Robust Stretchable Thermoplastic Polyurethanes with Long Soft Segments and Steric Semisymmetric Hard Segments

2020 ◽  
Vol 59 (10) ◽  
pp. 4483-4492 ◽  
Author(s):  
Hangtian Zhang ◽  
Fang Zhang ◽  
Yixian Wu
Keyword(s):  
Thermoplastic Polyurethanes ◽  
Soft Segments ◽  
Hard Segments

scholarly journals Structural and Viscoelastic Properties of Thermoplastic Polyurethanes Containing Mixed Soft Segments with Potential Application as Pressure Sensitive Adhesives

Polymers ◽  
2021 ◽  
Vol 13 (18) ◽  
pp. 3097
Author(s):  
Mónica Fuensanta ◽  
José Miguel Martín-Martínez
Keyword(s):  
Phase Separation ◽  
Potential Application ◽  
Viscoelastic Properties ◽  
Gravimetric Analysis ◽  
Scanning Calorimetry ◽  
Adhesion Properties ◽  
Pressure Sensitive Adhesives ◽  
Thermoplastic Polyurethanes ◽  
Pressure Sensitive ◽  
Soft Segments

Thermoplastic polyurethanes (TPUs) were synthetized with blends of poly(propylene glycol) (PPG) and poly(1,4-butylene adipate) (PAd) polyols, diphenylmethane-4,4′-diisocyanate (MDI) and 1,4-butanediol (BD) chain extender; different NCO/OH ratios were used. The structure and viscoelastic properties of the TPUs were assessed by infrared spectroscopy, differential scanning calorimetry, X-ray diffraction, thermal gravimetric analysis and plate-plate rheology, and their pressure sensitive adhesion properties were assessed by probe tack and 180° peel tests. The incompatibility of the PPG and PAd soft segments and the segregation of the hard and soft segments determined the phase separation and the viscoelastic properties of the TPUs. On the other hand, the increase of the NCO/OH ratio improved the miscibility of the PPG and PAd soft segments and decreased the extent of phase separation. The temperatures of the cool crystallization and melting were lower and their enthalpies were higher in the TPU made with NCO/OH ratio of 1.20. The moduli of the TPUs increased by increasing the NCO/OH ratio, and the tack was higher by decreasing the NCO/OH ratio. In general, a good agreement between the predicted and experimental tack and 180° peel strength values was obtained, and the TPUs synthesized with PPG+PAd soft segments had potential application as pressure sensitive adhesives (PSAs).

The effect of separation of blocks on the crystallization kinetics and phase composition of poly(butylene adipate) in multi-block thermoplastic polyurethanes

2022 ◽  
Author(s):  
Marina A. Gorbunova ◽  
Evgenii V. Komov ◽  
Leonid Yu. Grunin ◽  
Mariya S. Ivanova ◽  
Ainur F. Abukaev ◽  
...  
Keyword(s):  
Phase Composition ◽  
Phase Separation ◽  
Crystallization Kinetics ◽  
Separation Process ◽  
Degree Of Crystallinity ◽  
Thermoplastic Polyurethanes ◽  
Phase Separation Process ◽  
Hard Segments ◽  
Final Degree

Control of the phase separation process of soft and hard segments by selecting diisocyanates and by varying the thermal program allows defining the final degree of crystallinity and phase composition of TPUs.

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.

scholarly journals Shape-Memory Properties of Segmented Polymers Containing Aramid Hard Segments and Polycaprolactone Soft Segments

Polymers ◽  
2010 ◽  
Vol 2 (2) ◽  
pp. 71-85 ◽  
Author(s):  
Christian Schuh ◽  
Kerstin Schuh ◽  
Maria C. Lechmann ◽  
Louis Garnier ◽  
Arno Kraft
Keyword(s):  
Shape Memory ◽  
Soft Segments ◽  
Shape Memory Properties ◽  
Hard Segments

scholarly journals Thermoplastic polyurethanes with controlled morphology based on methylenediphenyldiisocyanate/isosorbide/butanediol hard segments

2015 ◽  
Vol 64 (11) ◽  
pp. 1607-1616 ◽  
Author(s):  
Ivan Javni ◽  
Olivera Bilić ◽  
Nikola Bilić ◽  
Zoran S Petrović ◽  
Eric A Eastwood ◽  
...  
Keyword(s):  
Thermoplastic Polyurethanes ◽  
Controlled Morphology ◽  
Hard Segments

scholarly journals The effect of the polar solvents on the synthesis of poly(urethane-urea-siloxane)s

2012 ◽  
Vol 77 (10) ◽  
pp. 1457-1481 ◽  
Author(s):  
Milica Balaban ◽  
Vesna Antic ◽  
Marija Pergal ◽  
Iolanda Francolini ◽  
Andrea Martinelli ◽  
...  
Keyword(s):  
Monomer Concentration ◽  
Gel Permeation Chromatography ◽  
Molar Ratio ◽  
Solvent Ratio ◽  
Solvent Mixtures ◽  
Scanning Calorimetry ◽  
Experimental Conditions ◽  
Water Contact ◽  
Soft Segments ◽  
Hard Segments

Segmented poly(urethane-urea-siloxanes) (PUUS) based on 4,4?- methylene diphenyl diisocyanate-ethylene diamine (MDI-ED) hard segments and hidroxypropyl-terminated poly(dimethylsiloxane) (PDMS, M n =1000 g mol-1) soft segments were prepared under various experimental conditions. The copolymers with constant molar ratio of hard and soft segments (PDMS:MDI:ED = 1:2:1; 20 wt. % of the hard segments) were synthesized in two different solvent mixtures, by two-step polyaddition procedure. The first one was THF/DMAc with different co-solvent ratio (1/1, 1/2 and 1/9, v/v), whereas the second one was THF/NMP (1/9, v/v). The reaction conditions were optimized by varying the co-solvents ratio, the concentration of the catalyst, the initial monomer concentration, as well as the time of the first and the second step of reaction. The effect of the experimental conditions on the size of PUUS was investigated by gel permeation chromatography (GPC) and viscometry of the dilute solutions [?]. The copolymers with the highest molecular weights were obtained in the THF/NMP mixture (1/9, v/v). The structure and composition of the copolymers were determined by 1H NMR and FTIR spectroscopy. The morphology of the synthesized copolymers was investigated by atomic force microscopy (AFM), while the thermal properties were studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The surface properties were evaluated by measuring the water contact angle (WCA). The copolymers showed phase separated microstructure and were stable up to 200?C in nitrogen.

Polyurethanes with aggregation-enhanced emission characteristics: preparation and properties

2017 ◽  
Vol 196 ◽  
pp. 43-54 ◽  
Author(s):  
Kun Wang ◽  
Jiping Yang ◽  
Chen Gong ◽  
Hao Lu
Keyword(s):  
Fluorescence Intensity ◽  
Soft Segment ◽  
Fluorescence Emission ◽  
Water Mixture ◽  
Stimuli Responsive ◽  
Scanning Calorimetry ◽  
Responsive Materials ◽  
Molar Ratios ◽  
Soft Segments ◽  
Hard Segments

An amino-terminated poly(propylene glycol)-modified tetraaryl-buta-1,3-diene derivative (TABDAA) was introduced to synthesize polyurethanes with different ratios of soft/hard segments. A mixture of TABDAA and poly(tetrahydrofuran) 1000 as the soft segments was reacted with 4,4-diphenylmethane diisocyanate and 1,4-butanediol as the hard segments in molar ratios of 1 : 2 : 1, 2 : 3 : 1, and 3 : 4 : 1 to give the desired polyurethanes named TMPU-211, TMPU-321 and TMPU-431, respectively. The three polyurethanes exhibited different aggregation-enhanced emission (AEE) behaviors because of their different soft/hard segment ratios. The polyurethanes with a higher soft segment content tended to form bigger particles in a DMF/water mixture solution, thus causing a sharper increase in their fluorescence intensity. In addition, the polyurethane films exhibited different fluorescence intensities after different heat treatments. After a quenching treatment of the soft segments in the polyurethane films, the fluorescence intensity dropped greatly. When these quenched polyurethane films were thermally annealed at 60 °C for 24 hours, their fluorescence intensity exceeded the initial intensity of the as-prepared films. Differential scanning calorimetry results showed that the polyurethane films in the quenched condition did not present the endothermal melting peak of the soft segments, and the melting peaks appeared again after thermal annealing. AFM experiments showed that an ordered arrangement was achieved after the heat treatment of these AEE polyurethane films. These results demonstrated that the polymer structure had a significant effect on the AEE properties of the polyurethane films, and more importantly, it is of great significance in improving the fluorescence emission of the AEE polymers and also for their potential application in fluorescent probes, stimuli-responsive materials, PLED devices and so on.

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