The polymorphism of 4-cyano-4 0 -pentylbiphenyl (5CB) was investigated by means of differential scanning calorimetry (DSC), X-ray diffraction, and proton nuclear magnetic resonance (NMR) experiments. Three new phases has been identified and characterized structurally and dynamically. By a slow cooling at a rate 0.2 K/min, the nematic phase crystallizes into a phase noted C1. Upon a fastest cooling ( ! 5 K/min) a glassy liquid crystal (GLC) phase with a glass transition temperature T g ¼ 208 K, is formed. Upon heating up both the solid state C1 and the GLC phase, a second crystalline phase C2 (DH ¼ 49 J/g.K) which is more stable than C1 (DH ¼ 36 J/g.K) can be obtained. The proposed phase diagram has been investigated by proton NMR lineshape analysis. The motional correlation time of end-chain methyl group motion was determined by means of spin-lattice relaxation time (T 1 ) analysis.

The thermal behavior of polyamide 6/amorphous polyamide blends has been investigated as a function of blend composition and temperature. Crystal phase nature and stability are probed by a combination of thermal analysis, X‐ray diffraction and Fourier transform infrared spectroscopy. Ductility appears to be strongly affected by the addition of the amorphous polyamide, but the corresponding decrease of the yield stress, either taken at the same draw temperature or under a comparable state of mobility of the amorphous phase, may not be simply accounted for by the reduction of overall ordered phase content.

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