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Promotion of the mechanical properties and thermal conductivity of epoxy by low Si 3 N 4 whisker content and its mechanisms
Author(s) -
Liu Xuan,
Zhang Dian,
Liu Yijun,
Liu Jing,
Yang Xiaofeng,
Gao Yunqin,
Ma Aiqiong
Publication year - 2020
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.48721
Subject(s) - materials science , epoxy , composite material , ultimate tensile strength , whisker , thermal conductivity , residual stress
Si 3 N 4 whisker (Si 3 N 4w ) 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 Si 3 N 4w /epoxy is investigated. The bending strength is 82.63 MPa at a Si 3 N 4w 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 Si 3 N 4w content of 7 vol%. However, Si 3 N 4w /epoxy becomes sensitive to precrack due to a weak CN 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 Si 3 N 4w , and rough fracture surface, is observed in Si 3 N 4w /epoxy. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137 , 48721.