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N.M. Garz on-Barrero et al. / International Biodeterioration & Biodegradation 115 (2016) 266e276 267
wood, principally from the Pinus and Eucalyptus genera. However, et al., 2009) on the growth of fungi. The long-term tests corre-
due to the great growth in the demand for construction and the spond to tests of exposure to the external environment in the
increase in the furniture sector for raw materials, alternative ma- presence of climate factors such as rain, solar radiation and tem-
terials must be sought out (Mendes et al., 2012). In this context, the perature; however, the responses to natural deterioration are slow.
lignocellulosic materials derived from agro-industrial waste, come Laboratory studies adopting accelerated conditions have been
as an alternative for particle board manufacturing and therefore the conducted to evaluate the degree of colonization by mold and
evaluation of its durability is very important (Garzon et al., 2012). In staining fungi in different types of wood and boards; boards like
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2013, the total world production reached 358 million m high- bamboo and superficially treated (Sun et al., 2010) Pinus sylvestris
lighting the particle board and OSB, plywood and MDF. The top five and spruce wood (Picea abies) with phenolic resin (Bok et al., 2013);
exporters (China, Malaysia, Germany, Canada and Thailand) multi-layered boards of cedar, tamarack, spruce and aspen woods
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exported 35 million m in 2013 (FAO, 2014). (Yang et al., 2007); oriented strand boards (OSB) with polyphenolic
Sugarcane is an important crop for the economic development resin, plywood and medium density fiber (MDF) particle boards
of Brazil, since it represents a source of ethanol and sugar, as well as (Yang et al., 2007). Among many studies the focus has been in
the biomass waste (bagasse) which is used to produce electrical analyzing and knowing the effects of temperature and humidity
energy (Hofsetz and Silva, 2012). The sugarcane harvest in Brazil in conditions, growth rates of molds growing in particular environ-
2014/15 was approximately 634.8 million tons, which represents ments (Yang, 2008), as well as the effects of surface coating
about 190 million tons of sugarcane bagasse (Silva et al., 2007). In (Fojutowski et al., 2009) and thermal treating (Kartal, 2007) in the
the world, the sugarcane bagasse has been the target of a number of protection against mold growth. However, comparative studies of
studies like reinforcing polymeric matrices, cementitious compos- resistance to mold between sugarcane bagasse particle boards and
ites, composites reinforced by bagasse pulp, and bagasse ash as an commercial wooden particle boards are rare in the literature.
added mineral to cement (Faruk et al., 2012). This is attributed This study aims at investigating mold growth resistance and
principally to the abundant availability from the sugar mills and the performance in alternative sugarcane bagasse particleboard (BCP)
low costs for pre-treatment (Loh et al., 2013). using a castor oil polyurethane resin adhesive in comparison with
The susceptibility to fungal decay in particle boards with the use commercial medium density wood particleboard (MDP) under
of sugarcane bagasse is reported in some studies that were carried natural and accelerated test conditions. As a secondary objective,
out in Brazil and devoted to applications in hot and humid regions. the work also evaluates the effect of castor oil based bicomponent
Teixeira et al. (1997) evaluated sugarcane bagasse particle boards polyurethane resin applied as a surface coating opposing on mold
produced with tannin based resin and urea formaldehyde resin; the growth in both materials BCP and MDP in humid and warm envi-
results designated the boards as moderately resistant to rotting ronments. The experimental procedures are designed to accelerate
fungi. Belini et al. (2014) examined particle boards produced from the mold growth under exposition to environments with high
wooden fibers of Eucalyptus grandis with percentages between humidity and high temperature. Therefore, there is an attempt to
0 and 25% of sugarcane bagasse with urea formaldehyde based exacerbate the effects of degradation of the studied materials.
resin, and indicated that the boards were not resistant to the decay
of white rot fungi. 2. Materials and methods
Resins (adhesive agents) are used in the manufacturing of par-
ticle boards to bind wood particles, giving them shape, support and 2.1. Particle boards
resistance (Zenid, 2007). Currently, 70% of all manufactured particle
boards in the world use some type of resin, and from that a majority Particle boards made from sugarcane bagasse (BCP) with castor
use synthetic phenolformaldehyde resins (PF resins), Urea- oil based bicomponent polyurethane resin were produced in a
formaldehyde (UF), Melamine-formaldehyde (MF), and Methylene laboratorial scale according to the recommendations established by
diphenyl diisocyanate (MDI). On the other hand, there is a global Maloney (1996) and adapted by Sartori et al. (2012). The process
trend towards the use of biodegradable products, which are clean began with the collection of sugarcane bagasse in two mills from
and originate from renewable supplies (Silva et al., 2015). the Pirassununga region, Sao Paulo State, Brazil. The material was
Polyurethane resin made from castor oil is a polymer with sieved in a 2 mm mesh to remove fine particles. Subsequently, it
biodegradable characteristics, showing great versatility with ap- was crushed in a knife mill with a sieve opening of 8 mm and oven
plications in different industrial sectors (Cangemi et al., 2010; dried (60 C) to reach 12% of moisture equilibrium. Castor oil based

Tib erio et al., 2012). The world's largest producers of castor seed polyurethane bi-component resin was used as an adhesive, one of
are India, China, and Mozambique. In Brazil, for the 2014/15 crop it the components polyol derived vegetable oil and the other the
is estimated an area of 90 thousand hectares of planted area, and 61 polyfunctional isocyanate (catalyst) in a ratio of 1 part polyol to 2
thousand tons of production (CONAB, 2015). parts catalyst, by 15% of the particle mass. The resin and the par-
Johansson et al. (2012) indicate that the susceptibility of con- ticles were mixed in a planetary mixer for 3 min. Then, board-
struction materials for mold growth varies. Some materials are forming frame (50 50 cm) was inserted and placed in thermo-
tolerant at relatively high humidity environments without showing hydraulic press conditions at 100 C and 5 MPa pressure for
mold growth. While other materials are less tolerant where mold 10 min. The board was squared by removing the edges for its final
can grow in such relatively low humidity environments as 75%. form. The MDP boards were produced with particles of Eucalyptus
Thus, the structures in a building are exposed to different tem- sp. This particle board (MDP) was produced on an industrial scale
peratures and humidity levels, whether in temperate or tropical with urea-formaldehyde resin for commercial use.
regions.
According to Clausen and West (2005), it is necessary to 2.2. Lateral and surface treatments of test samples
establish methods for evaluating the capacity for using wood and
composite materials in systems (framing) to support the growth of The 270 50 12 mm (length, width and thickness) prismatic
fungi when they are accidentally exposed to the rain during BCP and the 270 50 15 mm MDP test samples were subjected to
installation and maintenance. For this reason, tests of exposure to sealing of the lateral edge in order to reduce water entry during the
the external environment are used to evaluate the influence of natural aging tests and accelerated tests. This sealing procedure
weather (Hayashi et al., 2002; Petri c et al., 2007; Thelandersson was useful to mitigate the potential interference of different