Obtenção de micro/nanofibras poliméricas por fiação por sopro : parâmetros e aplicação no controle de pragas agrícolas

Abstract

This work presents the production of EVA micro/nanofibers using the solution blow spinning method and its possibility of application in agriculture, in pest control, through the incorporation of synthetic sex pheromones. Solutions with a concentration of 0.5-15% by mass of EVA in xylene: chloroform (96:4% by weight) were prepared based on the solubility parameter of the copolymer. The viscosity of the solutions as well as the concentration regime was determined by means of rheological measurements. The morphology and structure of the fibers were evaluated by means of scanning electron microscopy (SEM-FEG) and X-ray diffraction (XRD). The release profile of the pheromones was determined based on the loss of mass using thermogravimetry (TGA). Fibers were obtained in the solutions in the semi-diluted concentration regime. The fibers have diameters of 95 to 426 nm and their sizes are dependent on the feed rate. There is no evidence that feed rates used and concentration have an effect on macromolecular orientation of EVA, as well as the use of pheromones in spinning. The amount incorporated in the fibers, as well as the rate of release of the pheromones influences the solubility parameter. Therefore, depending on the release demand it is possible to obtain a release system with a balance between release rate and maximum release time based on the nature of the polymer/solvent/pheromone system.