engleski

SS-NMR STUDY OF POLYPHTHALAMIDES FOR USE IN AUTOMOTIVE INDUSTRY

Polyphthalamides (PPA) are a subgroup of polyamides in which a portion of aliphatic segments of the polymer backbone is substituted by aromatic moieties. The substitution results in an increase of melting point, glass transition temperature, thermal stability, oil and antifreeze resistance, etc., making PPAs very successful as a metal replacement for automotive components. Depending on the type and amount of aromatic species used, PPAs can be amorphous or semi- crystalline. This research was focused on representatives of both categories. An amorphous sample PA66/6I was investigated using 13C chemical shift anisotropy, 13C T2, and 1H-13C dipolar coupling measurements both in dry and wet state, in order to determine molecular origins of relaxation processes. This was of interest due to the extreme sensitivity of the material to moisture, i.e., a dramatic decrease of glass transition temperature upon water sorption [1]. On the other hand, semi-crystalline sample PA66/6T was investigated in regard to the phenomenon of co-crystallization. Traditionally, the ability of two copolymer components to co-crystallize is determined via melting point variations with copolymer composition [2]. This approach requires an array of samples with varying compositions, which is seldom obtainable. Here we show how solid-state NMR can provide several approaches to give required answers using a single sample. REFERENCES [1] M. Laurati, P. Sotta, D. R. Long, et al., Macromolecules 2012, 45, 1676. [2] T. F. Novitsky, C. A. Lange, L. J. Mathias, et al., Polymer 2010, 51, 2417.

solid-state NMR, polyamides

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