Study on thermal stability of polyurethane-urea based on polysiloxane and polycaprolactone diols (original) (raw)
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Journal of Applied Polymer Science, 2003
Two series of polyurethanes and polyurethaneureas were prepared using a two-step bulk-solution polymerization procedure. Each series consisted of three polymers based on three molecular weights of α,ω-bis(6-hydroxyethoxypropyl) polydimethylsiloxane (PDMS): 940, 1913, and 2955. The soft segment in all cases was an 80:20 mixture of PDMS and poly(hexamethylene oxide) (MW 700), and the hard segment was based on 4,4′-methylenediphenyl diisocyanate and mixed chain extenders (40 wt %). In the polyurethane (PU) series the chain extender was a 60:40 (mol) mixture of BDO and 1,3-bis(4-hydroxybutyl)1,1,3,3-tetramethyldisiloxane (BHTD), whereas in the polyurethaneurea (PUU) series it was a 60:40 (mol) mixture of BHTD and 1,2-ethylenediamine. The polymerization was carried out by preparing a prepolymer using a bulk polymerization procedure followed by chain extension in a solution of N,N-dimethylacetamide. Polymers were characterized by size-exclusion chromatography, tensile testing, differential scanning calorimetry (DSC), and dynamic mechanical thermal analysis (DMTA). The number-average molecular weights of the polymers in the PU series were in the range of 114,300–124,500, whereas they were in the 78,400–103,300 range for the PUU series. Polymers with good clarity and mechanical properties were obtained with PDMS-940 and PDMS-1913, but those obtained from PDMS-2955, despite having good tensile strength, had a low percentage of elongation, high modulus, and poor clarity. DSC and DMTA results indicated that regardless of the PDMS molecular weight, the siloxane segments existed as a highly phase-separated state. This poor compatibility was consistent with the low solubility of PDMS compared to that of the hard-segment-forming components. The polymers in the polyurethane series exhibited multiple melting endotherms, attributed to the melting of ordered domains from different hard segments. The combined heats of fusion were similar for the materials in the PU series. In contrast, the polymers in the PUU series showed a hard-segment order that was significantly less defined, with the heat of fusion approximately a third to a half that of the materials in the polyurethane series. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1565–1573, 2003
Polymers
A series of multiblock polyurethane-ureas (PUU) based on polycaprolactone diol (PCL) with a molecular mass of 530 or 2000 g/mol, as well as hard segments of different lengths and structures, were synthesized by the step-growth polymerization method. The chemical structure of the synthesized multiblock copolymers was confirmed by IR- and NMR-spectroscopy. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) were used to determine the relaxation and phase transition temperatures for the entire series of the obtained PUU. The X-ray diffraction (XRD) method made it possible to identify PUU compositions in which the crystallizability of soft segments (SS) is manifested due to their sufficient length for self-organization and structuring. Visualization of the crystal structure and disordering of the stacking of SS with an increase in their molecular mobility during heating are shown using optical microscopy. The change in the size of the hard phase domains and the...
Progress in Organic Coatings, 2017
Waterborne polyurethane urea dispersions (WPUUs) intended for coatings and adhesives were synthesized with mixtures of polyester polyol (PE) and polycarbonate diol (PCD) for combining the advantages of the polyurethane ureas made with pure polyols. WPUUs made with mixtures of polyols had higher mean particle size and lower viscosity than the ones made with one polyol only. Two types of hard segments totally separated (i.e. −(IPDI-DMPA/TEA-IPDI)and −(IPDI-HZ-IPDI)-) and two types of soft segments (i.e. −(IPDI-PCD-IPDI)and −(IPDI-PE-IPDI)-) were produced in polyurethane ureas made with PE + PCD mixtures. The segmented structure and phase separation of the polyurethane ureas made with PE + PCD mixtures differed depending on their PCD content, affecting the thermal, rheological and crystallinity properties. The adhesion of chlorinated vulcanized styrene-butadiene rubber/WPUU/roughened leather joints made with WPUUs prepared with PE + PCD mixtures was very similar to the ones made with PCD and PE only. After ageing in water at 70°C for 1-2 days, the adhesive strength of joints made with WPUUs containing more than 50 wt% PCD is excellent. The properties of the polyurethane ureas made with mixtures of polyols containing 50 wt% or more PCD were determined by lower degree of phase separation and interactions between hard and soft domains via carbonate groups.
Journal of the Serbian Chemical Society, 2014
In this study, the synthesis, structure and physical properties of two series of thermoplastic polyurethanes based on hydroxypropyl-terminated poly-(dimethylsiloxane) (HP-PDMS) or hydroxyethoxypropyl-terminated poly-(dimethylsiloxane) (EO-PDMS) as soft segments, and 4,4′-methylenediphenyl diisocyanate and 1,4-butanediol as hard segments were investigated. The polyurethanes were synthesized by two-step polyaddition in solution. The effects of the type and content of PDMS segments on the structure, thermal and surface properties of copolymers were studied by 1 H-, 13 C-nuclear magnetic resonance (NMR) spectroscopy and two-dimensional NMR spectroscopies (heteronuclear multiple bond correlation (HMBC) and rotating-frame nuclear Overhauser effect (ROESY)), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), wide-angle X-ray scattering (WAXS), scanning electron microscopy (SEM) and water contact angle and water absorption measurements. Thermal properties investigated by DSC indicated that the presence of soft PDMS segments lowers the glass transition and melting temperatures of the hard phase as well as the degree of crystallinity. SEM analysis of the copolymers with a lower soft segment content confirmed the presence of spherulite superstructures, which arise from the crystallization of the hard segments. When compared with polyurethanes prepared from HP-PDMS, the copolymers synthesized from EO-PDMS with the same content of the soft segments had a higher degree of crystallinity, better thermal stability and a less hydrophobic surface. The obtained results showed that the synthesized polyurethanes had good thermal and surface
Biomaterials, 2005
Polyurethanes based on poly(-caprolactone) (PCL) (750-2800 g/mol) and 1,4-butane diisocyanate (BDI) with different soft segment lengths and constant uniform hard segment length were synthesized in absence of catalysts for the production of a degradable meniscus scaffold. First the polyesterdiols were endcapped with BDI yielding a macrodiisocyanate with a minimal amount of side reactions and a functionality of 2.0. Subsequently, the macrodiisocyanates were extended with 1,4-butanediol in order to obtain the corresponding polyurethane. The polyurethanes had molecular weights between 78 and 160 kg/mol. Above molar masses of 1900 g/mol of the polyesterdiol crystalline PCL was found while the hard segment showed an increase in melting point from 78 to 122 1C with increasing hard segment content. It was estimated that the percentage crystallinity of the hard segment varied between 92 and 26%. The Young's modulus varied between 30 and 264 MPa, the strain at break varied between 870 and 1200% and tear strengths varied between 97 and 237 kJ/m 2 .
Segmented polyurethanes (PURs) were prepared f r o m α , ω-d i h y d r o x y p o l y (p r o p y l e n e o x i d e)-b-p o l y-(dimethylsiloxane)-b-poly(propylene oxide) (PPO−PDMS) as the soft segment and 4,4′-diphenylmethane diisocyanate and 1,4-butanediol as the hard segment, via two-step polyaddition process in solvent mixture. The content of hard segments is in the range from 10 to 60 wt %. The structure and composition of PURs are determined by 1 H NMR, 13 C NMR, and ATR-FTIR spectroscopy. Incorporation of PPO−PDMS leads to improvements in thermal stability. Small-and wide-angle X-ray scattering experiments indicate that synthesized PURs with higher content of hard segments have more developed and distinct phase separated morphologies. Dynamic mechanical thermal analysis shows that copolymers have multiple transitions, characteristic for phase-separated systems. The water contact angle increases while water absorption decreases with increasing content of PPO−PDMS segments. The PURs prepared in this work show good thermal, mechanical features with phase separated morphology and high water resistance that enable their widespread application.
Chemical Papers
The surface morphology and thermal properties of polyurethanes can be correlated to their chemical composition. The hydrophilicity, surface morphology, and thermal properties of polyurethanes (differed in soft segments and in linear/crosslinked structure) were investigated. The influence of poly([R,S]-3-hydroxybutyrate) presence in soft segments and blending of polyurethane with polylactide on surface topography were also estimated. The linear polyurethanes (partially crystalline) had the granular surface, whereas the surface of cross-linked polyurethanes (almost amorphous) was smooth. Round aggregates of polylactide un-uniformly distributed in matrix of polyurethane were clearly visible. It was concluded that some modification of soft segment (by mixing of poly([R,S]-3-hydroxybutyrate) with different polydiols and polytriol) and blending of polyurethanes with small amount of polylactide influence on crystallinity and surface topography of obtained polyurethanes.
Journal of Applied Polymer Science, 2008
Moisture-cured polyurethane is one of the commercially important polymers, which is widely used in sealants, coatings, and reactive hot-melt adhesives. A series of moisture-cured polyurethane/polysiloxane (PUSR) copolymers were successfully prepared using a two-step solution polymerization procedure. Both amine-terminated polysiloxane (PDMS) and polyester diol were together used as mixed soft segments to react with 4,4 0 -diphenlymethane diisocyanate (MDI), and the alkoxysilane was used as end-capping agents. The effects of structure variation of building blocks such as the polyester diol structure and NCO/OH ratio on the properties and morphology of PUSR copolymers were studied. The tensile properties, dielectric behavior, thermal stability, surface, and waterrepellency properties were investigated. The results showed that the properties and morphology of PUSR copolymers were greatly affected by the variations in molecular architecture.
Morphology and thermal properties of polyurethanes prepared under different conditions
European Polymer Journal, 1989
In this paper three representative structural chain extenders, including 1,4-butanediol (1,4-BDO), neopentyl glycol (NPG) and bisphenol-a (BPA), were chosen to prepare PUE due to their comparable structures. The way to choosing the chain extenders was new and interesting. After the synthesis of PUE, morphology and thermal properties were evaluated by different characterization methods.
Thermal and mechanical properties of multiple-component aliphatic degradable polyurethanes
Journal of Applied Polymer Science, 2015
Macroscopic thermal and mechanical properties of complex aliphatic polycarbonate-based polyurethane (PU) films containing degradable ester units in PU backbone were studied by a combination of several experimental techniques. Differential scanning calorimetry (DSC) revealed that the synthesized oligomeric diol (DL-L) contributes (in addition to polycarbonate diol) to the formation of soft-segment domains, while the hard-segment domains are formed from 1,6-diisocyanatohexane (HDI) and butane-1,4-diol (BD). Three main phase transitions were detected by DSC and by dynamic mechanical thermal analysis. Thermogravimetric analysis (TGA) of two-component PUs showed that the PU made from DL-L and HDI is the least thermostable product, while the PU made from polycarbonate diol and HDI is the most stable one. The differences in the thermal stability of different fourcomponent PUs are not important. Tensile properties very sensitively reflect the changes in composition and in microstructure of PU samples; the best tensile properties exhibits the degradable sample containing the equimolar ratio of hydroxyl groups of macrodiol,