Effects of guayule resin on structural performance and durability of wood strand-based composites

Abstract

Effects of guayule resin on mechanical, physical, and biological performance of wood strand-based panels were evaluated. Southern yellow pine (Pinus spp. L) wood strands were mixed with phenol formaldehyde (PF) resin to a target resin content of 5% and hot-pressed to manufacture wood strand-based panels. A guayule resin solution was prepared and sprayed on the wood strands immediately after PF resin to different guayule resin contents of 0.5% and 1.0%. Specimens cut from treated panels and control panels were subjected to tensile, internal bond, water absorption and thickness swelling, and fungi soil block tests. Guayule resin had a positive effect on tensile strength, as specimens showed 8.0% and 9.5% increase compared to control specimens. However, the internal bond strength decreased 5.3% and 6.4%, respectively. Water absorption and thickness swelling for the treated specimens with guayule resin decreased as compared to control specimens. The fungal decay resistance test indicated little differences in the average percent mass loss across the untreated and treated wood strand-based composite materials. Regardless of increase or decrease, the effects of guayule resin on mechanical, physical, and biological performances of wood strand-based panels were not statistically significant.

Improved Durability of Wood Strand-Based Panels Using Guayule

“…To understand the effect of guayule on the physical and mechanical bonding performance of wood strands, in-situ specimens with 5.00% guayule were submitted to IB and tensile tests. In Figure 3, the results of these tests are compared to that of control specimens that were submitted to the same test in our previous research [19]. The IB and tensile strengths of in-situ specimens were 55.00% and 26.00% lower than those of control specimens, respectively.…”

“…The guayule resin was provided by the United States Department of Agriculture (USDA) Agriculture Research Service (ARS) for research purposes, and we discovered that this product is extremely difficult to work with as it is a hard solid at room temperature (see Figure 1a in Entsminger et al [19]). Therefore, to reduce the viscosity of the guayule, it was kept in a laboratory conventional oven above 70 • C as stated by Bultman et al [27] and Schloman and Wagner [28].…”

“…Sci. 2024, 14, 4535 3 of 13 ((CH 3 ) 2 CO) at a 1:1 weight ratio [19,29,30]. The solid content of guayule resin was 100.00%, whereas the guayule-acetone solution had a solid content of ~57.00%.…”

“…The guayule-acetone solution was immediately sprayed on the pine wood strands right after the PF resin was applied using the same gravity feed air spray gun used for PF resin during the manufacturing process within the drum blender. In our previous research (Entsminger et al [19]), in-situ treatment using guayule solution to target contents of 0.50% and 1.00% of the oven-dry weight of pine wood strands was used. However, in this study, a higher guayule content of 5.00% of the oven-dry weight of pine wood strands was applied during the manufacturing process for a better understanding of the effects of guayule resin on the durability of the WSB panels.…”