Progress 03/01/24 to 02/28/25
Outputs
Target Audience:The target audience reached were wood composite manufacturers, researchers, industry leaders in the Pacific Northwest, and students. Efforts to reach this target audience included: 1. Technical presentation at Timber 2019 in London, UK. The audience included manufacturers, end users of wood composite panels, researchers, and students from different European countries. 2. Personal meetings with industry to discuss the potential of resin transfer molding of wood strands and natural fiber mats into architectural panels. 3. Samples of resin transfer molded wood strand composite panels were showcased at CleanTech Innovation Showcase 2019 in Seattle, WA. 4. Provided experiential learning experience to NSF Summer REU students. Students were taught and trained in the RTM of composite panels. With this experience, the REU students produced and evaluated hybrid composite panels of basalt and natural fiber. 5. Technical presentation at WSU Mechanical and Materials Engineering Research Symposium. Professors and students were informed about the potential of producing natural fiber composite panels from agricultural waste. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?One graduate student (PhD), Gemma Samantha Criollo, is working on the project alongside the PI and the co-PIs. She has been working this year and will continue to work to fulfill the research objectives. Postdoc was enable to mentor the graduate student and the undergraduate students with certain tasks to develop human and project management skills. How have the results been disseminated to communities of interest?Results were shared at the WSU Mechanical and Materials Engineering Research Symposium, and a manuscript is in preparation to be submitted to the Sustainable Materials and Technology Journal. What do you plan to do during the next reporting period to accomplish the goals?Results to complement the characterization of fiber types of Objective 1 would be reported, as well as a thorough analysis of the fabrication of single-particulate and hybrid natural fiber panels, as per Objectives 2 and 3. The results will also be disseminated as an article in the Sustainable Materials and Technology Journal. They will also be presented at the International Materials Research Congress 2025 in Cancún, Mexico, and the 6th International Conference on Materials Science and Engineering in Seattle, Washington.
Impacts
What was accomplished under these goals?
Objective 1 Research focused on hazelnut shells, einkorn and emmer hulls, coconut husk, and hemp hurd. Particle morphology was analyzed with SEM. Surface morphology shows that hazelnut shells have smooth epicarp surfaces with minimal root hairs. Einkorn and emmer hulls feature micro-bumps and trichomes, potentially improving interfacial bonding. Coconut husk has layered structures, creating an uneven texture, whereas hemp hurd has a rough, porous surface, which may enhance resin penetration. Cross-sectional analysis revealed that hazelnut husk consists of sclereids and thick sclerenchyma walls for mechanical support. Emmer and einkorn hulls have thin-walled parenchyma cells, crucial for water transport. Coconut husk contains sclerenchyma cells and coir, enhancing structural support. Hemp hurd has parenchyma cells and xylem vessels, improving water transport. Particulate wetting behavior, which affects fiber-polymer adhesion, was analyzed by contact angle and surface tension measurements over 240s at 15s intervals. Hazelnut shells, emmer and einkorn hulls, and coconut husks showed initial contact angles above 90°, indicating hydrophobicity, with gradual declines suggesting slow water interaction. In contrast, hemp hurd reflected strong hydrophilicity and high water absorption due to its porous structure. Surface tension trends confirmed these results, with hazelnut shells keeping the lowest value due to their hydrophobic nature. Particulate properties were analyzed to assess packing behavior. Table 1 presents the results, revealing a correlation between bulk density, tap density, and FVF. Particulates with higher bulk densities achieve higher FVFs, indicating better packing efficiency. This trend is also reflected in the porosity percentages, with hazelnuts having the lowest estimated porosity. Table 1: Particulate properties Particle Density g/cm³ Bulk Density g/cm³ Tap Density g/cm³ Est. Panel FVF % Est. Panel Porosity % Hazelnut 1.17 ± 0.08 0.64 ± 0.04 0.67 ± 0.01 58.5 ±0.6 48.5 ± 0.6 Emmer 0.62 ± 0.15 0.16 ± 0.01 0.18 ± 0.01 29.6 ± 0.5 71.1 ± 0.5 Einkorn 0.74 ± 0.05 0.09 ± 0.01 0.10 ± 0.01 13.6 ± 0.2 86.2 ± 0.2 Coconut 0.65 ± 0.02 0.11 ± 0.01 0.15 ± 0.01 22.8 ± 0.3 77.2 ± 0.3 Hemp 0.31 ± 0.12 0.13 ± 0.01 0.15 ± 0.01 25.0 ± 0.6 75.0 ± 0.6 This study reveals a complex interplay between particulate morphology, physical properties, and wettability in composite production. Future research will examine particulate wettability with epoxy and determine its chemical composition to assess its impact on panel production. Wheat and barley straw will also be studied for a broader fiber behavior perspective. Objective 2 Based on the findings from research objective 1, F-VARTM (Framed Vacuum-Assisted Resin Transfer Molding) was used to produce 12-inch panels. The fibers were infused with a 300-cps epoxy resin supplied by Composite Envisions. The panels' infusion process and physical properties were determined, as shown in Table 2. Hazelnut shell panels had the highest FVF and density, the lowest infusion time, and resin content, suggesting efficient resin uptake and minimal voids within the composite. Hemp hurd panels, however, had the lowest FVF and longest infusion time, indicating lower packing efficiency and high porosity. Table 2: Infusion and physical properties of panels Infusion time s FVF % Density g/cm³ Resin content g Hazelnut shells 157.5 ± 3.5 55.0 ± 0.8 1.04 ± 0.01 520.23 ± 18.21 Emmer hulls 405.0 ± 143.4 31.5 ± 1.6 0.94 ± 0.01 889.92 ± 65.64 Einkorn hulls 428.4 ± 60.6 18.4 ± 0.1 1.02 ± 0.01 889.54 ± 64.70 Coconut husk 1388.4 ± 4.8 24.8 ± 0.5 0.97 ± 0.03 793.60 ± 50.30 Hemp hurd 1779 ± 29.7 24.4 ± 1.9 0.98 ± 0.07 983.24 ± 111.96 Table 3 highlights the mechanical property differences among the panels. Table 3. Mechanical properties of panels Bending Strength MPa Bending Modulus GPa Withdrawal Strength N/mm Hazelnut shells 25.79 ± 2.27 3.31 ± 0.15 102.49 ± 4.73 Emmer hulls 22.63 ± 2.66 6.59 ± 1.07 219.00 ± 14.10 Einkorn hulls 25.27 ± 2.37 5.63 ± 0.53 208.10 ± 23.00 Coconut husk 28.76 ± 8.44 4.88 ± 0.24 208.48 ± 59.30 Hemp hurd 31.18 ± 4.29 7.12 ± 1.45 141.21 ± 8.00 The dimensional stability of the panels was assessed. Hazelnut shell panels showed the highest stability, with a water absorption (WA) of 0.93% and thickness swelling (TS) of 0.33%. Coconut husk and hemp hurd panels performed well, with WA values of 1.39 ± 0.02% and 1.88 ± 0.55% and TS values of 2.17 ± 0.54% and 1.36 ± 0.26%, respectively. Einkorn hull panels showed moderate stability with WA of 1.79 ± 0.09% and TS of 2.22 ± 0.89%. Emmer hull panels had the highest WA (2.02 ± 0.06%) and TS (2.72 ± 0.37%), showing the lowest resistance to dimensional changes. Objective 3 Research on Objective 3 is ongoing, with initial studies focusing on hybrid single-particulate panels with three-ply plywood backing. Table 4 presents the infusion and physical properties of hybrid panels infused with 300-cps epoxy resin. The results show that plywood backing increases infusion time due to the porosity difference between particulates and wood. However, the trend remains consistent, with hazelnut shell panels requiring the shortest infusion time. Plywood incorporation increases FVF in most panels and reduces resin content by about 20%. Table 4. Properties of hybrid panels Infusion time s Panel FVF % Density g/cm³ Resin content g Hazelnut shells 276.6 ± 63.6 57.8 ± 2.3 1.02 ± 0.01 540.81 ± 50.64 Emmer hulls 1044 ± 160.2 55.7 ± 0.5 0.80 ± 0.01 702.18 ± 0.81 Einkorn hulls 2106.6 ± 338.4 52.6 ± 1.4 0.82 ± 0.01 709.56 ± 40.72 Coconut husk 1104 ± 949.8 54.7 ± 1.3 0.81 ± 0.01 743.28 ± 37.99 Hemp hurd 2293.8 ± 150.0 41.3 ± 5.3 0.87 ± 0.01 835.15 ± 96.47 Mechanical properties of hybrid panels issummarized in Table 5. Emmer and einkorn hull panels had the highest bending strength and modulus, suggesting that the stiffness of the plywood layer works synergistically with these particulates. In contrast, hazelnut shells and hemp hurd panels showed the lowest values. Einkorn and emmer hull panels outperformed the others for withdrawal strength, while hazelnut shell panels demonstrated the weakest fastener-holding capability. Overall, plywood incorporation enhanced the panels' mechanical properties. Table 5. Mechanical properties of hybrid panels Bending Strength MPa Bending Modulus GPa Withdrawal Strength N/mm Hazelnut shells 95.80 ± 13.38 6.18 ± 0.29 217.49 ± 19.70 Emmer hulls 147.34 ± 19.36 13.72 ± 0.97 295.53 ± 14.08 Einkorn hulls 137.81 ± 5.73 13.14 ± 2.20 302.09 ± 15.40 Coconut husk 118.3 ± 5.77 9.00 ± 1.57 264.81 ± 66.04 Hemp hurd 110.39 ± 23.49 8.44 ± 0.99 268.05 ± 43.77 In the project's next phase, single particulate and hybrid panels would be scaled to assess whether the observed trends remain consistent and to evaluate the feasibility of large-scale production.
Publications
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Progress 03/01/23 to 02/29/24
Outputs
Target Audience:Currently, companies produce decorative panels using technology that requires high capital investment and longer processing times. Currently marketed natural fiber decorative panels are resin-rich, expensive, and very low in fiber volume fraction. Our technique will help produce decorative panels from natural fiber particulates in a setup that is not all-metal, provides process flexibility, requires lower capital investment, and produces panels with high fiber volume fractions and cost less. We are actively in touch with Formology, producers of decorative panels using hot-pressing. Formology is interested in F-VARTM technology to produce high-end panels for moisture-rich environments. Their clients, Dutch Brothers and Ferrero, are eager to use their waste streams to produce decorative panels for various applications. In addition, we have also reached out to growers of ancient grain crops (Bluebird Grain) and hazelnuts (Wazelnut Farms). These growers are interested in using their fiber waste streams to generate additional revenues. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?One PhD student, Gemma Samantha Criollo, has been recruited to work on the project alongside the PI and the co-PI. She joined the research team in January, 2024. Co-PI and postdoctoral research associate, Avishek Chanda, has been conducting part of the research since the project initiation and has been given the opportunity to present the results at a regional conference in Oregon. How have the results been disseminated to communities of interest?Preliminary results have been disseminated at a regional conference in Oregon. Chanda, A., Bakri, MKB., Yadama, V. (2023, August 27-30). Decorative Panels Fabricated from Agricultural Waste By-products, 34th AAIC Annual Meeting - Building sustainable bioeconomies with industrial crops and products, Oregon State University, Corvallis, Oregon, USA What do you plan to do during the next reporting period to accomplish the goals?Detailed characterization of the fiber types, as per Objective 1, will be the focus during the next reporting period. This will include characterization of different fiber types to analyze their physical properties and processing them into appropriately sized feedstock of fibers, particles or stalks for preform preparation. Research will concentrate on fiber processing techniques and understanding each fiber type's physical properties, including morphological aspects, porosity, void content, particle size distribution, structure, shape, wetting behavior, resin interaction, compaction ratio, and preform packing limitations. Prelimary resin flow analysis to understand the difference in fiber type will also be conducted. These results will be presented at a national conference as well as published in a refereed journal. Gemma Criollo will be primarily working on these tasks with help from Co-PI and PI.
Impacts
What was accomplished under these goals?
Research work on Objective 1 is ongoing, with preliminary studies on fabricating decorative panels using the framed-VARTM technique and extensive literature review is being currently carried out. Resin transfer molding, using VARTM, has been carried out for many decades, with studies focusing on using resins with varying viscosities. Viscosity plays a critical role in the infusion process, and therefore, studies have shown that lower viscosities (lower than 800 cps) worksatisfactorily with the process, whereas those higher than 800 cps often failto complete the process successfullywithout the influence of external pressures. Different furnish types have varying influence on the process as their shapes,sizes, and interaction with resin could vary. Therefore, structure of the fibers or stalks and how they breakdown during processing should be studied. It is also critical to evaluate the packing behavior of the fiber particles. Studies have proven that lower resin visosity helps to complete the infusion process faster in thin preforms in a given direction. But this could change even in thin preforms due to fiber orientation and flow direction of the resin. Resin flow becomes more complex and critical as preforms become thicker and wetting behavior changes with fiber type. Additionally, we need to also consider the particle shape relative to the packing bahavior as that would change the porous structure of the media that resin has to flow through.In Year 1, we have carried out preliminary studies with epoxy resins having viscosity of 600 cps and 300 cps, which were commercially available from Composite Envisions. F-VARTM, a novel modification of the traditional VARTM processes, has been used to produce decorative panels, extensively from hazelnut shells, while some preliminary panels have also been fabricated from emmer hulls, received from Bluebird Farms. Initial study was carried out to establish that the panels made from F-VARTM had similar properties to those made from all-metal molds. Mechanical studies conducted proved that the flexural strength of panels fabricated using F-VARTM were 25.5±1 MPa, which is only 8% lower than that in panels fabricated using an all-metal mold. This variation is negligible and can be attributed to the more condensed packing and ~10% increase infiber volume fraction using an all-metal mold. Similarly, the bending modulus also had a small variation of 6%, where the panels fabricated using F-VARTM yielded a modulus of 4.73±0.1 GPa, compared to 5±0.3 GPa for the panels fabricated in an all-metal mold. Hazelnut shells were dried to a MC of less than 1% before infusion. Lower fiber volume fraction directly infers that the amount of resin content is higher in the panels made using the F-VARTM techniques, making them dimensionally more stable, with only 0.9% water absorption and 0.2% thickness swell, compared to 2.8% and 1% obtained from panels fabricated in all-metal molds, respectively. The comparison was carried out with Infusion Grade Epoxy resin, sourced from Composite Envisions, having a viscosity of 600 cps. With the variations and similarities established, further studies were carried out to compare the mechanical properties and dimensional stabilities among panels made using the F-VARTM technique from different furnishes. Initial comparisons were carried out between panels made from the ancient emmer hulls and hazelnut shells with epoxy resin having 300 cps. The process time was significantly higher for the emmer panels, filling at a rate of 0.98 sec/mm compared to 0.52 sec/mm in the hazelnut panels. The flexural analysis indicated that the panels made from hazelnut as feedstock had superior structural properties; this can be attributed to significantly higher fiber volume fractions in hazelnut shell panels. The bulk densities of different feedstocks varied significantly, with hazelnut having 656.5±14.63 kg/m3 bulk density compared to only 154.2±9.2 kg/m3 of the emmer hulls. The variation in bulk density directly influenced the fiber volume fraction and the final panel density. The fiber volume fraction of the hazelnut panels was calculated to be 61.14±0.47%, compared to 38.62±1% in the panels made from ancient emmer hulls. The panel density was also lower (983.85±14.4 kg/m3) for the emmer reinforced panels compared to 1150.93±37.2 kg/m3 for the hazelnut panels. Interestingly, the flexural strength was observed to be 26.9±1.1 MPa, which was very similar to that observed for the hazelnut panels (25.5±1 MPa). Therefore, it can be concluded that the bending strength of the panels depended on that of the resin, as the epoxy resin failed first, resulting in the flexural failure in the panels. The modulus of the emmer panels was 3.8±0.04 GPa, which was slightly lower than that of the hazelnut panels. Thus, higher density had a direct influence on the panel stiffness. The comparison on the dimensional stability of the panels showed that those with hazelnut had higher stability with water absorption (WA) of 0.93% and thickness swell (TS) of 0.33%, compared to 1.1% WA and 0.95% TS in the emmer panels, once again fiber volume fraction influencing this behavior. One of the challenges in commercialization is having dried furnish every time before infusion. Our industry collaboratorare interested in reducing the furnish drying costs. Therefore, both the hazelnut shells and emmer hulls were used directly as supplied by the supplier for making panels using F-VARTM and the properties were compared to those made with dry furnish. The moisture content in the fiber supplied was calculated to be about 11.5% for both. The dimensional stability showed significant changes, with both the panels having about 0.84% WA and 0.26% TS. The flexural properties, however, were observed to be similar for both the furnish types, when compared to their dry counterparts, with the hazelnut as-is panels having a strength of 25.43±2.2 MPa and modulus of 4.4±0.2 GPa, and the emmer as-is panels having a strength of 27.5±1.3 MPa and modulus of 3.7±0.2 GPa. This helped establish that as-is furnish can be used without the need of drying, making the panels more dimensionally stable with similar mechanical properties. A trial on wet, 20% MC moisture content of hazelnut shells, was also carried out, where the infusion process failed to complete due to high moisture, resulting in bad quality panels. Therefore, although as-is furnishcan be used conveniently, it is important that they are at least dried to ambient conditions of less than 12% moisture content based on this initial study. More research will be conducted in this area. A comparison of screw withdrawal test between the as-is hazelnut and emmer panels showed that the emmer panels had higher strengths at 141.2±44.1 N/mm compared to 102.5±4.7 exhibited by the hazelnut panels. One of the possible reasons might be bulk density and relative hardness of the particulates, where the emmer hulls being softer with higher compaction of .1 inch or 2.54 mm compared to that of hazelnut shells (0.078 in or 1.98 mm), resulted in better gripping of the screws. However, elaborate studies will be required to further understand the reasons in detail. These will be carried out in the subsequent years of the project.
Publications
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