|Willett, Julious - J L|
|Doll, Kenneth - Ken|
Submitted to: Journal of Applied Polymer Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/24/2008
Publication Date: 10/1/2008
Citation: Shogren, R.L., Willett, J.L., Westmoreland, D., Gonzalez, S., Doll, K.M., Swift, G. 2008. Properties of Copolymers of Aspartic Acid and Aliphatic Dicarboxylic Acids Prepared by Reactive Extrusion. Journal of Applied Polymer Science. 110:3348-3354. Interpretive Summary: Synthetic water-soluble polymers made from petroleum such as polyacrylic acid (PAA) are commonly used to prevent hard water deposits in laundry and dishwasher detergents, industrial cooling systems, reverse osmosis systems, pools, etc. It would be desirable to find an alternative to PAA which is made from renewable materials such as corn, is non-toxic and biodegradable. Polyaspartic acid (PAS) has such properties but its preparation is time consuming and energy intensive. Through cooperative research between USDA/ARS and Folia, Inc., it was found that PAS can be prepared much more rapidly by adding a small amount of comonomer and using a heater auger called an extruder. These results should be useful to companies involved in formulating detergents and water treatment chemicals, especially where a low-toxicity, degradable product is desired.
Technical Abstract: Aspartic acid may be prepared chemically or by the fermentation of carbohydrates. Currently, low molecular weight polyaspartic acids are prepared commercially by heating aspartic acid at high temperatures (greater than 220 degrees C) for several hours in the solid state. In an effort to develop a more rapid, continuous, melt polymerization scheme, aspartic acid was copolymerized with adipic, azelaic, sebacic and dodecanedioic acids using a vented twin-screw extruder. Copolymers having ratios of aspartic/diacid less than or equal to 16 and Mw up to 7600 were prepared at temperatures of 240-260 degrees C and residence times of only about 5 minutes. Mw generally increased with aspartic/diacid ratio but melt viscosities became very high and processing became difficult at ratios greater than 16. Most of the copolymers exhibited inhibition of calcium carbonate precipitation at concentrations similar to that of pure polyaspartic acid and thus may find application as antiscalants