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\n\n \n \n \n \n \n \n Effect of Acetylation and Accelerated Weathering of Nigerian Grown Rubberwood ( Hevea brasiliensis , Müll. Arg.) on Equilibrium Moisture Content and Colour Change.\n \n \n \n \n\n\n \n Olaniran, S. O.\n\n\n \n\n\n\n
Drvna industrija, 73(1): 91–98. March 2022.\n
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@article{olaniran_effect_2022,\n\ttitle = {Effect of {Acetylation} and {Accelerated} {Weathering} of {Nigerian} {Grown} {Rubberwood} ( \\textit{{Hevea} brasiliensis} , {Müll}. {Arg}.) on {Equilibrium} {Moisture} {Content} and {Colour} {Change}},\n\tvolume = {73},\n\tissn = {18471153, 00126772},\n\turl = {https://hrcak.srce.hr/274117},\n\tdoi = {10.5552/drvind.2022.2113},\n\tabstract = {This study was conducted to investigate the effect of acetylation on equilibrium moisture content (EMC) of Nigerian-grown rubberwood and its effect on colour change in exposure of rubberwood to surface degradation through accelerated weathering. The samples were modified to two levels of acetylation, which yielded weight percent gain (WPG) of 7 \\% and 10 \\% after 8hr (8-hr Acetyl) and 48hr of acetylation (48-hr Acetyl), respectively. Accelerated weathering of unmodified (Ref) and acetylated wood was done using QUV-Accelerated Weathering Tester for four weeks. The unmodified and acetylated samples (weathered and unweathered) were oven-dried and conditioned in climate rooms at different relative humidity of 50 \\%, 65 \\% and 95 \\%, with samples being moved to each room after 14 days. Results showed that acetylation led to a significant decrease in equilibrium moisture content of rubberwood. After weathering, there was a decrease in EMC of rubberwood due to removal of hemicelluloses alongside the degraded lignin, and a slight increase in EMC of the acetylated wood. In terms of colour change, photo-bleaching of the acetylated samples was higher (10.46 for 48-hr Acetyl) after four weeks of weathering compared to the unmodified samples (6.43). Hence, the outcome of this study has shown that, although acetylation is effective in minimizing moisture ingress into wood, it resulted in photo-bleaching of the weathered samples. Additional surface coating is recommended to serve as a protective layer, preventing partial washing out of the acetyl groups, minimize photo-bleaching during weathering and prolong the aesthetic value of the wood especially in outdoor applications such as wall cladding and façade.\n , \n Ova je studija provedena kako bi se istražio utjecaj acetilacije na ravnotežni sadržaj vode (EMC) i na promjenu boje drva kaučukovca zbog površinske razgradnje prouzročene ubrzanim izlaganjem vremenskim utjecajima. Drvo je uzgojeno u Nigeriji, a uzorci su modificirani acetilacijom u dva stupnja, što je nakon osam sati (8-hr Acetyl) odnosno 48 sati acetilacije (48-hr Acetyl) rezultiralo povećanjem mase (WPG) od 7 i 10 \\%. Ubrzano izlaganje nemodificiranoga (Ref) i acetiliranog drva vremenskim utjecajima provedeno je u QUV uređaju tijekom četiri tjedna. Nemodificirani i acetilirani uzorci (izlagani i neizlagani) sušeni su u sušioniku i kondicionirani u klimatskim prostorijama pri različitim relativnim vlažnostima zraka, od 50, 65 i 95 \\%, a uzorci su nakon 14 dana premještani u svaku od prostorija. Rezultati su pokazali da je acetilacija dovela do znatnog smanjenja ravnotežnog sadržaja vode u drvu kaučukovca. Nakon izlaganja vremenskim utjecajima EMC drva kaučukovca smanjio se zbog nestajanja hemiceluloze uz razgradnju lignina, a EMC acetiliranog drva blago se povećao. Kad je riječ o promjeni boje, izbjeljivanje je nakon četiri tjedna izlaganja vremenskim utjecajima bilo veće na acetiliranim uzorcima (10,46 za 48-hr Acetyl) nego na nemodificiranima (6,43). Stoga je ovo istraživanje pokazalo da je acetilacija, iako je učinkovita glede smanjenja prodora vlage u drvo, rezultirala izbjeljivanjem uzoraka ubrzano izloženih vremenskim utjecajima. Stoga se preporučuje primjena površinskog premaza koji će služiti kao zaštitni sloj, sprječavati djelomično ispiranje acetilnih grupa, smanjiti izbjeljivanje tijekom izlaganja drva vremenskim utjecajima i dulje očuvati njegovu estetsku vrijednost, posebice u vanjskim uvjetima, primjerice kad je drvo kaučukovca upotrijebljeno kao zidna obloga ili fasada.},\n\tnumber = {1},\n\turldate = {2022-04-29},\n\tjournal = {Drvna industrija},\n\tauthor = {Olaniran, Samuel Oluyinka},\n\tmonth = mar,\n\tyear = {2022},\n\tpages = {91--98},\n\tfile = {Volltext:C\\:\\\\Users\\\\maicher\\\\Zotero\\\\storage\\\\SEEYXCIV\\\\Olaniran - 2022 - Effect of Acetylation and Accelerated Weathering o.pdf:application/pdf},\n}\n\n\n
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\n This study was conducted to investigate the effect of acetylation on equilibrium moisture content (EMC) of Nigerian-grown rubberwood and its effect on colour change in exposure of rubberwood to surface degradation through accelerated weathering. The samples were modified to two levels of acetylation, which yielded weight percent gain (WPG) of 7 % and 10 % after 8hr (8-hr Acetyl) and 48hr of acetylation (48-hr Acetyl), respectively. Accelerated weathering of unmodified (Ref) and acetylated wood was done using QUV-Accelerated Weathering Tester for four weeks. The unmodified and acetylated samples (weathered and unweathered) were oven-dried and conditioned in climate rooms at different relative humidity of 50 %, 65 % and 95 %, with samples being moved to each room after 14 days. Results showed that acetylation led to a significant decrease in equilibrium moisture content of rubberwood. After weathering, there was a decrease in EMC of rubberwood due to removal of hemicelluloses alongside the degraded lignin, and a slight increase in EMC of the acetylated wood. In terms of colour change, photo-bleaching of the acetylated samples was higher (10.46 for 48-hr Acetyl) after four weeks of weathering compared to the unmodified samples (6.43). Hence, the outcome of this study has shown that, although acetylation is effective in minimizing moisture ingress into wood, it resulted in photo-bleaching of the weathered samples. Additional surface coating is recommended to serve as a protective layer, preventing partial washing out of the acetyl groups, minimize photo-bleaching during weathering and prolong the aesthetic value of the wood especially in outdoor applications such as wall cladding and façade. , Ova je studija provedena kako bi se istražio utjecaj acetilacije na ravnotežni sadržaj vode (EMC) i na promjenu boje drva kaučukovca zbog površinske razgradnje prouzročene ubrzanim izlaganjem vremenskim utjecajima. Drvo je uzgojeno u Nigeriji, a uzorci su modificirani acetilacijom u dva stupnja, što je nakon osam sati (8-hr Acetyl) odnosno 48 sati acetilacije (48-hr Acetyl) rezultiralo povećanjem mase (WPG) od 7 i 10 %. Ubrzano izlaganje nemodificiranoga (Ref) i acetiliranog drva vremenskim utjecajima provedeno je u QUV uređaju tijekom četiri tjedna. Nemodificirani i acetilirani uzorci (izlagani i neizlagani) sušeni su u sušioniku i kondicionirani u klimatskim prostorijama pri različitim relativnim vlažnostima zraka, od 50, 65 i 95 %, a uzorci su nakon 14 dana premještani u svaku od prostorija. Rezultati su pokazali da je acetilacija dovela do znatnog smanjenja ravnotežnog sadržaja vode u drvu kaučukovca. Nakon izlaganja vremenskim utjecajima EMC drva kaučukovca smanjio se zbog nestajanja hemiceluloze uz razgradnju lignina, a EMC acetiliranog drva blago se povećao. Kad je riječ o promjeni boje, izbjeljivanje je nakon četiri tjedna izlaganja vremenskim utjecajima bilo veće na acetiliranim uzorcima (10,46 za 48-hr Acetyl) nego na nemodificiranima (6,43). Stoga je ovo istraživanje pokazalo da je acetilacija, iako je učinkovita glede smanjenja prodora vlage u drvo, rezultirala izbjeljivanjem uzoraka ubrzano izloženih vremenskim utjecajima. Stoga se preporučuje primjena površinskog premaza koji će služiti kao zaštitni sloj, sprječavati djelomično ispiranje acetilnih grupa, smanjiti izbjeljivanje tijekom izlaganja drva vremenskim utjecajima i dulje očuvati njegovu estetsku vrijednost, posebice u vanjskim uvjetima, primjerice kad je drvo kaučukovca upotrijebljeno kao zidna obloga ili fasada.\n
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\n\n \n \n \n \n \n \n Impregnation Properties of Nigerian-Grown Gmelina arborea Roxb. Wood.\n \n \n \n \n\n\n \n Olaniran, S. O.; Löning, S.; Buschalsky, A.; and Militz, H.\n\n\n \n\n\n\n
Forests, 13(12): 2036. December 2022.\n
Number: 12 Publisher: Multidisciplinary Digital Publishing Institute\n\n
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@article{olaniran_impregnation_2022,\n\ttitle = {Impregnation {Properties} of {Nigerian}-{Grown} {Gmelina} arborea {Roxb}. {Wood}},\n\tvolume = {13},\n\tcopyright = {http://creativecommons.org/licenses/by/3.0/},\n\tissn = {1999-4907},\n\turl = {https://www.mdpi.com/1999-4907/13/12/2036},\n\tdoi = {10.3390/f13122036},\n\tabstract = {The success of any wood treatment process and the measure of protection conferred on treated wood are determined by the uptake and penetration of the treatment chemicals, in addition to the efficacy of the chemicals used for the treatment. Hence, the level of treatability of wood species should be pre-determined prior to the wood treatment to ensure the overall protection of the treated wood. Gmelina arborea wood, due to its low durability, requires impregnation with chemicals for preservation or chemical modification to enhance its durability. However, more details are required to establish the influence of its anatomy on impregnation to recommend appropriate treatment methods. Therefore, gmelina wood samples were treated under pressure to determine the solution uptake and penetration, while anatomical studies were carried out with light microscopy, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX) measurements. Variations in stem heights, stem diameters, and samples from other tree stands were considered. The outcome of the study showed that the liquid uptake was generally low for gmelina wood among the selected stands (16–23\\%) and there was no significant difference in stem diameters; meanwhile, penetration was less than 4 mm in the axial direction, and very low in the lateral (radial and tangential) direction. Vessels of gmelina wood have abundant tyloses, while crystalline structures with needlelike shapes are present in a large proportion of the ray parenchyma cells, and are confirmed with SEM-EDX to be made up of calcium oxalate. The low liquid uptake and penetration in gmelina wood suggest that the impregnation of chemicals into its microstructure is next to impossible. Hence, alternative treatment methods other than those involving impregnation with chemicals should be sought to enhance its durability.},\n\tlanguage = {en},\n\tnumber = {12},\n\turldate = {2022-11-30},\n\tjournal = {Forests},\n\tauthor = {Olaniran, Samuel Oluyinka and Löning, Sophie and Buschalsky, Andreas and Militz, Holger},\n\tmonth = dec,\n\tyear = {2022},\n\tnote = {Number: 12\nPublisher: Multidisciplinary Digital Publishing Institute},\n\tkeywords = {light microscopy, impregnation, anatomy, uptake, Gmelina wood, Nigerian-grown, SEM-EDX},\n\tpages = {2036},\n\tfile = {Full Text PDF:C\\:\\\\Users\\\\maicher\\\\Zotero\\\\storage\\\\68CZE5TX\\\\Olaniran et al. - 2022 - Impregnation Properties of Nigerian-Grown Gmelina .pdf:application/pdf},\n}\n\n
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\n The success of any wood treatment process and the measure of protection conferred on treated wood are determined by the uptake and penetration of the treatment chemicals, in addition to the efficacy of the chemicals used for the treatment. Hence, the level of treatability of wood species should be pre-determined prior to the wood treatment to ensure the overall protection of the treated wood. Gmelina arborea wood, due to its low durability, requires impregnation with chemicals for preservation or chemical modification to enhance its durability. However, more details are required to establish the influence of its anatomy on impregnation to recommend appropriate treatment methods. Therefore, gmelina wood samples were treated under pressure to determine the solution uptake and penetration, while anatomical studies were carried out with light microscopy, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX) measurements. Variations in stem heights, stem diameters, and samples from other tree stands were considered. The outcome of the study showed that the liquid uptake was generally low for gmelina wood among the selected stands (16–23%) and there was no significant difference in stem diameters; meanwhile, penetration was less than 4 mm in the axial direction, and very low in the lateral (radial and tangential) direction. Vessels of gmelina wood have abundant tyloses, while crystalline structures with needlelike shapes are present in a large proportion of the ray parenchyma cells, and are confirmed with SEM-EDX to be made up of calcium oxalate. The low liquid uptake and penetration in gmelina wood suggest that the impregnation of chemicals into its microstructure is next to impossible. Hence, alternative treatment methods other than those involving impregnation with chemicals should be sought to enhance its durability.\n
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