scholarly journals Ionic Conductivity and Morphological Study of a Thermoplastic Polyurethane Based Electrolyte Comprising of Mixed Soft Segments

2000 ◽  
Vol 32 (11) ◽  
pp. 921-931 ◽  
Author(s):  
Mohanlal Digar ◽  
Ten-Chin Wen
Keyword(s):  
Ionic Conductivity ◽  
Morphological Study ◽  
Thermoplastic Polyurethane ◽  
Soft Segments

Rheology of Thermoplastic Polyurethanes

2007 ◽  
Author(s):  
Chang Dae Han
Keyword(s):  
Rheological Behavior ◽  
Thermoplastic Polyurethane ◽  
Complete Characterization ◽  
Chain Extender ◽  
Reaction Sequence ◽  
Molecular Weights ◽  
Soft Segments ◽  
Hard Segments ◽  
A Chain ◽  
Long Chain

Thermoplastic polyurethane (TPU) has received considerable attention from both the scientific and industrial communities (Hepburn 1982; Oertel 1985; Saunders and Frish 1962). Applications for TPUs include automotive exterior body panels, medical implants such as the artificial heart, membranes, ski boots, and flexible tubing. Figure 10.1 gives a schematic that shows the architecture of TPU, consisting of hard and soft segments. Hard segments, which form a crystalline phase at service temperature, are composed of diisocyanate and short-chain diols as a chain extender, while soft segments, which control low-temperature properties, are composed of difunctional long-chain polydiols with molecular weights ranging from 500 to 5000. The soft segments form a flexible matrix between the hard domains. TPUs are synthesized by reacting difunctional long-chain diol with diisocyanate to form a prepolymer, which is then extended by a chain extender via one of two routes: (1) by a dihydric glycol chain extender or (2) by a diamine chain extender. The most commonly used diisocyanate is 4,4’-diphenylmethane diisocyanate (MDI), which reacts with a difunctional polyol forming soft segments, such as poly(tetramethylene adipate) (PTMA) or poly(oxytetramethylene) (POTM), to produce TPU, in which 1,4-butanediol (BDO) is used as a chain extender. There are two methods widely used to produce TPU: (1) one-shot reaction sequence and (2) two-stage reaction sequence. The reaction sequences for both methods are well documented in the literature (Hepburn 1982). It should be mentioned that MDI/BDO/PTMA produces ester-based TPU. One can also produce ether-based TPU when MDI reacts with POTM using BDO as a chain extender. TPUs are often referred to as “multiblock copolymers.” In order to have a better understanding of the rheological behavior of TPUs, one must first understand the relationships between the chemical structure and the morphology; thus, a complete characterization of the materials must be conducted. The rheological behavior of TPU depends, among many factors, on (1) the composition of the soft and hard segments, (2) the lengths of the soft and hard segments and the sequence length distribution, (3) anomalous linkages (branching, cross-linking), and (4) molecular weight.

Preparation of microporous thermoplastic polyurethane by low-temperature supercritical CO2 foaming

2016 ◽  
Vol 53 (2) ◽  
pp. 135-150 ◽  
Author(s):  
Chien-Chia Chu ◽  
Shu-Kai Yeh ◽  
Sheng-Ping Peng ◽  
Ting-Wei Kang ◽  
Wen-Jeng Guo ◽  
...  
Keyword(s):  
Polyurethane Foam ◽  
Supercritical Co2 ◽  
Thermoplastic Polyurethane ◽  
Saturation Temperature ◽  
Phenyl Isocyanate ◽  
Blowing Agent ◽  
Soft Segments ◽  
Hard Segments ◽  
Poly Propylene ◽  
Foam Production

Thermoplastic polyurethane possesses many special characteristics. Its flexibility, rigidity, and elasticity can be adjusted by controlling the ratio of soft segments to hard segments. Due to its versatile physical properties, thermoplastic polyurethane is commonly used in transportation, construction, and biomaterials. However, methods for thermoplastic polyurethane foam production using CO2 are still under investigation. We have previously prepared nanoporous thermoplastic polyurethane foam using commercially available thermoplastic polyurethane; however, in this study, thermoplastic polyurethane was synthesized using 4,4′-methylenebis(phenyl isocyanate), poly(propylene glycol) and 1,4-butanediol, without solvents, using a pre-polymer method. The properties of the synthesized thermoplastic polyurethane were characterized by Fourier transform infrared spectroscopy, thermal analysis, and their mechanical properties were measured. The synthesized thermoplastic polyurethane was foamed by batch foaming using supercritical CO2 as the blowing agent. The effect of saturation temperature and saturation time on the cell morphology of the thermoplastic polyurethane foam was examined.

scholarly journals Mechano-responsive hydrogen-bonding array of thermoplastic polyurethane elastomer captures both strength and self-healing

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Youngho Eom ◽  
Seon-Mi Kim ◽  
Minkyung Lee ◽  
Hyeonyeol Jeon ◽  
Jaeduk Park ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Thermoplastic Polyurethane ◽  
Healing Process ◽  
Polyurethane Elastomer ◽  
Self Healing ◽  
Static Mode ◽  
Soft Segments ◽  
Hard Segments ◽  
Thermoplastic Polyurethane Elastomer ◽  
Dynamic Exchange

AbstractSelf-repairable materials strive to emulate curable and resilient biological tissue; however, their performance is currently insufficient for commercialization purposes because mending and toughening are mutually exclusive. Herein, we report a carbonate-type thermoplastic polyurethane elastomer that self-heals at 35 °C and exhibits a tensile strength of 43 MPa; this elastomer is as strong as the soles used in footwear. Distinctively, it has abundant carbonyl groups in soft-segments and is fully amorphous with negligible phase separation due to poor hard-segment stacking. It operates in dual mechano-responsive mode through a reversible disorder-to-order transition of its hydrogen-bonding array; it heals when static and toughens when dynamic. In static mode, non-crystalline hard segments promote the dynamic exchange of disordered carbonyl hydrogen-bonds for self-healing. The amorphous phase forms stiff crystals when stretched through a transition that orders inter-chain hydrogen bonding. The phase and strain fully return to the pre-stressed state after release to repeat the healing process.

Gelation of thermoplastic polyurethane/2-butanone solutions

e-Polymers ◽  
2005 ◽  
Vol 5 (1) ◽  
Author(s):  
Sonia Florez ◽  
María Eugenia Muñoz ◽  
Anton Santamaría
Keyword(s):  
Hard Segment ◽  
Critical Concentration ◽  
Thermoplastic Polyurethane ◽  
Crystallization Rate ◽  
Solution Viscosity ◽  
Scanning Calorimetry ◽  
Soft Segments ◽  
Gelation Concentration ◽  
Hard Segments ◽  
Chain Entanglements

AbstractNew features of thermoplastic polyurethane (PUR)/2-butanone gels are investigated, using dynamic viscoelastic measurements and differential scanning calorimetry. The work is focused on the effect of the hard-segments content on the gelation process. In the case of PUR with the highest hard-segment fraction (30%), soft segments are not able to crystallize on cooling from solution; consequently, gels are not formed. The copolymer with the lowest hard-segment content (12%) gives the shortest gel times. This is attributed to the low solution viscosity of this copolymer, which enhances the crystallization rate. All gels melt at 7°C, giving rise to a viscoelastic solution in a thermoreversible process. The critical gelation concentration is below the critical concentration for polymer chain entanglements.

Influence of Blend Proportions on Properties of ENR-25/TPU Simple Blends

2013 ◽  
Vol 844 ◽  
pp. 93-96
Author(s):  
Skulrat Pichaiyut ◽  
Charoen Nakason ◽  
Ekwipoo Kalkornsurapranee ◽  
Norbert Vennemann ◽  
Claudia Kummerlöwe
Keyword(s):  
Tensile Strength ◽  
Natural Rubber ◽  
Thermoplastic Polyurethane ◽  
Polymer Melt ◽  
Continuous Phase ◽  
Morphological Properties ◽  
Elongation At Break ◽  
Soft Segments ◽  
Lower Elongation ◽  
Thermoplastic Natural Rubber

Thermoplastic natural rubber (TPNR) based on blending of thermoplastic polyurethane (TPU) and epoxidized natural rubber with 25 mol % epoxide (ENR-25) was prepared by simple blend technique. Influence of various blend proportions was investigated. It was found that an incorporation of rubber caused decreasing of mechanical properties in terms of tensile strength, elongation at break and hardness. This is attributed to incorporation of rubber phase may cause chain restriction of the soft segments in TPU and hence lower elongation at break and tensile strength. It was also found that the tension set value decreased with increasing proportion of natural rubber which indicates greater elasticity or tendency to recover to the original shape after prolonged deformation. Additionally, shear stress and shear viscosity of the blends increased with increasing rubber proportions due to higher viscosity of the ENR-25 component which leads to higher force to compress the polymer melt flowing through a capillary channel. Morphological properties of the simple blend with various blend proportions exhibited formation of co-continuous phase structure was observed where larger rubber formation are observed in the blend with higher content of ENR-25 phase.

Investigation of soft segments of thermoplastic polyurethane by NMR, differential scanning calorimetry and rebound resilience

2006 ◽  
Vol 25 (2) ◽  
pp. 203-213 ◽  
Author(s):  
Alexandra Voda ◽  
Klaus Beck ◽  
Thomas Schauber ◽  
Matthias Adler ◽  
Thomas Dabisch ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Thermoplastic Polyurethane ◽  
Scanning Calorimetry ◽  
Soft Segments
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