Aromatic polyimides
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This document discusses aromatic polyimides, including their formation from reactions between pyromellitic dianhydride and diamines, their heat resistant and mechanical properties, and applications. Polyimides have excellent heat resistance due to their high thermoxidative stability and modulus of elasticity. They are used as insulators in electronics and aerospace applications like insulation and space suits due to their flexibility, strength, and stability from -269 to 400°C. The document also summarizes recent research partially carbonizing aromatic polyimide films to increase their electrical conductivity for applications.
Aromatic polyimides
- 1. By: FAKHIR JIBRAN E13-325 5th Semester Metallurgy and Materials Engineering
- 2. Introduction of Polyimides Aromatic Polyimide Formation Properties Applications Recent Research on this Material Conclusion References
- 3. Polymers of Imide-Monomer Excellent heat resistant properties Commercially prepared by reaction between pyromellitic dianhydride and Di-amines Have further three types Aliphatic Semi Aromatic Aromatic Do You Know? KAPTON is one of Oldest polyimide Manufactured by man
- 4. Benzene rings are attached with chains Most significant type of polyimide Heat resistant Thermoplastic Aromatic Polyimides are more commercially available in the form of uncured resins than thermosets
- 5. Reactions between Pyromellitic Di-anhydride and Di-amines Polymer in stage 1 is soluble which is converted into stable polyimide in stage 2
- 6. One of the oldest and most adopted method is: “Two Step Method Via Poly(Amic acid)s” By Synthesizing the soluble polymer precursor namely Poly-amic acid and then converting it into polyimide
- 7. Heat resistant due to high Thermoxidative Stability High Modulus of elasticity Superior Chemical resistance Good electrical properties High mechanical strength due to flexibility BUT Expensive
- 8. *Kapton is a common example of Polyimides being used as insulator in electronic circuits. *Kapton is a poly- Imide film which can remain stable from -269 to 400`C
- 9. Used in aerospace industry for making insulations, polyimide boost Due to their flexibility they are used in making space suits
- 10. Article 1: Partial carbonization of aromatic polyimide films •They are partially carburized between temperature of 700 to 100 degrees Celsius •Kapton films were sandwiched between graphite •Kept in hydrogen atmosphere in high temperature •Temperature was kept constant for 30 min. after carburizing temperature reached •The electrical conductivity can be expressed as: α = α* exp (2E / kT ) where k is the Boltzman’s constant; T is the absolute temperature, α and E were found to be a function of the carbonized temperature •It is concluded that impurity level’ lies about 0.4 eV below the conduction band for a specimen carbonized at 700ºC. The band gap depends on the carbonized temperature. When the carbonized temperature is higher, the band gap is smaller.
- 11. they can provide mechanical strength and heat resistance at the same time Expensive but reliable Its importance will increase in future Due to chemical inertness it can be used for insulations in severe atmospheres.
- 12. “Carraher’s Polymer Chemistry 8th Edition” by “Charles E Carraher, Jr” “Polyimides Fundamentals and Applications” by “Malay Ghosh” scholar.lib.vt.edu/theses/available/etd-051799- 162256/.../polyimide1.pdf www.researchgate.net/...Aromatic_polyimides.../004 635265c13ade5ec0 journals.tubitak.gov.tr/chem/issues/kim-06.../kim- 30-3-3-0506-12.pdf Images have been taken from various websites