Uniaxial deformation of nylon-6 and nylon-11: changes in orientation and crystal phase

Article Abstract:

Effects of uniaxial drawing on orientation of the crystalline fraction of two polymers that form hydrogen bonds has been studied through the use of X-ray diffraction. Nylon-6 and nylon-11 have similar crystal phases but differing hydrogen bond density. The ways in which they differ have little effect on the deformation mode in the first deformation stage. The study showed the significance of the initial crystal phase with regard to morphology relative to chain packing and organization of sheets that are hydrogen-bonded. Maximum orientation is similar. The relative amount of the gamma phase that shows up in crystallization is the primary behavior difference upon orientation.

Canada, Materials science, Polymers, Crystalline polymers, Nylon, Polymer rheology

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The crystal structure of 3,4,7,8-tetramethylglycoluril

Article Abstract:

The crystal structure of 3,4,7,8-tetramethylglycoluril has been examined using X-ray diffraction. A hydrogen-bonding motif that differs from that of related glycolurils was found in the crystal lattice. In each molecule the two sides are components of independent parallel infinite helical chains. The NH donor and C=O acceptor on one side of a glycoluril molecule form the chains. Two different H-bonds to two different molecules at adjacent positions in the helix are formed. A helix of opposite helicity is formed on the other side of the molecule.

Chemical structure

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The versatile BPh4- anion, or how organoammonium H(N) atoms compete for hydrogen bonding

Article Abstract:

Organoammonium cations that contain two or more N atoms have various ways for the H(N) atom introduced by protonation to bond. It can participate in an N-H(N)...Y bond to an external acceptor (anion or solvent molecule) or in an intra-cation (intra-annular) N-H(N)...N' bond or in a branched N-H(N)...N',Y bond or bonds. The bonding can be simultaneously intra-cation and to one or more external acceptors. Many interesting features are in the crystal structures of the comparison compounds, among them X-H(X)...phenyl bonding.

Protons, Nitrogen compounds, Proton capture, Borates

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