Fabrication of rigid polyimide foams with overall enhancement of thermal and mechanical properties

Abstract

Polyimide (PI) foams have been developed for decades and widely used as thermal insulation materials. However, the limited mechanical and thermal properties continually being a serious problem that restrict their further applications. In this study, a series of rigid PI foams with excellent mechanical and thermal performance were fabricated by the reaction of benzophenone-3,3',4,4'-tetracarboxylic dianhydride (BTDA) with two diamines of 2–(4-aminophenyl)-5-aminobenzimidazole (BIA) and 4,4'-diaminodiphenyl ether (ODA) with various molar ratios, and the cis-5-norbornene-endo-2,3-dicarbox-ylic acid (NA) was introduced as end-capping and foaming agent. The results demonstrate that the foaming degree decreases with increasing the BIA molar ratio in the polymer chains owing to the elevated melt viscosity of precursor. Furthermore, the prepared rigid PI foams exhibit excellent thermal and mechanical properties. When the BIA contend up to 40 mol%, the glass transition temperature ( Tg) and the temperature at 10% of weight loss ( Td 10 %) of PI foam increased ∼80°C and ∼35°C in comparison with the pristine PI-0, respectively. In addition, the compressive strength and modulus at 10% strain of PI-4 reached to 5.48 MPa and 23.8 MPa, respectively. For the above-mentioned advantages, the prepared rigid PI foams are promising candidates as thermal insulation and structure support composite materials in the aerospace and aviation industries.

Fabrication of Rigid Polyimide Foams by Constructing Dual Crosslinking Network Structures

“…A comparison of the normalized compressive strength between the PIFs fabricated in this work and the other foams such as dianhydride-diamine-based PIFs, isocyanate-based PIFs, and commercial PIFs ,− is given in Figure e. The values in the parentheses were related to the density and compressive strength at 10% strain.…”

Structure to Properties Relations of Polyimide Foams Derived from Various Dianhydride Components

“…A comparison of compressive strength of PIFs prepared in this work with other PIFs was presented in Figure and Table S3. − To facilitate direct comparison, the values of the compressive strength are normalized with density. The normalization of compressive strength with foam density is conducted as per eq . , where A is a constant which is related to temperature and matrix.…”

Solid-state foaming of poly(ether-ether-ketone)/hydroxyapatite composites

“…14,15 During the foaming process, the pore size and porosity of the polymer foam can be controlled by adjusting the gas foaming parameters. 16 However, currently, gas foaming is mainly used for amorphous plastics with a low melting temperature, such as polycaprolactone (PCL), polymethyl methacrylate (PMMA), and polyimide (PI). [16][17][18] There has been little research on solid-state foaming of PEEK or PEEK-based composites.…”