Submitted to: Journal of Biobased Materials and Bioenergy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/2/2008
Publication Date: 3/1/2009
Citation: Stevens, E., Ashby, R.D., Solaiman, D. 2009. Gelatin Plasticized with a Biodiesel Coproduct Stream. Journal of Biobased Materials and Bioenergy. 3(1):57-61.
Interpretive Summary: Biodiesel is produced from the chemical modification of animal fats and vegetable oils and, because of its improved fuel properties and reduced emissions, is gaining momentum as a renewable alternative to petroleum diesel. In 2006 alone, the United States produced approximately 225 million gallons of biodiesel but, while this increase may be favorable for the environment, it also resulted in about 22 million gallons of cheap, glycerol-rich coproduct. Glycerol is a large-volume chemical that is frequently used in oral-care products, tobacco, cosmetics and food and beverages. However, in order for glycerol from the biodiesel co-product stream (BCS) to be used in these industries it must be purified, which can be a costly process. A second option is to discover new applications for the BCS itself without the need for additional, costly chemical processes. In this study, we described a new potential application of the BCS as an additive in gelatin films which will help control their properties. Gelatin is an animal-derived chemical compound commonly used for film applications, particularly where degradability is desired, such as in mulching films and soil conditioners. We found that the addition of crude BCS to gelatin films made it possible to modulate film strength and flexibility based on the concentration of BCS added. By using BCS in this way, a new outlet for the crude coproduct has been established (increasing value) which will help expand gelatin applications and offset biodiesel production costs thereby making biodiesel use more attractive.
Technical Abstract: Cast gelatin films were plasticized with a biodiesel coproduct stream (BCS). Gelatin was found to be compatible with the non-glycerol components of BCS. Films were well formed and appeared homogeneous on the macroscopic level. A BCS content of 18–34% resulted in elongations of 35–182%, with corresponding tensile strengths of 45–6 MPa and elastic moduli of 1330–38 MPa. Factor analysis indicated that replacing glycerol with BCS increases elongation but has little effect on tensile strength or modulus. The use of BCS as a plasticizer for biopolymers would increase the value of BCS, increase the value of agricultural fats and oils from which biodiesel is synthesized, and increase the feasibility of fuel production in a biorefinery. The use of low-cost BCS may also increase the feasibility of producing thermoplastics from gelatin and from other biopolymers now more expensive than starch.