Characterization and biodegradation behavior of bio-based poly(lactic acid) and soy protein blends for sustainable horticultural applications
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Since 1905, the Department of Agricultural Engineering, now the Department of Agricultural and Biosystems Engineering (ABE), has been a leader in providing engineering solutions to agricultural problems in the United States and the world. The department’s original mission was to mechanize agriculture. That mission has evolved to encompass a global view of the entire food production system–the wise management of natural resources in the production, processing, storage, handling, and use of food fiber and other biological products.
History
In 1905 Agricultural Engineering was recognized as a subdivision of the Department of Agronomy, and in 1907 it was recognized as a unique department. It was renamed the Department of Agricultural and Biosystems Engineering in 1990. The department merged with the Department of Industrial Education and Technology in 2004.
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1905–present
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- Department of Agricultural Engineering (1907–1990)
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- College of Agriculture and Life Sciences (parent college)
- College of Engineering (parent college)
- Department of Industrial Education and Technology, (merged, 2004)
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Abstract
Adipic anhydride-plasticized soy protein (SP.A) was blended with poly(lactic acid) (PLA) at two concentrations (50/50 and 33/67) and was evaluated for use as a sustainable replacement for petroleum plastic in horticulture crop containers. Following the discovery that SP.A/PLA blends provide additional functions above that of petroleum plastic for this application, the present study evaluates the biodegradation behavior of these materials in soil and describes the substantial improvements in sustainability that result from the additional functions (intrinsic fertilizer and root improvement of plants) and the end-of-life option of biodegradation. After being buried in soil for designated time intervals, the residual degraded samples were analyzed to determine morphological and thermal properties at sequential stages of biodegradation. Samples were characterized by scanning electron microscopy (SEM), dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The results indicated that there was a compatible system between SP.A and PLA in the melt. Incorporation of SP.A accelerated the biodegradation rate of this binary blend significantly compared with pure PLA. Prior to the degradation process, both the glass transition temperatures and melting temperatures of the blends containing SP.A decreased as the concentration of the soy protein increased. With increasing degradation time of the blended samples in soil, the glass transition temperatures increased in the early stages of biodegradation then decreased, a trend associated with the decrease in the molecular weight of the blends as a result of biodegradation. In addition, the thermal stability of blends increased gradually with increasing degradation time, suggesting faster biodegradation loss of the soy component of the SP.A/PLA blends. These results support the use of soy-based polymer blends for horticulture crop containers and provide data for evaluating their use as sustainable materials for other potential applications.
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This is a manuscript of an article published as Yang, Shengzhe, Samy A. Madbouly, James A. Schrader, Gowrishankar Srinivasan, David Grewell, Kenneth G. McCabe, Michael R. Kessler, and William R. Graves. "Characterization and biodegradation behavior of bio-based poly (lactic acid) and soy protein blends for sustainable horticultural applications." Green Chemistry 17, no. 1 (2015): 380-393. DOI: 10.1039/C4GC01482K. Posted with permission.