In this study, the effects of applying wax on the colour, glossiness, and whiteness index (WI*) values of American black cherry (Prunus serotina Ehrh.) wood were investigated. Wax was applied to ...wooden material surfaces using a brush in one, two, and three layers. Tests were then conducted on surfaces with and without wax. The results were statistically significant according to the multivariate variance analysis. It was determined that the application of wax led to a decrease in L*, ho, and WI* values on the wooden material surfaces (parallel and perpendicular to the fibres), while the a*, b*, and C* parameters increased. In measurements parallel and perpendicular to the fibres, increases were observed in gloss values for two- and three-layer wax applications at 60° and 85°. The ∆L* values were negative when wax was applied in one, two, and three layers, whereas the ∆a*, ∆b*, and ∆C* values were positive. The ∆E* values were determined as 8.41 for one layer of wax, 11.29 for two layers, and 11.59 for three layers. Given the similarity between the ∆E* values of two and three layers of wax, it can be inferred that a third layer may not be necessary.
Proučevali smo vpliv nanosa voska na barvo, sijaj in indeks beline (WI*) lesa ameriške čremse (Prunus serotina Ehrh.). Vosek je bil nanesen na površine lesa s čopičem v enem, dveh in treh slojih. Teste smo opravili na premazanih in nepremazanih površinah. Analiza variance je pokazala statistično značilne razlike v rezultatih. Medtem ko smo po nanosu voska opazili zmanjšanje vrednosti L*, ho in WI* v smereh vzporedno in pravokotno na vlakna, smo ugotovili, da so parametri a*, b* in C* po nanosu narasli. Pri merjenju sijaja pri 60 in 85 stopinjah smo pri vzorcih z dvema in tremi plastmi voska opazili povečanje vrednosti pri merjenju vzporedno in pravokotno glede na smer lesnih vlaken. Vrednosti ∆L* so bile negativne za voskane sisteme, nanesene v 1, 2 in 3 slojih, medtem ko so bile vrednosti ∆a*, ∆b* in ∆C* pozitivne. Vrednost ∆E* je po 1-slojnem voskanju znašala 8,41, pri 2-slojnem 11,29 in pri 3-slojnem 11,59. Glede na to, da so bile vrednosti ∆E* po 2 in 3 nanosih voska podobne, lahko sklepamo, da 3. nanos voska ni potreben.
Za doseganje cilja evropske energetsko-podnebne politike, da do leta 2050 dosežemo podnebno nevtralnost s prehodom na obnovljive vire energije, je potrebno aktivirati različne razpoložljive ...obnovljive vire, vključno z biološkimi ostanki oz. odpadki. Eden od takih bioloških odpadkov, ki nastaja v velikih količinah in se večinoma nepredelan odlaga v okolje, so ostanki mlete kave. Ker ostanke mlete kave sestavljajo celuloza, hemiceluloza, lignin in proteini, predstavljajo velik potencial tudi kot biogorivo, ki lahko delno nadomesti lesno biomaso pri proizvodnji peletov. V raziskavi smo v laboratorijskih pogojih izdelali pelete iz ostankov mlete kave, ki smo jim dodali različne deleže (0 %, 25 %, 50 %, 75 %) žagovine. Izdelanim peletom smo določili lastnosti in jih glede na izmerjene vrednosti razvrstili v kakovostne razrede po standardu SIST EN ISO 17225-6:2021. Ugotovili smo, da imajo peleti z večjim deležem ostankov mlete kave višjo kurilno vrednost, večjo vsebnost pepela ter nižjo mehansko obstojnost. Peleti, izdelani iz ostankov mlete kave in dodatkom žagovine (50 % ali več), izkazujejo obetavne lastnosti kot vhodna surovina za proizvodnjo peletov.
In order to achieve the European energy and climate policy goal of climate neutrality by 2050, it is necessary to activate various available renewable energy sources, including biological residues or waste. One such biological waste, which is produced in large quantities and usually enters the environment unprocessed, is spent ground coffee. As spent ground coffee consist of cellulose, hemicellulose, lignin and proteins, it has great potential as a biofuel, and could partially replace wood biomass in the production of pellets. In our research, we have produced pellets under laboratory conditions from spent ground coffee to which we have added different proportions (0 %, 25 %, 50 %, 75 %) of sawdust. We determined the properties of the pellets and categorized them into quality classes based on the measured values according to the SIST EN ISO 17225-6:2021 standard. We found that pellets with a higher proportion of spent ground coffee residues have a higher calorific value, higher ash content and lower mechanical durability. Pellets made from spent ground coffee residues with the addition of sawdust (50 % or more) show promising properties for use as a raw material for pellet production.
The increasing scarcity of major commercial tropical hardwood species has necessitated the utilization of plantation grown exotic timber species as a potential means of maintaining Ghana's foundation ...of timber resources. To better consider Albizia lebbeck as a substitute for wood species which are being seriously over-exploited to the point of commercial extinction, its wood properties were characterized to expatiate its utilization potentials. Three mature plantation grown Albizia lebbeck trees with diameters 45-50 cm at breast height were purposively selected and sampled at four stem height levels of tree height. The samples were sawn into the required sizes in accordance with the British standard, BS 373 (1957) for testing. The heartwood and sapwood proportions were evaluated and the samples were examined for hardness, bending strength (MOE and MOR), compression strength parallel to grain, shear strength parallel to grain, and air-dry density. All trees had a significantly higher heartwood than sapwood percentage. The air-dry density values at 12% MC were 868 kg/m3, 806 kg/m3, 695 kg/m3 and 564 kg/m3 for four sections of the stem (heights 0-25%, 26-50%, 51-75% and 76-100%). In general, the plantation grown Albizia lebbeck exhibited favourable strength values, suggesting that it is endowed with adequate properties for being an alternative species to supply the wood industry.
Zaradi naraščajočega pomanjkanja lesa tradicionalnih tropskih listavcev morajo v Gani vse bolj uporabljati les eksotičnih lesnih vrst. Ta prihaja s plantaž, kar pripomore tudi k ohranjanju tradicionalnih gozdnih virov. Cilj prispevka je raziskati lastnosti lesa vrste Albizia lebbeck in odgovoriti, ali bi les lahko uporabili kot nadomestek za nekatere tradicionalne lesne vrste. V ta namen so bila izbrana tri odrasla drevesa Albizia lebbeck s premerom 45–50 cm v prsni višini, vzorce lesa pa so odvzeli na štirih nivojih debla. Vzorci so bili razžagani na zahtevane dimenzije v skladu z britanskim standardom BS 373 (1957). Ocenjen je bil delež jedrovine in beljave, nato pa je bila raziskana trdota, upogibna, tlačna in strižna trdnost ter gostota zračno suhega lesa. Pri vseh drevesih je bil delež jedrovine znatno višji od deleža beljave. Vrednosti gostote na štirih nivojih po višini debla (0–25 %, 26–50 %, 51–75 % in 76–100 % višine) pa so bile 868 kg/m3, 806 kg/m3, 695 kg/m3 in 564 kg/m3. Na splošno so bile trdnostne lastnosti lesa vrste Albizia lebbeck s plantaže ugodne, kar nakazuje, da ima les primerne lastnosti, da bi ga lahko uporabili za potrebe lesne industrije in za širšo uporabo.
