High Thermally Stable and Melt Processable Polyimide Resins Based on Phenylethynyl-Terminated Oligoimides Containing Siloxane Structure

Abstract

A series of 4-phenylethnylphthalic anhydride (PEPA)-terminated oligoimides were prepared by co-oligomerizing isomeric dianhydrides, i.e., 2,3,3′,4′-biphenyltetracarboxylic dianhydride (a-BPDA), 2,3,3′,4′-benzophenonetetracarboxylic dianhydride (a-BTDA) or 2,3,3′,4′-diphenylethertetracarboxylic dianhydride (a-ODPA), with diamines mixture of bis(4-aminophenoxy)dimethyl silane (APDS) and 2,2′-bis(trifluoromethyl) benzidine (TFDB). The effects of siloxane content and dianhydride structure on the rheological properties of these oligoimides and thermal stability of the corresponding cured polyimide resins were investigated. The results indicated that the introduction of the siloxane structure improved the melt processability of the oligoimides, while the thermal stability of the cured polyimide resins reduced. The oligoimide derived from a-ODPA revealed better melt processability and melt stability due to the existence of a flexible dianhydride structure. The oligoimide PIS-O10 derived from a-ODPA gave the lowest minimum melt viscosity of 0.09 Pa·s at 333 °C and showed the excellent melt stability at 260 °C for 2 h with the melt viscosity in the range of 0.69–1.63 Pa·s. It is also noted that the thermal stability of these resins can be further enhanced by postcuring at 400–450 °C, which is attributed to the almost complete chemical crosslinking of the phenyethynyl combined with oxidative crosslinking of siloxane. The PIS-T10 and PIS-O10 resins that were based on a-BTDA and a-ODPA, respectively, even showed a glass transition temperature over 550 °C after postcuring at 450 °C for 1 h.

Preparation of poly(melamine‐formaldehyde‐2,2′‐bis(trifluoromethyl)benzidine) high‐performance fibers

“…25,26 The 1625 cm À1 is the frequency-doubled absorption peak of the benzene ring. 27 It can be seen from the figure that with the increase of the amount of TFMB, its benzene ring frequency doubling absorption peak and C F absorption peak are more obvious, so it can be speculated that TFMB and MF have undergone a copolymerization reaction, but the NMR is still needed to further determine the MFF-TFMB molecular structure.…”

Sub-nm Pore Size of Phenylethynyl End-Capped Imide Oligomer-Derived Carbon for Molecular Sorption and Separation

“…Phenylethynyl-terminated imide (PETI) oligomers and their derived polymer networks are broadly employed in high-temperature polymer composite applications in the aerospace industry. − PETI-type oligomers undergo crosslinking through radical polymerization at elevated temperatures (325–400 °C), forming linear acetylenic structures at lower temperatures around 325 °C and crosslinked cyclized rings at temperatures greater than 350 °C. − Recent studies have incorporated ortho-hydroxyl functionalities into the backbone of PETI imide oligomers, enabling TR during network formation. − TR conversion and the resulting film properties such as dielectric constant, glass transition temperature ( T g ), and thermal degradation of the crosslinked TR-PBO networks (TR-PBOx) were elucidated, while their pore structures and properties remain less understood.…”

Thermal oxidative aging of satin weave and thin‐ply polyimide composites

“…[1] Carbon fiber composites based on organic resins with higher thermal stability have been available for a long time and have been used in a variety of electronics, energy, machinery, and aerospace applications. [2,3] Previous studies have reported on the development of a thermoset polyimide-based composite system, suitable for manufacturing by Resin Transfer Molding (RTM), with a glass transition temperature (T g ) between 340 and 466 C. [4][5][6] The effect of long-term exposures to high temperatures on the mechanical properties, as well as thermal cycling, have also been studied. [7,8] It was shown that during exposure to up to 320 C for 500 h in air, mostly the matrix and matrix-fiber interface properties were degraded.…”