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Fabrication and properties of polyimide copolymer fibers containing pyrimidine and amide units.
- Source :
-
Journal of Materials Science . Sep2020, Vol. 55 Issue 25, p11763-11778. 16p. 2 Color Photographs, 3 Diagrams, 4 Charts, 9 Graphs. - Publication Year :
- 2020
-
Abstract
- Polyimide (PI) fibers containing pyrimidine and amide moieties were fabricated by the copolymerization of 2,5-bis(4-aminophenyl)pyrimidine (PRM) and 4,4′-diaminobenzanilide (DABA) with 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) via a two-step method. The effects of chemical structure of PI fibers, i.e., various molar ratios of PRM/DABA, on their thermal property, crystallinity, orientation factor, microvoid defects, and mechanical property, were investigated in detail. The glass transition temperatures (Tg) of all PI fibers ranged from 282 to 310 °C, and the temperatures at 5% weight loss (T5%) under N2 and air atmosphere were respectively within 548–584 °C and 482–540 °C, demonstrating the excellent thermal stability and thermal oxidation stability of all fibers. The wide-angle X-ray diffraction data illustrated that the co-PI fibers had lower crystallinity than the homo-PI fibers due to a marked decrease in molecular order packing by copolymerization. However, the co-PI fibers possessed higher degrees of orientation relative to the homo-PI fibers. In particular, the co-PI fiber with PRM/DABA = 5/5 showed the highest orientation factor, fc = 0.872. Moreover, the small-angle X-ray scattering results, i.e., decrease in microvoid size, revealed that DABA incorporation helps to reduce the defects in PI fibers. When the PRM/DABA molar ratio was 5/5, the co-PI fiber possessed an optimal tensile strength and initial modulus of 3.43 and 136.92 GPa, respectively. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00222461
- Volume :
- 55
- Issue :
- 25
- Database :
- Academic Search Index
- Journal :
- Journal of Materials Science
- Publication Type :
- Academic Journal
- Accession number :
- 143700382
- Full Text :
- https://doi.org/10.1007/s10853-020-04830-0