Liquefied wood-based polyurethane wood coatings of an aesthetically acceptable light colour were prepared and characterised. Liquefied black poplar wood was obtained by solvolysis in a polyethylene ...glycol/glycerol mixture, and it was bleached with hydrogen peroxide. The bleaching treatment converted liquefied wood from a dark brown to a yellowish product. Polyurethane films were prepared by the curing of liquefied wood with polymeric diphenylmethane diisocyanate or trimethylolpropane toluene diisocyanate prepolymer (TMP/TDI) isocyanate-type hardeners. It was found that the selected properties of the films prepared from the bleached liquefied wood were, in general, equivalent to those prepared from unbleached liquefied wood. The mechanical properties of the films obtained with the TMP/TDI curing agent were acceptable for wood coating applications. The initial poor resistance of the films to water and ethanol was substantially improved by the addition of n-octyltriethoxysilane to the liquefied wood prior to the preparation of the polyurethane coatings; the hardness of the films also increased.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Liquefied wood (LW) is a promising natural material that can be used as a part of the adhesive formulation. However, adhesive bonds made of LW only, have low durability. The aim of this study was, ...therefore, to increase the durability of adhesive bonds containing LW. LW was obtained with liquefaction of black poplar wood in ethylene glycol (EG) as the solvent and sulphuric acid (SA) as the catalyst. An optimal time of 120 minutes and a wood/EG mass ratio of 1:3 was defi ned for liquefaction at 180 °C. After liquefaction, the EG was evaporated in order to achieve a low solvent content LW with a fi nal mass ratio of 1:1. A hydroxyl number for 1:3 and 1:1 LW was determined in order to examine the reduction of hydroxyl groups. Four different adhesive mixtures were prepared: LW with a mass ratio of 1:1 (LW1:1 ), LW with a mass ratio of 1:3 (LW1:3 ), LW with a mass ratio of 1:1 and added condensed tannin (CT) (LW1:1 /CT), and LW with a mass ratio of 1:3 and added CT (LW1:3 /CT). The solid beech wood lamellas, which were bonded with these adhesive mixtures, were tested directly after bonding, and later on, after 7, 30 and 50 days. The test results indicated greater bonding shear strength in the case of LW1:1 compared to LW1:3. The addition of CT did not contribute to essentially higher shear strength values. The adhesive mixtures LW1:1 and LW1:1 /CT (uncured and cured) were analyzed using FT-IR spectroscopy. No significant differences were observed between the cured LW1:1 and the LW1:1 /CT samples.
Recovered wood is frequently contaminated with biocides and therefore its use is limited. Even more, wood, impregnated with classical chromated copper arsenate (CCA) preservatives is classified as a ...hazardous waste, therefore solutions for reuse or recovery of this material are sought. One of the options, discussed in this paper is liquefaction and further applications of liquefied wood containing biocide remainings. In order to elucidate this possibilty, spruce and beech wood was impregnated with liquefi ed CCB treated and untreaded spruce wood of various concentrations and exposed to wood decay fungi according to the EN 113 procedure. In paralel, the leaching experiments (ENV 1250-2) were performed as well. The results do not clearly show that liquefied wood is bio-inactive. In most cases the mass loss by fungal attack is decreased compared to the untreated controls. On the other hand, copper leaching from spruce wood, impregnated with the liquefi ed CCB treated wood was significantly reduced. Thus, there are indications that the liquefied wood could be utilized as a binding agent for inorganic biocides.
•Cork dust can be converted into a liquid material for preparation of bio-polymers.•Liquefaction of cork can be performed under acidic or alkaline conditions.•With the acid catalyst only ...lignocellulosic components of cork are liquefied.•In the alkaline environment cork suberin is also liquefied.•The highest liquefaction yields are obtained with the mixture of glycerol and PEG.
The aim of this study was to develop polymers in a liquid solution, from renewable bio-resources, usable as intermediate materials in the preparation of plastics, adhesives or coatings. The liquefaction of cork with glycerol was investigated at 150°C, 180°C, and 200°C under acidic (sulphuric acid) or alkaline conditions (sodium hydroxide). Cork appears as a two-component material, containing suberin and lignocelluloses. In the presence of sulphuric acid, only the liquefaction of the lignocellulosic components was achieved, leading to liquefaction yield of less than 47% at all investigated conditions. The inverse phenomenon was observed with sodium hydroxide. Suberin was almost completely liquefied, but an increase of temperature and/or sodium hydroxide content was necessary to improve the liquefaction of lignocelluloses. Addition of polyethylene glycol to glycerol to a certain extent caused the conversion of suberin under acid conditions leading to liquefaction yield up to 93%. Therefore, it was demonstrated that it is possible to use cork dust, a less valuable by-product, for the production of various basic chemicals and/or polymers with a high added value.
Paper presents a larval cannibalism of green lacewings (Chrysoperla carnea), which was observed during the laboratory bioassay on non-target effect of entomopathogenic nematodes against green ...lacewings larvae. The most probable reason for larval cannibalism were undersized Petri dishes in which the bioassay was performed. Due to large number of larvae per surface unit, frequent crossing of green lacewings larvae appeared and this consequently lead to cannibalism. In most cases larger, elder larvae consumed smaller, younger larvae. Cannibalism increased with temperature rise and was the most intensive at 25 °C. At this temperature the larval mortality was 22.0 % after two days, while after four days the larval mortality reached 31.0 %.
Black poplar wood, diethylene glycol (DEG), and sulphuric acid as a catalyst were used as starting reactants for liquefaction. Optimal conditions for liquefaction were established: reaction ...temperature 150
°C, reaction time 95
min, ratio of wood:DEG
=
1:5 and 3% of sulphuric acid addition. The liquid mixture obtained by the liquefaction was composed of the real product of the reaction (the so called “excess solvent free liquefied wood” (ESFLW)) and of the remaining unreacted DEG. The unreacted DEG was successfully separated from the ESFLW and analysed with HPLC for levulinic acid content. Theoretical weight ratio between the wood and DEG required for the reaction was estimated. OH number investigation showed that the ESFLW in the liquid mixture contributes to maximally 60% of the free
OH groups. The crosslinking of the ESFLW without any curing agents or additives was performed for the first time, and the drying stages investigated. FT-IR investigations demonstrated that the obtained crosslinked polymer film could be an ether and/or ester network.
Utekućeno drvo (LW) perspektivan je prirodni materijal koji može biti upotrijebljen kao tvar za izradu ljepila. Međutim, vezivna ljepila napravljena samo od utekućenog drva imaju malu trajnost. Stoga ...je cilj provedenih istraživanja bio povećati trajnost vezivnih ljepila koja sadržavaju LW. U provedenim je istraživanjima LW dobiven utekućenjem drva topole u etilen glikolu (EG) kao otapalu i sumpornoj kiselini (SA) kao katalizatoru. Definirano je optimalno vrijeme utekućenja od 120 minuta i maseni omjer drvo:EG u iznosu 1:3 za utekućenje pri temperaturi 180 °C. Nakon utekućenja EG je ishlapljen da bi se postigao nizak sadržaj otapala u LW-u s konačnim masenim omjerom 1:1. Utvrđen je hidroksilni broj za LW s omjerom 1:3 i LW s omjerom 1:1 da bi se ispitalo smanjenje broja hidroksilnih skupina. Pripremljene su četiri različite mješavine ljepila: LW s masenim omjerom 1:1 (LW1:1 ), LW s masenim omjerom 1:3 (LW1:3 ), LW s masenim omjerom 1:1 te dodanim kondenziranim taninom (CT) (LW1:1 /CT), i LW s masenim omjerom 1:3 i dodanim CT-om (LW1:3 /CT). Lamele od bukovine lijepljene su navedenim mješavinama ljepila i ispitane odmah nakon lijepljenja, zatim nakon 7, 30 i 50 dana. Rezultati testa pokazali su veću smicajnu čvrstoću vezanja u slučaju LW1:1 u odnosu prema LW1:3 . Dodavanje CT-a nije znatno pridonijelo većoj smicajnoj čvrstoći. Mješavine ljepila LW1:1 i LW1:1 /CT (nesušene i osušene) analizirane su FT-IR spektroskopijom. Nisu zapažene signifi kantne razlike između osušenih uzoraka LW1:1 i LW1:1 /CT.
Recovered wood is frequently contaminated with biocides and therefore its use is limited. Even more, wood, impregnated with classical chromated copper arsenate (CCA) preservatives is classified as a ...hazardous waste, therefore solutions for reuse or recovery of this material are sought. One of the options, discussed in this paper is liquefaction and further applications of liquefied wood containing biocide remainings. In order to elucidate this possibilty, spruce and beech wood was impregnated with liquefied CCB treated and untreaded spruce wood of various concentrations and exposed to wood decay fungi according to the EN 113 procedure. In paralel, the leaching experiments (ENV1250-2) were performed as well. The results do not clearly show that liquefied wood is bio-inactive. In most cases the mass loss by fungal attack is decreased compared to the untreated controls. On the other hand, copper leaching from spruce wood, impregnated with the liquefied CCB treated wood was significantly reduced. Thus, there are indications that the liquefied wood could be utilized as a binding agent for inorganic biocides. Keywords: liquefied wood, wood decay fungi, wood preservation, leaching, CCB, copper Prikupljeno uporabljeno drvo cesto je onecisceno biocidima te je njegova ponovna uporaba ogranicena. Osim toga, drvo impregnirano klasicnim krom-bakar-arsenat (CCA) zastitnim sredstvima klasifi cirano je kao opasni otpad te je nuzno pronaci rjesenje za ponovnu uporabu ili sanaciju tako oneciscenog drva. Jedna od mogucnosti, prezentirana u ovome radu, jest utekucenje drva i daljnja primjena tako utekucenog drva koje sadrzava preostale biocide. Radi razjasnjenja te mogucnosti, smrekovo i bukovo drvo impregnirano je utekucenom nezasticenom smrekovinom i utekucenom smrekovinom zasticenom krom-bakar-boratom razlicitih koncentracija. Tako obradeno drvo izlozeno je djelovanju gljiva, sukladno postupku opisanom u normi EN 113. Paralelno je proveden eksperiment ispiranja (ENV 1250-2). Rezultati istrazivanja nisu jasno pokazali da utekuceno drvo nije bioaktivno. U vecini je slucajeva gubitak mase zbog djelovanja gljiva smanjen u usporedbi s neobradenim kontrolnim uzorcima. Osim toga, ispiranje bakra iz smrekovine impregnirane utekucenim drvom zasticenim CCB-om znatno je smanjeno. Prema tomu, postoje znakovi da se utekuceno drvo moze upotrijebiti kao vezivno sredstvo za anorganske biocide. Kljucne rijeci: utekuceno drvo, gljive truleznice, zastita drva, ispiranje, CCB, bakar
Liquefied wood (LW) is a promising natural material that can be used as a part of the adhesive formulation. However, adhesive bonds made of LW only, have low durability. The aim of this study was, ...therefore, to increase the durability of adhesive bonds containing LW. LW was obtained with liquefaction of black poplar wood in ethylene glycol (EG) as the solvent and sulphuric acid (SA) as the catalyst. An optimal time of 120 minutes and a wood/EG mass ratio of 1:3 was defined for liquefaction at 180°C. After liquefaction, the EG was evaporated in order to achieve a low solvent content LW with a final mass ratio of 1:1. A hydroxyl number for 1:3 and 1:1 LW was determined in order to examine the reduction of hydroxyl groups. Four different adhesive mixtures were prepared: LW with a mass ratio of 1:1 (LW.sub.1:1), LW with a mass ratio of 1:3 (LW.sub.1:3), LW with a mass ratio of 1:1 and added condensed tannin (CT) (LW.sub.1:1/CT), and LW with a mass ratio of 1:3 and added CT (LW.sub.1:3/CT). The solid beech wood lamellas, which were bonded with these adhesive mixtures, were tested directly after bonding, and later on, after 7, 30 and 50 days. The test results indicated greater bonding shear strength in the case of LW.sub.1:1 compared to LW.sub.1:3. The addition of CT did not contribute to essentially higher shear strength values. The adhesive mixtures LW.sub.1:1 and LW.sub.1:1 /CT (uncured and cured) were analyzed using FT-IR spectroscopy. No significant differences were observed between the cured LW.sub.1:1 and the LW.sub.1:1/CT samples. Key words: adhesive, condensed tannin, FT-IR, liquefied wood, shear strength Utekuceno drvo (LW) perspektivan je prirodni materijal koji moze biti upotrijebljen kao tvar za izradu ljepila. Medutim, vezivna ljepila napravljena samo od utekucenog drva imaju malu trajnost. Stoga je cilj provedenih istrazivanja bio povecati trajnost vezivnih ljepila koja sadrzavaju LW. U provedenim je istrazivanjima LW dobiven utekucenjem drva topole u etilen glikolu (EG) kao otapalu i sumpornoj kiselini (SA) kao katalizatoru. Definirano je optimalno vrijeme utekucenja od 120 minuta i maseni omjer drvo:EG u iznosu 1:3 za utekucenje pri temperaturi 180°C. Nakon utekucenja EG je ishlapljen da bi se postigao nizak sadrzaj otapala u LW-u s konacnim masenim omjerom 1:1. Utvrden je hidroksilni broj za LW s omjerom 1:3 i LW s omjerom 1:1 da bi se ispitalo smanjenje broja hidroksilnih skupina. Pripremljene su cetiri razlicite mjesavine ljepila: LW s masenim omjerom 1:1 (LW.sub.1:1), LW s masenim omjerom 1:3 (LW.sub.1:3), LW s masenim omjerom 1:1 te dodanim kondenziranim taninom (CT) (LW.sub.1:1/CT), i LW s masenim omjerom 1:3 i dodanim CT-om (LW.sub.1:3/CT). Lamele od bukovine lijepljene su navedenim mjesavinama ljepila i ispitane odmah nakon lijepljenja, zatim nakon 7, 30 i 50 dana. Rezultati testa pokazali su vecu smicajnu cvrstocu vezanja u slucaju LW.sub.1:1 u odnosu prema LW.sub.1:3. Dodavanje CT-a nije znatno pridonijelo vecoj smicajnoj cvrstoci. Mjesavine ljepila LW.sub.1:1 LW.sub.1:1/CT (nesusene i osusene) analizirane su FT-IR spektroskopijom. Nisu zapazene signifikantne razlike izmedu osusenih uzoraka LW.sub.1:1 i LW.sub.1:1/CT. Kljucne rijeci: ljepilo, kondenzirani tanin, FT-IR, utekuceno drvo, smicajna cvrstoca
Paper presents a larval cannibalism of green lacewings (Chrysoperla carnea), which was observed during the laboratory bioassay on non-target effect of entomopathogenic nematodes against green ...lacewings larvae. The most probable reason for larval cannibalism were undersized Petri dishes in which the bioassay was performed. Due to large number of larvae per surface unit, frequent crossing of green lacewings larvae appeared and this consequently lead to cannibalism. In most cases larger, elder larvae consumed smaller, younger larvae. Cannibalism increased with temperature rise and was the most intensive at 25 °C. At this temperature the larval mortality was 22.0 % after two days, while after four days the larval mortality reached 31.0 %.
V prispevku je predstavljen kanibalizem med ličinkami navadne tenčičarice (Chrysoperla carnea), ki se je pojavil pri laboratorijskem preučevanju neciljnega delovanja entomopatogenih ogorčic na ličinke omenjenega naravnega sovražnika. Najverjetnejši vzrok za pojav kanibalizma so bile premajhne petrijevke, v katerih je potekal poskus. Zaradi velikega števila ličink navadne tenčičarice na enoto površine, je prišlo do pogostega srečevanja ličink in posledično do kanibalizma. V večini primerov so ličinke višjega larvalnega stadija pojedle manjše ličinke. Kanibalizem se je povečeval z višanjem temperature in je bil najbolj intenziven pri 25 °C, kjer je bila smrtnost ličink dva dni po začetku poskusa 22,0 %, po štirih dneh pa 31,0 %.
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