1 / 17

Structure Determination of Aromatic Polyesters (Liquid Crystal Polymers)

Structure Determination of Aromatic Polyesters (Liquid Crystal Polymers). Cristina Contreras. Characteristics of LCPs. Flame retardant (140 °C) Chemical resistance (oxygen) Excellent flow in mold (~ 320 °C) Mesomorphism (neither liquid nor crystal) Transparent to microwave radiation.

ayala
Download Presentation

Structure Determination of Aromatic Polyesters (Liquid Crystal Polymers)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Structure Determination of Aromatic Polyesters (Liquid Crystal Polymers) Cristina Contreras

  2. Characteristics of LCPs • Flame retardant (140 °C) • Chemical resistance (oxygen) • Excellent flow in mold (~ 320 °C) • Mesomorphism (neither liquid nor crystal) • Transparent to microwave radiation

  3. Current Uses of LCPs • Electronic (electronic, optoelectronic, fiber- optics) • Fillers (glass fibers, carbon fibers, mineral fillers) • Electronic packaging

  4. LCPs in Space? • Stable (not oxidized) • Much lighter than metal • Fuel tanks for liquid oxygen

  5. Polymerization

  6. Monomers

  7. Questions • What are the structures of the polymers? • Internal groups -End groups

  8. Methods • Extraction of small molecules, MS - Hexafluoroisopropanol (HFIP) • Depolymerization, NMR - NaOD/D2O - Isopropylamine

  9. Mass Spectrometry

  10. Nuclear Magnetic Resonance http://www2.potsdam.edu/walkerma/341nmr1b.GIF

  11. Depolymerization with Amines

  12. Results • NaOD/D2O - 5 to 7% more acids than phenols • Isopropylamine - 5% of products indicating anhydrides

  13. Discussion • The presence of anhydrides was indicated by NMR methods • MS/MS also supported anhydrides but was not quantitative

  14. Conclusions • A quantitative procedure for converting LCPs back to monomers was developed • A mass spectral method for observing the smaller polymer molecules was found • Anhydrides units were observed in the polymer, making them less stable to water

  15. More Conclusions • Anhydrides can be avoided by starting with excess phenols • Identifying small molecules for environmental concerns

  16. Acknowledgements • NASA • Solvay • Dr. Hall and Dr. Bates

More Related