Assessment of the stain penetration in wood

Po postopku luženja z vodnim lužilom so v lesnoobdelovalnem podjetju naleteli na problem različnega nabreka posameznih letvic znotraj lepljenega elementa. Zaradi tega smo obstoječe lužilo poskušali modificirati na ta način, da bi zmanjšali njegovo penetracijo v les. Pripravili smo 15 novih formulacij, še pred tem pa smo morali razviti hitro, enostavno in zanesljivo metodo za določanje globine penetracije lužila v les. Ugotovili smo, da so štirje novi pripravki penetrirali signifikantno manj od izvornega vodnega lužila. Le-te bomo preskusili tudi v industrijskem merilu. Dobljene razlike v globini penetracije preskušenih pripravkov so izkazale, da je novo razvita metoda zanesljiva. Kljub temu pa jo bomo v naših nadaljnjih raziskavah poskušali izboljšati. Prav tako bomo proučili vpliv vlažnosti lesa pred luženjem na globino penetracije lužila.During the staining a company, producing wood furniture, encountered a problemof uneven swelling of small boards in glued elements. Therefore we tried to modify the used stain in the way that it would penetrate less into wood. We prepared 15 modified formulations of the waterborne stain, but firstly, we had to develop a simple, quick and reliable method for determination of the stain penetration into the wood. We have found that four modified waterborne stain formulations penetrated significantly less than the original one. Their performance on the industrial scale will be evaluated by further tests. The observed differences between penetration depths of the tested formulations proved that the new method is reliable. However, in order to improve the method, some further investigations will be carried out. We also intend to investigate the influence of wood moisture content on the penetration of the stain

Lastnosti ivernih plošč, izdelanih z uporabo lepila z dodanim utekočinjenim lesom

In this study, three-layer particleboards were produced using liquefied wood in an adhesive mixture. The influence of two different formaldehyde resins: melamine-formaldehyde and melamine-urea-formaldehyde resin and two various catalysts: ammonium sulfate and ammonium formate on the particleboard properties was investigated. There were also two pressing parameters examined: temperature and time. The following physical and mechanical properties of particleboards were measured: board thickness, density, moisture content, bending strength and modulus of elasticity, internal bonding strength, surface soundness, thickness swelling and formaldehyde content. The results showed that properties of produced particle boards were better when melamine-formaldehyde resin and ammonium formate as a catalyst were used in combination with liquefied wood in the adhesive mixture. Also, mechanical properties were improved as the press time and press temperature increased. The optimal mechanical properties of particleboards made with the utilization of the liquefied wood in the adhesive mixture were achieved at 3 min press time and 180 °C press temperature using melamine-formaldehyde resin and 3 % of ammonium formate as a catalyst. A very important characteristic is the low formaldehyde content and that is extremely important in the provision of better quality of life. With the liquefaction of wood and the application of liquefied wood in the particleboard production wood biomass exploitation could be significantly increased. We are able to produce new materials from renewable resources that can be a great alternative to the raw materials, originating from crude oil.Izdelali smo trislojne iverne plošče, kjer smo za pripravo lepila uporabili utekočinjen les. Ugotavljali smo, kako v kombinaciji z utekočinjenim lesom na lastnosti ivernih plošč vplivata dve različni formaldehidni smoli: melamin-formaldehidna in melamin-urea-formaldehidna smola, ter dva različna katalizatorja: amonijev sulfat in amonijev formiat. Ugotavljali smo tudi vpliv dveh parametrov stiskanja, in sicer temperature stiskanja in časa stiskanja. Fizikalne in mehanske lastnosti, ki smo jih ivernim ploščam določili, so bile: debelina plošče, gostota, vsebnost vlage, upogibna trdnost in modul elastičnosti, razslojna trdnost, čvrstost površine, debelinski nabrek in vsebnost prostega formaldehida. Rezultati so pokazali, da smo izboljšali lastnosti ivernih plošč, ko smo v kombinaciji z utekočinjenim lesom uporabili melamin-formaldehidno smolo in amonijev formiat kot katalizator. Ugotovili smo tudi, da so se lastnosti izdelanih ivernih plošč s časom in temperaturo stiskanja izboljšale. Optimalne lastnosti ivernih plošč, pri katerih smo lepilni mešanici dodali utekočinjen les, smo dosegli pri času stiskanja 3 min in temperaturi stiskanja 180 °C, pri uporabi melamin-formaldehidne smole in 3 % amonijevega formiata kot katalizatorja. Zelo pomembna pri izdelanih ivernih ploščah je tudi majhna vsebnost prostega formaldehida, kar močno vpliva na izboljšanje kvalitete bivanja. Z utekočinjanjem lesa in njegovo uporabo pri izdelavi ivernih plošč povečamo izrabo lesne biomase. Iz obnovljivih virov tako lahko sintetiziramo nove materiale, ki so odlična alternativa materialom, ki jih sicer pridobivamo iz surove nafte

Liquefaction of wood using ultrasound and production of particleboards using adhesive mixtures with added liquefied wood

Wood can be liquefied and used for the synthesis of different polymer materials as well as for the adhesives. The aim of our research was to evaluate the utilization of liquefied wood as a part of an adhesive mixture in particleboard production and to assess physical and mechanical properties of produced particleboards. We determined gelation time for different adhesive mixtures depending on the liquefied wood portion, the type and the amount of the catalyst and temperature. For particleboard production, we used melamine-formaldehyde resin with added liquefied wood and ammonium formate as a catalyst. We examined the influence of liquefied wood portion, the type and the amount of the catalyst and pressing temperature on the particleboard properties. Results showed that gelation time increased with higher liquefied wood portion and decreased as the amount of catalyst and temperature increased. The optimal properties of particleboards were obtained at 30 % portion of liquefied wood, at 3 % amount of the catalyst and at pressing temperature of 180°C

Air analysis in a varnish works with a gass chromatograph and mass spectrometer

V članku je opisana analiza delovne atmosfere v lakirnici ene izmed pohištvenih proizvodenj v Sloveniji. Adsorbcija substanc iz zraka je potekala na aktivnem oglju, desorbcija pa s stresanjem v ogljikovem disulfidu. Z uporabo GC-MS metode smo v vzorcih določili prisotnost benzena, toulena, butacilena in izomer ksilena.The article describes the analysis of the working atmosphere in a varnish works of one of the furniture factory in Slovenia. The adsorbtion of air substances was carried out on activated carbon and the desorption by means of shaking in carbon disulphide. By the application of the GC-MS method, the presence of benzene, toulene, butyl acetate and xylene isomers was determined in the samples

Ultrafiltration of water-based stains

V članku je opisana možnost čiščenja odpadnih vod, ki nastanejo pri luženju lesa z vodnimi lužili in sicer z ultrafiltracijo. Ultrafiltrirali smo simulirano odpadno vodo vodnega lužila in proučevali kvaliteto retentata in permeata.The article describes ultrafiltration as a possible way of purifying the waste water resulting from wood staining operations in which water-based stains are used. The waste water from a water-based stain was obtained under simulated conditions and submitted to ultrafiltration. The research included the study of the quality of retentate and permeate

Nanocomposites of LLDPE and Surface-Modified Cellulose Nanocrystals Prepared by Melt Processing

Cellulose nanocrystals (CNCs) were surface modified by esterification in tetrahydrofuran (THF) at 25 °C using different catalysts and anhydrides bearing different alkyl side chain lengths. Unmodified and acetic anhydride (AcAnh)-modified CNCs were studied as potential nanofillers for linear low-density poly(ethylene) (LLDPE). Nanocomposites were prepared by melt processing. Determination of the size and size distribution of CNCs in the nanocomposites by SEM revealed an enhanced compatibility of the AcAnh-modified CNCs with the LLDPE matrix, since the average size of the aggregates of the modified CNCs (0.5–5 μm) was smaller compared to that of the unmodified CNCs (2–20 μm). Tensile test experiments revealed an increase in the nanocomposites’ stiffness and strain at break—by 20% and up to 90%, respectively—at the CNC concentration of 5 wt %, which is close to the critical percolation concentration. Since the CNC nanofiller simultaneously reduced LLDPE crystallinity, the reinforcement effect of CNCs was hampered. Therefore, the molding temperature was increased to 120 °C, and, in this way, the greatest increase of the Young’s modulus was achieved (by ~45%). Despite the enhanced compatibility of the AcAnh-modified CNCs with the LLDPE matrix, no additional effect on the mechanical properties of the nanocomposites was observed in comparison to the unmodified CNC

Air analysis in a varnish works with a gass chromatograph and mass spectrometer

V članku je opisana analiza delovne atmosfere v lakirnici ene izmed pohištvenih proizvodenj v Sloveniji. Adsorbcija substanc iz zraka je potekala na aktivnem oglju, desorbcija pa s stresanjem v ogljikovem disulfidu. Z uporabo GC-MS metode smo v vzorcih določili prisotnost benzena, toulena, butacilena in izomer ksilena.The article describes the analysis of the working atmosphere in a varnish works of one of the furniture factory in Slovenia. The adsorbtion of air substances was carried out on activated carbon and the desorption by means of shaking in carbon disulphide. By the application of the GC-MS method, the presence of benzene, toulene, butyl acetate and xylene isomers was determined in the samples