Performance of Oriented Strand Board Made with Soy Substituted Resin in Termite Choice Tests with Southern Yellow Pine

Soy flour was evaluated as a partial substitute for resin in the manufacture of oriented strand board (OSB), a wood-based composite that often replaces solid lumber and plywood in structural applications in the construction industry. Since the presence of soy could alter OSB biodegradation properties, termite resistance of OSB panels made with 0, 10, and 20 percent of polymeric methylene diphenyl diisocyanate (pMDI) resin substituted with soy flour (OSB0, OSB10, and OSB20, respectively) was investigated. Single choice tests between three types of OSB and southern yellow pine (SYP) solid wood and an OSB choice test (OSB0 vs. OSB10) were evaluated. Results indicated that termites always showed a preference for SYP, with the OSB becoming less palatable when soy flour was present. Percentage weight losses for OSB0, OSB10, and OSB20 were 5.7×, 8.4×, and 8.6× less, respectively, compared with SYP. In the absence of SYP, termites did not differentiate OSB0 from OSB10, with OSB10 showing 1.5× less weight loss compared with OSB0. Visual rating data supported weight loss data, except significantly less damage was only found when the choice paired SYP with OSB made with soy (OSB10 or OSB20). Termite consumption preference for SYP was explained by differences in water absorption kinetics. SYP reached saturation (105% moisture content) within 1 week on moist sand, while moisture content of OSB composites slowly climbed to 79 percent over 4 weeks, never reaching a plateau. Lower moisture content was due to the presence of water-repellent resin and wax in the OSB.

Compression Properties of Small Clear Southern Yellow Pine Specimens Tested across Five Decades

Southern yellow pine (SYP) is one of the most used softwood species in the world. Most of this raw material come from fast-grown plantation trees. It is of interest to determine if SYP clear wood properties may have changed over the long term, in particular whether such properties may have declined. Herein, specific gravity (SG), ultimate compression strength parallel to grain (UCS‖), and UCS perpendicular to grain (UCS⊥) from three samples were compared: Sample 1 tested in 2014; Sample 2 from molding and millwork producers tested in 2017–2019; and Sample 3 from a study conducted in the mid-1960s. With respect to specific gravity (SG), the wood in Sample 1 was significantly lower than that from Samples 2 and 3. With respect to UCS‖, all three samples were statistically different. Adjusting to 12 percent moisture content had no influence on the mean separation of UCS‖. With respect to UCS⊥, no statistically significant differences were detected among the test data from any of the three samples. However, for the UCS data generated from the SG and moisture content–related model, Sample 2 was higher than Sample 3, and Sample 3 was higher than Sample 1, and these differences were statistically significant. Overall, these findings do not suggest that broad or consistent changes or declines of these wood strength properties have occurred during the past five decades.

Utilization of the western juniper (Juniperus occidentalis) in strandboards to improve the decay resistance

Naturally durable wood species such as western juniper (Juniperus occidentalis) are a potential source of bio-based wood preservatives for the improvement of non-durable timber species. This research investigated the durability of southern yellow pine (Pinus sp.) and western juniper lumber or strandboard. Single layer panels were made with six different types of wood or wood treatments: southern yellow pine, mixed juniper sapwood and heartwood, sapwood, heartwood, sapwood strands impregnated with juniper oil prior to and after panel manufacturing. Panels were fabricated with 560 kg/m3 oven-dry density with 5% of PF resin and 0.5% of wax. Durability testing was performed with the brown rot fungi Gloeophyllum trabeum and Rhodonia placenta and the white rot fungus Trametes versicolor. Internal bond as a crucial parameter of OSB was measured. Tests revealed that juniper heartwood and juniper heartwood strandboards were highly decay resistant, and juniper oil pre- and post-impregnation strandboard manufacture imparted increased resistance to decay against one brown rot fungus, Gloeophyllum trabeum. Juniper strandboard manufactured from non-impregnated strands showed significantly higher internal bond than pine. These results suggest there is excellent potential for manufacturing highly decay-resistant OSB from juniper, especially from heartwood and that juniper oil can increase the durability of juniper sapwood strandboard.

The Effect of Variables on Laboratory Termite Testing: Part 4—Test Block Species, Size, and Test Photoperiod

The objective of this study was to determine the impact on termite feeding of wood sample size and species and test photoperiod in standard tests. Native species (Reticulitermes flavipes) and introduced species (Coptotermes formosanus) were tested in an American Wood-Preservers' Association E1 standard laboratory test. For testing involving treated wood, southern yellow pine was determined to be preferable to spruce based on its treatability and availability. Test blocks of 25 by 25 by 6 mm were deemed adequate for testing, with large blocks presenting difficulty with retrieval of termites to determine mortality and smaller blocks being consumed too rapidly by the termites in the test. Photoperiod comparisons were not significantly different for R. flavipes; however, C. formosanus indicated a preference for 100 percent darkness. Therefore, the recommendation is to maintain tests using each species in a 100 percent dark environment.

Properties of the western juniper (Juniperus occidentalis) strandboard

This work investigated the feasibility of using western juniper (Juniperus occidentalis) as a material to manufacture oriented strandboard (OSB) panels. Four different material combinations of juniper sapwood, heartwood, and fibrous bark were compared with regular southern yellow pine (Pinus sp.) strands. The OSB panels were made at an oven-dry density of 560 kg/m3. One pine control panel was also made at a higher density of 650 kg/m3 with a 5% addition of phenol formaldehyde (PF) resin and a 0.5% addition of wax. The single-layer panels were formed with a hot press, and the physical and mechanical properties were tested according to the ASTM standard D1037 (2020). The testing indicated that western juniper is a potential material for manufacturing of OSB panels. The properties of the juniper panels were equivalent or slightly better than those of the southern yellow pine panels at the same density level, except for the modulus of elasticity (MOE). The lower density of the juniper OSB panels may have benefits in construction applications and can decrease transportation costs.

Industrial-scale Pelletization of Southern Pine Energy Pellets with Various Additives

The energy pellet industry desires to improve processing techniques and the characteristics of fuel pellets by including additives with the feedstock. In this study, the industrial-scale pelletization of southern yellow pine (SYP) planer shavings was performed along with experiments involving the effect of production rate and moisture on the energy required for production (measured in kWh Mg-1). Multiple additives were investigated to determine their effects on southern yellow pine pelletization performance and pellet characteristics. These additives included southern-yellow-pine-derived biochar (BC), southern-yellow-pine-derived bio-oil (BO), corn starch (CS), vegetable oil (VO), sweet potatoes (SwP), microcrystalline cellulose (MCC), micronized rubber powder (MRP), and mixed hardwood planer shavings (HW). A control was compared to 20 different treatments at various additive concentrations, and the effect on pellet durability, bulk density, and higher heating value was determined. The production rate of the pellets with additives varied but were able to be compared with the baseline regression line (production rate vs. energy required for production per Mg) control trials so that the appropriate amount of energy required to produce one Mg of biomass could be compared to the control. The data for the additives, which outperformed the control using the economic study, are listed below. The control, HW10%, HW 25%, HW 50%, BC 0.5%, BC 1%, BC 2%, BC 4%, MRP 1%, and BO 0.5% had a mean pellet durability index (PDI) of 97.9%, 98.1%, 98.1%, 97.7%, 98.2%, 98.6%, 98.4%, 98.7%, 98.0%, and 98.0%, respectively. The control, HW10%, HW 25%, HW 50%, BC 0.5%, BC 1%, BC 2%, BC 4%, MRP 1%, and BO 0.5% had mean bulk density values of 703.0, 700.8, 704.8, 692.2, 693.9, 695.6, 695.6, 683.2, 658.8, and 684.6 kg m-3, respectively. The mean higher heating values (HHV) for the control, HW10%, HW 25%, HW 50%, BC 0.5%, BC 1%, BC 2%, BC 4%, MRP 1%, and BO 0.5% were 19.0, 18.9, 18.6, 18.2, 19.4, 19.5, 19.6, 19.6, 19.6, and 19.2, MJ kg-1, respectively. The normalized energy requirements for production for the control, HW10%, HW 25%, HW 50%, BC 0.5%, BC 1%, BC 2%, BC 4%, MRP 1%, and BO 0.5% were 112.0, 110.5, 112.1, 115.3, 110.7, 111.7, 112.1, 118.1, 108.5, and 111.1 kWh Mg-1, respectively. An economic feasibility analysis showed that the discounted net present value (NPV) at a rate of 12% could be improved when using certain pellet additives in the feedstock. The following additives could increase the profit of the mill over just using the control: hardwood planer shavings at 10%, 25%, and 50%, biochar at 0.5%, 1%, 2%, and 4%, MRP at 1% and bio-oil (with volatiles removed) at 0.5% (all on a dry basis). Keywords: Biochar, Biomass pellets, Bio-oil, Corn starch, Hardwood, Micronized rubber powder, Microcrystalline cellulose, Sweet potato, Vegetable oil.