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Fracture toughness and mechanical properties of poly(n‐pentyl‐n‐alkylsilanes)
Author(s) -
Klemann Bruce M.,
DeVilbiss Tad,
Koutsky James A.
Publication year - 1996
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.10394
Subject(s) - materials science , fracture toughness , composite material , tearing , elastic modulus , ultimate tensile strength , toughness , modulus , residual stress , polymer , strain energy release rate , stress (linguistics) , linguistics , philosophy
The mechanical properties and fracture toughness of thin films of a series of poly(n‐pentyl‐n‐alkylsilanes) were investigated. Poly(n‐butyl‐n‐pentylsilane) is the strongest of these polymers with an elastic modulus of 2.96 × 10 8 Pa and a fracture strain of 85% at 25°C. The hexagonal mesophases of these polymers generally show elastic moduli on the order of 10 7 Pa and are often quite extensible. A J ‐integral analysis of the ductile tearing of thin films of poly(n‐butyl‐n‐pentylsilane) and poly(n‐propyl‐n‐pentylsilane) using an Instron tensile testing machine and specimens in the single edge notch (SEN) geometry yielded plane stress J 1 c (critical value of J for fracture initiation) of 1745 J/m 2 and 205 J/m 2 , respectively. Both values are significantly higher than the plane stress G 1 c (critical energy release rate) value of 109 J/m 2 obtained for poly(di‐n‐hexylsilane) with a residual stress analysis using the same apparatus and testing procedure.