Tensile Properties of Bark of Dirca (Leatherwood)

The genus Dirca consists of four species with strong, fibrous, tear-resistant bark.  These characteristics resulted in Aboriginal Americans’ use of the bark to make cordage and are reflected in its common names: leatherwood, thongwood, and ropewood.  During a pilot study, we measured the tensile properties of bark of Dirca mexicana by using an Instron 4500 Universal Testing Machine.  The average ultimate tensile strength (maximum force sustained) of the bark was 52.13 MPa and the average Young’s modulus (rate of change of strain versus stress) was 2.131 GPa.  We compared tensile properties of bark within all species in the genus and among taxonomically and ecologically allied genera.  The biological novelty of bark of Dirca and potential industrial applications will be reported.