DIAS, Kelly Bossardi 
BARREIROS, Ricardo Marques 
DIAS, Kelly Bossardi; BARREIROS, Ricardo Marques. Resistance to the Biodeterioration of the Fast Growth Woods Treated with Tall Oil and Derivatives. Multidisciplinary Scientific Journal. Edition 08. Year 02, Vol. 02. pp. 22-36, November 2017. ISSN:2448-0959
The increased concern with environmental issues, the health of operators of condoms and wood consumers, and the reuse of these treated woods after their use, has generated the need to develop less aggressive condoms treatments and the environment. The objective of this study was to test the potential of the Tall Oil in three conditions in the preservation of two species of wood of reforestation: Pinus elliottii and Eucalyptus grandis. The Tall Oil alternatives tested were Crude Tall Oil (CTO), which is a byproduct of pulp processing of softwoods for Kraft paper production, and two by-products of CTO refining, Ligth Oil (LO) and Ejector Oil (OE). The results showed that the conditions of Tall Oil have potential to protect the wood against attack of the fungus of white rot. The best results were obtained with the OE treatments, which resulted in samples with 55% hydrophobicity for the two woods, and loss of mass of 39.07% for eucalyptus and 39.18% for pine, after testing exposure to the rotting fungus.
Key words: Condom for Wood, Tall Oil, Biodeterioration.
For environmental reasons, both the preservation of traditional wood and the use of resistant wood species are subject to political and consumption restrictions. It is known that the effectiveness of traditional wood preservation systems is due to the biocidal effect of the products used, but, consequently, they pollute the environment. In addition to the risks involved in the use of such materials, there is a growing concern with the problems arising from the disposal of wood at the end of its commercial life (KOSKI, 2008). Thus, there is a growing need to develop effective antifungal chemicals that are non-toxic to humans and the environment.
The search for alternatives to current condoms has been efficient, but not effective, that is, a viable alternative to existing products has not yet been found. Based on several studies, the demand for a preservative for wood can be divided:
- The extracts of plants with natural resistance to biodeterioration: essential oils of aromatic plants (SBEGHEN, 2001; CELOTO et al., 2008), extractives of poisonous plants (GOKTAS et al., 2008), oils extracted from seeds and grains (GONZAGA And the extractives of the wood itself as the tannin (HASHIM et al., 2009, JAIN et al., 2007). Bocelli et al., 2002), and the resins (Bultman et al. (1991), Bultman et al. (1993) and Nakayama et al. (2001).
- By-products of processes: Chitosan – Byproduct of crustacean processing industries such as shrimp, crab and lobster (MAOZ; MORREL, 2004; EIKENES et al., 2005; TORRE et al., 2006; SREH et al., 2008; TREU et al. (1989), and Ahn et al. (2008), which is based on the production of soybean meal and tofu. (2003), Crude Tall Oil (CTO) and its derivatives – Kraft pulp by-product (JEMER et al., 1993, PAAJANEN and RITSCHKOFF, 2002, ALFREDSEN et al., 2004, VÄHÄOJA et al., 2005; HYVÖNEN et al. In the present study, the results obtained in this study are similar to those reported in the literature.
The extraction of plants with natural resistance to biodeterioration adds cost to the product, as there is a need for reforestation areas and a process of extraction and processing.
Focusing on the relation Cost x Benefit x Environment, was established the most viable alternative to develop a condom that contemplates great part of the desirable properties, and that is effective in the protection of the pine woods and Eucalyptus. And among the byproduct alternative processes Tall Oil was chosen for this investigation as we are located in a region of Kraft paper and pulp industries. In addition, in the evaluation of the properties of various oils, resins and waxes, no single component can satisfy all the requirements for protection against bio-deterioration and the surface coatings or impregnants used for the treatment of wood must therefore be made from a blend of oils, resins and waxes. According to Temiz et al. (2008) and Koski et al. (2008), unlike other natural oils, Tall Oil already contains all the necessary components for good protection: oils, resins and waxes.
The use of Tall Oil as a protective agent in wood has been considered promising because it significantly reduces sapwood capillary water absorption, removing one of the factors favoring wood being attacked by fungi and insects: water, oxygen and nutrients (HYVÖNEN et al. ., 2006). This is due to its precursors, which are extracts mainly found in coniferous trees (KOSKI, 2008; TEMIZ et al., 2008).
Investigations with Tall Oil indicate their potential as a protective agent for wood. Jermer et al. (1993), Paajanen and Ritschkoff (2002), Alfredsen et al. (2004), Vähäoja et al., 2005, Hyvönen et al. (2006), Temiz et al. (2008), Koski (2008), Anita et al. (2014), Durmaz et al. (2015) and Sivrikaya and Can (2016) focused their studies on developing alternatives to current preservatives using Tall Oil. In general, they indicate that the preventive effect of Tall Oil is probably related to the hydrophobic properties.
Jermer et al. (1993) tested the effect of Tall Oil derivatives against biological degradation, and compared them with preservatives in current use, such as CCA and creosote. They obtained results showing that the two derivatives of Tall Oil can be almost as effective as CCA and creosote.
Paajanen and Ritschkoff (2002) showed that the crude Tall Oil applied on varnish samples did not produce a zone of inhibition on the growth medium, thus the inhibitory effect of Tall Oil is not caused by fungal toxicity. Most likely, the preventive effect is related to hydrophobicity. Based on the effectiveness of Tall Oil products, be mainly due to hydrophobicity, the idea is that by reducing the moisture content of the wood, fungal growth is limited.
Alfredsen et al. (2004) tested the efficacy of four Tall Oil derivatives in growth rate assays of Coriolus versicolor brown rot fungus and Poria placenta brown rot fungus on filter paper and wooden mini-blocks of Pinus sylvestris L. the effectiveness of the Tall Oil tested was related to the chemical composition of the oils. This was confirmed in the filter paper assay, where the increase in efficacy was relatively proportional with increasing amounts of resin acids. However, this pattern was not found for the mini-block assay. The protective effect of Tall Oil on wood, therefore, seems to be more related to its hydrophobic properties than to its fungicidal properties.
Hyvönen et al. (2006) and Koski (2008) investigated the water-repellent efficiency of raw Tall Oil and emulsified in water. Treatments with Tall Oil reduces the water absorption of the pine sapwood. And, emulsion tall oil treatments showed that efficiency, compared to CTO, can be achieved. The emulsion technique is a potential method of decreasing the amount of oil needed to protect the wood from water absorption by capillarity.
Temiz et al. (2008) verified the potential of four commercially available Tall Oil derived products, tested separately and combined, with two concentrations of boric acid (1 and 2%) against the resistance to attack of two brown rot fungi. The results obtained showed that Tall Oil derivatives in combination with boric acid are promising as wood preservatives, since they combine fungicidal and water repellent effects. Tests of resistance to degradation indicated that only impregnation with Tall Oil, without the presence of boric acid, was not effective to protect the wood against the fungi tested. Samples with boric acid at a concentration of 2% combined with the Tall Oil derivative consisting of 90% of acids showed the best performance in relation to two brown rot fungi, with a mass loss of less than 3%.
Vähäoja et al. (2005) focused their studies on the determination of biodegradation of different products of Tall Oil and linseed oil in groundwater obtaining preliminary information about its environmental effects. They obtained promising results, showing that Tall Oil and linseed oil products are moderately biodegradable, not toxic to the assessed environment.
Anita et al. (2014) verified that the resistance to biodeterioration of the timber Jabon (Anthocephalus cadamba Miq.), Improved to the attack of fungi of white and brown rot in relation to the sample of untreated wood. Already, Durmaz et al. (2015) found the durability of Scotland's pine tree sapwood increased. Both studies used Tall Oil Crude (CTO) as a protective agent for biodeterioration.
Sivrikaya and Can (2016) found that wood treated with tall oil can provide some reduction in water absorption and increase resistance to decomposition. In this research, the CTO was dissolved in ethanol at concentrations of 5, 10 and 15% in the treatment of Scotch pine. They used dyes, iron oxide and sodium ascorbate as additives in 0.5%. The best results were obtained with 10% CTO and iron oxide.
There are several other ways to approach wood preservation without the use of toxicity as the mechanism of effectiveness. There is a very close relationship between the moisture content of wood and its biodeterioration (ROWELL, 2006). So, to avoid the attack of these organisms, some research has aimed to limit the water with the use of hydrophobic products.
In this context, Tall Oil, which is a natural renewable-source oil and exhibits hydrophobic properties, may be an alternative. Tall Oil is an industrially generated by-product of kraft pulp production. The amount of these components varies with age, wood species, geographic location, and also with all operations before and during the pulping process (KOSKI, 2008).
Crude Tall Oil (CTO) crude can be refined to various types of Tall Oil with different chemical compositions, being the main commercial products of the CTO, Tall Oil fatty acids (TOFA), Tall Oil Spirits (DOT) and Breu of Tall Oil (TOR). In addition to the commercial products already mentioned, Ejector Oil (OE) and Light Oil (LO), which do not have commercial application, are by-products of fractionation.
The objective of this study was to test the potentiality of three Tall Oil conditions in two wood species: Pinus elliottii and Eucalyptus grandis. The Tall Oil alternatives tested were Crude Tall Oil (CTO), Ligth Oil (LO) and Ejector Oil (OE). (KOSKI et al., 2008). In the present work, we have shown that the main mechanism of inhibition of CTO biodegradation organisms and their derivatives is hydrophobicity, as reported by KOSKI (2008)
MATERIAL AND METHODS
Two species of fast growing wood were sampled in this study: Pinus elliotti and Eucalyptus grandi with 18 and 8 years of age, respectively. For Pinus the samples were taken from the adult woodland. And for the Eucalyptus, the samples were taken from the sapwood. All specimens were submitted to the oven drying process at 40 ± 2 ° C until moisture content was 12%. After being conditioned in an oven at 25 ± 3 ° C. Test pieces 2.5 x 2.5 x 5.0 cm were used for the tests.
The effect of three samples of Tall Oil with variable chemical composition were tested separately and in combination with boric acid (AB) in two classes of wood – Pinus elliotti and Eucalyptus grandis. The Tall Oil samples were prepared by dissolving each of them in isopropanol.
The samples used for this study are crude oil (CTO), ejector oil (OE) and light oil (LO). The chromatographic analysis was performed with the objective of qualifying and quantifying resin and fatty acids in the samples. The characterization of CTO, LO and OE samples was performed by the product supplier industry. The equipment used for characterization was a gas chromatograph coupled to a mass spectrometer (GC-MS), HP 5890 series II mass chromatograph, equipped with an Ultra HP-5 capillary column (30 m, 0.25 mm internal diameter ). An HP 5970 mass detector was used.
The Tall Oil samples were prepared by dissolving each of them in isopropanol. The concentration of the solution was 25% (w / v), which is the ratio of the weight of the sample to the volume of solvent. E, solutions of boric acid (AB) were prepared in 2% (w / v) solution. The tested condom systems are described in Table 1. The condom treatment systems under study were applied to the specimens at room temperature, as described in Table 2. Condom systems were applied to specimens according to ASTM D1413 adapted instructions (2007).
Table 1 – Composition of condoms
|CTO||25% (w / v) in isopropanol|
|LO||25% (w / v) in isopropanol|
|OE||25% (w / v) in isopropanol|
Table 2 – Stages of application processes.
|Condom systems||Stage||Process of applying the systems in the Proof|
|1||Initial vacuum of 600 mmHg for 30 minutes.|
|2||Application of the product (CTO, LO or OE) under vacuum.|
|3||Vacuum 600 mmHg for 30 minutes with the product applied.|
|4||Samples taken out and dried in the air.|
In order to evaluate the hydrophobicity of the applied systems, measurements of the contact angle – Goniometry were performed. It is a macroscopic measure that allows the determination of the surface energy of a given material. The contact angle is a quantitative measure of the wettability of a solid by a liquid. The higher the contact angle, the lower the wettability, that is, the greater the hydrophobicity of the substrate (BURKARTER, 2010). The surfaces can be classified according to their contact angle, as shown in Table 3 (adapted BURKARTER, 2010).
Table 3 – Classification of surfaces according to the contact angle.
|Contact angle value||Type of Surface|
Because it is an anisotropic material, wood presents distinct properties in the three planes (transverse, radial and tangential). The contact angle measurements were performed in these three directions for the two wood samples analyzed. Samples of treated and untreated pine and eucalyptus were submitted to this assay. The sample was placed in the Goniometer, a drop of deionized water was then placed on the sample and the contact angle between the drop and the surface of the treated sample was measured. The analysis was performed under conditions of temperature and ambient humidity, respectively, 25 ± 2 ° C 60%.
The specimens were also submitted to rotting tests – field simulator in laboratory with rotting fungi of white rot, Trametes versicolor (L., Fr.) Pilát. White rot fungi are considered as important fungi for rotting commercial wood, as they can cause serious damage within a short period of time (TEMIZ et al., 2008).
The inoculums of the white rot fungus were previously prepared in liquid medium (malt and distilled water) and then deposited in the soil. The samples were placed in containers with soil contaminated with the rotting fungus of white rot. The soil used for this assay was collected at the Unesp Campus of Itapeva, and the fungus was inoculated into the soil without previous sterilization. Three replicates for each treatment and for each species of wood were used; and samples of untreated wood were included to measure the viability of the fungus strain. Thus, the treatments were established in the combination of the two wood species and the three condoms systems. Before being subjected to the accelerated rotting test, the specimens were oven dried at 40 ± 2 ° C until moisture of 12%. To verify if the humidity reached the desired value of 12%, every 24 hours were carried out moisture measurements with portable meter of Instrutherm model UM-626.
The incubation time in the climatic chamber was 12 weeks at 27 ± 2 ° C and 75% relative humidity. After the incubation period, the mycelium of the fungus was removed from the samples, and the specimens were oven dried at 40 ± 2 ° C until moisture of 12%. To verify if the humidity reached the desired value of 12%, every 24 hours were carried out moisture measurements with portable meter of Instrutherm model UM-626. The loss of mass of each sample, caused by fungi was calculated by Equation (1):
Loss of mass (%) = ((mo – mf) / mo) x 100
Another test was the difference in mass. Mass determination was performed to verify how much the condom systems can change the mass of the specimens of pinus and eucalyptus. The samples used to determine the mass were stored in a desiccator for 6 months to stabilize the systems in the specimens. The ambient conditions were maintained at 25 + 4 ° C temperature and 60 + 5% humidity. Afterwards, the samples were placed in a greenhouse with a temperature varying between 103º ± 2ºC until stabilization of the mass, assuming variations of mass less than 0.5%. The masses were determined by weighing the samples in analytical balance with 0.001g of precision.
RESULTS AND DISCUSSION
Figure 1 shows the result of the chromatographic analysis of the CTO, LO and OE samples. It is possible to observe that LO and CTO contain more fatty acids. The OE, however, contains equivalent amounts of fatty acids and of insoluble acids, which comprise sterols, alcohols and hydrocarbons, is higher in OE. The data obtained for the CTO were 59% of fatty acids, 34% of resin acids and 7% of insaponables, being within the limits of the literature. According to Koski (2008) and Sales (2007), the amounts of fatty acids, resin acids and insoluble acids in CTO vary, respectively, 40-60%, 30-55% and 1-10%. The composition of the by-products, LO and OE, of the CTO fractionation, have a concentrated composition in the fatty acids and unsaponable, because it is two chains composed of the lighter components of the CTO. The LO has 89% of fatty acids, 4% of resin acids and 7% of insaponables. The increase of the insoluble concentration in the OE sample, from 7% to 39%, was already expected due to the thermal degradation of fatty and resin acids during the thermal fractionation process.
The results of the Goniometric test showed that the specimens treated with the CTO, LO and OE samples improved the water repellency action. Regarding the direction of the plane (transverse, radial and tangential), the results did not present significant variations, showing that the impermeability that the preservative product offers is the same in all planes. The untreated Pinus samples had contact angle close to 0 (zero), showing to be superhydrophile; and the Eucalyptus samples, under the same conditions, showed variations of the contact angle between 23 and 26 °, showing to be hydrophilic. All samples of both pine and eucalyptus, submitted to CTO and OE treatments, showed an intermediate behavior between hydrophilicity and hydrophobicity with contact angle varying between 56 and 70 °. This result shows that the studied systems decrease hydrophilicity. Already, the samples treated with LO showed to be hydrophobic, with contact angles varying between 120 and 125 °. In combination with the chromatographic analysis, the LO sample has a higher amount of fatty acids (89%) than the CTO and OE samples, and may indicate that the high hydrophobicity must be impermeable to the film formed from the LO. The CTO samples present a higher amount of resin acids, indicating that the increase of resin acids decreases the hydrophobicity. In contrast, the almost absence of resin acids and the increase in similar proportions of insaponables and fatty acids, according to OE samples, further decrease the hydrophobicity. Therefore, the amount of fatty acids is proportional to the levels of hydrophobicity.
As for the rotting test, the test specimens were evaluated weekly to monitor the mycelial growth of the fungus. The presence of another biodegradator with green colored mycelia was observed. This is because the land has not been sterilized. White and green mycelium in eucalyptus samples; and whites in the pinus samples were observed at the 1st week of inoculation in the untreated samples and increased until the end of the assay. In the samples treated with CTO and LO, changes were observed in the 4th week; and with OE in the 5th week. For all systems no differences were observed in the treatments for the wood species. Both, eucalyptus and pinus presented similar results for the same treatment. The samples that presented the best resistance to attack of the white rot fungus were those treated with OE and consequently obtained the lowest mass loss, as shown in Table 4. All systems tested increase resistance to white rot, but with some observations:
- All condom systems showed improvement in resistance by changing the class of non-resistant (untreated samples) to moderate resistance. This slight improvement may be due to the hydrophobicity that all present, but at different levels;
- The OE systems were the ones with the lowest mass loss, showing that they may have some compound that inhibits the action of white rot fungus.
Table 4 – Classification of the mass loss of the samples submitted to the accelerated rotting test.
|PRESERVATIVE SYSTEMS||WEIGHT LOSS (%)||CLASS OF RESISTANCE (ASTM D-2017, 2005)|
|CTO||42.78||44.07||Moderate Resistance||Moderate Resistance|
|LO||40.09||40.42||Moderate Resistance||Moderate Resistance|
|OE||39.07||39.18||Moderate Resistance||Moderate Resistance|
The presence of all condom systems increased the mass of the specimens. This increase proves the fixation of the systems applied to the wood. Table 5 shows the means of the calculated values of six specimens of each sample and the percentages of increase. It is possible to observe an increase of approximately 8.3% in the samples of pine, and 4.3% in the eucalyptus samples, treated with boric acid. This difference of 4% in the increase of the mass between the species can be due to the lower characteristic density of the pinus, indicating greater permeability.
In the specimens treated with CTO, LO and OE, smaller increases were observed than those observed with boric acid alone, but they maintained the same increase behavior as the wood species. This increase, for systems with Tall Oil, may be due to the condom systems being retained in the wood. However, for the systems with LO, which presented the greatest increase, it may indicate that the condoms formed the rancid layer and did not penetrate the specimens. And, for OE and CTO systems it may be due to the total penetration of the systems into the specimens.
Therefore, it is possible to conclude that the specimens submitted to CTO and OE treatments obtained an increase in mass due to the penetration of these condoms into the sampled wood.
Table 5: Mass of the specimens of Pinus elliottii. and Eucalyptus grandis.
|wood||Treatment system||Mass (g)||Increase in mass (%)|
Alternative treatments with Tall Oil improved the resistance of reforestation woods, but not at the same intensity as the traditional treatment with boric acid.
Greater resistance to white rot was observed for the ejector oil treatment, for which a more effective penetration of the condom was also observed in the wood.
The results suggested that the effects of condoms are related both to their penetration rate in wood and to the presence of toxic components.
The sample that presented more satisfactory results for potential use as a preservative for wood was Ejector Oil, a byproduct of CTO fractionation.
AHN, S. H .; OH, S.C .; CHOI, I .; HAN, G .; JEONG, H .; KIM, K .; YOON, Y .; YANG, I. Environmentally friendly wood preservatives formulated with enzymatic-hydrolyzed okara, copper and / or boron salts. Journal of Hazardous Materials, v. 178, p. 604-611, 2010.
AHN, S. H .; OH, S.C .; CHOI, I .; KIM, K .; YANG, I. Efficacy of wood preservatives formulated from okara with copper and / or boron salts. Journal Wood Science, v. 54, p. 495-501, 2008.
ALFREDSEN, G .; FLAETE, P. O .; TEMIZ, A .; EIKENES, M .; MILITZ, H. Screening of the efficacy of tall oils against Wood decaying fungi. The international research group on wood preservation. IRG / WP 04-30354, 2004.
ANITA, S. H .; FATRIASARI, W .; ZULFIANA, D. Utilization of biopulping black liquor as preservative to fungal attack on jabon wood (Anthocephalus cadamba Miq.). Teknologi Indonesia, n.37, v.3, p. 147-153, 2014.
AMERICAN SOCIETY FOR TESTING AND MATERIALS (ASTM). ASTM D1413: Standard method for accelerated laboratory test of natural decay resistance for woods. West Conshohocken: ASTM International, 2007.
BROCCO, V. F .; PAES, J.B .; COSTA, L. G. da; BRAZOLIN, S .; ARANTES, D. C. Potential of teak heartwood extracts as a natural wood preservative. Journal of Cleaner Production, v. 142, Part 4, p. 2093-2099, 2017.
BULTMAN, J.D .; GILBERTSON, R. L .; ADASKAVEG, J .; AMBURGEY, T. L .; PARIKH, S. V .; BAILEY, C.A. The efficacy of guayule resin as a pesticide. Bioresource Technology, n. 35, p. 197-201, 1991.
BULTMAN, J.D .; SCHLOMAN, W. W. The leachability of guayule resin from treated wood. Industrial Crops and Products, n. 2, p. 33-37, 1993.
BURKARTES, E. Development of superhydrophobic surfaces of polytetrafluoroethylene. 2010 138 f. Thesis (Doctorate in Physics) – Sector of Exact Sciences, Federal University of Paraná, Curitiba, 2010.
CELOTO, M. I. B .; PAPA, M. F. S .; SACRAMENTO, L. V. S .; CELOTO, F. J. Antifungal activity of plant extracts to Colletotrichum gloeosporioides. Acta Scientiarum. Agronomy, v. 30, n. 1, p. 1-5, 2008
DURMAZ, S .; ERISIR, E .; YILDIZ, U. C .; KURTULUS, O. C. Using Kraft Black Liquor as A Wood Preservative. Procedia – Social and Behavioral Sciences. n. 195, p. 2177-2180, 2015.
EIKENES, M .; ALFREDSEN, G .; CHRISTENSEN, B.E .; MILITZ, H .; SOLHEIM, H. Comparison of chitosans with different molecular weights as possible wood preservatives. Journal Wood Science, n. 51, p. 387-394, 2005.
GOKTAS, O .; MAMMADOV, R .; DURU, M.E .; OZEN, E. A research on the use of extracts from a poisonous plant (Ornithogalum alpigenum Spapf) as a wood preservative. Abstracts / Journal of Biotechnology, n. 136S, p. S672, 2008.
GONZAGA, A. L. Wood: use and conservation. Brasília, DF: IPHAN / MONUMENTA. 246 p., 2006.
GORGIJ, R .; TARMIAN, A .; KARIMI, A. N. Effect of chitosan on the mold resistance of wood and its surface properties. International Journal of Lignocellulosic Products. n. 1, v. 1, p. 39-49, 2014.
HASHIM, R .; BOON, J. G .; SULAIMAN, O .; KAWAMURA, F .; LEE, C. Y. Evaluation of the decay resistance properties of Cerbera odollam extracts and their influence on properties of particleboard. International Biodeterioration & Biodegradation. v. 63, p. 1013-1017, 2009.
HYVÖNEN, A .; PILTONEN, P .; NIINIMÄKI, J. Tall oil / water – emulsions as water repellents for pine sapwood scots. Holz als Roh-und Werkstoff, n. 64, p. 68-73, 2006.
JAIN, S. H .; NAGAVENI, H.C .; VIJAYALAKSHMI, G. Effect of leaf and bark extracts of Cleistanthus collinus (Benth. & Hook) and Prosopis juliflora (Sw.) DC in combination with inorganic compounds against wood decay fungi. Journal Indian Academy of Wood Science, v.8, n.2, p. 198-200, 2011.
JERMER J .; BERGMAN Ö .; NILSSON T. Fungus cellar and field tests with tall oil derivatives. Final report after 11 years' testing. The international research group on wood preservation. Anais … 24th Annual Meeting in Orlando, Florida, USA, 16-21 May, 1993.
KOSKI, A. Applicability of crude oil for wood protection. Department of Processes and Environmental Engineering – Faculty of Technology – University of Oulu, Finland, 2008. 104 p. Masters dissertation.
MACHADO, G. O .; CALIL JÚNIOR., C .; POLITO, W .; PAWLICKA, A. Natural preservative of wood for use in construction – neem oil. Minerva, v. 3, n.1, p. 1-8, jan./jun. 2006.
MAOZ, M .; MORREL, J. J. Ability of chitosan to limit wood decay under laboratory conditions. The international research group on wood protection. IRG / WP 04-30339, 2004.
NAKAYAMA, F.S .; VINYARD, S. H .; CHOW, P .; BAJWA, D.S .; YOUNGQUIST, J.A .; MUEHL, J.H .; KRZYSIK, A. M. Guayule as a wood preservative. Industrial Crops and Products, n. 14, p. 105-111, 2001
PAAJANEN, L., RITSCHKOFF, A.C. Effect of crude oil, linseed oil and rapeseed oil on the growth of decay fungi. The International Research Group on Wood Preservation, IRG / WP 02-30299, 2002.
PAES, J.B .; DE SOUZA, A. D .; DE LIMA, C. R .; NETO, P. N. de M. Efficiency of neem and castor oils against xylophagous termites in forced feed test. Cerne, v.16, n.1, p. 105-113, Jan./mar. 2010
RAHHAL, M. M. H .; ISMAIL, I.A .; RAHMOU, A. A. Efficacy of repeated spray of neem oil for control of the gray mold disease of lentil plants caused by Botrytis cinerea and some of the chemical components of lentil seeds. Journal of Pest Control and Environmental Sciences, v. 15, n. 1 p. 43-67, 2007.
RODRIGUES, M .; PAIVA, R .; NOGUEIRA, R.C .; MARTINOTTO, C .; SILVA JR, J. M. In vitro morphogenesis of neem from cotyledonary explants. However, 33, n. 1, p. 21-26, 2009.
ROWELL, R. M. Chemical Modification: a non-toxic approach to wood preservation. In: ECOWOOD 2006 – International Conference on Environmentally, 2. Anais ... p. 227-237, Oporto, Portugal, 2006.
SATTOLO, N. M. S .; BRITTO, D. de; ASSIS, O. B. G. Chitosan as fungicide in wood Pinus sp. used in the manufacture of "K" boxes. Brazilian Journal of Food Technology, v. 13, n. 2, p. 128-132, abr./jun. 2010
SBEGHEN, A. C. Potentials of use of essential oils of aromatic plants for the control of Cryptotermes brevis. 2001. 80 f. Dissertation (Master degree) – University of Caxias do Sul, Caxias do Sul, 2001.
SINGH, T .; VESENTINI, D .; SINGH, A. P .; DANIEL, G. Effect of chitosan on physiological, morphological, and ultrastructural characteristics of wood-degrading fungi. International Biodeterioration & Biodegradation, n. 62, p. 116-124, 2008.
SIVRIKAYA ,; CAN, A. Effect of weathering on wood treated with tall oil combined with some additives. Wood. Science and technology n. 18, v.4, p. 723-732, 2016.
TASCIOGLU, C .; YALCIN, M .; SEN, S .; AKCAY, C. Antifungal properties of some plant extracts used as wood preservatives. International Biodeterioration & Biodegradation. n. 85, p. 23-28, 2013.
TEMIZ, A .; ALFREDSEN, G .; EIKENES, M .; TERZIEV, N. Decay resistance of Wood treated with boric acid and tall oil derivates. Bioresource Technology, n.99, p. 2102-2106, 2008.
TORR, K. M .; SINGH, A. P .; FRANICH, R.A. Improving stiffness of lignocellulosics through cell wall modification with chitosan melamine co-polymers. New Zealand Journal of Forestry Science, n. 36, p. 87-98, 2006.
TREU, A .; LARNOY, E .; MILITZ, H. Leaching of new environmental friendly wood protection agents. In: BERGSTEDT, A. 5., 2009, Copenhagen: Denmark. Anais ... 75 Proceedings of the 5th meeting of the Nordic-Baltic Network in Wood Material Science and Engineering, n. 43, p. 33-40, 2009
VÄHÄOJA, P .; PILTONEN, P .; HYVÖNEN, A. NIINIMÄRKI; J .; KUOKKANEN, T. Biodegradability studies of certain wood preservatives in groundwater as determined by the respirometric bod oxitop method. Water, Air and Soil Pollution, n. 165, p. 313-324, 2005.
 Chemical Engineer. Doctor. Paulista State University "Júlio de Mesquita Filho" – Campus of Itapeva.
 Forestry Engineer. Doctor. Paulista State University "Júlio de Mesquita Filho" – Campus of Itapeva.