Effects of Polymer Composition and Viscosity on Droplet Size of Recirculated Spray Solutions

✍ Scribed by H. Zhu; R.W. Dexter; R.D. Fox; D.L. Reichard; R.D. Brazee; H.E. Ozkan

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 275 KB
• Volume: 67
• Category: Article
• ISSN: 0021-8634
• DOI: 10.1006/jaer.1997.0151

✦ Synopsis

Twelve polymers used in commercial drift retardants were tested to determine shearing ef fect on physical properties and sprayed droplet size distributions . Shear was applied with a shear test stand which simulated agricultural sprayers . Polymers included polyethylene oxides , polyacrylamides , and a polysaccharide , with a range of molecular weights , anionicities and concentrations . Samples of solutions containing distilled water and polymer were taken after 0 , 1 и 0 , 2 и 3 , 3 и 9 , 6 и 4 and 11 и 4 passes through the test stand . Size distributions of samples sprayed through a flat fan nozzle were measured . Droplet sizes of all samples decreased as recirculation increased . Increasing concentration and molecular weight increased droplet sizes of unsheared spray samples for non-ionic and anionic polymers . After 2 и 3 recirculations , nonionic polymer-solutions with dif ferent concentrations and molecular weights showed D V0 и 5 values little greater than water alone . Shearing also reduced D V0 и 5 of anionic polymer-solutions , but even after maximum shearing , D V0 и 5 remained greater than water spray . Extensional viscosity (r 2 ϭ 0 и 78) and screen factor , a simple method of estimating extensional viscosity , (r 2 ϭ 0 и 72) were well correlated with spray D V0 и 5 values for all polymer samples . Most polymer based drift retardants lose ef fectiveness after recirculation through agricultural sprayers : these results showed that degradation varies greatly with polymer type .