Suspension testing is a standard way of characterizing the effectiveness of dispersants in wet or dry formulations. In a suspensibility test, a measured amount of material is diluted in hard water and given a specified amount of time to settle. The settled material is recovered and used to calculate the amount of material that remained suspended, yielding a suspension percentage. Different organizations use slightly different methods to conduct this characterization, and there are few studies which allow the experimentalist to correlate results between methods. The objective of this work is to compare two standard suspension tests, ASTM and CIPAC (Collaborative International Pesticides Analytical Council) and determine their correlation, if one exists. While similar, the methods vary by a few factors including the initial volume fraction of the material and the means of recovering the settled material. Several formulations of copper (II) hydroxide, dispersed with varying amounts of acrylic polymer, were dried and sieved into granule solids and powder solids. Suspension properties were tested using both methods. Resultant suspension percentages for each formula were charted, CIPAC results versus ASTM results. The coefficient of determination (R2) for the suspension percentages of the granule and powder solids was found to be 0.976 and 0.984, respectively. The granular solids showed a one-to-one relationship (slope=1) between results generated by these methods while the powder solids did not, y=0.56+0.37. The driver for this skew may be due to different particle volume fractions between the tests, a parameter which has the potential to affect viscosity in a predictable manner and which is represented mathematically by the Krieger-Dougherty equation.
In addition to the active ingredient, pesticide formulations typically contain surfactants, solvents, diluents, fillers, adjuvant substances, and utility additives such as foam control agents. Over the past several decades, innovations in pesticide formulation have yielded accelerated evolution toward reduced environmental impact and improved sustainability. These provide the key benefits of what are considered “greener” formulations. An example of how this approach manifests in the marketplace is end product ecolabeling as practiced in the consumer products industry. A review of a 2010 global survey of certifying organizations is included in order to provide perspective on how criteria and standards can vary. The range of materials available that might offer either or both the desired reductions in environmental impact and/or improved sustainability varies based on the definition of “green” applied. Important aspects to consider include selecting a definition, deciding which ingredients to use, screening replacements for non-green or less green ingredients, and measuring performance against appropriate benchmarks. Various criteria can be applied in order to define targets for “greener” inert ingredients. The Environmental Protection Agency’s Design for Environment program (DfE) focuses on individual ingredients in addition to formulations. For materials offering similar performance, the underlying chemical, toxicological, or environmental data affect selection. DfE utilizes a third-party ingredient review system (by National Sanitation Foundation [NSF] International and ToxServices) and database (CleanGredients, as managed by GreenBlue) that can provide a basis on which to select materials for evaluation and development as part of formulating safer pesticides with reduced environmental impact and greater sustainability.
High molecular weight polymers have been shown to improve the efficacy of systemic herbicides such as glyphosate. The mode of activity of these polymeric adjuvants is not well understood. In this study a commercial polymer/ammonium sulfate (AMS)-based adjuvant was tested with commercial glyphosate formulations. The effect of the various treatments on the mass of spray deposited, droplet bounce, and droplet run-off was determined. The polymeric/AMS adjuvant was found to improve the deposition of the commercial glyphosate formulations in that: the loss of active due to spray drift was reduced, i.e., the mass of spray deposited was increased; droplet bounce of the spray solutions was reduced, i.e., droplet retention was improved; the polymeric/AMS adjuvant did not significantly affect the angle at which droplets were detached from leaves, therefore the adjuvant should not affect droplet run-off.
A series of studies were conducted to evaluate the ability of a novel surface active nonionic star polymer to stabilize various aqueous dispersion formulations. Data developed within these studies indicated the polymer enabled these formulations to maintain consistent properties such as particle size distribution and dilution stability. In many instances, the star polymer outperformed the current benchmark technology composed of polymer pairs containing both AB and ABA block polymers. For herbicidal water emulsion formulations, the star polymer demonstrated considerable resistance to particle size growth where the same formulation using the ABA block polymer demonstrated substantial particle growth over the same time period. In herbicidal suspo-emulsion formulations, the star polymer was able to withstand freeze/thaw cycles and to resist particle size growth. The novel surface active star polymer structure was applied in a range of aqueous dispersions, providing flexibility in use along with offering considerable advantages in dispersion stability over the current benchmark polymeric stabilizer technology used in complex aqueous suspo-emulsion formulations.
Three experimental polyoxyethylene sorbitan monolaurate derivatives were synthesized with molecular fingerprinting techniques applied to experimental materials, confirming the target compounds had been produced. Chemical property measurements were compiled that aligned with theoretical predictions and physical property measurements confirmed their intentional differences yielded the anticipated changes in surfactant behavior. Imidacloprid uptake data confirmed penetration of leaf cuticles was enhanced in the presence of polyoxyethylene sorbitan monolaurates with several experimental materials providing uptake equivalent to reference material. Select materials were included in field and greenhouse trials where observations included good biological response with a range of individual herbicides as well as improved control of volunteer glyphosate tolerant corn with mixtures of glyphosate and clethodim over the control nonionic surfactant adjuvant when applied as a tank-added adjuvant. Antagonism of annual grass control was not observed. Manuscript
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