Thermal mechanical and dynamic mechanical property of biphenyl polyimide fibers

Abstract

High-performance polyimide fibers possess many excellent properties, e.g., outstanding thermal stability and mechanical properties and excellent radiation resistant and electrical properties. However, the preparation of fibers with good mechanical properties is very difficult. In this report, a biphenyl polyimide from 3,3Ј,4,4Ј-biphenyltetracarboxylic dianhydride and 4,4Ј-oxydianiline is synthesized in p-chlorophenol by one-step polymerization. The solution is spun into a coagulation bath of water and alcohol via dry-jet wet-spinning technology. Then, the fibers are drawn in two heating tubes. Thermal gravimetric analysis, thermal mechanical analysis, and dynamic mechanical analysis (DMA) are performed to study the properties of the fibers. The results show that the fibers have a good thermal stability at a temperature of more than 400°C. The linear coefficient of thermal expansion is negative in the solid state and the glass transition temperature is about 265°C. DMA spectra indicate that the tan␦ of the fibers has three transition peaks, namely, ␣, ␤, and ␥ transition. The ␣ and ␥ transition temperature, corresponding to the end-group motion and glass transition, respectively, extensively depends on the applied frequency, while the ␤ transition does not. The activation energy of ␣ and ␥ transition is calculated using the Arrhenius equation and is 38.7 and 853 kJ/mol, respectively.

Structure and properties of novel PMDA/ODA/PABZ polyimide fibers

“…As an important member of aromatic hetero-cyclic polymers, polyimides (PIs) exhibit several valuable properties such as chemical resistance, excellent mechanical and electrical properties, good resistance to high temperatures and irradiation, and outstanding thermal stability [15][16][17]. Extensive investigations have been performed in the preparation of high-performance aromatic PI fibers [18][19][20], but the study of the PI fibers with a lower cost and outstanding performance was insufficient. The PI fibers prepared with PMDA and ODA are the most low-cost and with commercial application foreground, but they possess poor mechanical properties.…”

Effect of alkyl side chain length on the properties of polyetherimides from molecular simulation combined with experimental results

“…Traditionally, there are two methods to obtain a stress–strain curve from atomistic modeling techniques 16. One is the use of a MM technique and the other is the use of a MD technique.…”

Polyimide Fibers with High Strength and High Modulus: Preparation, Structures, Properties, and Applications

“…The as‐spun fibers were further drawn with ratios as high as ten times and isothermally annealed at elevated temperatures above 400 °C to obtain HSHMPI fibers with tensile strength higher than 3.0 GPa and an initial modulus more than 110 GPa. Zhang et al synthesized BPDA/4,4′‐oxydianiline (ODA) PI solutions in p ‐chlorophenol via a one‐step polycondensation and prepared fibers via a dry‐jet wet‐spinning method. The HSHMPI fibers exhibited an initial modulus of 114 GPa and tensile strength of 2.4 GPa at a drawing ratio of 5.5.…”