Bonding properties and crystallization kinetics of thermoplastic polyurethane adhesive

Abstract

The advantages of heterophasic thermoplastic polyurethanes (TPUs), such as their phase behavior and mechanical properties, make these materials an important class of adhesives. Whereas the amorphous phase contributes to good adhesion properties, the crystalline phase is responsible for the cohesive force of TPU adhesives. This work investigates the performance of a polyester based TPU and its potential for being applied as adhesive in the shoe industry. The TPU was formulated with three different additives. The crystallization kinetics of the TPU was evaluated by Differential Scanning Calorimetry and the Avrami equation was used to assess the influence of the additives on the geometry of crystal growth and nucleation conditions. It was found that the additives had no effect on the nucleation process, whereas the polymer chains had reduced mobility, mainly in the TPU comprising polyisocyanate ε-caprolactam. The best T-peel strength on a poly(vinyl chloride) (PVC) substrate was determined for the TPU with polycarbodiimide, which improved the adhesive bonding from 3.23 N/mm to 3.32 N/mm.

Development of turkey feather fiber-filled thermoplastic polyurethane composites: Thermal, mechanical, water-uptake, and morphological characterizations

“…Based on the melting enthalpy of 100% crystalline TPU (196.8 J/g), the percent crystallinities X c (%) of all the products were determined using the equation as described in previous study. 51,52 The obtained results, regarding the crystallinity degree, were presented numerically in Table 1, and the dependence of X c (%) on TFFs content was graphically depicted in Figure 4. Prior to the serious discussions, it was to be stated that the computed X c (%) belonging to the composite samples showed a similar trend with T m(HS) .…”

Multi-physics properties of thermoplastic polyurethane at various fused filament fabrication parameters

“…The characteristic temperatures (glass-transition temperature, melting temperature and crystallization temperature) of TPU were determined. The crystallinity degree was calculated using equation (a) from the determined melting enthalpy ΔH m (J/g) and the enthalpy of 100% crystalline TPU ( ΔHm100= 196.8 J/g) (Bockorny et al , 2018). …”