Product Performance - FOREST PRODUCTS LABORATORY

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
123	0650	2000	25%
123	0650	2010	25%
123	0650	2020	50%

Progress 10/01/12 to 09/30/22

Outputs
OUTPUTS: Although water absorption by the wood cell walls is important for tree growth, it is undesirable in wood products leading to decay, dimensional change of the products, and problems with the connections. While these problems can be seen by the naked eye, understanding the detail structure of cell walls and the influence of water requires very sophisticated technology. The fundamental effects of water on the specific cell wall structural changes and the transport of ions that cause corrosion of wood connectors is now measurable using synchrotron-based micro X-ray fluorescence microscopy (μXFM). This avoids a lot of large-scale testing in the early stages of programs for new modified wood products and the adhesives used to bond them. This understanding of the dimensional changes in cell walls with water uptake and loss leads to an understanding of how to make adhesively bonded wood products more durable and what segments of the walls where changes in structure would be more effective. FPL efforts with others have led to a new standard for bond strength testing that allows more rapid testing of new adhesives and a better understanding of bond failure mechanisms. Reviewing the long history of the FPL in understanding wood durability is important for future development. This knowledge has been translated into the field of wood plastic composites that have good short term durability, but still can suffer from long term durability in more humid environments, which has been determined by experimental outdoor exposure tests. The use of zinc borate decreased decay and a UV stabilizer package helped in retaining coloration of the wood-plastic composite. One continuing area of concern for wood products has been the formaldehyde (a known carcinogen) emissions from wood products bonded with urea-formaldehyde (UF) emissions. Our continuing work on no-added-formaldehyde adhesives has been a part of our work, and the other part has shown that even after 3½ years of storage, the UF adhesives are still sensitive to heat and humidity leading to increased formaldehyde emissions. PARTICIPANTS: RWUs 4706, 4716, 4723; Adhesive Evaluation Systems, Inc., Corvallis, OR; American Wood Fibers, Columbia, MD, Argonne National Laboratory, Lemont, IL, Columbia Forest Products, Greensboro, NC, Holland Colors Americas, Richmond, IN, National Renewable Energy Laboratory, Golden, CO, Oak Ridge National Laboratory, Knoxville, TN, Rio Tinto, Chicago, IL, Struktol Company of America, Stow, Ohio, Solenis LLC, Wilmington, DE, University of Maine's Advanced Engineered Wood Composite Center, Orono, ME, Wescott Consulting, Minocqua, WI TARGET AUDIENCES: This research will benefit the forest products and general composite industries directly where guidance on new understanding of product performance or new product technology is presented for their benefit with the implicit invitation for them to enter in to collaboration on future research. PROJECT MODIFICATIONS: This problem area is fundamental and will be continued in our Research Work Unit Description. We will be reviewing and revising our Research Work Unit Description in 2021.

Impacts
This research will improve the understanding of the mechanisms for adhesive degradation of wood products both exposed outdoors and adverse indoor conditions and provide information for developing new wood-based products. This work leads to scientific approaches for producing improved wood products. Key publications on our best in class methods for wood utilization are critical for such products to regain market share versus inorganic (cement), metal (steel and aluminum), and petroleum-based products.

Publications

Frihart, Charles R.; Chaffee, Timothy L.; Wescott, James M. 2020. Long-term formaldehyde emission potential from UF- and NAF-bonded particleboards. Polymers. 12(8): 1852. 10 p.
Frihart, Charles R.; Hunt, Christopher G.; Plaza, Nayomi Z.; Jakes, Joseph E. 2019. Adhesive-wood interactions in relation to failure in bonded wood products from the centimeter to nanometer scale. In: Contributed Papers from Materials Science and Technology 2019 (MS&T19), September 29⿿October 3, 2019, Oregon Convention Center, Portland, Oregon, USA: 887-883.
Frihart, Charles R.; Lorenz, Linda. 2020. Standard test method ASTM D 7998-19 for the cohesive strength development of wood adhesives. Journal of Visualized Experiments. (159). 6 p.
Hunt, C.G.; Zelinka, S.L.; Jakes, J.E. 2020. Limiting polysaccharide motion protects wood from decay. In: IRG51 webinar on wood protection. June 10-11, 2020. Stockholm, Sweden: International Research Group on Wood Protection. 6 p.
Ibach, Rebecca E.; Clemons, Craig M.; Stark, Nicole M. 2020. Long-term field exposure of wood-plastic composites processed on a commercial-size extruder. Proceedings, 51st annual meeting of the international research group on wood protection . June, 10-11, 2020. 11 p.
Kirker, Grant; Ibach, Rebecca E. 2019. The life and work of Bruce Johnson at the Forest Products Laboratory and in the American Wood Protection Association. In: Proceedings, 115th annual meeting of the American Wood Protection Association. Birmingham, AL: American Wood Protection Association: 100-104.

Progress 10/01/12 to 09/30/19

Outputs
OUTPUTS: As an approach to meeting newer environmental standards, modified plant proteins have been studied as no-added formaldehyde wood adhesives for interior applications. Research demonstrated that adding periodate, permanganate, or iodate to soy flour improved the strength of soy adhesive bonds in small-scale testing and in plywood shear, especially when tested under wet conditions. The results are consistent with oxidation of the carbohydrate⿿protein mixture in plant flours to provide adhesives with increased wet strength in wood bonds. Additionally, soy protein isolate (SPI) and insoluble soy flour polymeric carbohydrates have been reacted with sodium periodate for the specific oxidation of vicinal ⿿OH groups to investigate the reactions involved in this approach to soy four adhesives. The reactions have been shown to generate carbohydrate oligomer fractions presenting one, two or multiple aldehyde groups. When the mix of SPI and soy insoluble carbohydrates is treated with periodate, the majority of the observed aldehyde carrying species appear to be higher molecular weight carbohydrate oligomer fractions. The combined findings from outdoor robotic strain weathering, lab testing, and finite element modeling of silicon building sealants were used to produce detailed yet widely accessible general technical report and a brief two page techline. These documents are written specifically for contractors and building/home owners. The principal concepts discussed in these documents are that compression loading of sealants results in significantly higher loads than tension, these loads are highly concentrated at the bondline, and that the amount of tension vs compression experienced in service depends on the state of the gap when the sealant was installed (season). Therefore, the take home message is that sealant installation temperature sets the strain profile the sealants will experience and likely has the greatest significance on durability. Methods for minimizing the resulting stress and proper installation were also provided. Thirteen commercially⿿bonded engineered wood products (structural plywood, oriented strand board, structural composite lumber, I⿿joists, and glued⿿laminated timber) from North America were evaluated for VOCs using methods developed for interior bonded wood products. The dominate volatiles for the different products were greatly dependent on wood species and bonding process used preventing a universal conclusion. These data provide a basis for any future studies on bonded structural engineered wood products. Novel hybrid panel composites based on wood, fungal mycelium, and cellulose nanofbrils (CNF) were developed and investigated in the present study. It was found that the composites made of mycelium-modified wood and CNF resulted in enhanced physical and mechanical properties compared to the ones made by physically mixing wood, mycelium, and CNF. Research also elucidated the development of a unique lightweight composite systems with physical and mechanical properties optimized at 5% CNF addition with potential to be used in packaging and furniture applications. PARTICIPANTS: RWU 4709, Dow (Dow Corning), Midland, MI, APA ⿿ The Engineered Wood Association, Tacoma WA, University of Lorraine, Epinal, France, King Abdulaziz University, Saudi Arabia, School of Forest Resources and Advanced Structures and Composites Center, University of Maine, Orono, ME, Ecovative Design, LLC., TARGET AUDIENCES: This research will benefit the forest products and general composite industries directly where guidance on new understanding of product performance or new product technology is presented for their benefit with the implicit invitation for them to enter in to collaboration on future research.

Impacts
This research will improve our understanding of the mechanisms for degradation of materials exposed outdoors, and adverse indoor conditions and provide information for developing new materials. This work leads to scientific approaches for producing products with improved performance. Key publications on best in class methods of wood utilization are critical for such products to regain market share versus petroleum based products.

Publications

Frihart, Charles R.; Lorenz, Linda F. 2019. Specific oxidants improve the wood bonding strength of soy and other plant flours. Journal of Polymer Science Part A: Polymer Chemistry. 57(9): 1017-1023.
Frihart, Charles R.; Pizzi, Antonio; Xi, Xuedong; Lorenz, Linda F. 2019. Reactions of soy flour and soy protein by non-volatile aldehydes generation by specific oxidation. Polymers. 11(9). 18 p.
Frihart, Charles; Zylkowski, Steve. 2018. Volatile organic compounds emissions from North American engineered wood products. Forestry Research and Engineering: International Journal. 2(4): 204-208.
Lacher, Steven J.; Hunt, Christopher G.; Schueneman, Gregory T. 2019. Making building sealants last. Techline. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. 2 p.
Rowell, R.M.; Ibach, R.E. 2018. Stable and durable wood products based on molecular modification. Journal of Tropical Forest Science. 30(5): 488-495. https://doi.org/10.26525/jtfs2018.30.5.488495.
Schueneman, Gregory T.; Lacher, Steven J.; Hunt, Christopher G. 2019. Installing sealants for long service life. Gen. Tech. Rep. FPL-GTR-267. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory: 1-11.
Sun, Wenjing; Tajvidi, Mehdi; Hunt, Christopher G.; McIntyre, Gavin; Gardner, Douglas J. 2019. Fully bio-based hybrid composites made of wood, fungal mycelium and cellulose nanofibrils. Scientific Reports. 9(1). 12 p.

Progress 10/01/12 to 09/30/17

Outputs
OUTPUTS: Evaluation of advanced composites: The flexural properties of wood⿿plastic composite (WPC) deck boards exposed to 9.5 years of environmental decay in Hilo, Hawaii, were compared to samples exposed to moisture and decay fungi for 12 weeks in the laboratory. Exposure to water (70°C/5 days) was adequate for simulating long-term composite exposure in Hawaii of 4 ÿ 15 ÿ 86 mm3 specimens. The wood flour used in WPCs can biologically deteriorate and thus the overall mechanical performance of WPCs decrease when exposed to moisture and fungal decay. Two different chemical modifications at 2 different levels were used: organosilicate (OS, 1% and 2.5%) and cobalt sulfate (CoS, 2.5% and 5%). All modifications had less weight loss than the unmodified controls with the 2.5% OS blend showing no weight loss from decay by either brown or white rot fungi. There are several options for mitigating the moisture sorption of WPCs. WPCs containing either a coupling agent (MAPE) or chemically modified wood flour were fabricated. The acetylated WPCs had the highest performance ratings in both Wisconsin and Mississippi, i.e. the highest decay and termite ratings and least thickness change for both above-ground and in-ground exposures compared to the control and those containing MAPE. Improve properties and performance of adhesives and coatings for advanced wood products: Lathe checks (cracks) in plywood veneers form on the side that passes over the knife blade due to the bending of the wood. This study indicated that the heating of the logs not only softened the wood during peeling, but also causes irreversible changes in the wood material which subsequently effects plywood bond strength development. These findings not only confirm the importance of minimizing the depth of lathe checks for product quality, but also demonstrate how check depth could influence a test (SFS-EN 314) which was designed mainly for testing adhesive properties and evaluate adhesive cure. We recently developed tools to study bondlines at these size scales. We have used synchrotron-based micro x-ray fluorescence microscopy (μXFM) and micro x-ray computed tomography (μXCT) to map the penetration of adhesive into the wood anatomical structure. We also developed nanoindentation into a tool capable of assessing the effects of moisture and adhesive infiltration on wood cell wall properties. Using custom-built in situ humidity chambers with μXCT and small angle neutron scattering, we can now study the moisture-induced swelling in wood across the relevant length scales in bondlines that span from the millimeter to nanometer length scales. Finally, we developed a new approach to study moisture-induced swelling forces using wood slivers. Recently, synchrotron based X-ray fluorescence microscopy (XFM) was used to examine the wood that had been in direct contact with metal fasteners in a corrosion test. These measurements showed a copper depleted region in the wood directly adjacent to the metal fastener. These measurements definitively confirm the mechanism of corrosion in treated wood and give further insights into where and how the cathodic reaction takes place.

Impacts
This research will improve our understanding of the mechanisms for degradation of materials exposed outdoors, and adverse indoor conditions and provide information for developing new materials. This work leads to scientific approaches for producing products with improved performance. Key publications on best in class methods of wood utilization are critical for such products to regain market share versus petroleum based products.

Publications

Birkeland, Michael J.; Frihart, Charles R. 2016. From the lab to commercial reality with biobased adhesives for wood. In: World Conference on Timber Engineering, WCTE 2016. 22-25 August 2016, Vienna, Austria. 8 pp.
Frihart, Charles R.; Beecher, James F. 2016. Factors that lead to failure with wood adhesive bonds. In: World Conference on Timber Engineering, WCTE 2016, 22-25 August 2016. Vienna, Austria. 8 pp.
Frihart, Charles R.; Coolidge, Thomas; Mock, Chera; Valle, Eder. 2016. High bonding temperatures greatly improve soy adhesive wet strength. Polymers 8, 394: 1-10.
Ibach, Rebecca; Gnatowski, Marek; Sun, Grace; Glaeser, Jessie; Leung, Mathew; Haight, John. 2017. Laboratory and environmental decay of wood⿿plastic composite boards: flexural properties. Wood Material Science & Engineering. 54(4): 1-16.
Hunt, Christopher G.; Lacher, Steven; Hirth, Kolby; Lorenz, Linda; Hammel, Kenneth E. 2017. Exploring the hypothesis that limiting diffusion of fungal oxidants underlies decay resistance in acetylated wood. In: Proceedings, COST action FP1407 - 3rd conference, Wood modification research and applications. Kuchl, Austria: Salzburg University of Applied Sciences: 37-39.
Ibach, Rebecca E.; Clemons, Craig M. 2017. Long term durability of wood-plastic composites made with chemically modified wood. In: Advancements in fiber-polymer composites conference proceedings. 16-18 May 2017. Madison, WI: 1-17 pp.
Ibach, Rebecca E.; Clemons, Craig M.; Chen, George C. 2017. The use of new, aqueous chemical wood modifications to improve the durability of wood-plastic composites. In: Forty-eighth Annual Meeting of the International Research Group on Wood Protection. IRG/WP 17-40787. 2017 June 4-8; Ghent, Belgium. pp. 1-9.
Jakes, Joseph E.; Plaza, Nayomi Z.; Arzola Villegas, Xavier; Frihart, Charles R. 2017. Improved understanding of moisture effects on outdoor wood⿿adhesive bondlines. Gen. Tech. Rep. FPL⿿GTR⿿246. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. 9 p.
Rohumaa, Anti; Hunt, Christopher G.; Frihart, Charles R.; Kers, Jaan; Denaud, Louis; Hughes, Mark. 2017. The impact of log heating on veneer quality and plywood performance. In: Proceedings, International Scientific Conference on Hardwood Processing. Lathi, Finland. 184-190.
Zelinka, Samuel L.; Jakes, Joseph E.; Kirker, Grant T.; Vine, David; Vogt, Stefan. 2017. Synchrotron based x-ray fluorescence microscopy confirms copper in the corrosion products of metals in contact with treated wood. NACE CORROSION Conference & Expo Paper No. 9017. 8 p.

Progress 10/01/15 to 09/30/16

Outputs
OUTPUTS: Evaluation of advanced composites: Wood-plastic composites deck boards (WPC) were manufactured and then evaluated in the laboratory and field (Hilo, Hawaii and Vancouver, British Columbia). Water absorption, biological activity, density change, and optical and scanning electron microscopy were used to monitor the field boards. The laboratory soil block test was performed with modifications to preconditioning the samples. Weight loss and density decrease were determined and then compared to the field results. Specimens were evaluated using micro x-ray and computed tomography (CT). There was a large discrepancy between the percentage of voids calculated and what was detected by CT imaging and analysis of reference samples and samples exposed to fungi in the laboratory soil block test. This was because of the significant percentage of voids present in the samples that were most likely at the nano- or micro below the scanning resolution used for such large specimens. The CT data shed light on changes in the WPC microstructure, particularly with respect to void size and distribution, during environmental exposure and decay. Improve properties and performance of adhesives and coatings for advanced wood products: A new ASTM test method was finalized and released with participation and leadership from the RWU, ASTM D7998. New reviews were assembled on the impact of wood porosity on adhesive penetration and bonding, biobased adhesives, and the influence of anatomical, physical and mechanical properties of diffuse ⿿porous hardwoods and moisture durability. Lathe checks (cracks) in plywood veneers form on the side that passes over the knife blade due to the bending of the wood. These checks are normally buried on the inside of the plywood so that they have not been of much concern for making plywood. However, this study shows that if the checks are too deep, they alter the bond failure mechanism and lead to what appears to be an adhesive failure. However, the actual failure is in the wood, and this type of deep checks can prevent a normally good adhesive from passing performance tests. The data also shows that the ASTM tests are more rigorous than a similar European test due to requirements on check orientation. This is not only commercially important information, but provides fundamental information on bond failure mechanisms and demonstrates international cooperation since most of the work was done at Aalto University in Finland.

Impacts
This research will improve our understanding of the mechanisms for degradation of materials exposed outdoors, and adverse indoor conditions and provide information for developing new materials. This work leads to scientific approaches for producing products with improved performance. Key publications on best in class methods of wood utilization are critical for such products to regain market share versus petroleum based products.

Publications

Frihart, Charles R. 2016. Adhesive Penetration of Wood and Its Effect on Bond Strength. 39th Annual Meeting The Adhesion Society, February 21-24, the Westin Riverwalk Hotel, San Antonio, Texas;
Frihart, Charles R. 2016. Potential for Biobased Adhesives in Wood Bonding. Proceedings of the 59th International Convention of Society of Wood Science and Technology March 6-10, 2016 - Curitiba, Brazil
Frihart, Charles R.; Birkeland, Michael 2016. Soy Products for Wood Bonding. In: Proceedings of the 59th International Convention of Society of Wood Science and Technology. 7 p.
Frihart, Charles R.; Yelle, Daniel J.; Ibach, Rebecca E. 2015. Wood properties influence bond durability. In: Proceedings of the 5th International Scientific Conference on Hardwood Processing 2015, Sept. 15-17, 2015 pp. 78-84; 2015
Jakes, Joseph E. 2016. Recent advances in forest products research and development. Journal of the Minerals, Metals and Materials. 68(9): 2381-2382.
Jakes, Joseph E.; Arzola, Xavier; Bergman, Rick; Ciesielski, Peter; Hunt, Christopher G.; Rahbar, Nima; Tshabalala, Mandla; Wiedenhoeft, Alex C.; Zelinka, Samuel L. 2016. Not just lumber--using wood in the sustainable future of materials, chemicals, and fuels. Journal of the Minerals, Metals and Materials. 68(9): 2395-2404.
Rohumaa, Anti; Antikainen, Toni; Hunt, Christopher G.; Frihart, Charles R.; Hughes, Mark 2016. The influence of log soaking temperature on surface quality and integrity performance of birch (Betula pendula Roth) veneer. Wood Science and Technology. 50(3): 463-474.
Rohumaa, Anti; Hunt, Christopher G.; Hughes, Mark; Frihart, Charles R.; Kers, Jaan. 2016. Lathe check formation and their impact on evaluations of veneer-based panel bond quality. In: WCTE 2016 World Conference on Timber Engineering. 22-25 August 2016. Vienna, Austria. 6 pp.
Rohumaa, Anti; Yamamoto, Akio; Hunt, Christopher G.; Frihart, Charles R.; Hughes, Mark; Kers, Jaan. 2016. Effect of log soaking and the temperature of peeling on the properties of rotary-cut birch (Betula pendula Roth) veneer bonded with phenol-formaldehyde adhesive. BioResources. 11(3): 5829-5838.
Sun, Grace; Ibach, Rebecca E.; Faillace, Meghan; Gnatowski, Marek; Glaeser, Jessie A.; Haight, John 2016. Laboratory and exterior decay of wood plastic composite boards: voids analysis and computed tomography. Wood Material Science and Engineering. DOI: 10.1080/17480272.2016.1164755. 16 pp.
Yelle, Daniel J.; Stirgus, Ashley M. 2016. Influence of anatomical, physical, and mechanical properties of diffuse-porous hardwoods on moisture durability of bonded assemblies. FPL-GTR-244. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. 8 p.

Progress 10/01/14 to 09/30/15

Outputs
OUTPUTS: Improve properties and performance of adhesives, sealants and coatings for advanced wood products: Synchrotron-based X-ray fluorescence microscopy (XFM) was found capable of mapping and quantifying infiltration of Br-labeled phenol⿿formaldehyde (BrPF) into wood cell walls. Nanoindentation on the same cell walls was performed to assess the effects of BrPF infiltration on cell wall hygromechanical properties. Lower MW BrPF adhesives were more effective at decreasing moisture-induced mechanical softening. Our studies have shown that soy isolate can provide 10 times the wet bond shear strength of soy flour at near neutral pH. We found that adding a variety of carbohydrates to commercial soy protein isolate caused a decrease in wet bond strength, but the carbohydrate plus commercial isolate is still much better than soy flour or a commercial soy concentrate. A research program seeking to discern the significance of environmental and strain effects on sealant durability utilized sealant bonded specimens fixtured in automated test instruments outdoors. Prestraining the sealants before starting the exterior testing resulted in a rapid softening of silicone sealants whereas urethane sealants remained relatively unaffected. Modify wood and bio-fiber materials to improve properties and to maximize end-use performance of advanced bio based composites.: Manufacturing panels from Tetra Pak® (TP) packaging material was investigated as an alternative to conventional wood-based panels. It was seen that especially polyose and lignin bands in FT-IR spectra were affected more than cellulose bands by fungal attack. No changes were observed by the fungi in the plastic component (LDPE) of the matrix; however, LDPE seemed more sensitive to weathering than cellulose. Outdoor durability research on plywood siding highlighted that contact between the bottom of the board and the flashing below is significantly detrimental for every property we observed. Using caulk between ends of boards and vertical trim resulted in slower ultrasonic propagation and lower substrate ratings than flashing the ends, even though the caulking was applied properly. Research on veneers from rotary cut birch (Betula pendula Roth) were produced from logs harvested in spring, autumn and winter, and soaked at 20°C and 70°C prior to peeling. The results show that soaking birch logs at 70°C rather than at 20°C before peeling, or harvesting trees in the spring rather than in the autumn or winter, gives rise to veneers with enhanced wettability and higher bond strengths with a phenol-formaldehyde adhesive. Evaluation of advanced composites: Two wood plastic composite (WPC) boards, one experimental and one commercial, were exposed to exterior conditions and evaluated non-destructively using a clinical magnetic resonance imaging (MRI) unit for moisture content (MC) and distribution. MRI detected the presence of free water and its distribution in both of the WPC boards. There was good correlation between the detection of free water by MRI and by destructive testing. MRI showed various major points of water entry in the WPC boards. MRI was further used to evaluate free water content and distribution in wood-plastic composite (WPC) materials decayed during exterior exposure near Hilo, Hawaii. MRI showed that the expected pattern of free water distribution⿿a moisture gradient from greatest on the outside of the board to least inside⿿was not evident in the decayed board evaluated in this study. On the contrary, a reverse moisture gradient was observed in some areas where there appeared to be a relatively high concentration of free water in the center of the board.

Impacts
This research improved our understanding of the degradation mechanism of materials exposed outdoors, and adverse indoor conditions and provide information for developing new materials. This work leads to scientific approaches for producing adhesives, sealants, coatings, WPCs, and panel products with improved performance. Key publications on best in class methods of wood utilization are critical for such products to regain market share versus petroleum based products.

Publications

Frihart, Charles R. 2015. Introduction to Special Issue: Wood Adhesives: Past, Present, and Future. Forest Products Journal. 65(1-2): 4-8.
Frihart, Charles R.; Birkeland, Michael J. 2014. Chapter 8: Soy Properties and Soy Wood Adhesives. Publication Date (Web): December 23, 2014. In Soy-Based Chemicals and Materials; Brentin; ACS Symposium Series; American Chemical Society: Washington, DC, Chapter 8, 2014; pp. 167-192.
Gnatowski, Marek; Ibach, Rebecca; Leung, Mathew; Sun, Grace 2014. Magnetic resonance imaging used for the evaluation of water presence in wood plastic composite boards exposed to exterior conditions. Wood Material Science and Engineering, 2014; 18p.
Hunt, Christopher G.; Schueneman, Gregory T.; Lacher, Steven; Wang, Xiping; Williams, R. Sam 2015. Non-destructive Analysis Reveals Effect of Installation Details on Plywood Siding Performance. USDA Forest Service, Forest Products Laboratory, General Technical Report, FPL-GTR-239, 2015; pp. 314-320.
Ibach, Rebecca; Sun, Grace; Gnatowski, Marek; Glaeser, Jessie; Leung, Mathew; Haight, John 2015. Exterior Decay of Wood-Plastic Composite Boards: Characterization and Magnetic Resonance Imaging. Forest Products Journal: 150706092112008-.
Jakes, Joseph E.; Hunt, Christopher G.; Yelle, Daniel J.; Lorenz, Linda; Hirth, Kolby; Gleber, Sophie-Charlotte; Vogt, Stefan; Grigsby, Warren; Frihart, Charles R. 2015. Synchrotron-based X-ray Fluorescence Microscopy in Conjunction with Nanoindentation to Study Molecular-Scale Interactions of Phenol⿿Formaldehyde in Wood Cell Walls. ACS Applied Materials & Interfaces. 7(12): 6584-6589.
Lorenz, Linda; Birkeland, Michael; Daurio, Chera; Frihart, Charles R. 2015. Soy Flour Adhesive Strength Compared with That of Purified Soy Proteins*. Forest Products Journal. 65(1-2): 26-30.
Senalik, Adam C.; Schueneman, Greg; Ross, Robert J. 2014. Ultrasonic-Based Nondestructive Evaluation Methods for Wood: A Primer and Historical Review. USDA Forest Service, Forest Products Laboratory, General Technical Report, FPL-GTR-235, 2014; 36 p.
Yilgor, Nural; Kose, Coskun; Terzi, Evren; Figen, Aysel Kanturk; Ibach, Rebecca; Kartal, S. Nami; Piskin, Sabriye 2014. Degradation Behavior and Accelerated Weathering of Composite Boards Produced from Waste Tetra Pak® Packaging Materials. BioResources, Volume 9, Number 3, 2014; pp. 4784-4807.
Rohumaa, Anti; Hunt, Christopher G.; Frihart, Charles R.; Saranpää, Pekka; Ohlmeyer, Martin; Hughes, Mark 2014. The influence of felling season and log-soaking temperature on the wetting and phenol formaldehyde adhesive bonding characteristics of birch veneer. Holzforschung Volume 68, Number 8, 2014; pp. 965⿿970.
Schueneman, Gregory T.; Lacher, Steven; Hunt, Christopher G. 2015. Monitoring Sealant Durability during Instrumented Outdoor Exposure with Variation in Prestrain. In: Proceedings of the Annual Meeting of the Adhesion Society, Savannah, GA 2015; 4 p.

Progress 10/01/13 to 09/30/14

Outputs
OUTPUTS: Evaluation of advanced composites: Wood-plastic composites deck boards (WPC) were manufactured and then evaluated in the laboratory and field (Hilo, Hawaii and Vancouver, British Columbia). Water absorption, biological activity, density change, and optical and scanning electron microscopy were used to monitor the field boards. The laboratory soil block test was performed with modifications to preconditioning the samples. Weight loss and density decrease were determined and then compared to the field results. Specimens were evaluated using magnetic resonance imaging (MRI) and micro x-ray and computed tomography (CT). This is the first research to show the structure of decayed WPCs using image void analysis to quantitatively analyze the decay process nondestructively. The research results were used to change the AWPA Standard E10 to add wood-based and WPC's to the Standard and to recommend conditioning of the specimens prior to decay evaluations. Chemically modified or treated wood flour were used to make WPC⿿s to improve the moisture and/or fungal durability of WPC⿿s. Acetylation decreased the moisture sorption of the WPCs and showed no mass losses due to decay. The WPC with an isothiazolone-based treatment did not show any mass losses due to fungal decay. In another study, the properties of WPCs reinforced with extracted and delignified wood flour were evaluated. Results showed the effect of removal of various wood components, and led to better understanding durability. Improve properties and performance of adhesives and coatings for advanced wood products: A new source of lignin is that recovered from partial acidulation of the black liquor from the Kraft pulping process. This study showed that the lignin had good reactivity and could replace some of the phenol in phenol-formaldehyde adhesives. Thus, this is a potential market for this new lignin source in a large market and would provide exterior and structural grade bonded wood products with a higher biobased content. Interior plywood was originally made with soy flour adhesives until the lower cost and better performing urea-formaldehyde adhesives replaced them. However, the concern over formaldehyde emissions and a new curing technology has brought increased use of soy flour adhesives. However, the economical soy flour has much poorer performance than does the commercial soy protein isolate. This research demonstrated that the high amount of carbohydrates in the soy flour compared to the soy protein is part of the cause of poorer performance. A variety of protein sources have been used as wood adhesives with soy and casein being the dominate ones Although egg whites have not been tested as a wood adhesive, we found that they provide very good wood adhesives in their unpurified state and were easier to use due to their very low viscosity. There is a considerable volume of non-food grade egg whites that are obtained by washing the residue out of egg shells from commercial egg processing. Thus bonded wood products can be made with an unusual biobased by-product. Lathe checks (cracks) in plywood veneers form on the side that passes over the knife blade due to the bending of the wood. These checks are normally buried on the inside of the plywood so that they have not been of much concern for making plywood. However, this study shows that if the checks are too deep, they alter the bond failure mechanism and lead to what appears to be an adhesive failure. However, the actual failure is in the wood, and this type of deep checks can prevent a normally good adhesive from passing performance tests. The data also shows that the ASTM tests are more rigorous than a similar European test due to requirements on check orientation. This is not only commercially important information, but provides fundamental information on bond failure mechanisms and demonstrates international cooperation since most of the work was done at Aalto University in Finland.

Impacts
This research will improve our understanding of the mechanisms for degradation of materials exposed outdoors, and adverse indoor conditions and provide information for developing new materials. This work leads to scientific approaches for producing products with improved performance. Key publications on best in class methods of wood utilization are critical for such products to regain market share versus petroleum based products.

Publications

Frihart, Charles R.; Satori, Holly; Rongxian, Zhu; Birkeland, Michael J. 2014. Ovalbumin as a Wood Adhesive. In: The Adhesion Society's 37th Annual Meeting February, 23-26, 2014, Bahia Resort Hotel, San Diego, CA. from CD TEH801043052B03. 2014; 3 p.
Ibach, Rebecca E.; Chen, Yao; Stark, Nicole M.; Tshabalala, Mandla A.; Fan, Yongming; Gao, Jianmin 2014. Decay resistance of wood-plastic composites reinforced with extracted or delignified wood flour. IRG/WP 14-40655, THE INTERNATIONAL RESEARCH GROUP ON WOOD PROTECTION Section 4, Processes and properties, Paper prepared for the 45th IRG Annual Meeting St George, Utah, USA, 11-15 May, 2014 pp. 2-9.
Chen, Yao; Frihart, Charles R.; Cai, Zhiyong; Lorenz, Linda F.; Stark, Nicole M. 2013. Lignin-based Phenol-Formaldehyde Resins from Purified CO₂ Precipitated Kraft lignin (PCO₂KL). In: International Conference on Wood Adhesives, October 9-11, 2013 Toronto, Ontario Canada from CD ISBN: 978-0-935018-37-0; 2013; pp. 601-610.
Ibach, Rebecca E.; Gnatowski, Marek; Sun, Grace 2013. Field and Laboratory Decay Evaluations of wood-plastic Composites. Forest Prod. J. Volume 63, Number 3/4, pp. 76⿿87.
Ibach, Rebecca E.; Lebow, Patricia K. 2014. Strength loss in decayed wood. In: the McGraw-Hill Encyclopedia of Science & Technology, 2014; pp. 368-371.
Rohumaa, Anti; Hunt, Christopher G.; Hughes, Mark; Frihart, Charles R.; Logren, Janne 2013. The influence of lathe check depth and orientation on the bond quality of phenol-formaldehyde-bonded birch plywood. Holzforschung 67(7): 779-786.
Chen, Yao; Stark, Nicole M.; Tshabalala, Mandla A.; Gao, Jianmin; Fan, Yongming 2014. Properties of wood-plastic composites (WPCs) reinforced with extracted and delignified wood flour. Holzforschung 2014; 8 p.
Frihart, Charles R.; Lorenz, Linda F. 2013. Comparing Soy Flour Wood Adhesives to Purified Soy Protein Adhesives. In: International Conference on Wood Adhesives, 2013; pp. 592-600.
Segerholm, B. Kristoffer; Ibach, Rebecca E. 2013. Moisture and Fungal Durability of Wood-Plastic Composites Made With Chemically Modified and Treated Wood Flour. THE INTERNATIONAL RESEARCH GROUP ON WOOD PROTECTION, Section 4, Processes and Properties, IRG/WP 13-40648; 2013; 8 p.
Sun, Grace; Ibach, Rebecca; Gnatowski, Marek; Glaeser, Jessie; Leung, Mathew; Haight, John. 2014. Modern Instrumental Methods to Investigate the Mechanism of Biological Decay in Wood Plastic Composites. IRG/WP 14-40674, The international Research Group on Wood Protection, section 4, Processes and properties, Paper prepared for the 45th IRG Annual Meeting, St George, Utah, USA, 11-15 May 2014; pp. 2-20;.

Progress 10/01/12 to 09/30/13

Outputs
OUTPUTS: Evaluation of advanced composites: Nanoindentation and Brinell hardness testing was used to understand the in﬿uence of formaldehyde/urea (F/U) mole ratio on the properties of urea⿿formaldehyde (UF) resins. Both hardness measurements were found to increase with F/U ratio and post cure temperature. Modulus values were more variant most likely due to the presence of crystalline and non-crystalline domains in the cured film. Polycaprolactone (PCL) filled with microcrystalline cellulose (MCC), wood flour (WF), or both were characterized before and after exposure to various environmental conditions. WF performed better when paired with PCL than MCC. Only minor deterioration was induced by environmental aging. Fungal exposure (Gloeophyllum trabeum) only decayed the WF composites. Improve properties and performance of adhesives and coatings for advanced wood products: Research was conducted to investigate the effect of temperature and humidity on newer commercial California Air Resources Board phase II��compliant particleboard produced with UF-type adhesives. The formaldehyde emissions from the commercial particleboard panel bonded with a UF-type resin increased greatly when panels were exposed to higher heat and humidity than in normal testing protocols. Furthermore, the rate of emission for these UF-bonded panels increased with longer exposure at 100 percent relative humidity. In contrast, formaldehyde emissions from particleboard bonded with the NAF adhesive were relatively stable and significantly lower compared with those bonded with UF at all temperature and relative humidity conditions. Research examined the performance of commercially available soy ﬿ours that have their proteins either mainly in their native (90 protein dispersibility index (PDI)) or denatured (70 and 20 PDI) states. We expected that the more native state soy proteins with their better dispersibility would provide better adhesion to wood surfaces and enhanced reaction with the curing agent. Small-scale wood bonding tests showed that neither of these effects was observed. In addition to research activities a book chapter reviewing wood adhesives was authored and published and we participated in the update and passing of ASTM D2559 Standard Specification for Adhesives for Bonded Structural Wood Products. The high temperature performance of soy meal processed to different protein concentrations (flour, concentrate, and isolate), as well as formulated soy-based adhesives, and commercial non-soy adhesives for comparison were evaluated for thermal stability and use temperature ranges. These were compared versus adhesives used in commercial applications that require heat resistance, such as structural adhesives. Soy based adhesives were found to perform sufficiently to likely pass heat resistance requirements for structural adhesives.

Impacts
This research will improve our understanding of the mechanisms for degradation of materials exposed outdoors, and adverse indoor conditions and provide information for developing new materials. This work leads to scientific approaches for producing products with improved performance. Key publications on best in class methods of wood utilization are critical for such products to regain market share versus petroleum based products.

Publications

Frihart, Charles R. 2013. Wood adhesion and adhesives. In: Rowell, Roger, ed. Handbook of Wood Chemistry and Wood Composites, Second edition. Boca Raton, FL: CRC Press: 255-319. Chapter 9.
Frihart, Charles R.; Satori, Holly. 2013. Soy flour dispersibility and performance as wood adhesive. Journal of Adhesion Science and Technology. 27(18-19): 2043-2052.
Frihart, Charles R.; Wescott, James M.; Chaffee, Timothy L.; Gonner, Kyle M. 2012. Formaldehyde emissions from urea-formaldehyde- and no-added-formaldehyde-bonded particleboard as influenced by temperature and relative humidity. Forest Products Journal. 62(7/8): 551⿿558.
Ibach, Rebecca E. 2013. Biological properties of wood. In: Rowell, Roger, ed. Handbook of Wood Chemistry and Wood Composites, Second edition. Boca Raton, FL: CRC Press. 99-126. Chapter 5.
O⿿Dell, Jane L.; Hunt, Christopher G.; Frihart, Charles R. 2013. High temperature performance of soy-based adhesives. Journal of Adhesion Science and Technology. 27(18-19): 2027-2042.
Park, Byung-Dae; Frihart, Charles R.; Yu, Yan; Singh, Adya P. 2013. Hardness evaluation of cured urea-formaldehyde resins with different formaldehyde/urea mole ratios using nanoindentation method. European Polymer Journal. 49(10): 3089-3094.
Sabo, Ronald; Jin, Liwei; Stark, Nicole; Ibach, Rebecca E. 2013. Effect of environmental conditions on the mechanical properties and fungal degradation of polycaprolactone/microcrystalline cellulose/wood flour composites. BioResources. 8(3): 3322-3335.