Development and characterization of graphite nanoplatelets filled copolymer of benzoxazine and epoxy

摘要

In this study, graphite nanoplatelets (GNPs) were dispersed in a copolymer matrix consisting of bisphenol-A based benzoxazine (BZ) and bi-functional cycloaliphatic epoxy (CER), using two solvent-free techniques: ultrasonication and three-roll mill (3RM). The effects of GNP addition on the tensile performance, storage modulus, glass-transition temperature (T-g), and electrical conductivity were evaluated. A maximum increase of nearly 46% and 20% in tensile modulus and strength, respectively, was found at 1.8 wt% of GNP content dispersed using the ultrasonication technique. In comparison, a superior enhancement with 55% and 37% increase in the tensile modulus and strength could be obtained at a lower GNP content, 0.9 wt%, dispersed via 3RM calendering, respectively. In the electrical conductivity measurement, a percolation threshold was achieved in the range between 0.6 wt% and 0.9 wt% of GNP content using the 3RM technique, which was in agreement with the predicted values. The theoretical stiffness obtained from the simplified Halpin-Tsai model corresponded with the experimental data at low fractions. The incorporation of GNPs into the BZ/CER copolymer resulted in the full recovery of all the performance losses from the addition of CER to BZ. Choosing a proper dispersing technique, the 3RM calendering in this case, could lead to a minimum required GNP content for achieving superior nanocomposite performances.