Thermal and mechanical properties of thermoplastic polyurethane elastomers from different polymerization methods

Abstract

Thermoplastic polyurethane elastomers (TPUs) based on 4,4'-methylenediphenyl diisocyanate, poly(tetramethy1ene glycol), diamine-terminated aliphatic nylon oligomer, and 1,4-butanediol were synthesized by two different polymerization methods, i.e. one shot and prepolymer methods. The effects of the polymerization method on the thermal and mechanical properties of the TPUs have been studied. A broader distribution of hard segment lengths in TPUs prepared by the one shot method was observed from thermal and tensile property measurements, compared with those prepared by the prepolymer method. TPUs by the one shot method showed a higher T,,, of the hard segments and better tensile properties when soft-hard segment interaction was relatively small. However, inferior tensile properties were observed when the soft-hard segment interaction was high; typically when nylon oligomer was used as a soft segment.

The Properties of Reactive Hot Melt Polyurethane Adhesives: Effects of Molecular Weight and Reactive Organoclay

“…PUs prepared with the same recipe can have different structural characteristics, such as molecular weight distribution (MWD) or hard segment length, and consequently their physical properties can differ according to the synthesis method used [14,15] . PUs with a linear structure will have the same average molecular weight (M n ) when prepared with the same recipe irrespective of preparation method, however the weight average molecular weight (M w ) can be made to differ by using an appropriate method of synthesis.…”

Carotid stent‐supported angioplasty in a patient with symptomatic and critical aortic stenosis

“…One can observe from Tables 5–7 that with increasing mesogen content, the mesophase‐transition temperature increases. As the mesogen content is increased, the average length of the hard segment is increased, and this seems to cause the increase in the transition temperature 34. In a comparison of PUs with the same soft segments and different mesogen contents, the transition temperatures increase with an increase in the mesogen content.…”

Sustained Release Drug Delivery Applications of Polyurethanes

“…The “one-shot method” involves mixing all of the ingredients together, while the “prepolymer method” features the reaction of the polyol with an excess of isocyanate, followed by a subsequent reaction with the chain extender to form a linear block copolymer with alternating blocks of hard segment and soft segment [ 29 ]. The prepolymer method has been shown to yield more ordered structure with better control of polymer properties [ 51 ].…”