Role of Increased Crystallinity in Deformation-Induced Structure of Segmented Thermoplastic Polyurethane Elastomers with PEO and PEO#PPO#PEO Soft Segments and HDI Hard Segments
The phase-segregated nature of polyurethanes allows meaningful connections to be made between morphological and physical properties. We have taken advantage of this behavior by synthesizing a series of polyurethanes with varying extents of crystallinity and studying their morphologies in both the unstrained and deformed states, going from a completely amorphous soft segment to one with similar chemistry that displays a high extent of soft domain crystallization, thus enhancing phase segregation. The presence of dispersed semicrystalline regions within the continuous soft domain has been shown to provide a reinforcing effect when compared to that of a non-crystalline soft segment polyurethane. Incorporating a semicrystalline soft segment (PEO, 1000 g/mol) has been shown to improve overall sample toughness; however, if higher molecular weight PEO soft segments are employed (4600 g/mol), extensibility and, consequently, toughness are adversely affected due to an increased continuous domain modulus. In-situ deformation experiments demonstrate two very different deformation responses. In the copolymer-containing polyurethane (PEO-PPO-PEO, 1900 g/mol), the hard domains retain a tilted configuration up to strains of 450%, with only a small fraction of the hard segments undergoing reshuffling. The PEO1000-containing polyurethane, on the other hand, begins to demonstrate meridional scattering at strains of 200%, with it being the dominant peak by a strain of 300%. These two deformation behaviors are indicative of the two primary responses to deformation, which are shear and tensile, respectively. Frequently, a tensile mechanism points to decreased polyurethane mechanical properties, though this phenomenon is not seen in the series of interest.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source
- Sponsoring Organization:
- Doe - Office Of Science
- DOE Contract Number:
- DE-AC02-98CH10886
- OSTI ID:
- 980440
- Report Number(s):
- BNL-93358-2010-JA; TRN: US201015%%1825
- Journal Information:
- Macromolecules, Vol. 42, Issue 6
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
BEHAVIOR
CHEMISTRY
CONFIGURATION
CRYSTALLIZATION
DEFORMATION
ELASTOMERS
MECHANICAL PROPERTIES
MOLECULAR WEIGHT
PEAKS
PHYSICAL PROPERTIES
PLASMA SWITCHES
POLYURETHANES
SCATTERING
SEGREGATION
SHEAR
STRAINS
THERMOPLASTICS
national synchrotron light source