Kinetics of imidization of poly(amic acid) in miscible and immiscible polymer blends

Makhija, S.; Pearce, Eli M.; Kwei, T. K.

doi:10.1002/app.1992.070440520

Cited by 10 publications

(9 citation statements)

References 11 publications

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“…The bands at 1015 and 1000 cm -1 appear to be the most satisfactory. 15 The bands at 1780 and 720 cm -1 were found to be insensitive to changes that could be detected by thermal techniques in the later stages. 16 A recent study 8 also found that bands at 1780 and 720 cm -1 are affected by anhydride absorption that appears during the thermal cycle.…”

Section: Methodsmentioning

confidence: 92%

“…16 The band near 1380 cm -1 shows very little effect from anisotropy when it is normalized to the 1500 cm -1 aromatic band. 15 The use of different methods and procedures to measure imidization has undoubtedly contributed to the general lack of agreement over the degree of imidization that is attainable. The chemical structure of polyamic acid also affects the imidization process.…”

Section: Methodsmentioning

confidence: 99%

“…The chemical structure of polyamic acid also affects the imidization process. [12][13][14][15][16][17] Since Raman spectra show a strong intensity for the symmetrical stretching of the bonds, this spectroscopic method can eliminate interference from the antisymmetric stretching band. Also, as shown later, poly(amic acid) in this study produced almost negligible (or undetectable) anhydride.…”

Section: Methodsmentioning

confidence: 99%

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Kinetic Study of the Imidization of a Poly(ester amic acid) by FT-Raman Spectroscopy

et al. 1997

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The kinetics of thermal imidization of a poly(ester amic acid) in solid state was investigated in the temperature range 120−180 °C. FT-Raman spectroscopy was used for the measurement of imidization. Data on changes in intensity were collected on compressed thin specimens that had been isothermally cured. FT-Raman spectral changes as a function of imidization time are adequately modeled by assuming two first-order imidization reactions. Activation energies for the first and second ring closure processes were almost the same, 20.5 and 19.9 kcal/mol, respectively. However, the activation energy increased slightly (24.6 kcal/mol) when the second-order reaction model was adopted for the first reaction. Increase in activation energy was screened by the increase of the pre-exponential factor, implying the absence of significant changes in the reaction rate ratio. A new time dependent model is proposed which is easy to apply and shows good agreement with the experimental data, both quantitatively and qualitatively. The activation energy calculated by the new model was 24.3 kcal/mol. It takes into consideration the evolution of different amic acid stages. The proposed model also correlates the two-step imidization reaction very well.

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Section: Methodsmentioning

confidence: 92%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Kinetic Study of the Imidization of a Poly(ester amic acid) by FT-Raman Spectroscopy

et al. 1997

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“…In especial, the introduction of new building blocks will bring great impacts on imidization process. A large number of papers have devoted to study on imidization . Recently, various in situ characterizations were employed to study thermal imidization process, which were able to reveal real‐time evolution of microstructure and property of PI and attributed to the study on dynamic mechanism.…”

Section: Introductionmentioning

confidence: 99%

The retarding effects and structural evolution of a bio‐based high‐performance polyimide during thermal imidization

Zheng

Liu

et al. 2018

J of Applied Polymer Sci

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The thermal imidization evolution of a bio-based high-performance polyimide, namely adenine-containing polyimide (API), was investigated by thermogravimetric analysis (TGA), in situ Fourier transform infrared spectroscopy (in situ FTIR), and wide-angle X-ray diffraction (WAXD), in contrast to an adenine-free 4,4 0 -oxydiphthalic anhydride (ODPA)/4,4 0 -oxydianiline (ODA) PI. The influence derived from adenine was focused. At precursor stage of API (polyamic acid, PAA), the H-bonding interaction of PAA-PAA type as well as the especial interaction between the secondary amine of adenine and solvent (dimethylacetamide, DMAc) was discovered. Structural evolution of API was traced by in situ FTIR and multistage WAXD from PAA stage to PI stage. Compared with OPI, the retarding effects were found in the process of thermal imidization of API, partly due to the formation of H-bonding derived from the extra secondary amine of adenine moieties, which complicated the H-bonding form in API. Finally, a hypothesis of evolution of thermal imidization process about API molecule was proposed in contrast with adenine-free ODPA ODA PI. Compared with the consistency of both API and ODPA ODA PI in PAA stage, API possessed a more delicate thermal imidization process.

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“…and polyvinylidene fluoride (16). In addition, other patents and published reports have described the compatibility or miscibility of the component polymers by various techniques and thermal behavior of these blends (17)(18)(19)(20)(21)(22)(23)(24)(25). Only a few papers (26,27) have discussed some mechanical and electrical properties of the blends prepared.…”

Section: Introductionmentioning

confidence: 99%

Polyimide and nylon 6 blend film: Preparation, characterization and thermal behavior

Niyogi

Maiti

Adhikari

2002

Polymer Engineering & Sci

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A polyimide blend system has been prepared from a base polyimide of BTDAODA by adding ε‐caprolactam at the poly(amic acid) stage where ε‐caprolactam undergoes polymerization to form nylon 6 during the thermal cyclodehydration of poly(amic acid). The blend has been characterized by elemental analysis. IR, 13C CPMAS NMR, XRD and simple chemical methods. The thermal analysis study (TGA and DTA) shows that the stability of the blend systems is more in the lower temperature region (up to 300°C) in comparison to the control polyimide system. The isothermal study at 400°C in inert atmosphere shows that the blend system is equally stable but the isothermal study in air at 400°C shows that the thermooxidative stability of the blend films (except BB 4) is higher. Also, isothermal study in air at 500°C shows more than 90% weight loss for all the films within 3 h, but in an inert atmosphere, the blend films show lower weight loss compared to the control film. Although the XRD pattern of all the blend and control films shows an amorphous character, the films developed some crystallinity when treated with boiling NMP where the blend films developed higher crystallinity.

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Kinetics of imidization of poly(amic acid) in miscible and immiscible polymer blends

Cited by 10 publications

References 11 publications

Kinetic Study of the Imidization of a Poly(ester amic acid) by FT-Raman Spectroscopy

Kinetic Study of the Imidization of a Poly(ester amic acid) by FT-Raman Spectroscopy

The retarding effects and structural evolution of a bio‐based high‐performance polyimide during thermal imidization

Polyimide and nylon 6 blend film: Preparation, characterization and thermal behavior

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