Thermodynamic properties affect the molecular motion of novolac type phenolic resin blended with polyamide

The effect of association reaction length on the substantial increase of molecular motion as well as entropy (-TDeltaS(m)) of phenolic-polyamide blends is investigated with the C-13 solid-state NMR and DSC. The H-bonding strength by forming the phenolic-polyarnide interaction is great enough to overcome the breaking off the self-association of phenolic. With respect to decreasing the association reaction, the polyamide resonance intensity of C-13 solid-state NMR spectra is weakened due to the reduction of the cross-polarization efficiency at a high mobile sample. The glass transition temperature of phenolic-polyamide blend as well as T-1P(H) value from NMR experiments is also decreased. The decreasing strength of H-bonding resulting from blending causes higher entropy (-TDeltaS(m)) and higher molecular mobility of the phenolic-polyamide blends. Accordingly. the polyamide-66 possesses higher H-bonding force and exhibits more mobile role in this phenolic/polyamide blends family. It can be concluded that the molecular segmental motion and entropy are progressively decreased while increasing the inter-association force of the polyamide within the miscible window. (C) 2002 Elsevier Science Ltd. All rights reserved.