مطالعه رفتار همگرايي در محلولهاي آبي غلظت دهنده هاي پلي يورتاني رشديافته مرحله اي

Study of Association Behavior in Step Growth HEUR Aqueous Solutions

Polyurethane thickeners are one of the important members in associative thickeners. These materials are divided in two groups of S-G HEUR and Uni-HEUR depending on their synthetic procedure and molecular weight distribution. In this work, three S-G HEURs (step growth hydrophobically modified ethoxylate urethane) were synthesized through a two-step polymerization. In the first step, prepolymers were produced via reaction of poly(ethylene glycol) with H12MDI Then, the synthesis of HEURs was finished by substituting of cetyl alcohol in the prepolymer. Molecular weights of thickener models were determined by GPC. Associative bahavior was studied by Ubbelohde viscometery. Also, a cone and plate rheometer was used to investigated the obtained results from Ubbelhodc viscometer. The results showed that some associations are present even at very low concentration. Also, the sample with shorter hydrophilic size showed stronger association behavior.