Melt-processable thermosetting polyimide: Synthesis, characterization, fusibility, and property

To obtain a melt-processable thermosetting polyimide having a high glasstransition temperature (T,,) and good solvent resistance, the effect of introducing a crosslinkable agent into the polymer chain ends of the melt-processable polyimide on its physical properties was studied. The polyimide (calculated number-average molecular weight (M-n) = 11,600 g/mol) capped with the crosslinkable agent exhibited poor melt flowability because its crosslinkable agent reacted at the processing temperature of 360 degreesC. To reduce the rate of crosslink reaction, two methods were investigated. One was lowering the processing temperature, and the other was decreasing the amount of crosslinkable agent. The low-molecular-weight oligomer (calculated M-n = 6300 g/mol) capped with the crosslinkable agent exhibited good melt flowability at the lower processing temperature of 340 degreesC where the crosslinkable agent did not react. However, the obtained molded part of this oligomer was too brittle to maintain its shape. However, the polyimide (calculated . = 11,600 g/mol) partially capped with the crosslinkable agent demonstrated good melt flowability at the processing temperature of 360 degreesC. Furthermore, the molded part of this resin was strong and tough. In addition, the cured part exhibited high T-g, and good solvent resistance. (C) 2004 Wiley Periodicals, Inc.