Influence of the prepolymerization on the properties of thermoplastic polyurethane elastomers. Part II. Relationship between the prepolymer and polyurethane properties

Abstract

The synthesis of thermoplastic polyurethane elastomers (TPUs) is generally carried out using the prepolymer method. To study the influence that the properties of the prepolymer may have in the final TPUs, four TPUs were prepared by using different NCO/OH ratios. The prepolymers and the macroglycol used in their synthesis were characterized in the first part of this article. TPUs were characterized by using gel permeation chromatography, strain-stress measurements, differential scanning calorimetry, and contact-angle measurements. To test their adhesion properties, the T-peel strength of PVC/TPU/PVC adhesive joints was determined. It was found that the properties of the prepolymers determine the properties of the TPUs when the amount of hard segments (related to the soft-segments size) is small. In contrast, when the amount of hard segments (related to the soft-segments size) is high, it is the chain extension step that determines the TPUs structure and properties. On the other hand, it was observed that a high amount of ever hard or soft segments gives TPUs with similar properties. This behavior is explained by the structure of the prepolymer (related to the degree of polymerization) and the TPUs. Finally, it was found that the adhesive properties of the finished TPUs are comparable to those of blocked prepolymers prepared with low NCO/OH ratio.

Structure–property relationships of poly(urethane‐urea)s with ultralow monol content poly(propylene glycol) soft segments. III. influence of mixed soft segments of ultralow monol poly(propylene glycol), poly(tetramethylene ether glycol), and tri(propylene glycol)

“…The elastomers analyzed in the current study were synthesized via two different reaction schemes (Fig. 2) in order to ascertain whether the method of synthesis could appreciably influence the elastomer morphology and properties 12–14. The first of these is essentially identical to the procedure used previously, in that all of the polyols (PPG, TPG, PTMEG) are mixed together first and then end capped with MDI.…”

Thermoplastic Polyurethanes-Fumed Silica Composites: Influence of NCO/OH in the Study of Thermal and Rheological Properties and Morphological Characteristics

“…Recent studies have demonstrated that the use of this kind of materials able to form hydrogen-bonds result in less direct interactions between phases, causing a higher phase separation. Furthermore, the interactions between silanol and carbonyl groups are weaker than those between NH and ester carbonyl groups, then silica addition increases the polyester chain mobility and, it allows to become more ordered in relation to the TPU without silica (Sánchez-Adsuar et al, 2000;Tien et al, 2001;Nunes et al, 2000;Nunes et al, 2001). …”

Use of thermoplastic polyurethane elastomers in the preparation of fabric/activated carbon composites

“…In this article, we investigate a new route to prepare fabric/activated carbon composites using a thermoplastic polyurethane as composite binder. The polymer choice was due, on one hand, to its good adhesion and mechanical properties and, on the other, to its versatile and controllable properties, depending on its composition and synthesis conditions 9–11…”