Novel techniques for polymer characterization

Zhe Zhou and Rongjuan Cong, The Dow Chemical Company, Analytical Sciences - R&D Support, Freeport, TX 77541 USA

27 November 2008 at 10:30

Location: JHE 326H

Chemical composition distribution (CCD) is one of the key factors controlling the performance of polyolefins. The classic techniques for determining CCD of polyolefins, temperature elution fraction (TREF) and crystallization analysis fractionation (CRYSTAF), are based on crystallizability in solution. The biggest challenge is cocrystallization. Crystallization Elution Fraction (CEF) (recently developed by Polymer ChAR in Spain), has been used to investigate cocrystallization behavior as a function of experimental conditions with well characterized polyolefin samples.

Microstructural details are very important for understanding properties of polymers and catalyst mechanisms of polymer synthesis. 13C NMR is the primary tool to get this information. However, its sensitivity has been a longstanding challenge which greatly affects the speed of developing new products. Recently, a revolutionary high temperature 10 mm cryoprobe was developed. It gives a significant sensitivity increase. This exciting technology provides unprecedented speed for NMR studies of comonomer content, sequence distribution, stereo- and regio-errors, chain ends, unsaturation, and diffusion of polyolefins.

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