CHLORINE DEGRADATION OF AROMATIC POLYAMIDES

In this work the effect of chlorine on the aromatic polyamides reverse osmosis membranes has been examined. An attempt is made to correlate the changes in the physical properties of polyamides with chlorine concentration, the pH of chlorine solution and the exposure time. It is intended as a first step towards developing possible tests which could determine whether a sample of aromatic polyamide membrane has been exposed to chlorine or not. It is concluded that a number of reactions are responsible for the degradation of the membrane depending on the pH and the conditions. Moreover, the chemical structure of aromatic polyamides before and after chlorination is investigated in detail with IR spectroscopy, and it is suggested that the aromatic chlorination, which occurs only in acidic chlorine solutions, transforms the crystalline structure of aromatic polyamides to an amorphous state.