Structure, composition, and adhesion properties of thermoplastic polyurethane adhesives

Abstract

The composition and hard segment content of 13 commercial thermoplastic polyurethane elastomers (TPUs) were obtained using 1 H-nuclear magnetic resonance ( 1 H-NMR). The properties of the TPUs were studied using differentialscanning calorimetry(DSC), wide-angle X-ray diffraction (WAXD), dynamic mechanical thermal analysis (DMTA), and contact angle measurements. Solventbased adhesives were prepared by dissolving the TPUs in 2-butanone. Films of the TPUs were obtained by solvent evaporation, and their properties were studied. Adhesion properties were determined from T-peel tests on solvent-wiped poly(vinyl chloride) (PVC)/ polyurethane adhesive joints. The in uence of the segmented structure on the properties of the TPUs was assessed. The increase in the hard segment content in TPUs favoured the incompatibility (i.e. reduced phase separation) between hard and soft domains. TPUs with a high hard segment content had a low crystallinity, a low wettability, and a high joint strength. The storage and loss moduli obtained using DMTA decreased as the hard segment content in the TPUs increased. Furthermore, the TPUs prepared using "-polycaprolactone as the macroglycol had a slower crystallization rate than those prepared using the polyadipate of 1,4-butanediol or the polyadipate of 1,6-hexanediol. The increase in the length of the hydrocarbon chain of the macroglycol improved both the rheological and the thermal properties of the TPUs. Finally, TPUs prepared using MDI as the isocyanate showed a higher crystallinity and a higher degree of crosslinking than those prepared using TDI.

Bio-Renewable Sources for Synthesis of Eco-Friendly Polyurethane Adhesives—Review

“…Bio-renewable resources constitute a rich source of precursors for the synthesis of polyols and isocynates which are being considered for the production of "greener" PU adhesives [28] and reaction between polyol and isocynate is shown in Figure 1. Various bio-renewable sources for synthesis of bio-based PU adhesives and their potential applications are discussed in this review.…”

Improved Adhesion of RF Plasma Treated Rubbers by Isocyanate Incorporation to Polyurethane Adhesive

“…GPC of PU + 4I was not obtained as reaction of polyurethane with isocyanate produced a non‐soluble adhesive film in tetrahydrofuran (THF) (solvent used to introduce the polymer into the GPC column), as well as in other solvents. The values we obtained are typical of segmented thermoplastic polyurethanes 35…”

“…Thus, from the relative intensity of each shift, the hard/soft segments ratio in the polyurethanes can be determined. Shifts at 1.80 ppm (soft segments) and 3.85 ppm (hard segments) were used, and a 13.8% hard segments percentage was obtained, which falls into the typical range of segmented thermoplastic polyurethanes 35…”

Constitutive Relations and Parameter Estimation for Finite Deformations of Viscoelastic Adhesives

“…[1][2][3][4]). The soft segments account for the high extension and elastic recovery, while the hard segments provide high modulus and strength [5].…”