Effect of the Molecular Structure of TPU on the Cellular Structure of Nanocellular Polymers Based on PMMA/TPU Blends

Abstract

In this work, the effects of thermoplastic polyurethane (TPU) chemistry and concentration on the cellular structure of nanocellular polymers based on poly(methyl-methacrylate) (PMMA) are presented. Three grades of TPU with different fractions of hard segments (HS) (60%, 70%, and 80%) have been synthesized by the prepolymer method. Nanocellular polymers based on PMMA have been produced by gas dissolution foaming using TPU as a nucleating agent in different contents (0.5 wt%, 2 wt%, and 5 wt%). TPU characterization shows that as the content of HS increases, the density, hardness, and molecular weight of the TPU are higher. PMMA/TPU cellular materials show a gradient cell size distribution from the edge of the sample towards the nanocellular core. In the core region, the addition of TPU has a strong nucleating effect in PMMA. Core structure depends on the HS content and the TPU content. As the HS or TPU content increases, the cell nucleation density increases, and the cell size is reduced. Then, the use of TPUs with different characteristics allows controlling the cellular structure. Nanocellular polymers have been obtained with a core relative density between 0.15 and 0.20 and cell sizes between 220 and 640 nm.

Prediction of Thermal Conductivities of Rubbers by MD Simulations—New Insights

“…It was observed that the density decreases linearly with an increase in the mass fraction of soft segments (see Figure 7 ). For comparison, the density of TPU depending on its chemical structure is in the range 1.1 g/ ... 1.21 g/ [ 48 ] (1.2 g/ [ 49 ], 1.11 g/ [ 50 ], ≈1.2 g/ [ 51 ]).…”

4D printing of polylactic acid (PLA)/thermoplastic polyurethane (TPU) shape memory polymer – a review

“…In the blend, TPU will act as a crystallization nucleation agent [100,103] that will decrease the free energy barrier and helps in cell nucleation. Nucleation is the first step of the crystallization process [111].…”

Current Trend and New Opportunities for Multifunctional Bio-Scaffold Fabrication via High-Pressure Foaming

“…A preliminary experiment reported the use of the method to achieve complex shapes endowed with morphological gradients, such as a 1:10 scale human femur. The authors adopted polystyrene as a model polymer and polycaprolactone for the femur, showing the versatility of the method for any foamable biomedical thermoplastic [ 70 , 71 , 72 , 73 , 74 ]. Most recently, the gas foaming method with time-varying boundary conditions has been coupled with additive manufacturing, providing additional versatility in terms of porosity architecture [ 75 ].…”