Adjuvant on spray solution physical properties droplets spectrum and electrification efficiency using electrostatic spraying/Adjuvantes nas propriedades fisicas da calda, espectro e eficiencia de eletrificacao das gotas utilizando a pulverizacao eletrostatica

Adjuvants have been used in pesticide spraying, however, there is a need of further information about the effect of these products, especially when employing the electrostatic system. Thus, the aim of this study was to evaluate ten spray solution (nine adjuvants + control) concerning on physical properties (viscosity and electrical conductivity) and concerning on droplet spectrum and efficiency of droplet electrification in electrostatic spraying. The electrostatic sprayer Electrostatic Sraying Systems, MB 4.0 model, was used for this experiment. The Ostwald methodology was used to evaluate the viscosity, while the electrical conductivity was measured using a conductivity meter Marte, MB-11 model. The Faraday cage was used for the analysis of electric charges in the droplets and the droplets spectrum was obtained by the particle size analyzer Malvern Spraytech. Adjuvants tested altered the viscosity of the spray solution between 0.94 and 1.03mPa s. For the electrical conductivity it was observed that the water had the mean conductivity of 67.7[micro]S [cm.sup.-1], and depending on the adjuvant type it was obtained values up to 607.5[micro]S [cm.sup.-1]. For the droplets electrification, there was an increasing up to 50.14% in the C/M ratio by using the adjuvants, demonstrating that adjuvants may assist the electrostatic spraying. Generally, adjuvants reduced the droplet diameter. Key words: technology pesticide application, charge/mass ratio, droplets size. Os adjuvantes tem sido empregados na pulverizacao de agrotoxicos, entretanto, ainda se carece de informacoes sobre o efeito destes produtos, principalmente quando se emprega o sistema eletrostatico. O presente trabalho foi conduzido com o objetivo de avaliar dez solucoes de pulverizacao (nove adjuvantes e uma testemunha), quanto as propriedades fisicas (viscosidade e condutividade eletrica) e quanto ao espectro e a eficiencia de eletrificacao da gota na pulverizacao eletrostatica. Utilizou-se um pulverizador eletrostatico da marca Electrostatic Spraying Systems e modelo MB 4.0. Para avaliar a viscosidade, a metodologia de Ostwald foi utilizada, enquanto a condutividade eletrica foi determinada com uso de um condutivimetro, marca Marte e modelo MB-11. Na analise da carga eletrica presente na gota, utilizou-se a metodologia da gaiola de Faraday e a avaliacao do espectro foi realizada por meio de um analisador de particulas a laser (Spraytech Malvern[R]). Os adjuvantes testados alteraram a viscosidade da c