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|Title:||Development of an improved dust control system based on polyvinyl acetate latex|
|Authors:||Union Carbide Corporation.|
United States. Army Materiel Command.
Anderson, D. F.
Durante, J. A.
Wartman, L. H. 1920-
Polyvinyl acetate latex
|Publisher:||U.S. Army Engineer Waterways Experiment Station.|
Engineer Research and Development Center (U.S.)
Abstract: While dusting and the formation of dust clouds have always been significant factors in military operations, the advent of modern large-scale airborne tactics has transformed what was once primarily an annoyance to a costly and serious problem because dust ingestion into moving parts of aircraft accelerates wear, resulting in increased maintenance time and reduced operational availability. The U. S. Army Engineer Waterways Experiment Station (WES) has undertaken the task of finding methods for suppressing dust. One of the systems developed employs DCA-70, a commercial dust-control agent manufactured by Union Carbide Corporation. The DCA-70 is sprayed on a graded soil surface where it forms a continuous film, anchored to the substrate, with good resistance to damage by air blasts and vehicular traffic. DCA-70 is a polyvinyl acetate latex compounded with dibutyl phthalate at a concentration of 10% of the contained solids in the latex. The dibutyl phthalate acts as a plasticizer, making films cast from the latex more pliable and resistant to rupture. Films cast from DCA-70 are very resistant to deterioration by the actinic radiation in sunlight and hence, the outdoor-life expectancy of stabilized soils would be expected to be good. However, because the dibutyl phthalate is quite volatile, it evaporates in hot climates resulting in decreased resiliency and strength. Since many commercial plasticizers of much lower volatility than dibutyl phthalate are available, a program was undertaken to find a plasticizer system which could be substituted for the dibutyl phthalate to yield a product with better aging characteristics. In Phase I of this project more than thirteen plasticizers were tested for compatibility with the polyvinyl acetate latex used in the manufacture of DCA-70. Those plasticizers which showed the most promise in the initial screening evaluation were selected for further trials involving preparation of laboratory latex samples, casting of films, and measurement of tensile properties both before and after oven aging and water extraction tests. As expected, all the products made with low volatility plasticizers retained their tensile properties much better than DCA-70. On the basis of the test results six formulations were selected for preparation of 110-gallon quantities and field evaluation by WES. Their evaluation has resulted in the elimination of four of these formulations from consideration. A selection remains to be made between the two remaining candidates, both of which are made with a mixed system containing FLEXOL 4-GO and Santicizer 140, but in different concentrations. WES evaluation confirms that the modified versions are superior to DCA-70. In Phase II of this project study, nine specification test methods, most of which are standard ASTM procedures for latex products, were applied to various commercial polyvinyl acetate latexes after addition of plasticizers using the formulations developed in Phase I of the contract research. Comparison of the data obtained with those attributes expected to be of importance for good performance in dust-control applications leads to a set of tentative specification values which should allow procurement of these products on a competitive basis. The tests used are tensile properties of films, total solids, surface tension, pH, viscosity, filterable solids, salt tolerance, storage stability at 140°F., and shear stability. In addition, it is recommended that only vinyl acetate homopolymers plasticized by the recommended formula be employed in this application.
|Rights:||Approved for public release; distribution is unlimited.|
|Appears in Collections:||Contract Report|
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|CR-S-71-9.pdf||7.85 MB||Adobe PDF|