Next Article in Journal
Characterisation and Modelling of Moisture Gradients in Polyamide 6
Next Article in Special Issue
Modification of Mechanical and Electromechanical Resonances of Cellular Ferroelectret Films Depending on the External Load
Previous Article in Journal
Properties of Degradable Polyhydroxyalkanoates (PHAs) Synthesized by a New Strain, Cupriavidus necator IBP/SFU-1, from Various Carbon Sources
Previous Article in Special Issue
Tannin-Furanic Foams Formed by Mechanical Agitation: Influence of Surfactant and Ingredient Ratios
Article

Analysis of the Foaming Window for Thermoplastic Polyurethane with Different Hard Segment Contents

1
Cellular Materials Laboratory (CellMat), Condensed Matter Physics Department, Faculty of Science, University of Valladolid, 47011 Valladolid, Spain
2
Department of Chemical Engineering, Faculty of Engineering, University of Babylon, Hilla 51001, Iraq
3
CellMat Technologies S.L. Paseo de Belén, 47011 Valladolid, Spain
4
School of Materials, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
5
GIR MIOMeT-IU Cinquima-Química Inorgánica, Faculty of Science, University of Valladolid, 47011 Valladolid, Spain
*
Author to whom correspondence should be addressed.
Academic Editor: Amir Ameli
Polymers 2021, 13(18), 3143; https://doi.org/10.3390/polym13183143
Received: 20 June 2021 / Revised: 7 September 2021 / Accepted: 11 September 2021 / Published: 17 September 2021
(This article belongs to the Special Issue Advanced Cellular Polymers)
A series of thermoplastic polyurethanes (TPUs) with different amounts of hard segments (HS) (40, 50 and 60 wt.%) are synthesized by a pre-polymer method. These synthesized TPUs are characterized by Shore hardness, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD), dynamic mechanical thermal analysis (DMTA), and rheology. Then, these materials are foamed by a one-step gas dissolution foaming process and the processing window that allows producing homogeneous foams is analyzed. The effect of foaming temperature from 140 to 180 °C on the cellular structure and on density is evaluated, fixing a saturation pressure of 20 MPa and a saturation time of 1 h. Among the TPUs studied, only that with 50 wt.% HS allows obtaining a stable foam, whose better features are reached after foaming at 170 °C. Finally, the foaming of TPU with 50 wt.% HS is optimized by varying the saturation pressure from 10 to 25 MPa at 170 °C. The optimum saturation and foaming conditions are 25 MPa and 170 °C for 1 h, which gives foams with the lowest relative density of 0.74, the smallest average cell size of 4 μm, and the higher cell nucleation density of 8.0 × 109 nuclei/cm3. As a final conclusion of this investigation, the TPU with 50 wt.% HS is the only one that can be foamed under the saturation and foaming conditions used in this study. TPU foams containing 50 wt.% HS with a cell size below 15 microns and porosity of 1.4–18.6% can be obtained using foaming temperatures from 140 to 180 °C, saturation pressure of 20 MPa, and saturation time of 1 h. Varying the saturation pressure from 10 to 25 MPa and fixing the foaming temperature of 170 °C and saturation pressure of 1 h results in TPU foams with a cell size of below 37 microns and porosity of 1.7–21.2%. View Full-Text
Keywords: thermoplastic polyurethane; foams; gas dissolution foaming; foaming window; hard segment thermoplastic polyurethane; foams; gas dissolution foaming; foaming window; hard segment
Show Figures

Graphical abstract

MDPI and ACS Style

Santiago-Calvo, M.; Naji, H.; Bernardo, V.; Martín-de León, J.; Saiani, A.; Villafañe, F.; Rodríguez-Pérez, M.Á. Analysis of the Foaming Window for Thermoplastic Polyurethane with Different Hard Segment Contents. Polymers 2021, 13, 3143. https://doi.org/10.3390/polym13183143

AMA Style

Santiago-Calvo M, Naji H, Bernardo V, Martín-de León J, Saiani A, Villafañe F, Rodríguez-Pérez MÁ. Analysis of the Foaming Window for Thermoplastic Polyurethane with Different Hard Segment Contents. Polymers. 2021; 13(18):3143. https://doi.org/10.3390/polym13183143

Chicago/Turabian Style

Santiago-Calvo, Mercedes, Haneen Naji, Victoria Bernardo, Judith Martín-de León, Alberto Saiani, Fernando Villafañe, and Miguel Á. Rodríguez-Pérez 2021. "Analysis of the Foaming Window for Thermoplastic Polyurethane with Different Hard Segment Contents" Polymers 13, no. 18: 3143. https://doi.org/10.3390/polym13183143

Find Other Styles
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

1
Back to TopTop