SYMPOSIA PAPER Published: 01 January 1994

The Use of Small-Scale Flexure Test Specimens to Evaluate the Mechanical Properties of Polymer Composites for Biomaterials Applications


Miniflexbars (MFBs), 1 by 5 by 30 mm, which are tested in three-point bending, have been used to study the mechanical properties of polymer composites. Chopped carbon fiber reinforced polyetheretherketone (PEEK) injection-molded bendbars, 6 by 12 by 120 mm, were chosen for analysis. MFBs were cut parallel and perpendicular to the mold fill direction from four sections of the standard size bendbar. Results of the flexure testing indicated that the strength of the MFBs was significantly decreased from the strength of the standard size bendbar. Strength also varied with position of the MFB in the standard size bendbar. To better understand these results, several factors were evaluated. Upon cutting the MFBs from the injection-molded bar, residual stresses were relieved. The decrease in strength, however, could not be associated entirely with the release of residual stresses. Local fiber orientation was examined with light microscopy. Results from this analysis indicated that flexure testing of MFBs is sensitive to local variation in microstructure. Evaluation of an injection-molded chopped fiber composite bend-bar using MFBs has indicated that these small-scale specimens can provide valuable information about the mechanical properties of polymer composites. With this understanding, MFBs can be used, with caution, in the development of in vitro and in vivo accelerated degradation test methods as well as other biomaterials applications.

Author Information

Jockisch, KA
Case Western Reserve University, Cleveland, OH
Brown, SA
Case Western Reserve University, Cleveland, OH
Moet, A
Macromolecular Science, Case Western Reserve University, Cleveland, OH
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Developed by Committee: F04
Pages: 212–224
DOI: 10.1520/STP18106S
ISBN-EB: 978-0-8031-5261-8
ISBN-13: 978-0-8031-1894-2