Interfacial shear strength of flax fiber/thermoset polymers estimated by fiber fragmentation tests

We study flax/thermoset polymer ISS [interfacial shear strength] for most common types of thermosets: vinylester, polyester, and epoxy. The effect of fiber surface treatment on ISS in such systems reinforced with flax fibers is investigated. Apparent ISS is evaluated from SFF tests by the Kelly-Tyson approach utilizing fiber strength at the critical length. Fiber strength at such small lengths is hardly accessible to direct testing, therefore it is usually extrapolated from test results at larger gauge lengths. We present ISS of flax fibers subjected to different treatments and thermoset polymers, derived from SFF tests using comprehensive fiber strength data.