Effects of carbon nanotubes on curing and properties of boron-containing bisphenol-S formaldehyde resin/o-cresol epoxy resin composites

Abstract

Boron-containing bisphenol-S formaldehyde resin (BBPSFR) with different amounts of carbon nanotubes (CNTs) was used to cure o-cresol formaldehyde epoxy resin (o-CFER). The curing kinetics, dynamic mechanical properties, and thermal stability of BBPSFR/o-CFER/CNTs (BCC) composites were investigated by DSC, DMA, and TGA. The morphology of BCC composites was characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The mechanical properties and electric properties were also determined. The results showed that the glass transition temperature Tg, initial decomposition temperature Tid all increased with increasing CNTs content. The Tg and Td5 is about 20°C and 30°C higher than that of pure BBPSFR/o-CFER (BC), when content of CNTs is 1.5 wt%. The curing reaction active energy Ea can be calculated by Kissinger’s method. When the conversions α is between 0.15 and 0.95, Ea has a slight increase for the BBPSFR/o-CFER (BC) composite, but it exhibits slight decrease for the BCC composites. The non-isothermal curing kinetics of the BCC can be described by the two-parameter (m, n) Sestak-Berggren kinetic model. The BCC has the highest tensile and impact strength when contains of CNTs is 1.0 wt%, which is 34 MPa and 13 kJ/m2 higher than that of pure BC laminate, respectively. The electric properties of BCC laminates were improved by the addition of 1.0 wt% CNTs.