The Effect of Mat Layers Moisture Content on Some Properties of Particleboard/Utjecaj sadrzaja vode u slojevima ploce iverice na njezina svojstva

In this study, the effect of mat moisture content on the physical and mechanical properties of particleboard was investigated. The experimental boards were produced by using 40% softwood, 45% hardwood chips, and 15% sawdust. The formaldehyde resin/adhesive was used in three-layers (bottom-top layer 12%, core layer 8%). Multi-opening press was used during manufacturing the experimental particleboards. The physical and mechanical properties of boards obtained were identified according to the TS-EN standards. The optimum core layer moisture content was determined as 6% and 7% according to the results, whereas the moisture content of bottom and top layers was 14%. Under these moisture content conditions, the bending strength was found to be 13.3 N/[mm.sup.2], the modulus of elasticity in bending 2466 N/[mm.sup.2], and internal bonding strength 0.44 N/[mm.sup.2]. The optimum bottom-top layer moisture content was determined to be between 13% and 15% and 6.5% for the core layer. Keywords: wood-based panels; particleboard; mat moisture content; properties U radu je istrazivan utjecaj sadrzaja vode u slojevima ploca od usitnjenog drva na njihova fizicka i mehanicka svojstva. Istrazivane su ploce proizvedene od iverja mekog drva u udjelu 45%, iverja tvrdog drva u udjelu 15% i drvne prasine u udjelu 15%. Ploce su se sastojale od tri sloja u kojima je upotrijebljena formaldehidna smola/ljepilo (u vanjskim slojevima 12%, u sredisnjim slojevima 8%), a presanje je obavljeno viseetaznom presom. Fizicka i mehanicka svojstva ploca odredena su prema TS-EN normama. Iz dobivenih je rezultata utvrden optimalan sadrzaj vode u sredisnjem sloju od 6 i 7%, dok je konstantni sadrzaj vode u vanjskim slojevima iznosio 14%. Pri tim sadrzajima vode dobiveni su ovi rezultati: cvrstoca na savijanje 13,3 N/[mm.sup.2], modul elasticnosti 2466 N/[mm.sup.2] i meduslojna cvrstoca 0,44 N/[mm.sup.2]. Utvrdeno je da je optimalan sadrzaj vode u vanjskim slojevima izmedu 13 i 15%, a u sredisnjem sloju 6,5%. Kljucne rijeci: drvne ploce, ploca od usitnjenog drva, sadrzaj vode u slojevima ploce, svojstva