Desenvolvimento de um compósito ativo epóxi/argila organofílica incorporando fios de ligas Ni-Ti com memória de forma.

Abstract

The effect of curing agent kind, curing conditions, and the incorporation of small amount of organoclay on the thermal properties of DGEBA epoxy resin was evaluated in order to develop an epoxy system for application as matrix in active composites (composites whose dispersed phase consists of shape memory alloy wires).The DGEBA resin was prepared using three amine derivatives as hardeners (TETA, DETA and DDS) under varied curing conditions, in the absence and presence of organoclay. Epoxy systems were characterized by dynamic mechanical analysis, optical microscopy and X-ray diffraction. According to results, the cured epoxy systems at elevated temperatures (DETA and DDS) showed higher glass transition temperature (Tg) and thermal stability values than the system cured at low temperature (TETA). In addition, when the post-cure treatment was used, the increases were superior. When 1 phr of organoclay was incorporated in DETA and DDS cured epoxy systems and post-cured, either the increase in the Tg or thermal stability values were more significant, especially for the system cured with DDS. Therefore, 1.55%, 2.56%, 3.57% and 4.54% by volume of Ni-Ti wires were added in epoxy/DDS/APOC systems (nanocomposite with predominantly exfoliated structure) in order to prepare active composite, because this nanocomposite is thermally stable in the working range of shape memory alloy Ni-Ti, whose transformation occurs between 70-80 9C. The incorporation of 3.5% of LMF wires to epoxy/DDS/APOC resulted in the increase of storage modulus of epoxy resin, resulting in a active composite.