Table 1 and Fig. 3).This behavior shows that water absorption is seldomcaused directly by the adhesive used for gluing lamina-tes, but rather directly by the rigidity of the adhesiveconnection (River et al. 1991).3.4 Thickness swelling3.4. Debljinsko bubrenjeFigure 4 illustrates the effect of press time on thic-kness swelling of glued laminated panels. The resultsshowed that the MDF laminate was more dimensionallystable than the particleboard laminate. Similar to waterabsorption, dimensional stability of the MDF laminateimproved as press time increased. Dimensional stabilityof particleboard laminates was adversely correlated topress time. Adverse influence of press time on dimensio-nal stability of particleboard laminates is explained bystructural failure in the particleboard.16 DRVNA INDUSTRIJA 58 (1) 13-17 (2007)Pourtahmasi, Tarmian, Mojarradi: Glued Laminated Panels as Kitchen Countertops ......Figure 3 Water absorption of glued laminated panels,  – laminated 12 mm thick particleboard,  – laminated 16 mm thickparticleboard ,  – laminated 16 mm thick MDFSlika 3. Apsorpcija vode lijepljenih lameliranih plo~a,  – lamelirana plo~a od iverice debljine 12 mm,  – lamelirana plo~aod iverice debljine 16 mm,  – lamelirana plo~a od MDF plo~a debljine 16 mmFigure 4 Thickness swelling of glued laminated panels,  – laminated 12 mm thick particleboard,  – laminated 16 mm thickparticleboard,  – laminated 16 mm thick MDFSlika 4. Debljinsko bubrenje lijepljenih lameliranih plo~a,  – lamelirana plo~a od iverice debljine 12 mm,  – lameliranaplo~a od iverice debljine 16 mm,  – lamelirana plo~a od MDF plo~a debljine 16 mmParticleboard laminates remained more stablethan 38 mm thick particleboard. In the 38 mm particle-board, higher porous structure in the core layer in com-parison with the glued laminated panels allows easy pe-netration and uptake of water, resulting in high waterabsorption as well as thickness swelling. In addition,the MDF laminates showed lower thickness swellingcompared to the 32 mm thick MDF.4 CONCLUSIONS4. ZAKLJU^CIThe results of this study revealed that the MDF la-minates had higher values of bending and shearstrengths in comparison with particleboard laminates.This behavior is explained by less absorption of PVAglue with MDF, resulting in higher glueline strength ofthe laminates. All mean thickness swelling and waterabsorption values for the MDF laminates were lowerthan those of particleboard laminates. The reason forthis behavior is attributed to better water resistance per-formance of medium density fiberboard in comparisonwith particleboard. This is also thought to occur becau-se of higher strength of adhesive connection in theMDF laminates.The 12 mm thick particleboard laminate showedlower strength but better water resistance than the 16mm thick particleboard laminate; however, the 12 mmthick particleboard laminate fabricated at press time of30 min had abnormally high bending strength. The rea-son for this abnormal behavior is relatively unclear.However, this is assumed to be due to complete curingof PVA glue at press time of 30 min, resulting in higherjoining strength in the fabricated laminate. In addition,excessive press time, namely 40 min is expected to de-stroy the laminate structure. The overpenetration ofglue into the laminate structure during press time of 40min caused by low surface quality of the used laminatesis another explanation for decreasing of the laminatestrength at that press time.From comparison between properties of the lamina-ted panels fabricated at different press times, it can be seenthat all properties of the MDF laminates improve as thepress time increases, whereas those of laminated particle-board panels remain almost constant or slightly decreasewith the increase of press time. However, the higheststrength value of 12 mm laminated particleboard panel isattained when the press time of 30 min is applied.Lower performance of particleboard laminates atpress time of 40 min is attributed to the overpentrationof glue into the particleboard laminate structure causedby low surface quality of particleboard panels.On the basis of the data obtained in this study, al-most all types of particleboard laminates can be substi-tuted for 38 mm particleboard as kitchen countertops.All properties of the MDF laminate, except bendingstrength, were found to be higher than those of the 32mm thick MDF. Thus, the MDF laminates fabricated inthis study can be used as kitchen worktops instead of 32mm MDF.Aside from press time, the performance of gluedlaminated panels is also affected by several other fac-tors, such as pressure and press temperature. Therefore,further studies for selecting proper press conditions toimprove performance of the laminates are recommen-ded.Acknowledgements - ZahvalaThe authors greatly appreciate Oraman Kitchen Cabi-net Co. for supplying the panels. The authors are alsograteful to Omid Hoseinaei and Saeid Abtahi.5 REFERENCES5. LITERATURA1. Aydin, I.; Colak, S.; Colakoglu, G.; Salih, E., 2004: Acomparative study on some physical and mechanical pro-perties of laminated veneer lumber (LVL) produced fromBeech (Fagus Orientalis Lipsky) and Eucalyptus (Eu-calyptus Camaldulensis Dehn.) veneers. Holz alsRoh-und Werkstoff 62: 155-163.2. Kawasaki, T.; Zhang, M.; Kawai, S., 1999: Sandwich pa-nel of veneer-overlaid low density fiberboard. Wood Sci45: 291-2983. McNatt, J.D.; Superfesky, J.M., 1984: How some test va-riables affect bending, tension, and compression valuesfor particle panel products. Res. Pap. FPL, Madison, WI:U.S. Department of Agriculture, Forest Service, ForestProduct Laboratory.4. Pizzi, A., 1983: Wood adhesive: chemistry and techno-logy. Marcel Dekker, 384 p.5. River, B.H.; Vick, C.B.; Gillespie, R.H., 1991: Wood asan adherend. Forest Products Labratory, USDA ForestService, Madison, Wisconsin, 233 p.6. Sellers, J.R.; Mcsween, J.R.; Nearn, W.T., 1988: Gluingof eastern hardwoods: a review. U.S. Department of Agri-culture, Forest Service, Forest Product Laboratory7. Sellers, J.R., 1985: Plywood and adhesive technology.Marcel Dekker, New York, 661p.8. Uysal, B., 2005: Bonding strength and dimensional stabi-lity of laminated veneer lumbers manufactured by usingdifferent adhesives after the steam test. 395-403.Corresponding author:ASGHAR TARMIAN, PhD studentWood Science and Technology DepartmentFaculty of Natural ResourcesTehran University, Karaj,P.O.BOX 31585-4314,Irane-mail: portahmsiºut.ac.irDRVNA INDUSTRIJA 58 (1) 13-17 (2007) 17..... Pourtahmasi, Tarmian, Mojarradi: Glued Laminated Panels as Kitchen Countertops

Lijepljene lamelirane ploče kao radne ploče u kuhinji

Abstract

Similar works

Full text

Available Versions

Hrčak - Portal of scientific journals of Croatia