40 KB545 KB40 KB197320132005Bučar, BojanResnik, JožeŠega, Bogdan25 straništevilka:76str. 123-146ISSN:0351-3114COBISSID:1538982URN:URN:NBN:SI:doc-RQ7UOF2GslInštitut za gozdno in lesno gospodarstvoUniverza v Ljubljani, Biotehniška fakulteta, Oddelek za gozdarstvo & Oddelek za lesarstvoZbornik gozdarstva in lesarstvadifuzivnostlepljenjelesvlagaVpliv lepilnega spoja na prečno difuzijo vode v lepljenem lesu|In the wood-glue-wood system, the glue-bond presents an additional resistance,hindering the water transition. The increased resistance of the glued test pieces is the consequence of adhesive being present in the bond, soas of altered wood properties, mainly the increased density and locally decreased wood hygroscopicity, resulting as a consequence of wood exposed to the gluing conditions. Using an unsteady-state method, the diffusion coefficients were defined. The kinetics of absorption of the massive beech test pieces, glued test pieces (PVAc, UF, MUF, PRF and epoxy liquid adhesives and PF film were used), and parallel ones with no glue bonds but exposed to the gluing conditions, were compared. It was established that the thin glue bonds made by using liquid glues do not present a barrier, which could effectively hinder the transition of bound water into the glued piece. A higher resistance was presented just by FF glue film bonds. There exist statistically significant differences among diffusion coefficients, calculatedby analytical solutions and solutions of an equation of the first order model. Transverse diffusion of water vapour and bound water can be described as the first order systemLepilni spoj v sistemu les-lepilo-les pomeni dodaten upor, ki ovira prehod vode. Povečan upor zlepljenih preskušancev je posledica lepila v spoju in tudisprememb v lastnostih lesa, zlasti povečane gostote ter lokalno manjše higroskopičnosti, ki sta posledici izpostavitve lesa pogojem lepljenja. Primerjali smo kinetike navlaževanja masivnih bukovih preskušancev in zlepljenih preskušancev (uporabili smo tekoča PVAc, UF, MUF, FRF in epoksidna lepila ter FF lepilni film) ter vzporednih preskušancev, ki so bili brez lepilnih spojev, so pa bili izpostavljeni pogojem lepljenja. Difuzijske koeficiente smo določili z uporabo nestacionarne metode. Ugotovili smo, da tanki lepilni spoji, izdelani s tekočimi lepili, niso bariera, ki bi učinkovito zadržala prodiranje vezane vode v lepljenec. Večji upor ustvarjajo le spoji s FF lepilnim filmom. Med difuzijskimi koeficienti, izračunanimi iz analitičnih rešitev in rešitve enačbe prvega reda, obstajajo statistično značilne razlike. Prečno difuzijo vodne pare in vezane vode v lesu lahko opišemo kot sistem prvega redaTEXTznanstveno časopisjejournalsSlovenian National E-content AggregatorNational and University Library of SloveniaUniverza v Ljubljani, Biotehniška fakulteta