Water Sorption in Polyamide 6/Poly(Amino-ether) Blends. I. Sorption Characteristics and Phase Behavior

Abstract

New partially miscible polyamide 6 (PA)/poly(amino-ether) (Blox) blends were immersed in water to study the change in both the significant water uptake of PA, and the phase behavior of the blends. Water sorption was partially irreversible and always Fickian, with a much greater decrease in the water uptake and in the diffusion coefficient of the blends than expected. This was attributed to hindering by Blox of water diffusion both at microscopic and molecular levels.

Plasticization of Blox was clearly less important than that of PA, as its T_g decreased 26°C in wet conditions while in the case of PA the decrease was 60°C up to sub-zero temperatures. No intermediate condition between fully dry or fully wet was seen either in PA or Blox. The displacement of the tan δ peak of PA to clearly lower temperatures and its greater intensity in wet conditions, suggest that the presence of a PA phase might be detected by water sorption, as the tan δ peak is difficult to detect in dry conditions.

Keywords:

• Polyamide
• Poly(amino-ether)
• Water sorption
• Phase structure

Acknowledgment

The financial support of the University of the Basque Country (Project n. 9/UPV-13540/2001) is gratefully acknowledged. The authors also acknowledge Dr. Ha Q. Pham and Dr. Asjad Shafi, from The Dow Chemical Company, for supplying the Blox sample.