Polypropylene (PP) based plastic baling twine, nets, or wraps are commonly used. They are often
ingested by cattle during hay feeding and over time can clog the digestive tract of cattle, causing
health issues or even death of the animals. This issue can be solved by increasing the digestibility
of the plastic baling material. In this project, we plan to develop a soymeal-based digestible baling
twine. A biodegradable plastic will be used as the matrix material to be blended with soymeal to increase twine strength. oil will be added to adjust the flexibility of the twine. Optimum formulation and processing conditions will be
developed through meticulous experimental studies. Proof-of-concept twine samples will be
produced and demonstrated at the end of the project.

To develop a novel soymeal-based plastic that features high digestibility and strength suitable for
baling twine use

Soymeal-based plastics that have desirable mechanical property and digestibility
Knowledge of the mechanical/digestive property of the new twine
Fabrication technique and user guidelines for the new twine

Update:
Mid-year report sent to PM

Update:
Final report sent to PM on 6/29/2023

View uploaded report

Bailing twine (and wraps) are mostly made of polypropylene (PP), an indigestible plastic. It can cause health issues or even death of animals when ingested. In addition, PP is made from petroleum and lacks biodegradability, thus posing significant environmental concerns. Therefore, a biobased, biodegradable, and more digestible bailing twine is highly desired. In this project, our goal is to develop a new twine material based on soymeal (SM) and polylactic acid (PLA), a biodegradable plastic made from corn starch.

SM and PLA at different ratios were compounded and extruded into ribbon- and filament-shaped products. Mechanical testing, thermal stability, microstructure, and digestibility of the products were investigated. Soy-based plasticizers and a small amount of crosslinker and initiator were added to the SM/PLA base formulation at different contents to improve the flexibility, toughness, and strength of the products. The filaments made of the optimal formulation were twisted into twine and its mechanical properties were evaluated. The properties were compared with those of PP twine produced using the same method.

SM and PLA can be blended and extruded into nice ribbon and filament products at different SM to PLA ratios. The higher the ratio, the lower the surface quality and mechanical properties, but the higher the digestibility of the products. The ratio of 3:7 was found suitable for achieving a balanced property matrix. Incorporating the additives (i.e., plasticizer, crosslinker, and initiator) can significantly improve the desirable properties of the twine. SM/PLA filaments were successfully twisted into a twine product, which shows superior properties to PP twine made using the same method. While pure PLA and PP show zero digestibility, about 20% SM/PLA twine (the highest rate) is digested at the end of a digestion test in cattle rumen.

A new application of soymeal has been developed, presenting an exciting opportunity for soybean farmers and diverse industries. This novel formulation incorporates 30% soymeal, which can be transformed into ribbons suitable for packaging strap utilization, as well as twines ideal for baling and various other applications. Notably, these products are predominantly biobased and biodegradable, as evidenced by the ingredients and processing methods employed during their production. Additionally, their digestibility surpasses that of conventional polypropylene (PP) twines, representing a remarkable improvement.

A potential high-volume new use of soymeal that can increase soybean value and farmers' income