- Email: [email protected]
Biostability of Wood in the Presence of Boron-Nitrogen Compounds
Available online at www.sciencedirect.com
ScienceDirect Procedia Engineering 91 (2014) 358 – 361
XXIII R-S-P seminar, Theoretical Foundation of Civil Engineering (23RSP) (TFoCE 2014)
Biostability of Wood in the Presence of Boron-Nitrogen Compounds Irina V. Stepinaa*, Olga A. Klyachenkovaa a
Moscow State University of Civil Engineering (MGSU), 129337, Yaroslavskoe sh., 26, Moscow, Russia
Abstract We have developed new compositions based on tetravalent boron-nitrogen compounds (amine borates), which are able to increase the bio-resistance and flame-retardancy of wood at the surface modification. Previously, it was shown that the obtained amine borate formed hydrolytic stable compositions with lignin and carbohydrates, which are the basis wood. So we can expect a longterm protective effect caused by the developed compositions. The full-scale tests conducted on bars in stand mycological site of MNIIS Dame Bay (Tropical Research Centre, Far East branch office, Nha Trang, Vietnam). Test samples were subjected to a pine wood size 50x50x10 mm, impregnated under standard conditions of boron-nitrogen compounds, as well as control samples of pine wood of the same size. The tests lasted 36 months, inspections were carried out every three months. According to the significant prepared by Tropical Research Centre laboratory changes in the state of modified pine wood samples for three testing years did not happen. Samples impregnated boron-nitrogen compounds, did not change its colour. Fouling fungi were observed. Control samples of the same unmodified wood completely overgrown by fungi. © 2014 2014The TheAuthors. Authors. Published by Elsevier Ltd. is an open access article under the CC BY-NC-ND license © Published by Elsevier Ltd. This Peer-review under responsibility of organizing committee of the XXIII R-S-P seminar, Theoretical Foundation of Civil (http://creativecommons.org/licenses/by-nc-nd/3.0/). Engineeringunder (23RSP). Peer-review responsibility of organizing committee of the XXIII R-S-P seminar, Theoretical Foundation of Civil Engineering (23RSP) Keywords: biological stability; biocorrosion; bacteria; fungi; boron-nitrogen compounds; fungal resistance; sporulation; mycelium.
1. Introduction It is known that the strength and durability of buildings and structures made of wood is primarily determined by its biological persistence. As the studies performed by American scientists [1] show, the destruction of wood materials and structures is by 50-70% a result of the action of micro-organisms. Under unfavourable maintenance conditions (exposure to water, poor ventilation, high humidity and temperature), the wood is quickly affected by microbes and fungi. The biological degradation of wood starts on the surface and quickly spreads inside the wood. As a result, the wooden structures may become unfit for use already after several years of maintenance, so bio-corrosion of wood causes considerable material damage [2].
* Corresponding author. Tel.: +79263407288; fax: +74991834438. E-mail address: [email protected].
1877-7058 © 2014 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/3.0/). Peer-review under responsibility of organizing committee of the XXIII R-S-P seminar, Theoretical Foundation of Civil Engineering (23RSP) doi:10.1016/j.proeng.2014.12.074
Irina V. Stepina and Olga A. Klyachenkova / Procedia Engineering 91 (2014) 358 – 361
359
A special role in the process corrosion of wood construction materials play fungi which easily adapt to the environment, have high mutability to produce new forms. With the growth of fungi hyphae (filiformations) are formed which absorb the water and the nutrients from the wood and give off the metabolic products. All this, accumulated, causes a corrosive destruction of wooden materials [3]. The wood warps, gets gray or brown color, is covered with cracks, so the strength becomes lower and the water absorption increases, which contributes to the following fungus affection [4]. In accordance with the rate of development of bio-degradation, the wood corrosion is subdivided into the following types: a rapid (acute) one and a slow (chronic) one. First the fungi infect the wooden structures contacting the water or the soil (ground and underground foundations structures, pillars, lower crowns of wooden houses, etc.), [5]. The bio-corrosion of wood is rather slow, if the wood contacts the atmosphere (house walls, roofs, decks, floors, etc.). With a proper maintenance process and no design mistakes, the biological damage is accumulated very slowly and the wooden structures maintain their performance characteristics as well as their appearance for decades [6, 7]. To protect the wood from bio-corrosion mostly the coating and impregnation are used which have combined action (antiseptics-and-flame retardants). It is known that boron compounds, and compositions based on them have combined protective properties [8]. 2. Results and discussion We have developed new compositions based on tetravalent boron-nitrogen compounds (amine borates), which are able to increase the bio-resistance and flame-retardancy of wood at the surface modification. Previously, it was shown that the obtained amine borate formed hydrolytic stable compositions with lignin and carbohydrates, which are the basis wood [9, 10]. So we can expect a long-term protective effect caused by the developed compositions. To study the bio-resistance the pine wood samples were modified through the immersion (for 3 hours) into the aqueous solution (10%, 30% and 50%) of mono- and diethanolamine (NĺB) borates (compositions 1 and 2, respectively). After their drying to the constant mass value, the samples surface (in accordance with GOST 9.048) was infected with thesuspension with the fungi spores (concentration of 1-2 million / ml fungi spores Aspergillus niger van Tieghem, Aspergillus terreus Thom, Aureobasidium pullulans (de Bary) Arnaud, Paecilomyces varioti Bainier, Penicillium funiculosum Thom, Penicillium ochro-chloron Biourge, Scopulariopsis brevicaulis Bainier, Trichoderma viride Pers. Ex Fr.) In addition to that the wood-destroying fungi spores Serpula lacrimans ȼɄɆ F-465 and Antrodia sinuosa ȼɄɆ F-1741 were introduced into the suspension. Unmodified wood samples were used as control ones. The infected samples were placed onto an open Petri dish and kept in a desiccator under conditions optimal for growth of mycelia (at the temperature 27-28 ° C and 98% RH) for 28 days. The stage of development of fungi on the wood surface was evaluated according with GOST 9.048-89. The six-point scale was used: - "0" score – the samples are clean, no germinated conidia or development of colonies were found visually and under a microscope; - "1" score – the samples are visibly clean (small foci of mycelium in separate spots are visible only under a microscope,), no sporulation was found; - "2" score - superficial mycelium development in numerous spots was found, no sporulation; - "3" score - abundant mycelial growth on the surface of the sample and the beginning of sporulation were; - "4" score - visual inspection clearly detects the continuous mycelial growth and sporulation; - "5" score - deep mycelium defeat the entire sample area with heavy sporulation were detected. Bio-resistance evaluation results are shown in Table 1. The presented data show that the surface of unmodified wood samples were covered with fungi for 80-85 %, rapid development of all kinds of test cultures and sporulation of fungi was detected. On the surface of wood samples modified with 10% aqueous solutions 1 and 2, abundant mycelial growth of mould and wood-destroying fungi was detected, the stage of fungi development was estimated at 3 points (according with GOST 9.048-89). The surface of wood samples modified with 30% aqueous solutions of modifiers demonstrated better fungal resistance, they were estimated at 3 points 2 points. Modification of wood with 50% aqueous solutions 1 and 2 provided 100% bio-resistance against mold and wood-destroying fungi. Environmental testing was performed in a heat-and-moisture chamber G-4 according with GOST 9.308-85 (method 6) and GOST 9.054-75 (method 1). The results of the test showed that due to properties such as weather resistance and
360
Irina V. Stepina and Olga A. Klyachenkova / Procedia Engineering 91 (2014) 358 – 361
fungal resistance, durability of the protective action of developed compositions made up for 10 % solutions of compounds 1 and 2 - 5 years for 30 % beam to 10 years for the 50% at least 20 years. Table 1. The results of evaluation of bio-resistance of wood. Concentration compositions %
Cipher sample
Appearance after test
Score
Bio stability %
composition 1 1-1 10
1-2
mycelial growth on the wood surface
1-3 1-1 30
1-2
mycelial growth on the wood surface
1-3 1-1 50
1-2
visually and microscopically pure
1-3
3
50
3
50
3
50
2
70
2
70
2
70
0
100
0
100
0
100
3
50
3
50
composition 2 2-1 10
2-2
mycelial growth on the wood surface
2-3 2-1 30
2-2
mycelial growth on the wood surface
2-3 2-1 50
2-2
visually and microscopically pure
2-3 control
3
50
2
70
2
70
2
70
0
100
0
100
0
100
Ʉ-1
80-85% of the surface
5
0
Ʉ-2
is overgrown fungi
5
0
5
0
Ʉ-3
3. The conclusions Thus, the most effective means of modification of wood are 50% aqueous solutions of compositions 1 and 2, which provide 100% bio-resistance of the modified samples for at least 20 years. The obtained results were confirmed by full-scale tests conducted on bars in stand mycological site of MNIIS Dame Bay (Tropical Research Centre, Far East branch office, Nha Trang, Vietnam. Test samples were subjected to a pine wood size 50x50x10 mm, impregnated under standard conditions compositions 1 and 2, the concentration of 50% by weight, as well as control samples of pine wood of the same size. The tests lasted 36 months, inspections were carried out every three months. According to the significant prepared by Tropical Research Centre laboratory changes in the state of modified pine wood samples for three testing years did not happen. Samples impregnated composition 1, slightly darkened, and the samples impregnated composition 2, did not change its color. Fouling fungi were observed. Control samples of the same unmodified wood completely overgrown by fungi. Thus, the efficiency of the developed fire-resistance formulations in terms of improving the biological stability of wood by modifying its surface boronnitrogen compounds has been proven in practice.
Irina V. Stepina and Olga A. Klyachenkova / Procedia Engineering 91 (2014) 358 – 361
361
4. Summary To study the bio-resistance the pine wood samples were modified through the immersion (for 3 hours) into the aqueous solution (10%, 30% and 50%) of mono and diethanolamine (NĺB) borates (compositions 1 and 2, respectively). After their drying to the constant mass value, the samples surface was infected with the suspension with the fungi spores (concentration of 1-2 million / ml fungi spores. The most effective means of modification of wood are 50% aqueous solutions of compositions 1 and 2, which provide 100% bio-resistance of the modified samples for at least 20 years. References [1]. Shupe, T.S.; Lebow, S.T.; Ring, D. Causes and control of wood decay, degradation and stain. Res. & Ext. Pub. No. 2703. Zachary, LA: Louisiana State University Agricultural Center. 2008. 27 p. [2]. Mzhachih E.I., Sukharev L.A., Yakovlev V.V. Bio-corrosion and physico-chemical methods to improve the durability of the coating // The practice of corrosion protection. 2006. Number 1. Pp. 55-58. [3]. Pokrovskaya E.N., Kovalchuk J.L. Chemical-mycological research and improving the environment inside buildings // Herald MGSU. 2012. Number 8. Pp. 181-188. [4]. Lugauskas A., Yaskelyavichyus B. Mycological condition of premises Bilnyusa // Mycology and Phytopathology. 2009. T. 43. Number 3. Pp. 207-215. [5]. Dashko R.E., Kotyukov P.V. Study bioagressivnosti underground environment of St. Petersburg in relation to construction materials transport tunnels and foundations // Notes Mining Institute. 2007. T. 172. Pp. 217-220. [6]. Kukoleva D.A., Akhmetshin A.S., Stroganov I.V., Stroganov V.F. Biodamage polymer composite building materials // Proceedings of the Kazan State Architectural University. 2009. Number 2 (12). Pp. 257-262. [7]. Lebow, S.T. Wood preservation. In: Wood handbook: wood as an engineering material. Gen. Tech. Rep. FPL–GTR–190. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. 2010. Chapter 15. [8]. Lebow, S., Lebow, P.; Halverson, S. Penetration of boron from topically applied borate solutions. Forest Products Journal. 2010. 60(1): 13–22. [9]. Kotljarova I.A., Koteneva I.V., Sidorov V. I. Modification of cellulose by monoethanolamine (N ĺ B)borat // Chemical industry today, 2011, ʋ 12, p.26-30. [10]. Koteneva IV, VI Sidorov, IA Kotliarov Analysis of modified cellulose by infrared spectroscopy // Chemistry of plant raw materials in 2011. Number 1, p. 21-24.
ScienceDirect Procedia Engineering 91 (2014) 358 – 361
XXIII R-S-P seminar, Theoretical Foundation of Civil Engineering (23RSP) (TFoCE 2014)
Biostability of Wood in the Presence of Boron-Nitrogen Compounds Irina V. Stepinaa*, Olga A. Klyachenkovaa a
Moscow State University of Civil Engineering (MGSU), 129337, Yaroslavskoe sh., 26, Moscow, Russia
Abstract We have developed new compositions based on tetravalent boron-nitrogen compounds (amine borates), which are able to increase the bio-resistance and flame-retardancy of wood at the surface modification. Previously, it was shown that the obtained amine borate formed hydrolytic stable compositions with lignin and carbohydrates, which are the basis wood. So we can expect a longterm protective effect caused by the developed compositions. The full-scale tests conducted on bars in stand mycological site of MNIIS Dame Bay (Tropical Research Centre, Far East branch office, Nha Trang, Vietnam). Test samples were subjected to a pine wood size 50x50x10 mm, impregnated under standard conditions of boron-nitrogen compounds, as well as control samples of pine wood of the same size. The tests lasted 36 months, inspections were carried out every three months. According to the significant prepared by Tropical Research Centre laboratory changes in the state of modified pine wood samples for three testing years did not happen. Samples impregnated boron-nitrogen compounds, did not change its colour. Fouling fungi were observed. Control samples of the same unmodified wood completely overgrown by fungi. © 2014 2014The TheAuthors. Authors. Published by Elsevier Ltd. is an open access article under the CC BY-NC-ND license © Published by Elsevier Ltd. This Peer-review under responsibility of organizing committee of the XXIII R-S-P seminar, Theoretical Foundation of Civil (http://creativecommons.org/licenses/by-nc-nd/3.0/). Engineeringunder (23RSP). Peer-review responsibility of organizing committee of the XXIII R-S-P seminar, Theoretical Foundation of Civil Engineering (23RSP) Keywords: biological stability; biocorrosion; bacteria; fungi; boron-nitrogen compounds; fungal resistance; sporulation; mycelium.
1. Introduction It is known that the strength and durability of buildings and structures made of wood is primarily determined by its biological persistence. As the studies performed by American scientists [1] show, the destruction of wood materials and structures is by 50-70% a result of the action of micro-organisms. Under unfavourable maintenance conditions (exposure to water, poor ventilation, high humidity and temperature), the wood is quickly affected by microbes and fungi. The biological degradation of wood starts on the surface and quickly spreads inside the wood. As a result, the wooden structures may become unfit for use already after several years of maintenance, so bio-corrosion of wood causes considerable material damage [2].
* Corresponding author. Tel.: +79263407288; fax: +74991834438. E-mail address: [email protected].
1877-7058 © 2014 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/3.0/). Peer-review under responsibility of organizing committee of the XXIII R-S-P seminar, Theoretical Foundation of Civil Engineering (23RSP) doi:10.1016/j.proeng.2014.12.074
Irina V. Stepina and Olga A. Klyachenkova / Procedia Engineering 91 (2014) 358 – 361
359
A special role in the process corrosion of wood construction materials play fungi which easily adapt to the environment, have high mutability to produce new forms. With the growth of fungi hyphae (filiformations) are formed which absorb the water and the nutrients from the wood and give off the metabolic products. All this, accumulated, causes a corrosive destruction of wooden materials [3]. The wood warps, gets gray or brown color, is covered with cracks, so the strength becomes lower and the water absorption increases, which contributes to the following fungus affection [4]. In accordance with the rate of development of bio-degradation, the wood corrosion is subdivided into the following types: a rapid (acute) one and a slow (chronic) one. First the fungi infect the wooden structures contacting the water or the soil (ground and underground foundations structures, pillars, lower crowns of wooden houses, etc.), [5]. The bio-corrosion of wood is rather slow, if the wood contacts the atmosphere (house walls, roofs, decks, floors, etc.). With a proper maintenance process and no design mistakes, the biological damage is accumulated very slowly and the wooden structures maintain their performance characteristics as well as their appearance for decades [6, 7]. To protect the wood from bio-corrosion mostly the coating and impregnation are used which have combined action (antiseptics-and-flame retardants). It is known that boron compounds, and compositions based on them have combined protective properties [8]. 2. Results and discussion We have developed new compositions based on tetravalent boron-nitrogen compounds (amine borates), which are able to increase the bio-resistance and flame-retardancy of wood at the surface modification. Previously, it was shown that the obtained amine borate formed hydrolytic stable compositions with lignin and carbohydrates, which are the basis wood [9, 10]. So we can expect a long-term protective effect caused by the developed compositions. To study the bio-resistance the pine wood samples were modified through the immersion (for 3 hours) into the aqueous solution (10%, 30% and 50%) of mono- and diethanolamine (NĺB) borates (compositions 1 and 2, respectively). After their drying to the constant mass value, the samples surface (in accordance with GOST 9.048) was infected with thesuspension with the fungi spores (concentration of 1-2 million / ml fungi spores Aspergillus niger van Tieghem, Aspergillus terreus Thom, Aureobasidium pullulans (de Bary) Arnaud, Paecilomyces varioti Bainier, Penicillium funiculosum Thom, Penicillium ochro-chloron Biourge, Scopulariopsis brevicaulis Bainier, Trichoderma viride Pers. Ex Fr.) In addition to that the wood-destroying fungi spores Serpula lacrimans ȼɄɆ F-465 and Antrodia sinuosa ȼɄɆ F-1741 were introduced into the suspension. Unmodified wood samples were used as control ones. The infected samples were placed onto an open Petri dish and kept in a desiccator under conditions optimal for growth of mycelia (at the temperature 27-28 ° C and 98% RH) for 28 days. The stage of development of fungi on the wood surface was evaluated according with GOST 9.048-89. The six-point scale was used: - "0" score – the samples are clean, no germinated conidia or development of colonies were found visually and under a microscope; - "1" score – the samples are visibly clean (small foci of mycelium in separate spots are visible only under a microscope,), no sporulation was found; - "2" score - superficial mycelium development in numerous spots was found, no sporulation; - "3" score - abundant mycelial growth on the surface of the sample and the beginning of sporulation were; - "4" score - visual inspection clearly detects the continuous mycelial growth and sporulation; - "5" score - deep mycelium defeat the entire sample area with heavy sporulation were detected. Bio-resistance evaluation results are shown in Table 1. The presented data show that the surface of unmodified wood samples were covered with fungi for 80-85 %, rapid development of all kinds of test cultures and sporulation of fungi was detected. On the surface of wood samples modified with 10% aqueous solutions 1 and 2, abundant mycelial growth of mould and wood-destroying fungi was detected, the stage of fungi development was estimated at 3 points (according with GOST 9.048-89). The surface of wood samples modified with 30% aqueous solutions of modifiers demonstrated better fungal resistance, they were estimated at 3 points 2 points. Modification of wood with 50% aqueous solutions 1 and 2 provided 100% bio-resistance against mold and wood-destroying fungi. Environmental testing was performed in a heat-and-moisture chamber G-4 according with GOST 9.308-85 (method 6) and GOST 9.054-75 (method 1). The results of the test showed that due to properties such as weather resistance and
360
Irina V. Stepina and Olga A. Klyachenkova / Procedia Engineering 91 (2014) 358 – 361
fungal resistance, durability of the protective action of developed compositions made up for 10 % solutions of compounds 1 and 2 - 5 years for 30 % beam to 10 years for the 50% at least 20 years. Table 1. The results of evaluation of bio-resistance of wood. Concentration compositions %
Cipher sample
Appearance after test
Score
Bio stability %
composition 1 1-1 10
1-2
mycelial growth on the wood surface
1-3 1-1 30
1-2
mycelial growth on the wood surface
1-3 1-1 50
1-2
visually and microscopically pure
1-3
3
50
3
50
3
50
2
70
2
70
2
70
0
100
0
100
0
100
3
50
3
50
composition 2 2-1 10
2-2
mycelial growth on the wood surface
2-3 2-1 30
2-2
mycelial growth on the wood surface
2-3 2-1 50
2-2
visually and microscopically pure
2-3 control
3
50
2
70
2
70
2
70
0
100
0
100
0
100
Ʉ-1
80-85% of the surface
5
0
Ʉ-2
is overgrown fungi
5
0
5
0
Ʉ-3
3. The conclusions Thus, the most effective means of modification of wood are 50% aqueous solutions of compositions 1 and 2, which provide 100% bio-resistance of the modified samples for at least 20 years. The obtained results were confirmed by full-scale tests conducted on bars in stand mycological site of MNIIS Dame Bay (Tropical Research Centre, Far East branch office, Nha Trang, Vietnam. Test samples were subjected to a pine wood size 50x50x10 mm, impregnated under standard conditions compositions 1 and 2, the concentration of 50% by weight, as well as control samples of pine wood of the same size. The tests lasted 36 months, inspections were carried out every three months. According to the significant prepared by Tropical Research Centre laboratory changes in the state of modified pine wood samples for three testing years did not happen. Samples impregnated composition 1, slightly darkened, and the samples impregnated composition 2, did not change its color. Fouling fungi were observed. Control samples of the same unmodified wood completely overgrown by fungi. Thus, the efficiency of the developed fire-resistance formulations in terms of improving the biological stability of wood by modifying its surface boronnitrogen compounds has been proven in practice.
Irina V. Stepina and Olga A. Klyachenkova / Procedia Engineering 91 (2014) 358 – 361
361
4. Summary To study the bio-resistance the pine wood samples were modified through the immersion (for 3 hours) into the aqueous solution (10%, 30% and 50%) of mono and diethanolamine (NĺB) borates (compositions 1 and 2, respectively). After their drying to the constant mass value, the samples surface was infected with the suspension with the fungi spores (concentration of 1-2 million / ml fungi spores. The most effective means of modification of wood are 50% aqueous solutions of compositions 1 and 2, which provide 100% bio-resistance of the modified samples for at least 20 years. References [1]. Shupe, T.S.; Lebow, S.T.; Ring, D. Causes and control of wood decay, degradation and stain. Res. & Ext. Pub. No. 2703. Zachary, LA: Louisiana State University Agricultural Center. 2008. 27 p. [2]. Mzhachih E.I., Sukharev L.A., Yakovlev V.V. Bio-corrosion and physico-chemical methods to improve the durability of the coating // The practice of corrosion protection. 2006. Number 1. Pp. 55-58. [3]. Pokrovskaya E.N., Kovalchuk J.L. Chemical-mycological research and improving the environment inside buildings // Herald MGSU. 2012. Number 8. Pp. 181-188. [4]. Lugauskas A., Yaskelyavichyus B. Mycological condition of premises Bilnyusa // Mycology and Phytopathology. 2009. T. 43. Number 3. Pp. 207-215. [5]. Dashko R.E., Kotyukov P.V. Study bioagressivnosti underground environment of St. Petersburg in relation to construction materials transport tunnels and foundations // Notes Mining Institute. 2007. T. 172. Pp. 217-220. [6]. Kukoleva D.A., Akhmetshin A.S., Stroganov I.V., Stroganov V.F. Biodamage polymer composite building materials // Proceedings of the Kazan State Architectural University. 2009. Number 2 (12). Pp. 257-262. [7]. Lebow, S.T. Wood preservation. In: Wood handbook: wood as an engineering material. Gen. Tech. Rep. FPL–GTR–190. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. 2010. Chapter 15. [8]. Lebow, S., Lebow, P.; Halverson, S. Penetration of boron from topically applied borate solutions. Forest Products Journal. 2010. 60(1): 13–22. [9]. Kotljarova I.A., Koteneva I.V., Sidorov V. I. Modification of cellulose by monoethanolamine (N ĺ B)borat // Chemical industry today, 2011, ʋ 12, p.26-30. [10]. Koteneva IV, VI Sidorov, IA Kotliarov Analysis of modified cellulose by infrared spectroscopy // Chemistry of plant raw materials in 2011. Number 1, p. 21-24.