The morphology, electrochemical property, photoabsorption ability and photocatalytic activity of BiOBr/g-C3N4 composites are discussed. A rational photocatalytic mechanism is proposed.

The improvement of the mechanical properties of brittle epoxies by various fillers, especially by carbon-related materials, has attracted significant attention and achieved impressive results. However, the dielectric properties of an epoxy may be compromised along with the improvement, and there is an urgent need to develop electrical insulating fillers to address this issue. In this study, Si 3 N 4 whiskers (Si 3 N 4w) are first introduced as the filler used to prepare a composite of Si 3 N 4w /epoxy. The results indicate that Si 3 N 4w has an outstanding capability to comprehensively improve the mechanical properties of an epoxy. The maximal reinforcing and toughening effect could be obtained at a low filler content of 3.0%. The bending strength, Young's modulus, K IC and work of fracture of the composite can be augmented by 34.05%, 23.00%, 57.53%, and 513.50%, respectively, in comparison with those of the neat epoxy. The abundant energy dissipation mechanisms responsible for these effects are observed and interpreted. Finally, a brief phenomenological fracture process of Si 3 N 4w /epoxy is proposed. K E Y W O R D S bending strength, epoxy, Si 3 N 4 whisker, toughness, work of fracture 1 | INTRODUCTION Epoxy resin is widely used in aerospace, automobile, military, electronic, and energy industries due to its good mechanical properties, sealing performance, electrical insulation and convenient processing. [1] However, as the performance requirements increase, its mechanical

Si3N4 whisker (Si3N4w) is selected as epoxy filler. The influence of filler content on the bulk density, porosity, bending strength, Young's modulus, critical stress intensity factor, work of failure, morphologies of fracture surface, and thermal conductivity of Si3N4w/epoxy is investigated. The bending strength is 82.63 MPa at a Si3N4w content of 5 vol% and increases to 25.29% more than that of neat epoxy. Compared with that of neat epoxy, the work of failure and thermal conductivity increase by 455% and 34.78% to 18 248.92 J·m−2 and 0.31 W·m−1·K−1, respectively, at a Si3N4w content of 7 vol%. However, Si3N4w/epoxy becomes sensitive to precrack due to a weak CN bond and residual tensile stress at the interface, thereby resulting in the decline of critical stress intensity factor. The coexistence of various energy dissipation mechanisms, namely, steps, craters or depressions, stress whitening, plastic flow, pull out of Si3N4w, and rough fracture surface, is observed in Si3N4w/epoxy. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48721.

No abstract