Submitted to: Electronic Publication
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/17/2009
Publication Date: 3/1/2009
Citation: Singh, M., Milano, J., Stevens, E.S., Ashby, R.D., Solaiman, D. 2009. Gelatin films plasticized with a simulated biodiesel coproduct stream. eExpress Polymer Letters. 3(4):201-206.
Interpretive Summary: As renewable fuels continue to gain popularity worldwide, the economics of the production processes for these fuels fluctuate based on variations in starting material costs and disposal costs for any coproduct materials that may be concurrently generated. Biodiesel is one biofuel that is gaining momentum as a renewable alternative to petroleum diesel. It is produced from the chemical modification of animal fats and vegetable oils and in the United States has historically been produced primarily from soybean oil. Because of the sharp increase in soy-based biodiesel production over the past few years, the soybean oil market has expanded resulting in a spike in the price of soybean oil and hence an increase in biodiesel production costs. This increase has negatively effected the comparative production costs with petroleum diesel resulting in a slower than expected merge into mainstream use. In order to help offset the increase in biodiesel production costs, new outlets for the coproduct glycerol are being discovered to help glycerol maintain its value. Glycerol is a large-volume chemical that is frequently used in oral-care products, tobacco, cosmetics and food and beverages but, 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 more appealing option is to find new applications for the crude BCS itself. While all BCS materials are composed primarily of glycerol and water, each is unique in that they contain different residual components from the starting fat or oil. Therefore, in order to gain an understanding of new potential uses for the BCS it is necessary to study a number of different BCS coproducts with varying compositions. In this study, we prepared a number of simulated BCS coproducts by varying the type and concentration of typical minor BCS components and used these materials as additives in gelatin films to help control film properties. Gelatin is an animal-derived chemical compound commonly used for film applications, such as in mulching films and soil conditioners. We found that the addition of different simulated BCS to gelatin films made it possible to modulate film strength and flexibility. By using BCS in this way, a new outlet for the crude BCS coproduct has been found which will help enlarge the crude glycerol market and make biodiesel use more economical.
Technical Abstract: Cast gelatin films were plasticized with glycerol to which compounds found in an unrefined biodiesel coproduct stream (BCS) had been added, including linoleic acid, methyl linoleate, oleic acid, and methyl oleate, in various amounts. The tensile properties of the films were measured as a function of composition, and the effects of individual components were analyzed by factor analysis. Film homogeneity is improved by adding ammonium hydroxide solution before casting. The methyl ester components, when present at 5% of the total weight of the film, are not compatible and lead to film heterogeneity, but when present in the smaller amounts typical of BCS, they are dispersed sufficiently to prevent deterioration of tensile properties. The tensile properties of gelatin films plasticized with a simulated BCS are similar to those of films plasticized with BCS. There is no statistically significant difference between the tensile properties of gelatin films plasticized with a composition simulating a soy-derived BCS and those of gelatin films plasticized with a composition simulating a canola-derived BCS.