Assessment of polymer matrices for composite cores in overhead conductors

Recently, a new overhead conductor design was introduced that is supported by a composite core of longitudinal glass and carbon fibers embedded in a polymer matrix produced by pultrusion. Overhead conductors are expected to operate between 100° and 170°C, with short excursions to as high as 200°C. Two composite cores were produced and tested to assess performance at projected operating temperatures by measurement of mechanical properties. The composite cores were produced using developmental epoxy formulations with T_g's (glass transition temperatures) of 176°C and 202°C, respectively. The tensile strength of the two prototype composites exhibited different temperature dependencies. The high-T_g composite retained full strength to 170°C, while the low-T_g composite retained full strength only to 80°C. The fiber-matrix adhesion was the major factor affecting strength retention at high temperatures.