Structure–property evolution of poly(ethylene terephthalate)/poly(trimethylene terephthalate) side‐by‐side self‐crimp filament

Abstract

To investigate the microstructure and mechanical properties of self‐crimping two‐component side‐by‐side bicomponent filament, this paper focuses on systematically investigating the structure–property evolution of poly(ethylene terephthalate) (PET)/poly(trimethylene terephthalate) (PTT) side‐by‐side bicomponent filament prepared via melt spinning with various component ratios, drawing and heating treatment. The investigation was operated upon the combination of morphology analysis, thermal analysis, crystallization, and orientation analysis. The variation of cross section and curl‐morphology, crystallization, and microstructures mainly containing lamellar and microfibrillar crystals as well as their effects on the mechanical and self‐crimping properties were discussed. As the draft ratio (DR) increases, the crystallinity, sonic orientation factor, tensile strength, and crimp‐recovery rate of the filaments were increased. The sonic orientation factor in the crystalline region decreases from 0.923 to 0.777 but increases from 0.677 to 0.903 in the amorphous region. In contrast to the variation of the DR, heating temperature has a limited effect on the tensile strength of the PET/PTT hybrid filaments. Crimp‐recovery rate, however, first increases to 11.8 and then decreases to 9.8 with an increasing heating temperature from 144 to 168°C. Most of these behaviors have been attributed to changes in the ratio of contractile stress for both PTT and PET components, originating from microstructural evolution in hybrid filaments, including crystal growth, breakage, deflection, and deformation of chains along the axial direction. As a summary, an interpretive diagrammatic sketch has been proposed to clarify the structure–property relationships of the commercial PET/PTT filaments.