Rubber wood utilization in Nigeria has become a viable alternative because of over-exploitation of more durable species. The use of rubber wood in its native form has some disadvantages including dimensional instability, low durability and susceptibility to weathering in outdoor uses. However, it may be improved through chemical modification such as acetylation. In this study, we revealed the effectiveness of acetylation on the protection of rubber wood against weathering in terms of weight loss (WL), colour change, lignin degradation, and mechanical properties. Acetylation was carried out using two different reaction times to achieve weight percent gains (WPG) of around 7% and 10%. Understanding of the effect of acetylation and subsequent weathering on mechanical properties was enabled by analysing wood chemistry with Fourier transform infrared (FTIR) analysis and Raman spectroscopy. The mechanical tests of weathered unmodified and acetylated rubber wood revealed a decrease of tensile stiffness of the unmodified samples as a function of weathering time, while stiffness was retained for the acetylated samples. Weathered unmodified samples showed a bi-phasic stress-strain pattern with a high strain at breakage indicating a slippage of fibres under stress due to degradation of the middle lamella. This was hardly visible for acetylated samples. Thus, acetylation was shown to be effective for protecting rubber wood used in outdoor conditions.
We acknowledge Mr. Kehinde Olonisakin for his efforts of organising the procurement of rubber tree harvested during the field work in Nigeria. The kind efforts of Adrian Wick, Bachtiar Erik, Thomas Schnider, and Philippe Grönquist are well appreciated for their assistance in the workshop for sample preparation and valuable discussions in the course of this study.
Author contributions: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.
Research funding: S.O. Olaniran acknowledges the Swiss Government Excellence Scholarship through the Federal Commission for Scholarships for Foreign Students for the financial support provided for this doctoral study (Grant Number: 2015.0612).
Employment or leadership: None declared.
Honorarium: None declared.
Ashton, H.E. (1973) The swelling of wood in polar organic solvents. Wood Sci. 6:159–166.Search in Google Scholar
Chai, Y., Liu, J., Wang, Z., Zhao, Y. (2016) Dimensional stability and mechanical properties of plantation poplar wood esterified using acetic anhydride. BioResources 12:912–922.10.15376/biores.12.1.912-922Search in Google Scholar
Chauhan, S., Aggarwal, P., Karmarkar, A., Pandey, K. (2001) Moisture adsorption behaviour of esterified rubber wood (Hevea brasiliensis). Holz Roh Werkst. 59:250–253.10.1007/s001070000152Search in Google Scholar
Colom, X., Carrillo, F., Nogués, F., Garriga, P. (2003) Structural analysis of photodegraded wood by means of FTIR spectroscopy. Polym. Degrad. Stab. 80:543–549.10.1016/S0141-3910(03)00051-XSearch in Google Scholar
Coutand, C., Jeronimidis, G., Chanson, B., Loup, C. (2004) Comparison of mechanical properties of tension and opposite wood in Populus. Wood Sci. Technol. 38:11–24.10.1007/s00226-003-0194-4Search in Google Scholar
Devi, R.R., Ali, I., Maji, T. (2003) Chemical modification of rubber wood with styrene in combination with a crosslinker: effect on dimensional stability and strength property. Bioresour. Technol. 88:185–188.10.1016/S0960-8524(03)00003-8Search in Google Scholar
Dreher, W. (1964) Mechanical properties of acetylated wood. For. Prod. J. 14:66–68.Search in Google Scholar
EN 927-6 (2006) Paints and varnishes – coating materials and coating systems for exterior wood – Part 6: Exposure of wood coatings to artificial weathering using fluorescent UV lamps and water, 2006. CEN (European Committee for Standardization) Brussels.Search in Google Scholar
Feist, W.C., Hon, D.N.-S. (1984) Chemistry of weathering and protection. In: The Chemistry of Solid Wood. Ed. Rowell, R. American Chemical Society, Washington, DC. pp. 401–451.10.1021/ba-1984-0207.ch011Search in Google Scholar
Feist, W.C., Rowell, R.M., Ellis, W.D. (1991) Moisture sorption and accelerated weathering of acetylated and methacrylated aspen. Wood Fiber Sci. 23:128–136.Search in Google Scholar
Freeman, M.H., Shupe, T.F., Vlosky, R.P., Barnes, H. (2003) Past, present, and future of the wood preservation industry: wood is a renewable natural resource that typically is preservative treated to ensure structural integrity in many exterior applications. For. Prod. J. 53:8–16.Search in Google Scholar
Gascón-Garrido, P., Oliver-Villanueva, J., Ibiza-Palacios, M., Militz, H., Mai, C., Adamopoulos, S. (2013) Resistance of wood modified with different technologies against Mediterranean termites (Reticulitermes spp.). Int. Biodeter. Biodegr. 82:13–16.10.1016/j.ibiod.2012.07.024Search in Google Scholar
Gierlinger, N., Goswami, L., Schmidt, M., Burgert, I., Coutand, C., Rogge, T., Schwanninger, M. (2008) In situ FT-IR microscopic study on enzymatic treatment of poplar wood cross-sections. Biomacromolecules 9:2194–2201.10.1021/bm800300bSearch in Google Scholar
Gindl, W., Keckes, J. (2004) Tensile properties of cellulose acetate butyrate composites reinforced with bacterial cellulose.Compos. Sci. Technol. 64:2407–2413.10.1016/j.compscitech.2004.05.001Search in Google Scholar
Gnanaharan, R., Dhamodaran, T. (1993) Mechanical properties of rubberwood from a 35-year-old plantation in central Kerala, India. J. Trop. For. Sci. 6:136–140.Search in Google Scholar
Hill, C.A., Hale, M.D., Ormondroyd, G.A., Kwon, J.H., Forster, S.C. (2006) Decay resistance of anhydride-modified Corsican pine sapwood exposed to the brown rot fungus Coniophora puteana. Holzforschung 60:625–629.10.1515/HF.2006.105Search in Google Scholar
Hon, N. (1989) Surface chemistry of oxidized wood. In: Cellulose and Wood Chemistry and Technology. Eds. Schuerch, C. John Wiley and Sons, New York. pp. 1401.Search in Google Scholar
Le Troedec, M., Sedan, D., Peyratout, C., Bonnet, J.P., Smith, A., Guinebretiere, R., Gloaguen, V., Krausz, P. (2008) Influence of various chemical treatments on the composition and structure of hemp fibres. Compos. Part A Appl. Sci. Manuf. 39:514–522.10.1016/j.compositesa.2007.12.001Search in Google Scholar
Lim, S., Ten Choo, K., Gan, K. The Characteristics, Properties and Uses of Plantation Timbers-Rubberwood and Acacia Mangium. Timber Technology Centre, FRIM, 2002.Search in Google Scholar
Lionetto, F., Del Sole, R., Cannoletta, D., Vasapollo, G., Maffezzoli, A. (2012) Monitoring wood degradation during weathering by cellulose crystallinity. Materials 5:1910–1922.10.3390/ma5101910Search in Google Scholar
Militz, H. (1991) The improvement of dimensional stability and durability of wood through treatment with non-catalysed acetic acid anhydride. Holz als Roh- und Werkstoff 49:147–152.10.1007/BF02607895Search in Google Scholar
Naji, H., Bakar, E., Sahri, M., Soltani, M., Hamid, H.A., Ebadi, S. (2014) Variation in mechanical properties of two rubberwood clones in relation to planting density. J. Trop. For. Sci. 25:503–512.Search in Google Scholar
Nazarpour, F., Abdullah, D.K., Abdullah, N., Motedayen, N., Zamiri, R. (2013) Biological pretreatment of rubberwood with Ceriporiopsis subvermispora for enzymatic hydrolysis and bioethanol production. Biomed Res. Int. 2013:268349.Search in Google Scholar
Nobuchi, T., Daneetha, M. (2011) Formation and anatomical characteristics of tension wood in plantation-grown Hevea brasiliensis (Willd.) Muell.-Arg. Malays. For. 74:133–142.Search in Google Scholar
Pandey, K. (1999) A study of chemical structure of soft and hardwood and wood polymers by FTIR spectroscopy. J. Appl. Polym. Sci. 71:1969–1975.10.1002/(SICI)1097-4628(19990321)71:12<1969::AID-APP6>3.0.CO;2-DSearch in Google Scholar
Papadopoulos, A.N. (2008) The effect of acetylation on bending strength of finger jointed beech wood (Fagus sylvatica L.). Eur. J. Wood Wood Prod. 66:309–310.10.1007/s00107-007-0223-3Search in Google Scholar
Papadopoulos, A.N., Hill, C.A.S. (2003) The sorption of water vapour by anhydride modified softwood. Wood Sci. Technol. 37:221–231.Search in Google Scholar
Rafidah, K.S., Hill, C., Ormondroyd, G. (2006) Dimensional stabilization of rubberwood (Hevea brasiliensis) with acetic or hexanoic anhydride. J. Trop. For. Sci. 18:261–268.Search in Google Scholar
Rowell, R.M., Dickerson, J.P. (2014) Acetylation of wood. In: Deterioration and Protection of Sustainable Biomaterials. Eds. Schultz, T. P., Goodell B., Nicholas D.D., ACS Publications, Washington, DC. pp. 301–327.10.1021/bk-2014-1158.ch018Search in Google Scholar
Rüggeberg, M., Saxe, F., Metzger, T.H., Sundberg, B., Fratzl, P., Burgert, I. (2013) Enhanced cellulose orientation analysis in complex model plant tissues. J. Struct. Biol. 183:419–428.10.1016/j.jsb.2013.07.001Search in Google Scholar PubMed
Salla, J., Pandey, K.K., Prakash, G., Mahadevan, K. (2012) Photobleaching and dimensional stability of rubber wood esterified by fatty acid chlorides. J. Wood Chem. Technol. 32:121–136.10.1080/02773813.2011.624665Search in Google Scholar
Sandberg, D., Söderström, O. (2006) Crack formation due to weathering of radial and tangential sections of pine and spruce. Wood Mater. Sci. Eng. 1:12–20.10.1080/17480270600644407Search in Google Scholar
Schwanninger, M., Rodrigues, J.C., Pereira, H., Hinterstoisser, B. (2004) Effect of short-time vibratory ball milling on the shape of FTIR spectra of wood and cellulose. Vib. Spectrosc. 36:23–40.10.1016/j.vibspec.2004.02.003Search in Google Scholar
Severo, E.T.D., Calonego, F.W., Sansígolo, C.A., Bond, B. (2016) Changes in the chemical composition and decay resistance of thermally-modified Hevea brasiliensis wood. PLoS One 11:e0151353.10.1371/journal.pone.0151353Search in Google Scholar PubMed PubMed Central
Simatupang, M.H., Schmitt, U., Kasim, A. (1994) Wood extractives of rubberwood (Hevea brasiliensis) and their influences on the setting of the inorganic binder in gypsum-bonded particleboards. J. Trop. For. Sci. 6:269–285.Search in Google Scholar
Teoh, Y.P., Don, M.M., Ujang, S. (2011) Assessment of the properties, utilization, and preservation of rubberwood (Hevea brasiliensis): a case study in Malaysia. J. Wood Sci. 57:255–266.10.1007/s10086-011-1173-2Search in Google Scholar
Thygesen, L.G., Engelund, E.T., Hoffmeyer, P. (2010) Water sorption in wood and modified wood at high values of relative humidity. Part I: results for untreated, acetylated, and furfurylated Norway spruce. Holzforschung 64:315–323.10.1515/hf.2010.044Search in Google Scholar
Tserki, V., Zafeiropoulos, N., Simon, F., Panayiotou, C. (2005) A study of the effect of acetylation and propionylation surface treatments on natural fibres. Compos. Part A Appl. Sci. Manuf. 36:1110–1118.10.1016/j.compositesa.2005.01.004Search in Google Scholar
Wang, C.L., Lin, T.S., Li, M.H. (2002) Decay and termites resistance of planted tree sapwood modified by acetylation. Taiwan J. For. Sci. 17:483–490.Search in Google Scholar
Weber, J., Montes, C.S. (2005) Variation and correlations among stem growth and wood traits of Calycophyllum spruceanum Benth. from the Peruvian Amazon. Silvae Genet 54:31–41.10.1515/sg-2005-0005Search in Google Scholar
Winandy, J., Rowell, R. (1984) The chemistry of wood strength. In: The Chemistry of Solid Wood. Advances in Chemistry, American Chemical Society, Washington, DC.10.1021/ba-1984-0207.ch005Search in Google Scholar
Xie, Y., Fu, Q., Wang, Q., Xiao, Z., Militz, H. (2013) Effects of chemical modification on the mechanical properties of wood. Eur. J. Wood Wood Prod. 71:401–416.10.1007/s00107-013-0693-4Search in Google Scholar
Zhou, C., Chui, Y.-H., Gong, M. (2012) Within-stem variation in wood properties of red pine (Pinus resinosa Ait.). Wood Fiber Sci. 44:412–421.Search in Google Scholar
The online version of this article offers supplementary material (https://doi.org/10.1515/hf-2018-0274).
©2019 Walter de Gruyter GmbH, Berlin/Boston