RESUMEN
The current study investigated the effect of adding a carbon nanotube-alumina (CNT-Al2O3) hybrid on the fracture toughness of epoxy nanocomposites. The CNT-Al2O3 hybrid was synthesised by growing CNTs on Al2O3 particles via the chemical vapour deposition method. The CNTs were strongly attached onto the Al2O3 particles, which served to transport and disperse the CNTs homogenously, and to prevent agglomeration in the CNTs. The experimental results demonstrated that the CNT-Al2O3 hybrid-filled epoxy nanocomposites showed improvement in terms of the fracture toughness, as indicated by an increase of up to 26% in the critical stress intensity factor, K1C, compared to neat epoxy.
RESUMEN
This study attempted to clarify the influence of a cross-linker, N,N-methylenebisacrylamide (MBA), and N-isopropylacrylamide (NIPAM) on the non-isothermal kinetic degradation, solid state and lifetime of hydrogels using the Flynn-Wall-Ozawa (F-W-O), Kissinger, and Coats-Redfern (C-Red) methods. The series of dual-responsive Cs-PNIPAM-MBA microgels were synthesized by soapless-emulsion free radical copolymerization in an aqueous medium at 70 °C. The thermal properties were investigated using thermogravimetric analysis (TG) and differential scanning calorimetry (DSC) under nitrogen atmosphere. The apparent activation energy using the chosen Flynn-Wall-Ozawa and Kissinger methods showed that they fitted each other. Meanwhile, the type of solid state mechanism was determined using the Coats-Redfern method proposed for F1 (pure Cs) and F2 (Cs-PNIPAM-MBA hydrogel series) types, which comprise random nucleation with one nucleus reacting on individual particles, and random nucleation with two nuclei reacting on individual particles, respectively. On average, a higher Ea was attributed to the greater cross-linking density of the Cs hydrogel.