scholarly journals Synthesis, structure and properties of thermoplastic poly(ester-siloxane) elastomers

2006 ◽  
Vol 71 (7) ◽  
pp. 839-842
Author(s):  
Vesna Antic ◽  
Jasna Djonlagic
Keyword(s):  
1H Nmr Spectroscopy ◽  
Mechanical Analysis ◽  
Structure And Properties ◽  
Mass Ratio ◽  
Scanning Calorimetry ◽  
Constant Length ◽  
Melting Temperatures ◽  
Soft Segments ◽  
In Series ◽  
Hard Segments

Two series of thermoplastic poly(ester-siloxane) elastomers (TPES), with hard segments based on poly(butylene terephthalate) (PBT) and soft segments based on poly(dimethylsiloxane) (PDMS), were synthesized by high-temperature two-step transesterification reaction in the melt. In series I, the mass ratio of hard and soft segments was kept constant (57:43), while the length of the segments was varied, whereas in series II, the mass ratio of hard and soft segments was varied in range from 70:30 to 40:60, with a constant length of the soft segments. The segmented structure of the poly(ester-siloxane) copolymers was verified by 1H-NMR spectroscopy of the soluble and insoluble fractions, obtained after extraction of the samples with chloroform. The influence of the structure and composition of the TPES on the melting temperatures and degrees of crystallinity was investigated by differential scanning calorimetry (DSC). The rheological properties were investigated by dynamic mechanical analysis (DMA).

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.

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.

Structure and Properties of Chitosan and Polyvinyl Alcohol Blend Film

2017 ◽  
Vol 727 ◽  
pp. 895-899
Author(s):  
Gui Zhen Ke ◽  
Kun Di Zhu ◽  
Yi Fei Li
Keyword(s):  
Polyvinyl Alcohol ◽  
Polymer Chains ◽  
Light Transmittance ◽  
Solution Casting ◽  
Structure And Properties ◽  
Mass Ratio ◽  
Scanning Calorimetry ◽  
Blend Films ◽  
Structures And Properties ◽  
Scanning Electron

Chitosan (CS) and polyvinyl alcohol (PVA) blend films were prepared by solution casting of various mass ratio of CS and PVA. The structures and properties of the blended films were analyzed by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectrum, differential scanning calorimetry, tensile test and light transmittance measurement. The results showed that CS and PVA had good compatibility and there was no phase separation in the blends. There was strong hydrogen bonding association between CS and PVA polymer chains. Tensile strength and light transmittance of the blend films increased with the CS addition.

scholarly journals Synthesis of thermoplastic poly(ester-siloxane)s in the melt and in solution

2005 ◽  
Vol 70 (12) ◽  
pp. 1469-1485 ◽  
Author(s):  
Biljana Dojcinovic ◽  
Vesna Antic ◽  
Marija Vuckovic ◽  
Jasna Djonlagic
Keyword(s):  
1H Nmr Spectroscopy ◽  
Hard Segment ◽  
Soft Segment ◽  
Weight Ratio ◽  
Thermoplastic Elastomers ◽  
Degree Of Crystallinity ◽  
Mechanical Spectroscopy ◽  
Scanning Calorimetry ◽  
Melting Temperatures ◽  
High Boiling Solvent

Two series of thermoplastic elastomers, based on poly(dimethylsiloxane) PDMS, as the soft segment and poly(butylene terephthalate), PBT, as the hard segment, were synthesized by catalyzed transesterification, from dimethyl terephthalate, DMT, silanol-terminated poly(dimethylsiloxane), PDMS-OH Mn=1750g/mol, and 1,4-butanediol, BD. The mole ratio of the starting comonomers was selected to result in a constant hard to soft weight ratio of 55:45. The first series was synthesized in order to determine the optimal mole ratio of BD and DMT for the synthesis of high molecular weight thermoplastic poly(ester-siloxane)s, TPESs. The second series was performed in the presence of the high-boiling solvent, 1,2,4-trichlorbenzene in order to increase the mixing between the extremely non-polar siloxane prepolymer and the polar reactants, DMT and BD, and, therefore, avoid phase separation during synthesis. The structure and composition of the synthesized poly(ester-siloxane)s were verified by 1H-NMR spectroscopy, while the melting temperatures and degree of crystallinity were determined by differential scanning calorimetry (DSC). The effectiveness of the incorporation of the silanol-terminated poly( dimethylsiloxane) into the polyester chains was verified by chloroform extraction. The rheological properties of the poly(ester-siloxane)s were investigated by dynamic mechanical spectroscopy (DMA).

scholarly journals Rheological behaviour of thermoplastic poly(ester-siloxane)s

2010 ◽  
Vol 64 (6) ◽  
pp. 537-545 ◽  
Author(s):  
Vesna Antic ◽  
Marija Pergal ◽  
Malisa Antic ◽  
Jasna Djonlagic
Keyword(s):  
Dynamic Viscosity ◽  
Microphase Separation ◽  
Soft Segment ◽  
Rheological Behaviour ◽  
Thermoplastic Elastomers ◽  
Degree Of Crystallinity ◽  
Mass Ratio ◽  
Complex Dynamic ◽  
Constant Length ◽  
Soft Segments

Two series of thermoplastic elastomers (TPES) based on poly(dimethylsiloxane), (PDMS) as the soft segment and poly(butylene terephthalate) (PBT) as the hard segment, were analyzed by dynamic mechanical spectroscopy. In the first TPES series the lengths of both hard and soft segments were varied while the mass ratio of the hard to soft segments was nearly constant (about 60 mass%). In the second series, the mass ratio of hard and soft segments was varied in the range from 60/40 to 40/60, with a constant length of soft PDMS segments. The influence of the structure and composition of TPESs on the rheological properties, such as complex dynamic viscosity, ?*, the storage, G?, and loss, G?, shear modulus as well as the microphase separation transition temperature, TMST, was examined. The obtained results showed that the storage modulus of the TPESs increased in a rubbery plateau region with increasing degree of crystallinity. The rheological measurements of TPESs also showed that a microphase reorganization occurred during the melting process. The microphase separation transition temperatures were in the range from 220 to 234 ?C. In the isotropic molten state, the complex dynamic viscosity increased with increasing both the content and lenght of hard PBT segments.

scholarly journals Branched Polyurethanes Based on Synthetic Polyhydroxybutyrate with Tunable Structure and Properties

Polymers ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 826 ◽  
Author(s):  
Joanna Brzeska ◽  
Anna Elert ◽  
Magda Morawska ◽  
Wanda Sikorska ◽  
Marek Kowalczuk ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Water Sorption ◽  
Structure And Properties ◽  
Oil Sorption ◽  
Soft Segments ◽  
Tunable Structure ◽  
Hard Segments ◽  
Dsc Thermograms

Branched, aliphatic polyurethanes (PURs) were synthesized and compared to linear analogues. The influence of polycaprolactonetriol and synthetic poly([R,S]-3-hydroxybutyrate) (R,S-PHB) in soft segments on structure, thermal and sorptive properties of PURs was determined. Using FTIR and Raman spectroscopies it was found that increasing the R,S-PHB amount in the structure of branched PURs reduced a tendency of urethane groups to hydrogen bonding. Melting enthalpies (on DSC thermograms) of both soft and hard segments of linear PURs were higher than branched PURs, suggesting that linear PURs were more crystalline. Oil sorption by samples of linear and branched PURs, containing only polycaprolactone chains in soft segments, was higher than in the case of samples with R,S-PHB in their structure. Branched PUR without R,S-PHB absorbed the highest amount of oil. Introducing R,S-PHB into the PUR structure increased water sorption. Thus, by operating the number of branching and the amount of poly([R,S]-3-hydroxybutyrate) in soft segments thermal and sorptive properties of aliphatic PURs could be controlled.

Effects of Hard Segment Contents on Dynamic Mechanical Properties of Gap-Based Polyurethane Elastomers

2013 ◽  
Vol 376 ◽  
pp. 125-129
Author(s):  
Hai Qin Ding ◽  
Le Qin Xiao ◽  
Wei Liang Zhou ◽  
Li Rong He ◽  
Huai Long Zhang
Keyword(s):  
Mechanical Properties ◽  
Hard Segment ◽  
Dynamic Mechanical Properties ◽  
Mechanical Analysis ◽  
Polyurethane Elastomers ◽  
Elongation At Break ◽  
Dynamic Mechanical ◽  
Soft Segments ◽  
Hard Segments ◽  
Fragility Parameter

Gap-based polyurethane elastomer (GAPE) with different hard segment contents are synthesized with 44-Diphenylmethane diisocyanate (MDI), 1,4 butylene glycol (BDO) as hard segments and GAP as soft segments. Dynamic mechanical analysis (DMA) is applied to investigated the dynamic mechanical properties and the mechanical properties of GAPE are studied by materials laboratorial instrument. The results show that GAPE-2 with 33 wt% hard segment has better mechanical properties, of which the tensile strength is 11.3MPa and elongation at break is 460.5%.As shown in DMA, T g of GAPE-2 is-18.4°C, and the low-temperature fragility parameter and activation energy of GAPE-2 are lower, 55.6 and 271.0 KJ·mol-1 respectively. Elastomer with good stiffness and flexibility is obtained.

Preparation and properties of waterborne siloxane-containing polyurethane for moisture permeable textile coating

e-Polymers ◽  
2011 ◽  
Vol 11 (1) ◽  
Author(s):  
Haibo Lei ◽  
Yunjun Luo ◽  
Zhen Ge ◽  
Xiaomeng Li ◽  
Shengpeng Wang
Keyword(s):  
Hard Segment ◽  
Soft Segment ◽  
Water Vapor Permeability ◽  
Mechanical Analysis ◽  
Vapor Permeability ◽  
Gravimetric Analysis ◽  
Scanning Calorimetry ◽  
Coated Fabric ◽  
Soft Segments ◽  
Textile Coating

AbstractWaterborne siloxane-containing polyurethanes (WSPU) were prepared by polyaddition reaction using poly(tetramethylene oxide)glycol (PTMG), polyethylene glycol (PEG), and α,ω-aminopropyl polydimethylsiloxane (APDMS) as mixing soft segments; 2,2-di(hydroxymethyl)propionic acid, as a hydrophilic chain extender; 1,4-butanediol and isophorone diisocyanate as hard segment; triethylamine as a neutralization agent. The thermal properties of WSPU films were analyzed by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and thermal gravimetric analysis (TGA). The mechanical properties of WSPU film were also investigated. Water vapor permeability (WVP) was examined according to GB_T 12704-1991. The DSC and DMA results indicated that there is a micro-phase separation in the WSPU film. The incorporation of APDMS into PU made the thermal stability of hard segment worse while that of soft segment better. The elasticity of WSPU was improved when the APDMS content was not more than 10%, the vapor permeability of coated fabric increased firstly and then decreased as the APDMS content increased, which was resulted from the hydrophilicity change and microstructure change of membrane. When 10% APDMS was incorporated into the WSPU, the WVP of coated fabric was 2130.15 g/(m2·24h), equal to one coated with a widely used solvent-based PU sample (UECCOAT), and the water resistance (WR) reached 30.0 KPa.

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