Promotion of the mechanical properties and thermal conductivity of epoxy by low Si₃N₄ whisker content and its mechanisms

Abstract

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.

Thermal and dielectric multiple percolation in α‐Si3N4 whiskers/silicone rubber

“…However, particles of these fillers can only enhance the κ to an unsatisfactory extent even at high f of 50 vol%. Again, one-or two-dimensional fillers are applied to construct a more effective thermal pathway to enhance κ at low f. [18] However, the reported enhancement is much lower than expected [23] and a clear thermal percolation phenomenon has not been observed in such electrical insulating TIMs till now. This indicates that there are great obstacles to building an efficient thermal pathway for phonons, which are thermal carriers in such electrical insulating fillers.…”

Balanced Mechanical and Biotribological Properties of Polymer Composites Reinforced by a 3D Interlocked Si3N4 Nanowire Membrane

“…Inspired by the above works, we select silicon nitride nanowires (SNs) to construct a uniformly continuous preforming reinforcement with the 3D structure. SNs have high Young’s modulus and excellent mechanical, physical, and chemical properties and are considered to be suitable reinforcement materials. , SNs have been incorporated into a wide range of matrixes, including carbon matrix and metal matrix, to form composites possessing unique properties and capabilities. − This makes SNs great candidates as reinforcement materials for the polymer matrix to manufacture composites used for hip joint replacement.…”

Epoxy composite with high thermal conductivity by constructing 3D-oriented carbon fiber and BN network structure

“…8,9 Usually, thermally conductive llers, such as metals (Ag, 10,11 Cu, 12,13 Al 14,15 ), nitride (BN, [16][17][18] AlN, [19][20][21] Si 3 N 4 (ref. [22][23][24]) and carbon materials (carbon nanotube, 25,26 carbon ber, [27][28][29][30] graphene 31 ) are used to modify polymers for high thermal conductivity. However, it is difficult for particle llers to achieve continuous thermal transport at low ller content, while the mechanical performance of polymer-based composite at high-ller loading will be changed and destroyed.…”