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 (−TΔSm) of phenolic–polyamide blends is investigated with the 13C solid-state NMR and DSC. The H-bonding strength by forming the phenolic–polyamide 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 13C 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 TH1ρ value from NMR experiments is also decreased. The decreasing strength of H-bonding resulting from blending causes higher entropy (−TΔSm) 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.