Dynamic mechanical analysis of carbon black filled, elastomer-toughened ethyl cyanoacrylate adhesive bulk films

Abstract

This paper reports on a dynamic mechanical analysis (DMA) study of carbon black filled, elastomer-toughened ethyl cyanoacrylate (ETECA) adhesive bulk films. The bulk films were cured at room temperature, both with and without premixed initiators, between poly (ethylene) (PE) substrates and in poly (tetrafluoroethylene) (PTFE) moulds. Adhesive batches with different strong and weak acid concentrations were used to study the influence of the curing speed on the phase separation behaviour of the elastomer. The mechanical properties of the bulk adhesive films and electron micrographs of the fracture surface of the tensile tested bulk specimens are reported in the previous publication by Ștefanov et al. [1; International Journal of Adhesion & Adhesives, 68: 142–155, 2016]. For all tested bulk adhesive films similar peaks were observed in the DMA curves, i.e., a peak at low temperature, before the glass transition region of the polymer, and a peak corresponding to the glass transition temperature of the poly (cyanoacrylate) adhesive. The results of this investigation show that the amount of the phase-separated elastomer increases with the increase in weak acid concentration for the samples cured without the use of initiators. An opposite trend was observed for the samples cured using initiators. Another important finding is that for a complete phase-separation of the elastomer from the poly CA a secondary step, following curing at room temperature, is necessary which should consist of heating the sample to 110 °C.