APPLICATION OF MULTILAYER CARBON NANOTUBES ( MWCNT ) ON NINE TROPICAL WOOD OF COSTA RICA AND THEIR IMPACT ON MECHANICAL RESISTANCE

Carbon nanotubes (CNTs) are carbon allotropes such as diamond, graphite or fullerenes, and its structure can be like a graphene sheet rolled on itself (Lariza et al., 2012). They are cylinders of one or more layers with open or closed ends (De Volder et al., 2013), can have a diameter of nanometers and their length can reach up to 1mm, so the ratio of length-width is very high (Pérez, 2010). The commercial interest in CNTs is ref lected in its production capacity, which exceeds several thousand tons per year. The characteristic advantages of CNTs like high mechanical strength and good thermal stability (Orináková and Oriňák, 2011) make them important for a perfect scientific environment product (Pérez, 2010). However, the disadvantages involve adoption of regular shapes like pentagons and heptagons during mass production, which is not the perfect union of the CNT and hence the properties can be degraded (De Volder et al., 2013). Moreover, lack of solubility in organic solvents or aqueous solutions is also a drawback of these structures (De Volder et al., 2013), but they can undergo chemical reactions that make them soluble in various solvents, and can be integrated with inorganic, organic and biological systems (Saeb et al., 2015), a process known as ‘functionalization’ of the nanotubes. CNTs have several applications and can be utilized at different sectors. In medicine, they can be used for diagnosis and treatment of cancer, nervous system disorders and infectious diseases (Zhang et al., 2010). They can be exploited in compound materials as electrical conductive fillers in plastics; to improve fiber compounds among wind turbine blades or vanes boats; in paints to help reducing biofouling of ship hulls (De Volder et al., 2013); and very importantly as an anticorrosive coating for metals to improve the rigidity of coating (De Volder et al., 2013). On the other hand, the complex structure of the wood cell and the physical and mechanical properties of its wall has attracted the attention of scientists, and has recently led to the study of the effects of nanotechnology on wood structure (Moon et al.; 2006; Kamel, 2009). Among many studies, the major concern has been evaluating the possibility of working with wood in a nano scale to have more absorbent, lightweight and strong products (Shmulsky and Jones, 2011). For example, Kordkheili et al. (2012) have studied the influence of mixture of cement, wood fiber and CNT’s, and they found that the static bending was higher when a mixture of 1.5% multilayer nanotubes (MWCNT), 20% fiber and 43% of cement is used. Another study, in Ficus hispida, has shown the improvement in structural properties (Hazarika and Maji, 2014). This type of wood grows in the tropics, it is soft and is not suitable for structural applications due to their poor physical and mechanical properties. However, hydroxyl group multilayered nanotubes (MWCNT-OH) in different concentrations were added to wood in a solution of ethanol and Vochysia ferruginea were tested for the effectiveness of MWCNT on five types of mechanical strength. As a result of absorption studies, Vochysia ferruginea was found to absorb the most with 455.45L/m3 at 0.05% and 466.40L/m3 at 0.10%, while Cedrela odorata was the least absorbing species with 215.78L/m3 at 0.05% and 215.78L/m3 at 0.10%. However, no pattern of improvement in either of the species was detected as per expectation, which could be due to several reasons such as the origin of the material, functionalization with hydroxyl group nanotubes or the chemical composition of the species. SUMMARY