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

Preparation of nanocellulose by hydrolysis with ionic liquids and two-step hydrolysis with ionic liquids and enzymes

The aim of this study was to compare parameters of nanocellulose obtained by two different procedures: hydrolysis with ionic liquids (1-allyl-3-methylimidazolium chloride and 1-ethyl-3-methylimidazolium acetate) and hydrolysis with ionic liquids in combination with hydrolysis using a cellulolytic enzyme from Trichoderma reesei. Avicel cellulose was treated with two ionic liquids: 1-allyl-3-methylimidazolium chloride (AmimCl) and 1-ethyl-3-methylimidazolium acetate (EmimOAc). In the two-step hydrolysis cellulose after treatment with ionic liquids was additionally hydrolyzed with a solution of enzymes. In order to characterize the obtained material, the following analyses were used: infrared spectroscopy, X-ray diffraction and dynamic light scattering. The results indicated that cellulose obtained by two-step nanocellulose production methods (first hydrolysis with ionic liquids and then with enzymes) showed similar parameters (particle size, XRD patterns and degree of crystallinity) as the material after the one-step process, i.e. hydrolysis with ionic liquids.Otrzymywanie nanocelulozy poprzez hydrolizę cieczami jonowymi oraz hydrolizę dwuetapową cieczami jonowymi i enzymami. Celem pracy było porównanie parametrów nanocelulozy otrzymanej dwoma różnymi metodami: na drodze hydrolizy cieczami jonowymi (chlorek 1-allilo-3-metyloimidazoliowy i octan 1-etylo-3-metyloimidazoliowy) z hydrolizą cieczami jonowymi w połączeniu z hydrolizą enzymatyczną, przy użyciu enzymów celulolitycznych z Trichoderma reesei. Celuloza Avicel została potraktowana dwoma cieczami jonowymi: chlorkiem 1-allilo-3-metyloimidazoliowym (AmimCl) i octanem 1-etylo-3-metyloimidazoliowym (EmimOAc). W hydrolizie dwuetapowej, celuloza po obróbce cieczami jonowymi była dodatkowo poddana hydrolizie roztworem enzymów. W celu scharakteryzowania otrzymanego materiału zastosowano następujące analizy: spektroskopię w podczerwieni, dyfrakcję rentgenowską oraz dynamiczne rozpraszanie światła. Wyniki wykazały, że celuloza otrzymana w wyniku dwuetapowego procesu produkcji nanocelulozy (w pierwszej kolejności hydroliza cieczami jonowymi, a następnie enzymami) wykazuje podobne parametry (wielkość cząstek, strukturę nadcząsteczkową i stopień krystaliczności) jak materiał po jednoetapowym procesie - hydrolizie cieczami jonowymi

The effect of the time process of enzymatic hydrolysis on nanocellulose properties

The effect of the time process of enzymatic hydrolysis on nanocellulose properties - the aim of the study was to evaluate the effect of enzymatic hydrolysis time on the properties of obtained nanocellulose. Two cellulose materials were tested as a raw material for nanocellulose production in the experiment: Avicel and Whatman. The cellulolytic enzyme obtained from the fungus Trichoderma reesei was used to carry out the enzymatic hydrolysis reaction. Enzymatic hydrolysis was performed on cellulose using the reaction times of 0.5, 1, 2 and 4 hours. In order to characterize the obtained materials, the following analyses were used: infrared spectroscopy, X-ray diffraction and dynamic light scattering. The recorded results showed that cellulose after enzymatic hydrolysis showed similar parameters (particle size, XRD patterns and degree of crystallinity) after all the applied reaction times.Wpływ czasu procesu hydrolizy enzymatycznej na właściwości nanocelulozy. Celem pracy było określenie wpływu czasu hydrolizy enzymatycznej na właściwości otrzymanej nanocelulozy. W badaniach wykorzystano dwa materiały celulozowe do produkcji nanocelulozy: Avicel i Whatman. Do przeprowadzenia reakcji hydrolizy enzymatycznej zastosowano enzym celulolityczny uzyskany z grzyba Trichoderma reesei. Hydrolizę enzymatyczną przeprowadzono na celulozie stosując czas reakcji wynoszący 0,5, 1, 2 i 4 godziny. W celu scharakteryzowania otrzymanych materiałów zastosowano następujące analizy: spektroskopię w podczerwieni, dyfrakcję rentgenowską oraz dynamiczne rozpraszanie światła. Uzyskane wyniki wykazały, że celuloza po hydrolizie enzymatycznej wykazywała podobne parametry (wielkość cząstek, strukturę nadcząsteczkową i stopień krystaliczności) po wszystkich zastosowanych czasach reakcji

Impact of the Heat Treatment Duration on Color and Selected Mechanical and Chemical Properties of Scots Pine Wood

The aim of this study was to assess the effect of the duration of heat treatment on changes in the color, as well as the chemical and mechanical properties of Scots pine sapwood. An important element of the research was to obtain the assumed temperature in the entire volume of samples. Quantitative changes in color and its components were recorded, while mechanical properties were determined in tests of compressive strength parallel and perpendicular to the grain, longitudinal tensile strength and modulus of elasticity and impact strength. The novelty of the research was to determine the above-mentioned parameters for twin samples with identical moisture contents. Chemical analyses were conducted on heat-treated wood that was subjected to heat treatment at 220 °C for a period from 1 to 8 h. Extension of the heat treatment duration resulted in the increasing darkening of the wood, as well as a further reduction in the impact strength and tensile strength parallel to the grain by approx. 40 and 50%, respectively, compared to the control wood, but also compared to heat-treated wood for a shorter treatment duration. The heat treatment of wood caused changes in the contents of the wood components, as well as the elemental composition in the heat-treated wood, compared to the control pine. The changes in the structure of the heat-treated wood were confirmed by the attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). Observed quantitative changes in the main wood components, its structural changes, as well as wood decomposition and increased crystallinity of cellulose explain significant changes in both the mechanical properties and the color of heat-treated wood

Color as an Indicator of Properties in Thermally Modified Scots Pine Sapwood

The aim of this study was to determine the dependencies between mechanical properties of modified wood and its color. Within its scope, quantitative changes in color and chemical composition (mass loss, total carbon content, content of extractives and main components of wood), as well as mechanical properties (compressive strength along the grain, strength and modulus of elasticity in longitudinal tension tests, compression across the grain and impact resistance) of the modified Scots pine sapwood, were determined. Modifications were conducted in the atmosphere of superheated steam (time—4 h, temperature of 130, 160, 190, 220 °C). Thermal modification of wood results in an increase in the modulus of elasticity, a reduction of elasticity, longitudinal tensile strength and compressive strength perpendicular to grain. It was found that color parameters ∆E, ∆L and ∆a are linear functions of the modification temperature. The existence of functional dependencies between mass loss, longitudinal tensile strength, radial modulus of elasticity and parameters of ∆E and ∆L makes it possible to determine these properties of modified wood based on color. In turn, chemical analysis indicated that an increase in the temperature of wood modification caused a decrease of holocellulose and hemicelluloses contents, especially in wood samples modified at 220 °C

Chemical and Structural Characterization of Maize Stover Fractions in Aspect of Its Possible Applications

In the last decade, an increasingly common method of maize stover management is to use it for energy generation, including anaerobic digestion for biogas production. Therefore, the aim of this study was to provide a chemical and structural characterization of maize stover fractions and, based on these parameters, to evaluate the potential application of these fractions, including for biogas production. In the study, maize stover fractions, including cobs, husks, leaves and stalks, were used. The biomass samples were characterized by infrared spectroscopy (FTIR), X-ray diffraction and analysis of elemental composition. Among all maize stover fractions, stalks showed the highest C:N ratio, degree of crystallinity and cellulose and lignin contents. The high crystallinity index of stalks (38%) is associated with their high cellulose content (44.87%). FTIR analysis showed that the spectrum of maize stalks is characterized by the highest intensity of bands at 1512 cm−1 and 1384 cm−1, which are the characteristic bands of lignin and cellulose. Obtained results indicate that the maize stover fraction has an influence on the chemical and structural parameters. Moreover, presented results indicate that stalks are characterized by the most favorable chemical parameters for biogas production

Nanocellulose Production Using Ionic Liquids with Enzymatic Pretreatment

Nanocellulose has gained increasing attention during the past decade, which is related to its unique properties and wide application. In this paper, nanocellulose samples were produced via hydrolysis with ionic liquids (1-ethyl-3-methylimidazole acetate (EmimOAc) and 1-allyl-3-methylimidazolium chloride (AmimCl)) from microcrystalline celluloses (Avicel and Whatman) subjected to enzymatic pretreatment. The obtained material was characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), dynamic light scattering (DLS), scanning electron microscopy (SEM), and thermogravimetric analysis (TG). The results showed that the nanocellulose had a regular and spherical structure with diameters of 30–40 nm and exhibited lower crystallinity and thermal stability than the material obtained after hydrolysis with Trichoderma reesei enzymes. However, the enzyme-pretreated Avicel had a particle size of about 200 nm and a cellulose II structure. A two-step process involving enzyme pretreatment and hydrolysis with ionic liquids resulted in the production of nanocellulose. Moreover, the particle size of nanocellulose and its structure depend on the ionic liquid used