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Polyimide Fibers (polyimide + fiber)

Distribution by Scientific Domains
Polymers and Materials Science100%

Selected Abstracts

Novel aromatic polyimide fiber with biphenyl side-groups: Dope synthesis and filament internal morphology control

POLYMER ENGINEERING & SCIENCE, Issue 2 2006
Xiangyang Liu
A new organic-soluble aromatic polyimide with biphenyl side-groups has been synthesized from 4,4,-oxydiphthalic anhydride and 3,5-diamino-benzonic-4,-biphenyl ester (DABBE) via a one-step polymerization in m -cresol. A higher molecular weight polyimide has been obtained by the addition of chlorotrimethylsilane (TMSCl) in the solution of DABBE to form, in situ, silylated diamine. The optimum mole amount of TMSCl relative to the number of amino groups is 100%. This polyimide is soluble in m -cresol, allowing fibers to be spun from isotropic solution using a dry-jet wet spinning method. Based on a ternary phase diagram of m -cresol, ethanol, and water, controlling of the internal morphology of as-spun fibers has been achieved by varying the rate of polyimide coagulation through adjustment of nonsolvent/solvent miscibility in the coagulation bath. Scanning electron microscopic pictures show that filament internal morphologies ranged from porous-like to fully solid. The solid as-spun fibers can be drawn at high temperatures (>330°C) under tension to high drawn ratios (up to 6×), which produces a remarkable increase in tensile strength to about 1.0 GPa and an initial modulus higher than 60 GPa. POLYM. ENG. SCI. 46:123,128, 2006. © 2005 Society of Plastics Engineers [source]

Simulation of dry-spinning process of polyimide fibers

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2009
Gang Deng
Abstract As one type of high-performance fibers, the polyimide fibers can be prepared from the precursor polyamic acid via dry-spinning technology. Unlike the dry-spinning process of cellulose acetate fiber or polyurethane fiber, thermal cyclization reaction of the precursor in spinline with high temperature results in the relative complex in the dry-spinning process. However, the spinning process is considered as a steady state due to a slight degree of the imidization reaction from polyamic acid to polyimide, and therefore a one-dimensional model based on White-Metzer viscoelastic constitutive equation is adopted to simulate the formation of the fibers. The changes of solvent mass fraction, temperature, axial velocity, tensile stress, imidization degree, and glass transition temperature of the filament along the spinline were predicted. The effects of spinning parameters on glass transition temperature and imidization degree were thus discussed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source]

Correlation between hydrogen-bonding interaction and mechanical properties of polyimide fibers

POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 4 2009
Xiangyang Liu
Abstract Novel co-polymerization polyimide (PI) fibers based on 4,4,-oxydianiline (ODA)-pyromellitic dianhydride (PMDA) were prepared. 2-(4-Aminophenyl)-5-aminobenzimidazole (PABZ) containing the NH group was introduced into the structure of the fibers as the proton donor. The results of Fourier transform infrared (FTIR) and dynamic mechanical analysis (DMA) showed that hydrogen bonding occured between the NH group and chains, which strongly enhanced interchain interaction. This hydrogen bonding interaction increased the tensile strength and initial modulus of the PI fibers up to 2.5 times and 26 times, respectively, compared to those of homo-PI PMDA-ODA fibers with no hydrogen-bonding interaction because of the absence of proton donors after the imidization process. In the mean time, glass transition temperature (Tg) of the modified PI fibers was found to be 410,440°C, which was higher than that of the homo-PI PMDA-ODA fibers. From the result, a novel access to molecular design and manufacture of high performance PI fibers with good properties could be provided. Copyright © 2009 John Wiley & Sons, Ltd. [source]