The Dependence of Air-textured PES Thread Mechanical Properties on Texturing Parameters

Abstract

Stress-strain properties including loop strength, stress relaxation and elastic recovery of air-textured PES/PES corewrap
sewing threads manufactured on “Eltex” air-texturing machine with HemaJet® air-texturing nozzle are
investigated. Torlen FY HT PES 13.3 tex multifilament yarn distinguished by increased strength was used as raw
material. Two PES yarns were fed to the nozzle as core threads and one as wrap effect. The properties of threads
manufactured alternatively with thermosetting and without it are studied in dependence on overfeed of wrap yarn and
pressure of air fed into the texturing nozzle.
ZWICK/ROELL BDO-FBO.5TH testing machine with a 50 N load cell was used performing the tests. Mechanical
properties of the PES multifilament yarns are markedly changed by air-texturing. Breaking tenacities of PES/PES airtextured
sewing threads are only one half of those of the raw PES yarn due to core-wrap structure of the air-textured
threads and the disordering of filaments of core threads during air-texturing. PES/PES threads are pretty less responsive
to loop testing if comparing with straight thread test than the raw PES yarn. Air-pressure and overfeed in texturing are
influential factors in respect of stress-strain properties and loop strength of air-textured PES/PES sewing threads. Their
influence is markedly affected by thread thermosetting: lower air pressure and overfeed values are advantageous factors
while texturing without thermosetting but they are disadvantageous ones while texturing with thermosetting. The
thermosetting of threads does not markedly influences relaxation behaviour of air-textured PES/PES threads, but the
thermoset threads show to have more stable elastic power at higher strains.