The fine structure of bicomponent polyester fibers

Abstract

ABSTRACT:The application of alkaline hydrolysis to study the change in the fine structure of bicomponent polyester fibers as their surface is removed progressively was explored. The samples were prepared with a poly(butylene terephthalate) (PBT) sheath and a poly(ethylene terephthalate) (PET) core. The reagent used to hydrolyze the PBT was 1M NaOH in 75/25 methanol to water since it appeared to react topochemically with the fiber. The solution reacted more rapidly with PET than with PBT. Thus, when necessary to retard the weight loss of the bicomponent fibers, after a 2-h hydrolysis with this reagent to remove PBT, it was replaced with aqueous 1M NaOH solution containing 0.1% cetrimmonium bromide. Unlike homofil PET or PBT fibers, where alkaline attack appeared to be confined to the surface and left the residue relatively smooth, the bicomponent fiber was attacked unevenly, and penetration to the PET core occurred before all the PBT at the surface was removed. Nevertheless, most of the reaction was confined initially to the PBT sheath. The tenacity and extension at break of the PBT-PET fiber passed through a maximum as hydrolysis progressed. The fall in tenacity at high weight losses is ascribed to increasing surface defects in the fiber surface. After removal of the PBT by the hydrolysis, the birefringence of the residue became progressively higher. The synergistic effect of the PBT sheath on the properties of the PET core and the possible causes of the nonuniform hydrolysis at the PBT surface are discussed. An equation is proposed that includes an interaction parameter, which can be utilized to determine which property is affected most by the hydrolysis of a bicomponent fiber. In this instance, it appears from the parameters that the order is strength Ͼ extension at break Ϸ birefringence.

New functional bicomponent fibers with core/sheath‐configuration using poly(phenylene sulfide) and poly(ethylene terephthalate)

“…Bicomponent fibers with PET in the sheath showed significant changes in weight and surface structure, as expected. Interestingly, the measured weight losses between 5.2% and 9.4% are relatively small in comparison with the observed weight losses during hydrolysis of other polyesters like poly(trimethylene terephthalate) (PTT)25 and poly(butylene terephthalate) (PBT) 16. Kotek and Zeronian reported on weight losses larger than 15%, strongly depending on spinning speed and hydrolysis time 16, 25.…”

“…Interestingly, the measured weight losses between 5.2% and 9.4% are relatively small in comparison with the observed weight losses during hydrolysis of other polyesters like poly(trimethylene terephthalate) (PTT)25 and poly(butylene terephthalate) (PBT) 16. Kotek and Zeronian reported on weight losses larger than 15%, strongly depending on spinning speed and hydrolysis time 16, 25. The difference in weight loss between the NaOH and KOH can be explained by the higher concentration of the NaOH solution and, presumably, by the better mobility of the smaller Na + ‐ions into the pores of the PET‐sheath.…”

“…At elevated temperature, the sheath melts creating bonding prints 6, 7. Although a vast amount of literature is available on various aspects of PET single component spinning,8–12 there are only few reports on bicomponent spinning of PET with polypropylene (PP),13 polyethylene (PE),14 polystyrene (PS),15 poly(butylene terephthalate) (PBT),16 poly(butylene succinate/ l ‐lactate) (PBSL) or poly( l ‐lactic acid) (PLLA) 3…”

Synthesis and Characterization of Star-Shaped (PCL-B-PEG) as Potential Electrospun Microfibers

“…Fibres extensively used by human for centuries in many fields ranging from clothing, sensors, automotive and medical applications (Lee et al 2015;Li et al 2012;Rosic et al 2013;Tao 2001;Zhu et al 2003). The growth of fibre applications has led to the preparation of man-made fibre with better and increased properties such as nylon, polyesters and polypropylene (Fong et al 2002;Zeiml et al 2006;Zeronian et al 1999). Nanofibres possess unique properties such has having extraordinary high surface area per unit mass with remarkably high porosity, good mechanical properties and low basis weight that enable them to be used for various applications (Bao et al 2008;Bosworth & Downes 2011).…”

Filtering properties of nap-raised nonwoven materials

“…One relatively new direction in modification of nap-raised materials with simultaneous fixation of their porosity is to incorporate bicomponent fibres in the materials [3][4][5][6] and then treat them with heat.…”