Structural characterization and mass transfer properties of dense segmented polyurethane membrane: Influence of hard segment and soft segment crystal melting temperature

2008 ◽  
Vol 48 (2) ◽  
pp. 233-239 ◽  
Author(s):  
S. Mondal ◽  
J.L. Hu
Keyword(s):  
Mass Transfer ◽  
Melting Temperature ◽  
Structural Characterization ◽  
Hard Segment ◽  
Soft Segment ◽  
Segmented Polyurethane ◽  
Crystal Melting ◽  
Transfer Properties ◽  
Polyurethane Membrane

Generalized Concept of the Reinforcement of Elastomers. Part 3: Self-Reinforcement by the Formation of Continuous Hard Phase in Segmented Polyurethane Elastomer

2007 ◽  
Vol 80 (5) ◽  
pp. 777-808 ◽  
Author(s):  
Yoshihide Fukahori
Keyword(s):  
Hard Segment ◽  
Volume Fraction ◽  
Soft Segment ◽  
High Stress ◽  
Matrix Phase ◽  
Structural Defects ◽  
Segmented Polyurethane ◽  
Polyurethane Elastomers ◽  
The Third ◽  
The Matrix

Abstract The author proposed the third concept in the reinforcement of elastomers for segmented polyurethane with the direct observation by microscopic techniques. The structure in segmented polyurethane elastomers fundamentally consists of three domains of different sizes, two kinds of micro-domain, cluster of 100 nm in diameter and spherulite of µm order. Of the micro-domains, one is the hard-segment (HS)-rich micro-domain consisting of hard segment (4 nm thickness) and soft segment (7 nm) and the other is the hard-segment (HS)-poor micro-domain of hard segment (4 nm) and soft segment (15∼20 nm). The HS cluster is constructed by the assembly of the HS-rich micro-domains. The spherulite seems to be composed of the dense packing of the HS cluster, growing up radially or circularly from the center to the outside surface. From physical and mechanical points of view, we can regard the above structures in the segmented polyurethane as bi-continuous structure of the HS clusters whose volume fraction is 0.2, and the matrix phase consisting of the HS-poor domains (0.8 in the volume fraction). The characteristic stress-strain relation of the segmented polyurethane is generated by the combination of both the continuous structures. That is, the initial very high stress (modulus) at small extension and the following gradual increase in stress at medium extension mainly result from the extension and the sliding of the HS cluster, respectively. The very large stress-upturn at large extension and the final great tensile strength are generated by the contribution of both the continuous structures. Thus, the third reinforcement is achieved by the formation of bicontinuous structure of the hard and strong cluster and also the strong matrix phase, in which the absolute structural defects seem not to be included.

High-Field Maxwell Stress Effect of Dielectric Actuator Based on Segmented Polyurethane

2007 ◽  
Vol 26-28 ◽  
pp. 753-756 ◽  
Author(s):  
Hyun Ok Lim ◽  
Gyeong Mi Bark ◽  
Hyun Park ◽  
Ho Hwan Chun ◽  
Nam Ju Jo
Keyword(s):  
Hard Segment ◽  
Dielectric Material ◽  
Soft Segment ◽  
Coulomb Force ◽  
Polar Phase ◽  
Stress Effect ◽  
Maxwell Stress ◽  
Diphenylmethane Diisocyanate ◽  
Segmented Polyurethane ◽  
Promising Candidate

This study dealt with the bending-electrostrictive response of segmented polyurethane (SPU) films, which was a promising candidate for a material to be used in polymeric actuators. Electrostriction is the phenomenon that a material is strained due to both Maxwell stress effect and electrostriction effect developed by the applied voltage. When a dielectric material is subject to an electric field, it will experience Maxwell stress caused by the Coulomb force between accumulated charges and electrostriction by the reorientation of polar phase in the material. In order to SPU having large deformation and force, SPU was composed of the soft segment with poly(tetramethylene glycol), the hard segment with 4, 4’-diphenylmethane diisocyanate, and 1, 4-butanediol. Dielectric actuator based on SPU had good mechanical properties, field-induced strain, and force.

scholarly journals Investigating the Proton and Ion Transfer Properties of Supported Ionic Liquid Membranes Prepared for Bioelectrochemical Applications Using Hydrophobic Imidazolium-Type Ionic Liquids

Membranes ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 359
Author(s):  
László Koók ◽  
Piroska Lajtai-Szabó ◽  
Péter Bakonyi ◽  
Katalin Bélafi-Bakó ◽  
Nándor Nemestóthy
Keyword(s):  
Mass Transfer ◽  
Ionic Liquid ◽  
Ionic Liquids ◽  
Microbial Fuel Cells ◽  
Transport Numbers ◽  
Liquid Membranes ◽  
Ion Transfer ◽  
Supported Ionic Liquid ◽  
Supported Ionic Liquid Membranes ◽  
Transfer Properties

Hydrophobic ionic liquids (IL) may offer a special electrolyte in the form of supported ionic liquid membranes (SILM) for microbial fuel cells (MFC) due to their advantageous mass transfer characteristics. In this work, the proton and ion transfer properties of SILMs made with IL containing imidazolium cation and [PF6]− and [NTf2]− anions were studied and compared to Nafion. It resulted that both ILs show better proton mass transfer and diffusion coefficient than Nafion. The data implied the presence of water microclusters permeating through [hmim][PF6]-SILM to assist the proton transfer. This mechanism could not be assumed in the case of [NTf2]− containing IL. Ion transport numbers of K+, Na+, and H+ showed that the IL with [PF6]− anion could be beneficial in terms of reducing ion transfer losses in MFCs. Moreover, the conductivity of [bmim][PF6]-SILM at low electrolyte concentration (such as in MFCs) was comparable to Nafion.

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