Characterization of geometric isomers of norbornene end‐capped imides

Young, Philip R.; Chang, An-Hwa

doi:10.1002/jhet.5570200137

Cited by 26 publications

(5 citation statements)

References 5 publications

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“…The C-H stretch region has been shown to be sensitive to the conformation of the norbornene end group. 17 Nadic anhydride exists as endo and exo isomers and, as can be seen from Fig. 8, the spectra of the two conformations are markedly different.…”

Section: Discussionmentioning

confidence: 89%

The vibrational spectra of norbornene and nadic anhydride

Parker

Williams

Steele

et al. 2003

Phys. Chem. Chem. Phys.

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Section: Discussionmentioning

confidence: 89%

The vibrational spectra of norbornene and nadic anhydride

Parker

Williams

Steele

et al. 2003

Phys. Chem. Chem. Phys.

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“…The influence of oxygen in the cure behavior of endo-endo, endo-exo, and exo-exo bisnadimide isomers was investigated by Young and Chang. 19 This work strongly showed that oxygen influenced crosslinking of the exo isomer to a much greater extent that the endo isomer. The weight loss of the exo isomer cured in air was significantly less than the endo isomer cured in the same manner.…”

Section: (B) Kinetics Of Thermal Curementioning

confidence: 95%

Kinetics of the crosslinking reaction of a bisnadimide model compound in thermal and microwave cure processes

Liu

Sun

Xie

et al. 1998

J. Polym. Sci. A Polym. Chem.

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The kinetic studies of the crosslinking reaction of a nadic end‐capped imide model compound, N,N′‐(oxydi‐3,4′‐phenylene) bis(5‐norbornene‐2,3‐dicarboximide), a bisnadimide, in thermal and microwave processes were investigated. The conversion of the endo isomer to exo isomer proceeds at a much lower temperature than the crosslinking reaction. The crosslinking reaction was monitored by the combined decrease in the infrared absorptions of the endo and exo isomers at 840 and 780 cm−1, respectively. The decrease in the concentration of starting materials follows first‐order kinetics in the thermal and microwave processes. At the same temperatures (230 or 280°C), the crosslinking reaction proceeds at about 10 times faster in the microwave process than in the thermal process. Solid‐state 13C‐NMR showed no significant loss in C=C double bond resonance in the cured products by comparison with the starting material. This study provides direct evidence that the microwave process may be an efficient method to cure nadic end‐capped polyimides. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2653–2665, 1998

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“…The reactions which occur when a nadic end-cap compound or oligomer undergoes a thermally induced cross-linking reaction have been investigated and the cross-linked structures initially proposed [1][2][3] (figure 1), have been under scrutiny. There have been several mechanism studies on model compounds, and these studies have contributed to defining the cross-linked structure [3][4][5][6][7][8][9][10]. However, solid state 13 C NMR studies by Meador et al [11] on the cure of PMR-15, a nadic end-capped polymide [12], using 13 C labeled 4,4 1 methylenedianiline provided new evidence and insight for the structure involved in the cross-linking reaction as a result of cure at 315 2 C for 1.5 h. These investigators propose a radical-induced homopolymerization mechanism to define the major product, shown in figure 1(d).…”

Section: Introductionmentioning

confidence: 99%

Some Aspects of the Cure of RP-46, a Nadic End-capped Polyimide, and Phenyl Nadimide and Bis-Nadic-3,4'-ODA Model Compounds

Simone¹,

Xiao²,

Sun³

et al. 2005

High Performance Polymers

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Infrared studies of the initial cure and post-cure of RP-46 resin, a nadic end-capped polyimide and a model bisnadimide compound N, N' -(oxydi-3,4 phenylene) di-5,6-norbornene-2,3-dicarboximide (Bis-nadic-3,4'-ODA) were conducted at 316, 325 and 350° C for various time periods. Infrared studies of another model compound, N-phenylnadimide, were conducted at lower temperatures, from 100 to 270° C. N-Phenylnadimide cures at much lower temperatures than Bis-nadic-3,4 -ODA and RP-46. The crosslinking reaction was followed by monitoring the absorption peaks at 841 and 785 cm-1, the endo and exo bands in the 2,3 positions of the nadic end caps and cyclo-aliphatic and cyclo-olefinic peaks on the region 1000 to 600 cm-1 associated with the nadic end-cap curing reaction. Weight losses and changes in the glass transition temperature of the RP-46 resin due to cure and post-cure, were also examined. The infrared changes suggest that complete cross-linking requires a temperature of 325° C or above, and that several new infrared bands are generated in the process. The simple thermally induced reverse Diels–Alder cyclopentadiene N-substituted maleimide recombination reaction or norbornene to norbornene, norbornene to cyclopentadiene or norbornene to substituted maleimide addition reactions may adequately define the cross-linked products derived from the initial cross-linking reaction at 316° C for 1 to 2 h. However, postcure of RP-46 resin or the nadic-3,4 -ODA model compound at 325 or 350° C for several hours generates additional infrared bands in the cyclo-aliphatic and cyclo-olefinic regions (1000–600 cm-1), which are absent in material cured at 316° C for 1 to 2 h. Therefore, completely cured resin consists of simple addition reaction products from the initial cure at 316° C and more complex products from the elevated temperature post-cures. A post-cure at 325° C for about 8 h or at 350° C for 2 h is required for a maximum Tgof 391° C. This is accompanied by a stabilization weight loss of about 2–3%. The weight loss and Tgdata are supporting evidence for the infrared studies.

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Characterization of geometric isomers of norbornene end‐capped imides

Cited by 26 publications

References 5 publications

The vibrational spectra of norbornene and nadic anhydride

The vibrational spectra of norbornene and nadic anhydride

Kinetics of the crosslinking reaction of a bisnadimide model compound in thermal and microwave cure processes

Some Aspects of the Cure of RP-46, a Nadic End-capped Polyimide, and Phenyl Nadimide and Bis-Nadic-3,4'-ODA Model Compounds

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