Avaliação do comportamento de degradação da PCL e de sistemas PCL/argila.

Abstract

The present work had as main objective to research the degradation behavior of PCL and PCL/clay systems. During experimental procedure the bentonite clay called MMT was treated by using the salt Praepagen HY which is an ammonium quaternary salt; from XRD analyzes the salt's incorporation's efficiency was verified between clay's layers evidencing an organophilization state, the organoclay was named OMMT. The thermal behavior of neat PCL and its composites systems were investigated applying a Torque Rheometer, four different clay loading levels were applied, 3, 10, 20 and 50 wt.%. It was observed that PCL presented a good thermal stability in the clay systems added to 3 and 10 wt. %. An extruder was used to mix the neat PCL and clays (MMT and OMMT), and the sample testes were obtained by injection process. Different series of specimens tests were placed on plaques inside an oven at 40°C and under vacuum, where several series were maintained immersed in water. Shared series were maintained in that experimental condition for 15, 30 and 45 days, respectively. From XRD diffractograms of the specimens slight alterations in the basal spacing could be observed, similar results were acquired to PCL/MMT systems immersed in water. Diffratograms of PCL/OMMT systems showed longer basal spacing and one peak in the (002) Plan. Distinct behaviors were visualized in the PCL/MMT and PCL/OMMT not immersed in water, having been undergone to different degradation periods. From tensile tests, lower values of Modulus Young were observed in the clays systems in relation to neat PCL; after 30 days of exposure all compositions showed an increase in this tensile parameter. According to SEM images, subtle modifications were observed in polymer's morphology whatever may have been the exposure period. Poor interaction between clay and PCL was noticed which justified the mechanical results.