Study of the Effect of Soft-Segment Length and Concentration on Properties of Polyetherurethanes. I. The Effect on Physical and Morphological Properties

1985 ◽  
Vol 58 (4) ◽  
pp. 685-700 ◽  
Author(s):  
Zoran S. Petrović ◽  
Jaroslava Budinski-Simendić
Keyword(s):  
Phase Inversion ◽  
Hard Segment ◽  
Soft Segment ◽  
Degree Of Polymerization ◽  
Morphological Properties ◽  
Segment Length ◽  
Hard Phase ◽  
Soft Phase ◽  
Soft Segments ◽  
Two Phases

Abstract 1. Densities of elastomers with crystallizing soft segments were higher than that of the noncrystallizing ones. However, the effect of the soft segment length is not regular and may reflect some specific interactions between two phases as well as instantaneous morphology. 2. Phase inversion as judged by drop of hardness takes place at about ssc=60° or more; a shift to higher ssc gives a greater segment length. 3. Tg of the soft segment in samples with well separated phases is independent of ssc, e.g., the presence of hard phase does not change mobility of the soft phase in samples with ssc=50° or more, in all series. However, Tg is strongly dependent on the soft-segment length. Tg for the soft segment of Mn=650 was −43°C, for Mn=1000 was −62°C, and for Mn=2000, Tg was −75°C. The effect of the presence of the hard phase on mobility of the soft phase seems to vanish for M>2500. 4. Tg of the hard segment at 77°C was clearly observed only in quenched samples with a high hard-segment concentration (80%) and at 93°C in a pure hard segment. 5. Melting of both phases were observed in polymers with long soft segments (Mn=2000). Soft segments of Mn=650 and 1000 do not crystallize. The hard phase crystallizes if its Mn is about 1000 or more or if the degree of polymerization of the hard segment is 3 or above, although exceptions were found in the A series. 6. Spherulitic structures were observed in polymers with low ssc (20% and 40%) polymers and in one with ssc=80°. Thus, both hard and soft phases can form spherulitic structures.

Chain Conformation in Elastomeric Multiblock Copolymers as Measured by Small-Angle Neutron Scattering

1985 ◽  
Vol 58 (5) ◽  
pp. 899-912 ◽  
Author(s):  
Stuart L. Cooper ◽  
John A. Miller
Keyword(s):  
Small Angle ◽  
Hard Segment ◽  
Elevated Temperatures ◽  
Soft Segment ◽  
Random Coil ◽  
Radius Of Gyration ◽  
Soft Phase ◽  
Soft Segments ◽  
Hard Segments ◽  
Increasing Temperature

Abstract Small-angle neutron scattering has been shown to be an effective technique for investigating segment conformation in two-phase multiblock copolymer systems. By choosing the appropriate isotopic compositions, either segment can be investigated, as can the whole chain. The best approach to the experiment is to use a phase-contrast matched sample, one where no interphase scattering occurs. This allows the experiments to be carried out on a single sample, simplifying the experiment, and reducing the beam time requirements. Equations (2) and (3) describe the phase-contrast matched criterion. At room temperature, the polyether soft segments in the polyurethane elastomer-and in the polyether-polyester block copolymers are somewhat extended on the average relative to the bulk oligomer conformation. In the polyether-polyester with a lower hard-segment content, the soft segments are less extended than in the higher ester content material. A distribution of conformations occurs in these materials, with a majority of the soft segments being nearly in a random-coil conformation. A substantial number of segments are fairly taut, leading to an average conformation that is somewhat extended relative to the random coil conformation. The soft-segment radius of gyration in the polyurethane material initially decreases with increasing temperature. As the temperature rises, the retractive force on the taut soft segments increases, thus facilitating the extraction of hard segments from the amorphous hard phase into the soft phase. One would expect that the degree of phase separation would decrease with increasing temperature due to such a mechanism, and in fact this is borne out by small-angle x-ray scattering studies. Above 150°C, an upturn in the soft-segment radius of gyration is observed. Koberstein et al. propose a phase mixing transition around this temperature in polyurethane systems. Such a transition implies a greater compatibility between the hard and soft segment types at elevated temperatures. Thus, a swelling of the soft segments is seen due to favorable interactions with the hard segments located in the soft phase. A schematic diagram of the polyurethane microstructure and chain conformation is presented in Figure 9. The soft-segment radius of gyration in the polyether-polyester materials decreases smoothly with increasing temperature. This is primarily due to a decrease in the number of taut tie molecules present at elevated temperatures due to the rearrangement of the hard crystalline domains. In addition, relaxation of stresses introduced by molding these samples below the hard-segment crystalline melting temperature may contribute to the decrease in the soft-segment Rg.

Study on the Influences of Domain Structure of Hydrophilic Polyurethane with Partially Crystalline on its Moisture Permeability

2011 ◽  
Vol 233-235 ◽  
pp. 281-287
Author(s):  
Heng Quan ◽  
Zhen Ya Gu
Keyword(s):  
Chemical Structure ◽  
Hard Segment ◽  
Microphase Separation ◽  
Soft Segment ◽  
Moisture Permeability ◽  
Soft Segments ◽  
Separation Degree ◽  
Polyethylene Glycol 1000 ◽  
Segmented Polyurethanes ◽  
Hydrophilic Polyurethane

Multiphase, segmented polyurethanes with mixed soft segment phase were prepared from 4,4’- diphenylmethane diisocyanate (Pure MDI), polybutylene adipate (glycol) 2000 (PBA2000) and polyethylene glycol 1000 (PEG1000) with 1,4-butanediol (BDO) as the chain extender. Further more, the relationships between domain separation structure, crystallizability of soft segment and moisture permeability, hydrophilic property, phase inversion temperature (PIT) of the polyurethanes were investigated. The studies show that the chemical structure, concentration of hydrophilic soft monomers and the microphase separation degree of the mixed soft segments from hard segment domain have remarkable effects on the application properties of polyurethane.

Study of the Effect of Soft-Segment Length and Concentration on Properties of Polyetherurethanes. II. The Effect on Mechanical Properties

1985 ◽  
Vol 58 (4) ◽  
pp. 701-712 ◽  
Author(s):  
Zoran S. Petrović ◽  
Jaroslava Budinski-Simendić
Keyword(s):  
Mechanical Properties ◽  
Chain Length ◽  
Plastic Flow ◽  
Soft Segment ◽  
Maximum Strength ◽  
Segment Length ◽  
Elongation At Break ◽  
Mechanical Methods ◽  
Soft Segments ◽  
Segmented Polyurethanes

Abstract Three series of segmented polyurethanes with different soft segment lengths and concentrations were examined by TMA, DMA, and mechanical methods. Maximum tensile strengths were obtained when ssc was 40–50%, which was explained by a specific interlocking morphology. No significant effect of soft-segment chain length on maximum strength was found, but higher values were found in the C series when ssc was 60%. Elongation at break increases linearly with ssc but indications that shorter soft segments produce higher extensions was attributed to plastic flow. TMA showed that Tg was independent of ssc in the C and, to a degree, in the B series, while temperature of α-transition in DMA was independent of ssc only in the C series at ssc above 50%.

Study on Microphase Separation of Polyether-Urethane Block Copolymers

2011 ◽  
Vol 282-283 ◽  
pp. 557-560
Author(s):  
Zhen Liu ◽  
Chang Fa Xiao ◽  
Yu Feng Zhang
Keyword(s):  
Block Copolymers ◽  
Hard Segment ◽  
Microphase Separation ◽  
Soft Segment ◽  
Phenyl Isocyanate ◽  
Scanning Calorimetry ◽  
X Ray Scattering ◽  
Weight Content ◽  
Two Phases ◽  
Tetramethylene Oxide

A set of polyether-urethane block copolymers were prepared that poly (tetramethylene oxide) PTMO was regarded as soft segment, 4,4'-methylenebis(phenyl isocyanate)(MDI) and m-diphenylamine (MDM) was regarded as hard segment in this article. The microphase separation of polyether-urethane block copolymer was investigated by using infrared spectroscopy(FTIR), differential scanning calorimetry(DSC), small-angle X-ray scattering(SAXS),there obtained that there are two phases structure in polyether-urethane block copolymers and degree of phase separation decrease with increasing hard segment weight content.

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.

Effect of Catalysts on the Properties of Fluorinated Polyurethanes

2013 ◽  
Vol 464 ◽  
pp. 9-13 ◽  
Author(s):  
Zan Li ◽  
Xia Wang ◽  
Ying Li ◽  
Wei Chain ◽  
Jiao Jiao Hu
Keyword(s):  
Hard Segment ◽  
Soft Segment ◽  
Force Microscopy ◽  
Atomic Force ◽  
Structure Surface ◽  
Improved Stability ◽  
Ft Ir ◽  
Tin Metal ◽  
Polyether Polyol ◽  
Catalyst Efficiency

Fluorinated polyurethanes (FPU) was prepared using fluorinated polyether polyol (FPO) as the soft segment, 4,4`-diphenylmethane diisocyanate (MDI) as the hard segment, 1,4-butanodiol (BDO) as the chain extender and catalysts. Tin metal catalysts were used to catalyze the polyurethane reaction of polyether polyols and isocyanate. The effect of different catalysts including stannous octoate (T-9) and dibutyltindalautrate (DBTDL) on the structure, surface properties and thermal properties of FPU was studied. The structural elucidation of the synthesized FPU was performed by Fourier transform infrared (FT-IR) and discovered that with decreasing catalyst efficiency or without catalyst, the strength of hydrogen bounds were enhanced. The FPU films surface was characterized by contact angle (CA) and atomic force microscopy (AFM) and it was found that the phase separation was increasing with increasing catalyst efficiency. The thermal property was exhibited by Thermo gravimetric (TG) and showed that joining catalyst improved stability significantly.

Inelasticity of hard-phase reinforced elastomers: A study of copolyurethanes with varying hard and soft segments

2017 ◽  
pp. 465-470
Author(s):  
P.C. Buckley ◽  
C. Prisacariu ◽  
A.A. Caraculacu ◽  
C.M. Martin
Keyword(s):  
Hard Phase ◽  
Soft Segments
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