In this project, we will explore the approaches for the development of a new biodegradable soybased composite material (BSCM) for agricultural and landscaping applications. We will be using a soy-derived polymer that can work as a binder in composites containing a high content of cellulose- and/or lignin-based fillers derived from different agricultural sources. The polymer binder will be a soybean oil-based thermoplastic elastomer which will be co-extruded with cellulose/lignin filler. The BSCM will be developed for the application as a biodegradable mulching material for weed suppression. The new BSCM will be pressed in form of panels of customized shape and size and the panels will be applied as soil cover for moisture and weed control. The soy-based composite material will compete with existing on the market nonsustainable plastic mulching film (PMF) and sustainable biodegradable plastic mulch (BPM). Both materials are widely used in the production of vegetables, berries, hemp, and other specialty crops. The sustainable BPM offers lower environmental impact than PMF, however, is not completely biodegradable. It is expected that the new soy-based composite material will be an inexpensive alternative to BPM while being completely biodegradable will beneficially impact the soil.

The main objective of this project is to develop a new soy-based composite material that will be used as a biodegradable mulching material. We will be exploring a new polymer binder synthesized from soybean oil that will be able to form the flexible film. The soy-based polymer binder will be combined with various cellulose- and/or lignin-containing fillers derived from different agricultural sources and the new soy-based material will be tested for physical properties and decomposition rate. It is intended that the new biodegradable mulching material will compete with the existing starch-based material for its price and performance.

This project aims to achieve a proof of concept, testing the material in the laboratory and in-field environment, to evaluation of the feasibility of launching a commercial product. The short-term desired deliverable includes the development of new soybean oil-based polymer that will work as a binder for cellulose/lignin-filled composites, formulation of composites and laboratory testing to determine sustainability as a mulching film. The desired longterm outcome includes the testing of new soy-based material in a field environment and the proof of concept for commercial use.

Updated November 29, 2021:

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Updated November 30, 2022:

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A soy-based aqueous latex coating formulation was developed using modified soybean oil, acrylic acid, and vinyl acetate. The content of soybean oil in the latex formulation and in the polymer is 19.2% and 57.1%, respectively. The biobased polymer obtained from soy latex was studied for film-forming and physical properties, while the latex was tested for stability. The formulation containing soy-based polymer emulsion was developed and applied as a coating to different papers such as landscaping weed barrier paper (WBP) and brown kraft paper (BKP). WBP is a commercial product used as a biodegradable mulching material. It has limited application due to its high decomposition rate. Soy polymer-coated and uncoated paper samples were tested for decomposition and weight decrease on the field from 06.04.2022 till 10.09.2022 (Figure 1). The uncoated WBP and BKP show much higher decomposition rates than their soy-coated counterparts and were completely degraded after 14 weeks. The soy polymer-coated WBP and BKP showed some visible degradation only after 10 weeks but were intact until the end of the test.
Dry soy polymer film which was used for the coating of paper was tested for aerobic biodegradability in the laboratory following the standard test method ASTM D5988. The results presented in Figure 2 confirm the biodegradability of soy polymer however the degradation rate is 2.3 times slower than the degradation rate for corn starch used as a reference.
The concept of the use of polymer from modified soybean oil for biodegradable mulching material was successfully demonstrated and the new polymer shows promising results in reducing the degradation rate of cellulose-based material, while still being biodegradable. The synthesis and formulation of new biobased waterborne latex are free from solvents and harsh chemicals, and the polymer is biodegradable. The new biobased polymer emulsion can have wide applications for biodegradable mulching material and other materials for landscaping and agricultural use.

The global use of agricultural plastic films reached 7.4 million tons in 2019 [Sintim H. Y. and Flury M. Environ. Sci. Technol. 2017, 51, 3, 1068–1069]. The global Biodegradable Film market is projected to grow by US$ 25.9 Million, according to www.businesswire.com. In North American countries such as the USA and Canada, the BPM market has a huge potential to grow as these countries have adopted the world’s best cultivation techniques. The market growth for BPM in North America is driven by favorable government regulations regarding the usage of eco-friendly products. The biodegradable mulching film is a high-volume agricultural material. The replacement of only 1% of agricultural mulching material with soy-based biodegradable composite containing 10% of soybean oil-based polymer will result in a usage of about 26,000 tons of soybean oil, which converts to 5.4 million bushels of soybeans. A partial replacement of BPM with a new BSCM will benefit the soybean farmers with the growing demand for soybean oil as the raw material for the production of the soy-based composite binder.