Swelling properties of urethane elastomers and their bearing on microphase separation

Nierzwicki, W.; Majewska, Z.

doi:10.1002/app.1979.070240421

Cited by 12 publications

(8 citation statements)

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“…This way, the coherent scattering signal increased by one order of magnitude and allowed the use of accurate model fitting to reveal details of the microphase morphology. The early work by Nierzwick et al [ 25 ] proved that microphase separation influences the swelling properties of the material, and some information on the extent of microphase separation can be obtained from measuring the swelling ratio. When swelling is done with selective solvents, such as toluene, the hard domains are resistant to the solvent, and the domain structure can remain, though deformed, even in the swollen state.…”

Section: Discussionmentioning

confidence: 99%

Microstructure Changes in Polyester Polyurethane upon Thermal and Humid Aging

et al. 2016

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Abstract:The microstructure of compression molded Estane 5703 films exposed to 11%, 45%, and 80% relative humidity and 70˝C for 1 and 2 months has been studied by small-angle neutron scattering (SANS), Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), and differential scanning calorimetry (DSC). Scattering data indicated increase of the interdomain distance and domain size with a higher humidity and longer aging time. GPC data showed a progressive shortening of polyurethane chains with increasing humidity and aging time. The shortening of the polyurethane chains caused a drop of the glass transition temperature of soft segments, and promoted crystallization of the soft segments during long-time storage of the aged samples at room temperature. FTIR showed a substantial increase in the number of inter-urethane H-bonds in the aged samples. This correlates with the increase of the hard domain size and the degree of phase separation as measured by SANS. The data collected reveals that the reduced steric hindrance caused by hydrolysis of ester links in polybutylene adipate residues promotes the organization of hard segments into domains, leading to the increase of domain size and distance, as well as phase segregation in aged Estane. These findings provide insight into the effects of humidity and thermal aging on the microstructure of aged polyester urethane from molecular to nanoscale level.

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Section: Discussionmentioning

confidence: 99%

Microstructure Changes in Polyester Polyurethane upon Thermal and Humid Aging

et al. 2016

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“…The degree of phase separation has been raised repeatedly as important to properties of segmented polyurethanes: domain composition is interrelated with the domain structure, and therefore, it is essential to understanding the material mechanical properties. Consequently, considerable effort has gone into characterizing the extent of phase separation. ,,, Information on the domain compositions also is useful to determine the thermodynamic parameters that drive equilibrium phase segregation. Overall, this type of information will provide a basis for predicting the performance of multiphase polymers.…”

Section: Introductionmentioning

confidence: 99%

“…The principal strength of SANS is the increased scattering that can be manipulated by isotopic substitution of deuterium for hydrogen. The combination of swelling and scattering from contrast variation experiments has a sound fundamental basis since solvent swelling experiments have been commonly used in polymer physics for assessing the thermodynamics of mixing and characterization of polymer networks, including those of polyurethanes. ,– In addition, the analysis of data using contrast variation techniques is well understood. – Early work by Nierzwick and Majewska pointed out that such studies could even give information on polyurethane domain composition …”

Section: Introductionmentioning

confidence: 99%

Small-Angle Neutron Scattering of a Solvent-Swollen Segmented Polyurethane as a Probe of Solvent Distribution and Polymer Domain Composition

et al. 2008

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Segmented polyurethanes consist of alternating rigid aromatic (hard) and flexible (soft) segments that phase separate into hard and soft segment-rich nanodomains. The domain structure results in what has been presumed to be an extended, cross-linked network, giving these materials unique mechanical properties. Because of poor contrast and volume fractions of the discontinuous phase, previous scattering studies have focused on polyurethanes with hard segment contents greater that 30 wt %. This study focused on a commercial poly(ester urethane), Estane 5703, containing only 23 wt % hard segment content. To probe the domain structure and composition, we used small-angle neutron scattering (SANS) with contrast variation methods on bulk samples swollen with deuterated/protonated mixtures of benzene, toluene, or o-, m-, or p-xylene isomers. We used the fluid model and Pedersen’s micelle model to describe the SANS data as a function of contrast. Both the fluid and micelle models consider Estane as a fluid of spherical, discrete domains in a soft segment-rich matrix. The discrete domains have a closest center-to-center approach defined by the Percus−Yevick hard-sphere potential. The micelle model divides the discontinuous domain into a core and a surrounding corona. We find that the micelle model completely described the data, whereas the fluid model required the ad hoc addition of an additional length scale. The models, which were in good agreement with each other, show that in Estane the discrete domains comprised a small fraction, 0.05−0.06, of the sample volume and have a radius of about 5 nm, giving a number density of the order 1017 cm−3. Furthermore, the discrete domains contain a higher hard segment concentration than the matrix, but incorporated only 0.06−0.13 of the hard segment volume. The results also show there is considerable mixing of the hard and soft segments, and there is a significant amount of soft segment in the discrete domains. Using these results, we were able to determine some important factors behind the thermomechanical properties of Estane. Furthermore, we make a critical assessment of the view that the discrete domains are cross-links for a continuous network and forward the hypothesis that the domains are more like filler particles coupled to the matrix by polymer entanglements.

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“…The authors suggested the small aggregates may be made up of hard segments originating from the diminished larger hard segment domains. Nierzwicki and Majewska34 determined that the degree of swelling of MDI/BD/PEA [PEA, poly(ethylene adipate) diol, molecular weight, 2000] films by various solvents is affected by the degree of microphase separation. Cooper reported the solvation of the soft and hard segments of a polyester urethane (Estane 5740‐100) by various concentrations of benzene–methanol mixtures 25.…”

Section: Introductionmentioning

confidence: 99%

Mechanical properties of polyurethane film exposed to solutions of nonoxynol‐9 surfactant and poly(ethylene glycol)

McDermott

Schroeder

Balsis

et al. 2003

J of Applied Polymer Sci

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Mechanical properties of two polyether urethane films (Estane and Tecoflex) were studied after exposure to solutions of nonoxynol 9 (N9) surfactant and poly-(ethylene glycol) 400 (PEG) for various times. Large amounts of N9 were absorbed from N9/PEG solutions, resulting in soft-segment plasticization and lower mechanical properties. As the N9 concentration increased, Estane absorbed more liquid and its mechanical properties decreased more compared to Tecoflex, although the mechanical properties of Estane were higher than Tecoflex at low concentrations of N9. Hard-segment domain disruption is probably not occurring because the relationship between the elastic modulus and polymer volume fraction followed Flory's theory for swollen elastic rubber networks and the liquids do not fully dissolve the polymers. The diffusion behavior of N9 and PEG was observed to follow Fickian behavior. Most of the absorption and decrease in mechanical properties occurred within the first 20 h after soaking, implying that additional loss in strength over longer times would be minimal. Mechanical property anisotropy suggests that condoms should be cut from Estane film in an orientation that optimizes the property-orientation relationship for specific end uses.

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Swelling properties of urethane elastomers and their bearing on microphase separation

Cited by 12 publications

References 0 publications

Microstructure Changes in Polyester Polyurethane upon Thermal and Humid Aging

Microstructure Changes in Polyester Polyurethane upon Thermal and Humid Aging

Small-Angle Neutron Scattering of a Solvent-Swollen Segmented Polyurethane as a Probe of Solvent Distribution and Polymer Domain Composition

Mechanical properties of polyurethane film exposed to solutions of nonoxynol‐9 surfactant and poly(ethylene glycol)

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