Svojstva furnirskih ploča proizvedenih s ureaformaldehidnim adhezivom modificiranim nanocelulozom i mikrocelulozom

Urea-formaldehyde adhesives are widely used in the wood-based materials industry. The study investigates the possibility of using cellulosic particles as a filler that modifies the properties of the resin and consequently improves the properties of plywood. Moreover, the study also examines the differences between microcellulose and nanocellulose used as a filler for UF adhesive. Based on the investigations, it was found that the addition of MFC and NCC significantly affected the curing process and rheological behaviour of adhesive mixtures. Modification led to increase of viscosity and extension of a gel time caused by lowering solid content of the resin. The experimental and reference plywood were tested in terms of bonding quality and mechanical properties such as modulus of elasticity and modulus of rigidity in accordance with applicable standards. The results of the tests confirmed that both the amount and the type of modifier added to the resin had a significant effect on the properties of plywood. The bonding quality and the above mentioned mechanical properties improved in all variants of modification; however the most effective was the addition of NCC in the amount of 10 %/100 g of solid resin. The slight decrease of formaldehyde emission was only observed for 5 % cellulosic particles added to 100 g of solid UF.Urea-formaldehidni (UF) adhezivi imaju široku primjenu u industriji materijala na bazi drva. U radu je opisano istraživanje mogućnosti upotrebe celuloznih čestica kao punila koje mijenja svojstva smole i posljedično poboljšava svojstva furnirske ploče. Nadalje, u istraživanju su ispitane razlike između mikroceluloze (MFC) i nanoceluloze (NCC) koje su upotrijebljene kao punilo za adheziv na bazi UF adheziva. Na temelju ispitivanja utvrđeno je da MFC i NCC dodatci znatno utječu na postupak stvrdnjavanja i reološko ponašanje adhezivnih smjesa. Modifikacija je rezultirala povećanjem viskoznosti i produljenjem vremena geliranja uzrokovanoga smanjenjem sadržaja čvrste smole. Ispitani su kvaliteta vezanja i mehanička svojstva eksperimentalne i referentne furnirske ploče poput modula elastičnosti i modula krutosti, sukladno odgovarajućim normama. Rezultati ispitivanja potvrdili su da i količina i vrsta modifikatora dodanoga u smolu imaju znatan utjecaj na svojstva furnirske ploče. Kvaliteta vezanja i spomenuta mehanička svojstva poboljšana su pri svim varijantama modifikacija, no najučinkovitije je bilo dodavanje NCC-a u količini od 10 % na 100 g čvrste smole. Blago smanjenje emisije formaldehida uočeno je samo za 5 % celuloznih čestica dodanih u 100 g čvrstog UF adheziva

Mogućnost uporabe melamin-ureaformaldehidnog ljepila ojačanog nanocelulozom u proizvodnji furnirskih ploča

The possibility of using nanocellulose (NCC) as a filling substance for melamine-urea-formaldehyde (MUF) adhesive was investigated for the process of manufacturing plywood. The adhesive mixtures were prepared with various nanocellulose concentrations. The amount of introduced filler had a significant effect on both resin and plywood characteristics. Fourier transform infrared spectroscopy (FTIR) did not show any major changes between experimental and reference variants. The viscosity of resin increased after the introduction of nanocellulose. The addition of NCC in the amount of 5 g and 10 g per 100 g of solid resin led to an improvement in bonding quality, modulus of elasticity and bending strength. Further increase of NCC concentration caused a deterioration of manufactured plywood properties. In summary, the addition of proper amount of nanocellulose resulted in manufacturing plywood with improved properties.U radu je prikazano istraživanje mogućnosti uporabe nanoceluloze (NCC) kao punila za melaminurea-formaldehidno ljepilo (MUF) koje se upotrebljava u proizvodnji furnirskih ploča. Smjese ljepila pripremljene su dodavanjem različitih koncentracija nanoceluloze. Količina dodanog punila znatno je utjecala na svojstva smole i furnirske ploče. Furierovom infracrvenom spektroskopijom (FTIR) nisu utvrđene veće promjene između eksperimentalnih i referentnih varijanti. Viskoznost smole povećala se nakon dodatka nanoceluloze. Dodatak 5 i 10 g nanoceluloze na 100 g otvrdnute smole rezultirao je poboljšanjem kvalitete vezanja, modula elastičnosti i čvrstoće na savijanje. Daljnje povećanje koncentracije nanoceluloze uzrokovalo je pogoršanje svojstava proizvedenih furnirskih ploča. Ukratko, dodatak odgovarajuće količine nanoceluloze rezultirao je furnirskom pločom poboljšanih svojstava

Odabrana kemijska i fizička svojstva drvne sječke od borovine inokulirane plijesnima Aspergillus i Penicillium

Mold fungi representing genera of Penicillium and Aspergillus commonly develop on the surface of freshly harvested wood chips during storage. As a result, they are often considered as low-quality material and intended for incineration. Thus, the aim of the present study was to investigate the effect of wood chips infestation with mold fungi representing genera of Aspergillus and Penicillium on their basic chemical and physical properties, such as: chemical structure (evaluated with FTIR spectroscopy), mass loss and hygroscopicity, after an incubation of 3, 6 and 9 weeks. Based on the visual assessment and ergosterol content analysis, it was found that inoculation of wood chips with molds led to the intense fungal development on their surface. However, as observed in FTIR spectra, the presence of molds caused no changes in wood chemical structure. Furthermore, no mass loss and no significant increase in the hygroscopicity of wood were observed. Therefore, pine wood chips overgrown by studied genera of fungi seem to be a valuable material for various applications.Plijesni rodova Aspergillus i Penicillium najčešće se razvijaju na površini svježe pripremljene drvne sječke tijekom skladištenja, zbog čega se takva sječka često smatra nekvalitetnim materijalom i spaljuje se. Stoga je cilj ovoga istraživanja bio istražiti utjecaj zaraženosti drvne sječke plijesnima rodova Aspergillus i Penicillium na njezina osnovna kemijska i fizička svojstva kao što su kemijska struktura (ispitano FTIR spektroskopijom), gubitak mase i higroskopnost nakon ikubacije od tri, šest i devet tjedana. Na temelju vizualne procjene i analize sadržaja ergosterola, utvrđeno je ddrvne sječke. Međutim, na FTIR spektrima je uočeno da plijesni nisu uzrokovale promjene u kemijskoj strukturi drva. Nadalje, nije uočen gubitak mase niti znatno povećanje higroskopnosti drva. Stoga se može zaključiti da je drvna sječka od borovine zaražena promatranim rodovima plijesni upotrebljiv materijal za različite primjenea je inokulacija drvne sječke plijesnima prouzročila intenzivan razvoj plijesni na površin

The possible reduction of phenol-formaldehyde resin spread rate by its nanocellulose-reinforcement in plywood manufacturing process

The possible reduction of phenol-formaldehyde resin spread rate by its nanocellulose-reinforcement in plywood manufacturing process. The aim of the study was to investigate the possibility of phenol-formaldehyde (PF) resin consumption in plywood by its reinforcement with cellulosic nanoparticles (NCC). In order to determine the possible reduction of resin spread rate bonding quality was assessed both after boiling in water for 24h and after ageing test including i.e. boiling in water. Studies have shown that the addition of nanocellulose made it possible to significantly reduce the amount of the applied adhesive. Reference samples were characterized by similar shear strength values to experimental plywood manufactured with the adhesive application of 140 g/m2. NCC-reinforcement resulted also in the increase of mechanical properties such as modulus of elasticity and bending strength. The analysis of the data confirmed the tendency observed during bonding quality evaluation and it was concluded that resin modification allowed to reduce its spread rate by 30 g/m2.Możliwość obniżenia ilości nanoszonej żywicy PF w produkcji sklejki poprzez jej modyfikację z wykorzystaniem nanocelulozy. Celem badań było określenie możliwości obniżenia ilości nanoszonej na forniry żywicy fenolowo-formaldehydowej (PF) poprzez jej modyfikację z wykorzystaniem nanocelulozy. Zbadana została jakość sklejenia sklejki zarówno po moczeniu w wodzie przez 24 h, jak i po gotowaniu. Na podstawie otrzymanych wyników stwierdzono, iż nanomodyfikacja żywicy pozwoliła na zmniejszenie ilości mieszaniny klejowej nanoszonej w procesie produkcyjnym sklejki. Próbki referencyjne charakteryzujące się naniesieniem w ilości 170 g/m2 osiągnęły wartości na poziomie próbek wytworzonych z naniesieniem modyfikowanej żywicy w ilości 140 g/m2. Dodatek nanocelulozy spowodował również poprawę właściwości mechanicznych sklejki takich jak moduł sprężystości czy wytrzymałość na zginanie. Na podstawie uzyskanych wyników stwierdzono, iż wprowadzenie nanocząstek do żywicy PF pozwoliło na obniżenie ilości nanoszonej żywicy o 30 g/m2

Properties of fiber-gypsum composite formed on the basis of hemp (Cannabis sativa L.) fibers grown in Poland and natural gypsum

Properties of fiber-gypsum composite formed on the basis of hemp (Cannabis sativa L.) fibers grown in Poland and natural gypsum. The popularity of composites reinforced with natural fibers is constantly growing and therefore, they are a subject of many scientific works as well. An example of interesting concept is the use of hemp fibers to reinforce a gypsum matrix and therefore, presented study was aimed to determine the effect of their content on the properties of resultant composites. Moreover, the influence of setting temperature was also investigated. The scope of the research included determination of properties such as: density, setting time, bending strength, modulus of elasticity and thermal conductivity coefficient. Studies have shown that as the amount introduced fibers increases, the density of manufactured composites decreases. Furthermore, increase in the content of hemp causes a significant extension in setting time of the gypsum matrix. Based on the outcomes of mechanical properties, it was found that the optimal content of fibers is 4% and further increase in their share results in a deterioration of flexural strength characteristics. The increase in a setting temperature leads to the reduction in their bending strength and modulus of elasticity. Composites reinforced with hemp fibers demonstrate significantly improved thermal insulation propertiesWłaściwości kompozytów włóknisto-gipsowych powstałych na bazie włókien konopi siewnej (Cannabies sativa L.) uprawianych w Polsce i gipsu naturalnego. Popularność kompozytów wzmacnianych włóknami naturalnymi nieprzerwanie rośnie, co sprawia, że są one przedmiotem wielu badań naukowych. Przykładem interesującej koncepcji jest wykorzystanie włókien konopi siewnej w celu wzmocnienia płyt gipsowych. A zatem, przeprowadzone zostały badania dotyczące wpływu ilości dodawanych włókien konopnych oraz temperatury sieciowania wzmocnionej matrycy na właściwości wytworzonych kompozytów gipsowych. Zakres przeprowadzonych eksperymentów obejmował określenie gęstości, czasu sieciowania, wytrzymałości na zginanie, modułu sprężystości oraz współczynnika przewodzenia ciepła. Badania wykazały, iż wraz ze wzrostem udziału włókien czas sieciowania matrycy znacznie się wydłuża, a gęstość otrzymywanych kompozytów maleje. Wykazano również, iż optymalną ilością wzmocnienia konopnego zapewniającą najlepsze właściwości wytrzymałościowe jest 4%, a dalsze zwiększenie jego udziału powoduje znaczne pogorszenie wytrzymałości. Ponadto zwiększenie temperatury podczas sieciowania wpływa negatywnie na charakterystykę wytrzymałościową wyprodukowanych płyt. Właściwości izolacyjne ulegały natomiast znacznej poprawie wraz z rosnącym udziałem włókien konopnych w płycie gipsowej

Pine Logs Sorting as a Function of Bark Thickness

The process of sorting softwood raw materials is aimed at full automation. Techniques such as laser and optical scanning, used in measuring and sorting wood raw material with the layer of bark, are based on an analysis of the external shape of the log. The consequence of this is the use of constant ranges of bark deductions, which are often affected by errors resulting from averaging the values. The thickness of the bark is influenced by many factors, such as the tree species and the quality of habitat in which the trees have grown. In the case of pine wood, the range of adopted diametral intervals for the processed raw material plays a significant role. The analysis of the automatic sorting results showed numerous cases of a log-size mismatch. In methods that assume the measurement of wood with the bark, deductions for bark should be made based on experiments that take into account the raw resources base. Despite the high correlation between the size of the deduction and the average thickness of the bark (r = 0.85), the mean value of an error of the adjustment to the maximum thickness of the bark in the automatic sorting was 45%. The maximum bark thickness for the analyzed sorting intervals was correlated. The level of the correlation coefficient value was r = 0.72. In order to increase the accuracy of the sorting process, the value of the deduction for bark should be adjusted to the maximum values in each sorting group

Influence of qualitative and dimensional classification of Pinewood raw material as an efficiency indicator in the production of selected timber assortments

Wood processing plants in Poland are recipients of more than 50% of round wood, which is delivered by the State Forests National Forest Holding. Thus playing a crucial role in the technological processing of raw material for all other wood industry branches. Each group of recipients has individual needs and expectations concerning the quality of the raw material such as, its type and the size of the cross-sections of the assortment used for further production. Therefore, it is economically justified for small production plants to abandon the production of narrow groups of assortments, which usually meets the standards of timber for general purposes. The aim is to make wood processing more flexible and lower the quality of raw material to produce assortments for a specific branches of the wood industry. Wood processing experiments were conducted to produce laths for construction purposes. These materials are one of the most important elements of roof constructions. The research proved empirically that it was possible to produce quality class 1 laths (88% of all laths produced) from WC0 class pinewood used as the input raw material and that the quantitative efficiency exceeded 55%.Wpływ doboru jakościowo wymiarowego surowca sosnowego, jako wskaźnik wydajnościowy w produkcji wybranych sortymentów tarcicy. Zakłady pierwiastkowego przerobu drewna w Polsce są odbiorcami ponad 50% drewna w postaci okrągłej, sprzedawanego przez Państwowe Gospodarstwo Leśne „Lasy Państwowe”. Tym samym odgrywają decydującą rolę na drodze technologicznego przetworzenia surowca dla pozostałych gałęzi przemysłu drzewnego. Każda z grup odbiorców posiada indywidualne potrzeby dotyczące jakości wykorzystywanego surowca, gatunku oraz wielkości przekrojów poprzecznych sortymentu wykorzystywanych do własnej dalszej produkcji. Stąd ekonomicznie uzasadnione jest, odchodzenie mały zakładów produkcyjnych od wytwarzania wąskich grup sortymentów, często zgodnych z normami tarcicy tartacznej ogólnego przeznaczenia. Dąży się do uelastycznienia przerobów i wytwarzanie sortymentów pod konkretną gałąź przemysłu z surowca niższej jakości. Dla celów badawczych przeprowadzone zostały przeroby doświadczalne uwzględniające pozyskanie łat budowlanych. Są to materiały, będące jednym z ważniejszych elementów konstrukcji dachowych. Doświadczalnie oraz empirycznie udowodnione zostało, że w odniesieniu do surowca wejściowego, jakim jest drewno sosnowe klasy WC0, możliwe jest wytwarzanie łat zaklasyfikowanych do I klasy jakości (stanowiącej 88% z wszystkich wytworzonych łat) z wydajnością ilościową przekraczającą 55%

Effect of sawn zone on the quality of lumber in the evaluation of selected pine wood defects

Effect of sawn zone on the quality of lumber in the evaluation of selected pine wood defects. In the course of research on the sawn pine raw material with defined distribution of the defects, a variable level of change in the presence of knots was assessed. Initially, the experimental material was classified in terms of the general-purpose timber, and then the strength classes of wood for structural applications were assigned. The proportion of sound knots increased in case of wood obtained from the middle and top zones. In the case of buttend logs, an increase in the share of the rotten knots having an average diameter of 2-4 cm was observed. The intensity of the defect’s occurrence corresponded with the zone of origin along the large-sized roundwood length.Wpływ strefy przetarcia na jakość tarcicy w ocenie wybranych wad drewna sosnowego. W trakcie badań na surowcu tartacznym sosnowym o określonym rozkładzie wad oceniono zmienny poziom występowania sęków. Początkowo materiał doświadczalny sklasyfikowano w kategoriach tarcicy ogólnego przeznaczenia, a następnie przypisano klasy wytrzymałościowe drewna do zastosowań konstrukcyjnych. Udział sęków zdrowych wzrósł w przypadku drewna pozyskanego ze strefy środkowej i górnej. W przypadku kłód odziomkowych zaobserwowano wzrost udziału sęków zepsutych o średniej średnicy 2-4 cm. Intensywność występowania wady tarcicy odpowiadała lokalizacji strefy jej pochodzenia na długości wielkowymiarowej drewna okrągłego

The possibility to use a side-timber in glulam beams manufacturing for structural applications

The possibility to use a side-timber in glulam beams manufacturing for structural applications. The aim of presented study was to determine the mechanical properties of three-layered glued structural beams manufactured with the use of side-timber pieces as an outer layers and the fragmented main yield as an inner layer. Four types of beams were pressed and tested in terms of four-point bending strength and modulus of elasticity. Variants differed from each other in the direction of the fibers in the inner layer and in the presence of adhesive layer between the fragmented wood. Studies have shown that the bending strength of the beams depended on the calculation method. Moreover, no significant effect of the inner layer arranging method on the bending strength of the beams was found. The values of modulus of elasticity (MOE) were low. The presented study is a starting point for further investigations concerning the possible way of the rational application of fragmented timber pieces and the side-timber for structural applications.Możliwość wykorzystania tarcicy bocznej do produkcji klejonych belek konstrukcyjnych. Celem przeprowadzonych badań było określenie właściwości mechanicznych trójwarstwowych, klejonych belek konstrukcyjnych wytworzonych z wykorzystaniem tarcicy bocznej oraz tarcicy głównej w postaci odpadów kawałkowych jako warstwy wewnętrznej. Wytworzono i przebadano cztery typy belek aby określić ich wytrzymałość na zginanie w próbie zginania czteropunktowego oraz moduł sprężystości. Warianty różniły się pomiędzy sobą kierunkiem przebiegu włókien w warstwie wewnętrznej oraz występowaniem spoiny pomiędzy fragmentami drewna w warstwie środkowej. Badania wykazały, iż wytrzymałość na zginanie wahała się od 44 N/mm2 do 48 N/mm2. Ponadto nie stwierdzono aby sposób ułożenia warstwy wewnętrznej miał istotny wpływ na właściwości mechaniczne wytworzonych elementów konstrukcyjnych. Wartości modułu sprężystości były niskie (w najkorzystniejszym wariancie 11,6 kN/mm2). Prezentowane badania są punktem wyjścia do dalszych poszukiwań racjonalnego sposobu wykorzystania odpadów kawałkowych drewna powstających np. w procesie manipulacji wad oraz tarcicy bocznej w zastosowaniach konstrukcyjnych

The Application of Oak Bark Powder as a Filler for Melamine-Urea-Formaldehyde Adhesive in Plywood Manufacturing

The woodworking industry generates a great amount of bark which has not yet found a wider industrial application. None of the previously conducted research has considered oak bark application (which is one of the most often processed wood species in Poland) as a filler for wood adhesives. Moreover, no studies have determined the properties of bark containing melamine-urea-formaldehyde resin (MUF), which increasingly replaces pure urea-formaldehyde adhesives. Thus, the aim of the study was to determine the possibility of grinded oak bark application as a filler for MUF adhesive in plywood manufacturing. The chemical composition of oak bark was evaluated. Properties of liquid resins, such as viscosity, gel time, pH, and solid content, were determined. Chemical interaction between the filler and resin was assessed with using Fourier-transform infrared (FTIR) spectroscopy. Plywood panels manufactured using MUF adhesive filled with different bark concentrations (10%, 15%, 20%, 25%) were tested in terms of such properties as formaldehyde release and bonding quality. Studies have shown an improvement in liquid resin properties. The course of FTIR spectra did not explain the chemical interaction between the polymer and the filler. The addition of oak bark at a concentration of 15% made it possible to produce plywood panels characterized by reduced formaldehyde release and improved bonding quality