Scholarly Works, Sustainable Biomaterials
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- Optimizing Lumber Densification for Mitigating Rolling Shear Failure in Cross-Laminated Timber (CLT)Pradhan, Suman; Mohammadabadi, Mostafa; Seale, Roy Daniel; Thati, Manikanta; Entsminger, Edward D.; Nkeuwa, William Nguegang (MDPI, 2024-04-04)Rolling shear in cross-laminated timber (CLT) has been identified as the governing factor influencing design value. Likewise, densification has been found to be an effective method of enhancing the rolling shear strength of lumber and in turn, CLT. In this study, utilizing knowledge of material properties, optimization of the compression ratio for densification has been presented. Three-layered CLT beams made from non-densified lumber, grade #1 loblolly pine (Pinus taeda L.), were subjected to a bending load at a span-to-depth ratio of eight and had a rolling shear failure at the mid-layer with a shear strength of 3 MPa. Assuming the same modulus of rupture (MOR) for both lumber and CLT made from the same species and grade, the MOR of lumber was used to calculate the minimum required shear strength (MRSS) of the transverse mid-layer to change the failure mode of the CLT beam from rolling shear to tensile failure. Using the relationship between the compression ratio and the increase in rolling shear strength, the optimized compression ratio for densification was calculated. This procedure resulted in a compression ratio of 16.67% for densification of the mid-layer to avoid rolling shear in the case of CLT beams with a span-to-depth ratio of eight. To verify this process, CLT beams with mid-layers densified at 16.67% were fabricated and submitted to a bending test. Rolling shear failure was mitigated and densified CLT beams failed in tension with a MOR similar to that of lumber, 47.45 MPa. Likewise, rolling shear strength was observed to increase by 48% for CLT that had a densified mid-layer at 16.67%.
- Measurement and Analysis of the Shock and Drop Levels Experienced by Small and Medium Packages in the Korean Parcel Delivery SystemKim, Saewhan; Horvath, Laszlo; Lee, Sangwook (MDPI, 2024-05-08)South Korea is one of the leading markets for the e-commerce industry. In line with the rapid growth of the e-commerce industry, the parcel delivery volume in Korea has also proliferated. Despite the developments in the Korean e-commerce and courier industries, consumers still experience a high package damage rate. In response, many packaging engineers in Korea have raised the need for new parcel shipping environment tests that reflect the Korean ground shipping environment in order to properly optimize packages. However, only limited information on the Korean parcel shipping environment is currently available. Therefore, this study focused on measuring and analyzing the shock and drop levels that parcels experience during ground shipping in Korea. Shock data were collected from a total of sixty one-way shipments for small, lightweight packages and medium, mid-weight packages. The findings revealed that the two types of boxes do not experience significantly different numbers of shock events or drop heights in the Korean parcel delivery environment. Furthermore, the number of shock events that occur in Korea is substantially less than the international testing standard and less than in previous studies conducted in both Europe and the USA. In contrast, however, the drop heights are higher than those in the international testing standard and previous studies. Shock events were found to occur most frequently on the edges and to be concentrated around the bottoms of the packages. Most shock events happen while packages are loaded and unloaded at hub terminals and sub terminals.
- Analysis of Deformation Fixation of Thermally Compressed Scots Pine (Pinus sylvestris L.)Li, Lili; Shan, Xiaofei; Luo, Zhiying; Liu, Wenwen; Liu, Jianxia; Yu, Jianfang; Chen, Zhangjing; Wang, Ximing (MDPI, 2024-05-11)Heat treatment effectively inhibits the water absorption recovery of compressed wood. To elucidate this phenomenon, we prepared compressed pine and thermally compressed pine (heartwood and sapwood) using the hot pressing method at 160 °C, 180 °C, 200 °C, and 220 °C. The effects of chemical components, swelling stresses, and monosaccharides on modified wood recovery were investigated using regression analyses. Notably, the recovery of both compressed heartwood and sapwood during water absorption declined from 18.89% to 2.66% and from 58.40% to 1.60%, respectively, after heat treatment. Similarly, the swelling stresses of the compressed heartwood and sapwood at 220 °C, respectively, ranged from 0.693 MPa to 0.275 MPa and from 0.783 MPa to 0.330 MPa. These were close to the values of untreated heartwood (0.175 MPa) and sapwood (0.225 MPa). Regression functions indicated that the recovery of compressed wood is chemically dependent on hemicellulose and mechanically related to swelling stress. For monosaccharides, regression functions indicated that modified heartwood recovery primarily relied on mannose, whereas modified sapwood recovery was remarkably affected by mannose and xylose. This confirmed that the pyrolytic monosaccharides in hemicellulose promoted stress relaxation, which induced the deformation fixation of thermally compressed wood.
- Measurement and Analysis of Last-Mile Parcel Delivery Truck Vibration Levels in KoreaKim, Saewhan; Horvath, Laszlo; Lee, Soohyung; Lee, Sangwook (MDPI, 2024-04-12)South Korea has one of the largest e-commerce markets in the world. The last-mile delivery segment of e-commerce often causes critical damage to products in protective packages. Despite the rapid growth of the e-commerce market in Korea, the last-mile distribution environment has not yet been thoroughly investigated. The main aim of this study was to provide an understanding of the vibration levels that were measured from various parcel delivery routes within Seoul, Korea, using common types of parcel delivery trucks. Vibration levels of ten delivery trucks were measured and analyzed in terms of power spectral densities (PSDs) and presented as PSD spectra. The last-mile delivery vehicle vibration levels in Korea were found to be consistently lower (in the 1 to 200 Hz frequency range) than those recommended by international standards and lower than the vibration levels of parcel delivery vehicles in the U.S. and Hungary. The results also revealed that the highest intensity peak of the PSD spectrum for Korea was located in the lower frequency range (1.5 to 2 Hz) compared to the ISTA 3A pickup and delivery test profile (3 to 4 Hz) and the test profile recommended for Hungary (13 to 16 Hz). A smoothed composite spectrum was also provided to support Korean packaging engineers in optimizing their packages by simulating proper last-mile truck delivery vibration levels in lab conditions.
- Realizing a dream: linking sustainable enterprise development with sound forest management – the case for Black Walnut SyrupHammett, A. L. (Tom) (New River Symposium, 2024-04-12)Virginia Tech and Future Generations University have been collaborating on projects in the region that foster sustainable nature-based enterprises. For several years, the focus has been on maple syrup, a product with a deep heritage in the New River Valley and surrounding areas. Recently, we have built on the experience with sugar maple, and have conducted research and outreach with another tree syrup – black walnut. Black walnut is plentiful and well suited to many sites in the region. The tapping process ensures that the tree is not harmed and will continue to provide ecological benefits. Well known in other regions for its timber quality, the species is not well known for producing tree syrup. But black walnut syrup is not well-known but is fetching higher prices than maple syrup and is popular among bakers, especially in the New York City area. The author won first prize for his black walnut syrup at the 2022 New River Valley Fair! Our outreach and research projects have focused on tree syrup and non-timber forest products. Many in the area request assistance to assess the potential for tree saps. Our team has developed demonstration sites and conducted outreach activities with landowners at several sites including Tazewell, Montgomery, and Giles Counties. Research is needed to gather input from landowners, evaluate the potential for sustainable economic development, and incorporate black walnut in forest management plans. We will discuss black walnut syrup’ potential to foster sustainable development, build community resilience, and ensure sustainable land management.
- Reflecting on East Africa: Incorporating Sustainable Development Goals into Curriculum in VirginiaHammett, A. L. (Tom) (2023-11-14)Organized, presented, and moderated; for International Education Week
- Branching Out: Alternative Tree Saps Integrated with AgroforestryHammett, A. L. (Tom) (2023)
- Understory Botanicals and Eatables: A Guide to Educational Resources for Appalachian Agroforestry by the Livelihoods Knowledge Exchange NetworkHammett, A. L. (Tom) (2023)The purpose of this series is to describe particular production systems for small holdings in Appalachian cove forests. In this scenario, we will describe how to use the forest understory to grow forest botanicals for nutrition and health uses, and as a source of income. There are numerous examples of understory plants that can be grown in the region - each of which can contribute to income and nutrition and sustain the landscape. Agroforesters recognize and celebrate the historical legacy these plants represent for residents in the region.
- Agroforestry in Appalachia-Laurel Fork SapsuckersHammett, A. L. (Tom) (2023)
- Making Maple Syrup in VirginiaHammett, A. L. (Tom) (2023-03-14)Invited presentation to the Lifelong Learning Institute.
- Linking Agriculture and Sustainable Natural Resource Management: Opportunities for Social ChangeHammett, A. L. (Tom) (2023-11-13)
- SDGs in East Africa-Centered Education: Lessons from a Fulbright-Hays InstituteCranwell, Lindy; Emmett, Robert; Fitzgerald, Rachel; Hammett, A. L. (Tom) (2023-11)
- Commercial products derived from plants: Maple SyrupHammett, A. L. (Tom) (2023-02-13)An invited lecture to biology students at Radford University.
- East African History, Geography, and Sustainability: Tanzania and KenyaCoffee, Frances; Hammett, A. L. (Tom); Gibson, Lisa (2023-11-30)
- Engaging Students in NTFPs- Opportunities for Experiential LearningHammett, A. L. (Tom); Hindman, Daniel (2023-06-07)
- Unpacking the Complexities of International Learning: Reflections from East AfricaCouncil, Austin; Thompson, Joshua; Emmett, Robert; Hammett, A. L. (Tom) (2024-02-08)International education is complex and fraught with nuances, especially in the context of Africa, a continent that has been historically exploited and continues to be absent from many western curricula. Therefore, it is important to critically attend to the dynamics facing communities we interact with abroad. In June 2023, a group of Virginia Tech instructors, professors, graduate students, administrative/professional faculty and Virginia public school educators embarked on a cross-cultural, professional learning experience to Tanzania and Kenya as part of the Virginia Tech East Africa Summer Institute for Educators.
- Chinese Consumers' Attitudes Toward Certified Wood ProductsLiu, Lijun; Sun, Xiufang; Hammett, A. L. (Tom) (Forest Products Society, 2024-01-19)While environmental nongovernmental organizations (NGOs) have been active in China in promoting forest certification, Chinese consumers’ perceptions of certified wood products in the marketplace are unclear. A survey focused on consumers’ wood-product consumption patterns was conducted in three cities—Beijing, Guangzhou, and Shanghai—from July to August 2015. This study used data from the survey to assess urban Chinese consumers’ attitudes toward certified wood products and the demographic differences affecting these attitudes. Regression analysis was conducted to test whether consumers’ social-economic characteristics link with their attitudes toward certified wood. We found mixed correlations between these consumers’ attitudes and their demographics and positive correlations between their attitudes and exposure to environmental campaigns and environmental education. The results from this study will improve the understanding of Chinese consumers’ attitudes toward certified wood products and help producers and marketers better understand the market potential for certified products and more efficiently meet consumers’ needs. This study will also help NGOs interested in conservation to develop their future programs in China.
- Synthesis and Characterization of Poly(Butylene Sebacate-Co-Terephthalate) Copolyesters with Pentaerythritol as Branching AgentJang, Hyunho; Kwon, Sangwoo; Kim, Sun Jong; Kim, Young-Teck; Park, Su-il (MDPI, 2023-12-19)Poly(butylene sebacate-co-terephthalate) (PBSeT) copolyesters are prepared by melt polymerization via two-step transesterification and polycondensation using pentaerythritol (PE) as a branching agent. The effects of the incorporated PE on its chemical, thermal, mechanical, and degradation properties, along with the rheological properties of its melt, are investigated. The highest molecular weight and intrinsic viscosity along with the lowest melt flow index were achieved at a PE content of 0.2 mol%, with minimal reduction in the tensile strength and the highest tear strength. The addition of PE did not significantly influence the thermal behavior and stability of the PBSeT copolyesters; however, the elongation at break decreased with increasing PE content. The sample with 0.2 mol% PE exhibited a higher storage modulus and loss modulus as well as a lower loss angle tangent than the other samples, indicating improved melt elasticity. The incorporation of more than 0.2 mol% PE enhanced the enzymatic degradation of copolyesters. In summary, including within 0.2 mol%, PE effectively improved both the processability-related characteristics and degradation properties of PBSeT copolyesters, suggesting their potential suitability for use in agricultural and packaging materials.
- Dimensional Stability and Equilibrium Moisture Content of Thermally Modified HardwoodsMasoumi, Abasali; Bond, Brian H. (BioResources, 2024-01-04)The dimensional stability and equilibrium moisture content (EMC) of thermally modified hardwoods were studied. Lumber of yellow-poplar (Liriodendron tulipifera); red oak (Quercus borealis); white ash (Fraxinus americana), red maple (Acer rubrum); hickory (Carya glabra), and black cherry (Prunus serotina) were modified in industrial thermo-vacuum system. The water absorption rate, EMC, swelling, anti-swelling efficiency, shrinkage, anti-shrinkage efficiency, and anisotropy of the specimens were measured and compared to unmodified wood. The results show that thermal modification significantly decreased water absorption of wood which leads to improved dimensional stability. Specifically, thermally modified wood showed reduced EMC (22% in hickory to 59% in red maple), increased water absorption repellent (14.9% in black cherry to 29.6% in yellow-poplar), increased anti-swelling efficiency (14.2% in hickory to 71.4% in ash), increased anti-shrinkage efficiency (23.5% in red maple to 65.6% in ash), and reduced anisotropy coefficient (4.7% in red oak to 31.9% in black cherry).