Preparation and performance of a novel polyimide foam

Abstract

A new type of polyimide foam (PIF) was prepared and characterized based on a one-pot process by the reaction of a first solution with different ratios of a second solution. The first solution was comprised of pyromellitic dianhydride (PMDA), N, N-dimethyl formamide (DMF), methanol, water, surfactant, and catalysts, while the second solution contained polyaryl polymethylene isocyanate (PAPI). In the present study, the relationships among compositions, structures, and properties of PIFs were investigated. The results indicated that with the increase in the weight ratio of PAPI/(first solution), the foaming degrees of PIFs increased from 10.14 to 10.52 times and the apparent densities before postcure decreased from 15.96 to 14.51 kg/m 3 . The open cell contents, average sound absorption coefficients, and average cellular diameters of PIFs after postcure increased with increase in the weight ratio of PAPI/(first solution). The glass transition temperatures (T g ) of PIFs after postcure first increased from 287 to 299-C, then decreased to 292-C, and the 5% weight loss temperatures and 10% weight loss temperatures presented the same trend as well. The compressive and flatwise tensile properties scaled very well with the relative densities of the foams after postcure, with the highest compressive strength of 0.03 MPa and the highest flatwise tensile strength of 0.15 MPa.

Effects of hydrotalcites and tris (1-chloro-2-propyl) phosphate on thermal stability, cellular structure and fire resistance of isocyanate-based polyimide foams

“…Another process for preparing PIFs is through utilization of a first solution of aromatic dianhydride or its derivatives and a second solution of isocyanate via the free-foaming approach; the foams formed from this process are called isocyanate-based PIFs [7,10e12]. Isocyanate-based PIFs also present excellent thermal stability, acoustic absorption, and thermal insulating properties [7,10]. The free-foaming process significantly simplifies the technical route, thereby decreasing process costs and material prices.…”

“…Because of these excellent properties, PIFs are recognized as ideal thermal and acoustic insulation materials for application in many high technology fields. The preparation methods of PIFs mainly include powder and friable microsphere foaming processes; however, high thermal energy and economic costs limit the applicability of these techniques [7]. Another process for preparing PIFs is through utilization of a first solution of aromatic dianhydride or its derivatives and a second solution of isocyanate via the free-foaming approach; the foams formed from this process are called isocyanate-based PIFs [7,10e12].…”

Preparation and properties of polyimide/chopped carbon fiber composite foams

“…Furthermore, it is noteworthy that the compressive strength of PI‐2 improved compared with PI‐0 even though the density of PI‐2 is less than PI‐0. This reinforcement effect can be assigned to the fine dispersion and high orientation of chopped CF in the cell arrises that significantly improved the strength of cell skeletons, leading to a considerable portion of load transferred from the matrix to the chopped carbon fibers . On the other hand, the improved cell size distribution and density also play an important role in enhancing compressive strength of composite foams.…”

Preparation and characterization of cyanate/epoxy foam

“…T g-tan is normally used as the proper T g in literatures. 41,52 As shown in Figure 14, the DSC curve of CE/EP foam shows a T g-DSC of around 183 C. The data calculated from DSC were much lower than that evaluated from the tan peak of DMA curves as it approaches T g-E 0 and T g-E 00 . The Figure 13.…”