Polybenzimidazolone

Polybenzimidazolone membrane 21 developed by Teijin Ltd. had the following permeative characteristics Water permeation, 840 1/m2 - day salt rejection, 99.5% (1% NaCl aqueous solution, 80 kg/cm2)69). The membrane was less sensitive to plasticization with water than cellulose acetate and aromatic polyamide membranes... 

After this first development of the CA membrane, different types of membranes followed CAB, CTA, PBIL, and PA membranes. CAB is membrane of cellulose acetate butyrate CTA is cellulose triacetate. The PBIL membrane is a polybenzimidazolone polymer and PA are polyamide membranes. The structure of a PBIL unit is as follows ... 

In recent years, RO membrane research has proceeded in two diredrions. First, there has been a continuing search for new polymeric membrane materials. Some of the materials with interesting properties that could be cited include other cellulose esters polybenzimidazolea polybenzimidazolone (PBIL), poly-imides and new aromatic polyamides... 

The company Teijin in Japan introduced a polybenzimidazolone membrane which was claimed to be on the market. 

By varying the heating rate, cyclodehydration takes place, giving either a semi-ladder or ladder structure. The semi-ladder polybenzimidazolone is soluble in some solvents. The ladder polymer subsequently formed is insoluble. This type of polymer is stable to 450—650°C in nitrogen. 

A third class of material that have been used are the polybenzimidazoles, polybenzimidazolones, polyamidehydrazide and polyimides. The chemical structures of these materials have been given in chapter H. 

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