Tensile properties of GF-polyester, GF-nylon, and GF-polypropylene commingled yarns

Abstract

Commingled yarns for composite applications consist of combination of high-performance filaments and matrix-forming thermoplastic filaments that have quite different tensile characteristics. The commingling process mixes these filaments along with introduction of nips and open sections alternately along the length of commingled yarns. Thismakes the tensile behavior of commingled yarns to be quite different from that of constituent individual filaments. This article describes the effects of commingling on axial and nonaxial strengths of commingled yarns. The nonaxial performance of commingled yarns is evaluated in terms of ratio of loop strength or knot strength to the axial tensile strength. This may be used as an effective tool to understand the response of commingled yarns to negotiate curvatures and complex yarn paths during textile preforming process, particularly during formation of multiaxial weaves, knits, or braids. The nonaxial tensile testing of commingled yarns like knot and loop tensile tests gives an idea about the mixing of the filaments in the cross section. Commingled yarns in knotted or looped form retain almost 55%-60% of the axial tensile strength.