Microconfinement effect on gas barrier and mechanical properties of multilayer rigid/soft thermoplastic polyurethane films

Abstract

In this article, rigid/soft thermoplastic polyurethane (TPU) films were produced via layer-multiplying co-extrusion and the effect of confinement on morphology and gas barrier and mechanical properties is studied. The soft TPU, which is 52% hardsegment, shows phase separation, while the rigid, 100% hard-segment TPU exhibits amorphous structures. Even though the viscosity ratio of the two TPUs is over 10 and the elasticity ratio around 100, optical and atomic force microscopies show that a multilayer structure was successfully achieved. Then, the multilayer TPU films were uni-axially stretched to different amounts of deformations, from 0% to 300%. DSC and WAXS results show that microconfinement occurs during orientation, which causes a significant reduction in oxygen permeability of multilayer TPU films, when stretched at 75%, by comparison to the mono and bi-layer TPU. The dependence of gas barrier properties on temperature and deformation was also investigated, and a 100% improvement in elongation at break was found when compared to films of the rigid TPU.

Layer multiplication co‐extrusion of cross‐linked polymer microsphere‐filled systems

“…The HAR multipliers used in this work perform better with higher viscosity mismatch materials than traditional multipliers. These multipliers keep the cross‐sectional area constant during the splitting and stacking (depicted in Figure 1C), resulting in simultaneous contraction and expansion of the melt, leading to decreased viscous encapsulation and better layer stability 1,38–43 . Equation (1) is used to calculate the layer number as a function of the number of multipliers “n.” …”

“…These multipliers keep the cross-sectional area constant during the splitting and stacking (depicted in Figure 1C), resulting in simultaneous contraction and expansion of the melt, leading to decreased viscous encapsulation and better layer stability. 1,[38][39][40][41][42][43] Equation ( 1) is used to calculate the layer number as a function of the number of multipliers "n."…”

Development of high‐performance zinc stannate based multifunctional thermoplastic polyurethane nanocomposite films

“…Emissivity is defined as the effectiveness of the surface of any material in emitting energy as thermal radiation. Radiative cooling or high emissivity is essential for inflatable strcutures 39–41 that can facilitate the heat dissipation from the structure. For instance, in materials where TPU is used as polymer matrix such as in TPU‐coated inflatable structure, 42,43 if they possess low emissivity, the material will get heated up and it will cause thermal degradation of TPU.…”

Organosilica-Modified Multiblock Copolymers for Membrane Gas Separation

“…The permeability of gases through polyurethane-based membranes can also be controlled by changing the ratio of rigid and flexible segments [ 20 , 21 ]. Usually, the mechanical properties of polyurethanes improve with an increase in the content of rigid segments, but their gas permeability decreases [ 22 , 23 ]. This is due to a decrease in both the free volume and an increase in the content of rigid blocks having a higher glass transition temperature than flexible segments [ 24 , 25 , 26 ].…”