Design and Investigation of Polyurethane End-Capped Polyesters with Controlled Hydrolytic Stability

by Shaoguang Yang

Institution: University of Akron
Department: Polymer Engineering
Degree: MSin Polymer Engineering
Year: 2014
Keywords: Chemical Engineering; Engineering; Polymer Chemistry; Polymers; Oligoesters, Hydrolysis, steric effects, anchimeric effects
Record ID: 2025426
Full text PDF: http://rave.ohiolink.edu/etdc/view?acc_num=akron1407971721


The hydrolytic stability of a series of oligoesters comprised of two, three, and four different monomers was compared and investigated. The monomers were selected based on predictive structural effects on the rate of hydrolysis. The oligoesters were prepared from adipic acid (AA), phthalic acid (PA) and isophthalic acid (IPA), with 1,6-hexanediol (16HD), and neopentyl glycol (NPG). The hydroxyl-terminated oligoesters were then end-capped with phenol isocyanate (PI) to eliminate initial end-group effects. Thus, the auto catalysis effect of end-groups at the beginning of hydrolysis can be excluded, allowing the proper evaluation of intrinsic behavior of oligoesters in aqueous systems. Hydrolysis process were monitored by measuring the acid number of oligoesters, acetone and water mixture. Hydrolysis rate constants can be calculated from the plots of acid number vs. time. Based on previous results from Dr. Soucek’s group[2,3], it was observed that quaternary oligoesters had higher hydrolysis rates than ternary oligoesters at ambient temperature at 40¿. In this research, hydrolysis were operated at a relatively high temperature at 60¿ that steric effects and anchimeric effects can have different combination of influence on the hydrolysis rates of oligoesters.