Thermoplastic Polyurethane Elastomers With Mixed Dl(2- Hydroxyethyl) Disulfide-1,4-Butanediol Hard Segment

摘要

Di(2-hydroxyethyl) disulfide is a glycol with terminal primary hydroxyl groups and two sulfur atoms in the middle of the molecule. It was used as a chain extender in thermoplastic polyurethanes (TPU) in combination with 1,4-butane diol in order to modify polymer properties. Cast polyurethane elastomers having 50% soft segment concentration were prepared from polypropylene glycol of molecular weight 2000, 4,4,AEo-methylenebis-(phenylisocyanate) and combined chain extender from 1,4-butanediol (BD) and di(2-hydroxyethyl) disulfide (DD). Molar ratio of BD:DD was 1:0, 3:1, 1:1, 1:3 and 0:1. The samples were prepared by the prepolymer method and characterized by spectroscopic, thermal and mechanical methods. Chain extension reaction was slower with increasing DD-content, which allowed comfortable handling of the synthesis. Thermal analysis and mechanical tests showed that the samples with mixed chain extenders had lower phase separation than the samples prepared with pure BD or DD, which was reflected in higher Tg, lower tensile strength and elongation at break. The samples displayed similar decomposition patterns. Increasing DD content in the hard segment decreased to a small extent thermal stability of the urethane group. DD can be successfully used in many applications offering longer pot life during chain extension.