I asked a question of AMMRL on October 1 regarding CPMAS relaxation
studies of polyesters. Here are the answers I received.
>From our own study we found strong correlations between contact time
array data (T1rho and TCH) and relative drawing strength.
Differences in amorphous/crystalline content were observed by fitting
the data to 2 component exponentials.
No attempt was made to investigate the presence of an inter-crystalline
phase.
Thanks to those who responded.
John C. Edwards, Ph.D.
Manager, Process and Analytical NMR Services,
Process NMR Associates, LLC
87A Sand Pit Rd,
Danbury, CT 06810, U.S.A.
Tel: +1 (203) 744-5905
Mobile: +1 (203) 241-0143
Fax: +1 (203) 743-9297
e-mail: john_at_process-nmr.com
web: http://www.process-nmr.com
Original Question to AMMRL
Does anyone have any experience using CP-MAS contact time arrays and the
resultant calculated TCH and T1rho values to measure crystallinity in
polyester fibers?
I would be interested to know of any successful correlations between
relaxation times and measured crystallinity values as well as any
references on the topic.
Thanks,
Responses
> I recently see that you posted a question about PET fiber
> crystallinity on AMML. there is a new paper published on
> "macromolecules" ( H. Kaji and K. Schmidt-Rohr, Macromolecules, 35,
> 7993, 2002). you might find the information of NMR for polyester fiber
> in the paper.
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PET crystallinity is about 40-50% by weight. we also find that there
might no clear relationship between ordered polymer chains and
crystallinity. someone also indicated that there is the third state
between crystalline and amorphous.
I seem to remember Dave Van
> der Hart looking at T1rho and cross-relaxation in polymer blends 8-12
> years ago. I know its the dark age.
Received on Mon Nov 25 2002 - 19:17:24 MST