POLYIMIDES

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POLYMERS PLAYING LEADING ROLE IN ELECTRONICS AND AUTOMOBILE INDUSTRIES

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POLYIMIDES

  1. 1. POLYIMIDES<br />-K.SAI MALLESWAR<br />
  2. 2. INTRODUCTION<br />What are polyimides? what is the basic structural unit?<br />Polyimides are polymers formed by the combination of <br />acid dianhydrides and diamines.<br />
  3. 3. TYPES OF POLY IMIDES :<br /><ul><li> Linear polyimides
  4. 4. Aromatic hetero cyclic polyimides</li></ul>3<br />
  5. 5. PHYSICAL AND THERMAL PROPERTIES:<br />4<br />
  6. 6. Other properties:<br /><ul><li>Characteristic colour – orange/yellow
  7. 7. Very low creep
  8. 8. Inherent resistance to flame combustion
  9. 9. Un effected by commonly used solvents and oils
  10. 10. Un effected by hydro carbons, esters, alcohols</li></ul> and freons<br /><ul><li> Resistant to weak acids
  11. 11. Not usable in alkaline or highly acidic </li></ul> environment.<br />5<br />
  12. 12. Significance of polyimides:<br /><ul><li> Polyimides have high tensile strength.
  13. 13. They are highly heat resistant and chemical resistant.
  14. 14. They can often replace glass and metals such as steel.
  15. 15. They are transparent to microwave radiation.</li></li></ul><li>WHY POLYIMIDES ARE SO STRONG???<br />CHARGE TRANSFER COMPLEX<br />7<br />
  16. 16. 8<br />WHY POLYIMIDES ARE SO STRONG???<br />
  17. 17. SYNTHESIS:<br />By Step Growth Polymerization in two steps:<br /><ul><li>1.Poly addition
  18. 18. 2.Subsequent Dehydration
  19. 19. They are prepared by the reaction of </li></ul> Acid Anhydrides and Diamines<br /><ul><li>Intially, soluble and fusible high molecular weight polyamic Acid is formed in polar aprotic solvent.
  20. 20. Later, Polyamic acid is processed into final insoluble and infusible polymer product. </li></ul>9<br />
  21. 21. 10<br />
  22. 22. APPLICATIONS:<br /><ul><li> Polyimides are used as struts and chasis in cars</li></li></ul><li>Polyimides are used as the outer<br />layer of thermal insulation <br />covering of external surfaces of <br />aircrafts<br />They are also used in vane brushes,<br />bearings and washers for aircrafts<br />
  23. 23. They are also used as <br />polyimide heaters.<br />
  24. 24. Polyimides are used in the cooking cavity of microwave <br />oven.<br />Polyimides are also used in food packaging.<br />
  25. 25. <ul><li>Polyimides are used as mechanical stress buffers
  26. 26. As an insulating layer in the manufacture of </li></ul> IC chips<br /><ul><li>As flexible cables in electronics industry
  27. 27. As a coating on tubes used in surgeries
  28. 28. As a photoresist in IC chip fabrication.</li></li></ul><li>BEARINGS MADE OF POLY IMIDE<br />A POLYIMIDE RESIN<br />A POLYIMIDE TAPE<br />16<br />
  29. 29. 17<br />
  30. 30. DEGRADATION OF POLYIMIDES:<br />Photo Degradation:<br /><ul><li> It is molecular degradation caused by </li></ul> ultraviolet radiation.<br /><ul><li> Here bond between carbonyl carbon(C=O) </li></ul> and alkyl group breaks.<br />Oxidative Degradation:<br /><ul><li> It leads to hardening, discolouration and </li></ul> surface changes.<br /><ul><li> In this R-C=O will be converted into R=C.</li></ul>|<br />18<br />
  31. 31. <ul><li> Structural and Environmental factors lead to</li></ul> thermal degradation of Polyimides<br /><ul><li> This may be Thermal or thermo oxidative degradation
  32. 32. Cross linked bonds will break during thermal degradation
  33. 33. They will become insoluble in nature after</li></ul> thermal degradation<br /><ul><li>They retain their weight at elevated temperatures
  34. 34. Incase of aromatic polyimides, delocalization energy of </li></ul> Pi-electrons is released.<br />THERMAL DEGRADATION OF POLYIMDES:<br />19<br />
  35. 35. BIBLIOGRAPHY:<br />www.wikipedia.org<br /> Polymer Science and Technology by Joel R.Fried<br />www.google.com<br />4. Text Book Of Polymer Science by <br /> Fred W. Billmeyer<br />20<br />
  36. 36. THANK YOU<br />21<br />

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