Slot liner for an electric machine

A slot liner 40 is provided for a stator 12 and/or a rotor 14 of an electric machine 10 and includes a body 54 extending a length from a first end 58 to an opposite second end 60 and a width from a first edge to an opposite second edge. The body includes an inner segment 70 flanked by first and second outer segments 72,74 that extend along the length of the body. The inner segment includes at least one different material from the first and second outer segments such that the thermal conductivity and rigidity of the inner segment is greater than that of the first and second outer segments. The thermal conductivity of the inner segment is between 1.5 - 2.5W/mK and that of the outer segments is less than 0.2W/mK. The inner segment may be a polyimide filled with boron nitride particles, and/or reinforced with at least one of glass fibres, PEEK fibres, PEKK fibres, para-aramid synthetic fibres or polybenzimidazole fibres. The outer segments may be of neat polyimide.