# Improved Durability of Wood Strand-Based Panels Using Guayule
###### Abstract  
In this study, the most effective application method of guayule resin and its effects on termite and fungal decay biological performances of wood strand-based (WSB) panels were explored. Southern yellow pine (_Pinus_ spp. L) wood strands were mixed with phenol formaldehyde (PF) resin to a target resin content of 5.00% and hot-pressed to manufacture the control WSB panels. For the in-situ process, a guayule resin solution was prepared and sprayed on the wood strands immediately after spraying the PF resin to a target content of 5.00%. For brushing and spraying methods, a sub-set of the control panel specimens were further brushed or sprayed with guayule resin solution on all surfaces. To understand the effects of guayule on durability, specimens cut from control and treated panels were subjected to termite resistance and fungal degradation soil block tests. The in-situ specimens with 5.00% guayule were subjected to tensile, internal bond, water absorption, and thickness swelling tests to find out whether guayule affects the mechanical performance of WSB panels. The results showed that in-situ treatment resulted in a significant reduction in the mechanical properties of wood stand-based panels. The sprayed technique resulted in more durable panels, as the mass loss was 2.21% for termites and 3.24% for fungi specimens, which decreased by 76.66% and 80.86%, respectively, when compared to the WSB controls. internal bond (IB); water absorption and thickness swelling tensile; fungal decay resistance; termite resistance; guayule resin; southern yellow pine (SYP); wood strand-based (WSB) product +
Footnote †: journal: Medical  
Guayule (_Parthenium argentatum_ [PERSON]), pronounced wy-oo-lee, is a low perennial desert shrub, native throughout the Chihauhuan Desert Ecoregion in Arizona, New Mexico, Texas, and northern Mexico in North America [11; 12]. The shrub has large amounts of natural latex rubber in its stems, and cultivated fields have been established with genetically diverse seeds that have been harvested mechanically for rubber production since the before the early 1900s [11; 12; 13]. The harvested materials are ground into bagasse and the natural latex rubber is chemically extracted from its cells [13]. After the latex rubber is extracted, a viscous resin byproduct is left over called guayule resin [14; 15]. U.S. tire producers such as Firestone, Bridgestone, Cooper Tires, and Goodyear companies are currently the main sources of the available byproducts of guayule resin [16] within the U.S. market. Guayule comes from a mature and established industry, as the United States was able to process guayule to produce over 13.60 metric tons (15.00 U.S. tons) of natural rubber daily during the 1940s [12]. However, such production was replaced with synthetic rubber post-War World II [12]. From 2012 to present day, Bridgestone has opened a Biorubber Processing and Research Center in Arizona, USA, to develop natural rubber from guayule [16]. The guayule resin byproduct has the potential to act as a low-toxicity component of coatings, tackifiers, adhesives, composite components, emulsifiers, bio-control agents, insecticides, anti-microbials, and anti-fungals [17; 18; 19]. Guayule resin is an effective natural biocide with termiticidal and fungicidal properties that may have uses in lumber and engineered wood products to provide longevity and protection for many years to come [19; 20; 21; 22; 23; 24; 25]. In our previous research ([PERSON] et al. [19]), wood strand-based (WSB) panels were fabricated and treated up to the target PF resin content of 5.00% and guayule resin contents of 0.50% and 1.00% to determine the effects of guayule resin on the durability and mechanical performance of such panels. However, due to the low percentage of guayule, it was difficult to make a clear conclusion.