Thermoplastic polyurethane hydrolysis stability

Abstract

This paper reviews several types of thermoplastic polyurethane elastomers, and the unique properties these polymers have. In discussing the hydrolysis stability of thermoplastic polyurethane elastomers the suitability of these polymers for such study was pointed out. A relationship between poly(ester‐urethane) composition in terms of methylene group concentration, hardness and chain stiffness, and hydrolysis stability was shown. The dominant role of polyurethane acid number in thermoplastic poly(ester‐urethane) hydrolysis stability was demonstrated and the origin of this unexpected acid number was discussed. The pronounced stabilizing action of added poly(carbodiimide) in thermoplastic poly(ester‐urethane) hydrolysis was shown, as well as the severe destabilizing action of a carboxylic acid, stearic acid. The hydrolysis stabilities of thermoplastic poly(ester‐urethane) elastomers based on poly(ϵ‐caprolactone) glycol and on poly(hexamethylene carbonate) glycol were also described.

Double-layered reactive microcapsules with excellent thermal and non-polar solvent resistance for self-healing coatings

“…41 Another reason for the deterioration of shell compactness may be that more water molecules diffused into the core of the microcapsules and consumed more HDI with longer reaction duration. The released amount of core material aer the isothermal process decreased gradually with increasing reaction duration, and reached a lowest value (0.9 wt%) when the reaction duration was 2 h. Subsequently, the released amount of core material aer the isothermal process started to increase from 0.9 wt% to 1.9 wt% with increasing reaction duration to 2.5 h. This phenomenon indicates that the tightness of the microcapsule shell is rst improved and then deteriorated with the extension of reaction duration.…”

Controlled Synthesis of Multi‐Arm Star Polyether–Polycarbonate Polyols Based on Propylene Oxide and CO2

“…The additional free hydroxyl groups in polycarbonate polyols provide sites for the attachment of dyes, flame retardants, bioactive molecules, or cross‐linking of materials. In addition, polycarbonate polyols have been introduced for the manufacture of polyurethanes for high‐performance coating applications . However, the respective cyclic carbonate monomers have to be prepared in multistep reactions, which represent a drawback for actual application.…”

Degradation of a poly(ester urethane) elastomer. I. Absorption and diffusion of water in Estane® 5703 and related polymers

“…Poly(ester urethanes) are known to degrade by several mechanisms,2, 3 one of which is hydrolysis 4–9. To study the hydrolysis of Estane® 5703 and related poly(ester urethanes), it is necessary to first determine their absorption of water and the diffusion of water through them.…”

“…The hard segments in poly(ester urethanes) tend to clump together to produce a microphase separation between hard‐ and soft‐segment domains 4–6. The extent of the microphase separation depends on the hard‐segment fraction of the polymer, and the domains are expected to differ in their attraction and permeability to water.…”

“…This is a low fraction of hard segments as compared with many poly(ester urethanes). The polymers used by Schollenberger and coworkers4–6, 14 and Brown et al7–9 had about the same molecular weight PBA but had molar fractions of 0.5 MDI, 0.25 PBA, and 0.25 BDO so that they have a higher hard‐segment fraction than Estane® 5703. Three of the samples used by Potts15 were commercial poly(ester urethanes) that are probably similar to Estane® 5703, but they are not identified in his article.…”