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

Abstract

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 (Tg), 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.

Low‐temperature gelling phenomenon for a class of slow‐curing phthalonitrile‐benzoxazine resin

“…Generally, such rough features reflected the toughness of the thermosetting resin. 6,15 Instead, PNBZ gel with 1:1 PNBZ/EDA molar ratio showed a smooth surface (Figure 3e,f), representing a typical brittle fracture. 7,8,20 On the one hand, these results indicate the morphology of PNBZ gel can be easily adjusted by varying PNBZ/ EDA molar ratio (Figure 3).…”

“…[10][11][12] Meanwhile, BZ inherits the favorable processibility, self-flammability, excellent thermal stability, low water absorption, and near-zero shrinkage of phenolic resin. [13][14][15] Bifunctional phthalonitrile-benzoxazine resin (PNBZ) is a new category of PN and BZ family. On the one hand, PNBZ has overcome the rigid curing condition of PN resin to some extent.…”

“…The disadvantages of traditional phenolic resin, that is, the release of curing volatile and the need of strong acid catalyst, have been overcome in the synthesis and curing of BZ resin 10–12 . Meanwhile, BZ inherits the favorable processibility, self‐flammability, excellent thermal stability, low water absorption, and near‐zero shrinkage of phenolic resin 13–15 …”

Fluorinated SnO2/ER as an antistatic coating for enhancing the surface insulating strength of epoxy insulators

“…14,15 For epoxy-made insulators, epoxy composite exactly can be the effective kind of matrix materials for coating. [16][17][18] Considering that the thickness of the conventional coating is several 100 microns, it is proper to choose filler in nano diameter to guarantee the uniformity of the coating. SnO 2 is a kind of commonly used semiconductor filler for improving the charge transport performance of polymers.…”

“…For insulators in service, adopting post‐treatment method, such as, surface treatment and coating, own a stronger industrial practicability 14,15 . For epoxy‐made insulators, epoxy composite exactly can be the effective kind of matrix materials for coating 16–18 . Considering that the thickness of the conventional coating is several 100 microns, it is proper to choose filler in nano diameter to guarantee the uniformity of the coating.…”