Synthesis and characterization of a carborane-containing monofunctional imide monomer as a modifier for imide oligomer

Abstract

A novel carborane-containing imide monomer (CB-PEPA) was synthesized and used as a modifier for phenylethynyl-terminated imide oligomer (PI-mPDA) to study the effect on the performance of the oligomers and thermosetting polyimide materials. The curing behavior of the blends of CB-PEPA and PI-mPDA was investigated by differential scanning calorimetry (DSC). It showed that CB-PEPA had a melting point at 183°C. Nonisothermal DSC showed that imide monomer had higher activation energy than that of bifunctional imide oligomer. Rheometer study showed that the monomer CB-PEPA could be used as a reactive diluent for PI-mPDA to reduce the minimum melt viscosity and broaden the process window of imide system. Thermogravimetric analysis showed that the char yield of resin increased with the addition of CB-PEPA. The resin derived from a 25 wt% CB-PEPA loading in PI-mPDA exhibited a high char yield of 81.0% at 800°C in nitrogen. Due to the steric hindrance and rigid group of carborane, the Tg of composites also increased with the addition of CB-PEPA. Composites derived from a 10 wt% CB-PEPA loading in PI-mPDA exhibited the relatively higher flexural strength and interlaminar shear strength.

HighTgand Thermo‐Oxidatively Stable Thermosetting Polyimides Derived from a Carborane‐Containing Diamine

“…[26] A carborane-containing imide monomer was synthesized as well and used as a modifier to improve the thermal stability and T g of PI. [27] Cheng et al also reported a series of carborane-containing copolymer PIs, which showed that the T g , thermal and thermo-oxidative stability of the resulting PIs were improved by the addition of an acetylenic monomer containing carborane; and the thermoset derived from the pure carborane-containing acetylenic monomer exhibited the highest T g value of 455 °C. [7] However, all these PIs are obtained via copolymerization of imide oligomers with reactive monomer containing carborane, which has limited improvement in T g and thermal stability.…”

Carborane-containing bismaleimide resins with excellent heat resistance and dimensional stability

“…Obviously, as shown in Figure 7, the carborane-containing monomer CB-MI showed the highest thermal stability, and is well in agreement with the results previously reported for carborane-containing imide monomer. 25,26 The char yield at 600°C of cured CB-MI reached 85.1%. It could be attributed to the presence of a passivation layer with oxidized carborane formed on the sample surface to prevent further erosion.…”

“…Further, the blend resins exhibit lower T 5 and T 10 together with higher char yield at 600°C than the cured BDM due to the introduction of carborane into the system, and it is well in agreement with the previously reported carborane-containing polyimides. 25,26 For example, the T 5 of BMI-CB20 decreased by around 26°C compared to BDM, while the corresponding char yield at 600°C increased from 56.0% to 69.5%. The results indicated that the incorporation of carborane group into a polymer could significantly enhance the thermal stability.…”

Phenylethynyl-terminated Imide Oligomers Modified by Reactive Diluent for Resin Transfer Molding Application

“…Due to their outstanding thermal stability, icosahedral carboranes, a class of carbon-containing boron-cluster compounds, were also utilized to prepare reactive diluents. [39] Chen et al [40] synthesized a carborane-containing imide oligomer (CB-PEPA). It was found that CB-PEPA not only improves melting processability, but also improves the thermal stability and mechanical properties of the cured resins.…”