Abstract
An isotactic polypropylene (iPP-1) resin with low melting temperature (Tm) is synthesized by a metallocene catalyst and investigated for melt-spun fiber applications. The structure, thermal and mechanical properties, and feasibility of producing fibers of a commercial metallocene iPP (iPP-2) and a conventional Ziegler–Natta iPP (iPP-3) are carefully examined for comparison. Tm of iPP-1 is about 10 °C lower than the other two samples, which is well addressed both in the resin and the fiber products. Besides, the newly developed iPP-1 possesses higher isotacticity and crystallinity than the commercial ones, which assures the mechanical properties of the fiber products. Thanks to the addition of calcium stearate, its crystal grain size is smaller than those of the two other commercial iPPs. iPP-1 shows a similar rheological behavior as the commercial ones and good spinnability within a wide range of take-up speeds (1200–2750 m/min). The tensile property of fibers from iPP-1 is better than commercial ones, which can fulfill the application requirement. The formation of the mesomorphic phase in iPP-1 during melt spinning is confirmed by the orientation and crystallization investigation with wide angle X-ray diffraction (WAXD), which is responsible for its excellent processing capability and the mechanical properties of the resultant fibers. The work may provide not only a promising candidate for the high-performance PP fiber but also a deep understanding of the formation mechanism of the mesomorphic phase during fiber spinning.
Highlights
The majority of nonwoven polyolefin fibers are of great commercial interest because of their unique properties, including hydrophobicity, good mechanical properties, and excellent chemical resistance [1,2]
We present a low-melting-temperature metallocene isotactic polypropylene (iPP) for melt spinning fiber application
Isotactic polypropylene sample 1 is synthesized from C2 -symmetric metallocene catalysts (rac-Me2 Si(2-Me-4-Ph-Ind)2 ZrCl2 ) [24] with a molecular weight (Mw) of 147,000 and polymer dispersity index (PDI) of 2.5, which is a pilot product synthesized by the China Petroleum Lanzhou Chemical Research Center (Lanzhou, China)
Summary
The majority of nonwoven polyolefin fibers are of great commercial interest because of their unique properties, including hydrophobicity, good mechanical properties, and excellent chemical resistance [1,2]. Traditional commercial iPP is generally polymerized with a heterogeneous titanium-based Ziegler–Natta catalyst, whose tacticity, molecular weight (Mw ), and polymer dispersity index (PDI) are tightly dependent on the catalysts and the polymerization. In comparison with the Ziegler–Natta-catalyzed polypropylene (PP), metallocene polypropylenes are uniform polymers with precisely controlled Mw , end groups, stereoregularity, and narrow PDI [6]. Those characters make metallocene-based iPP a great candidate for producing high-quality industrial fibers by melt spinning
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.