X-ray investigations concerning the physical structure of cross-linking in urethane elastomers. II. Butanediol as chain extender

Bonart, R.; Morbitzer, L.; Hentze, G.

doi:10.1080/00222346908205099

Cited by 245 publications

(108 citation statements)

References 6 publications

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“…Upon stretching of such a copolymer, both the soft and the hard phases are deformed, and for a high enough strain, yielding of the hard phase occurs [13,[16][17][18]. During this yielding, the crystallites are sheared and their orientation changed ( Fig.…”

Section: Introductionmentioning

confidence: 99%

Tensile properties of segmented block copolymers with monodisperse hard segments

2008

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The tensile properties of segmented block copolymers with mono-disperse hard segments were studied with respect to the hard segment content (16-44 wt.%) and the temperature (20-110°C). The copolymers were comprised of poly(tetramethylene oxide) segments with the molecular weights of 650-2,900 Da and of mono-disperse bisester-tetra-amide segments (T6A6T) based on adipic acid (A), terephthalic acid (T) and hexamethylene diamine (6). An increasing content of T6A6T gave rise to an increased modulus, yield stress and fracture stress. The modulus could be modeled by a composite model. Moreover, a strain-softening was observed well below the yield stress, due to the shearing of the T6A6T crystallites. At strains [200%, a strain-hardening of the PTMO segments took place and this even for PTMO segments that were amorphous in the isotropic state. The strain hardening increased the tensile properties. An increase in temperature had little effect on the modulus of the copolymers, but was found to lower the yield and fracture stresses. At temperatures above the melting temperature of the oriented PTMO, no strain-hardening took place. The yield stress as a function of temperature could be described by the Eyring relationship, but a modulus-yield stress relationship could not be established.

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Section: Introductionmentioning

confidence: 99%

Tensile properties of segmented block copolymers with monodisperse hard segments

2008

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“…In general, the segmented thermoplastic elastomers require a greater stress to produce a given elongation in the first extension than during subsequent extensions. 10 Bonart [11][12][13] proposed that the lamellalike hard-segment domains orient at low elongations with their long axis toward the stress direction due to local torques acting through the force strands of the soft segments. Further stretching causes the hard segments to slip past one another, breaking up the original structure.…”

Section: Resultsmentioning

confidence: 99%

Preparation and properties of segmented thermoplastic polyurethane elastomers with two different soft segments

Kim

Lee

Huh

et al. 1999

J. Appl. Polym. Sci.

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Thermoplastic polyurethane elastomers were prepared from 4,4-diphenylmethane diisocyanate (MDI)/1,4-butanediol (BD)/poly(propylene glycol) (PPG) and MDI/BD/poly(oxytetramethylene glycol) (PTMG). The MDI/BD-based hard-segment content of polyurethane prepared in this study was of 39 -65 wt %. These polyurethane elastomers had a constant soft-segment molecular weight (M n , 2000), but a variable hard-segment block length (n, 3.0 -10.1; M n , 1020 -3434). The effects of the hardsegment content on the thermal properties and elastic behavior were investigated. These properties of the PPG-based MPP samples and the PTMG-based MPT samples were compared. The polyurethane prepared in this study had a hard-segment crystalline melting temperature in the range of 185.5-236.5°C. With increasing hard-segment content, the dynamic storage modulus and glass transition temperature increased in both the MPP and MPT samples. The permanent set (%) increased with increasing hard-segment content and successive maximum elongation. The permanent set (%) of the MPP samples was higher than that of MPT samples at the same hard-segment content. The value of K (area of the hydrogen-bonded carbonyl group/area of the free carbonyl group) increased with increasing hard-segment content in both the MPP and MPT samples, and the K value of the MPT samples was higher than that of the MPP samples at the same hard-segment content.

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“…In segmented polyurethanes, the molecular units and sequences are commonly divided into "hard segments" and "soft segments,, [238][239]. The soft segments are flexible and generally consist of polyether or polyester long chains.…”

Section: Copolymers With Amorphous and Crystallizable Blocksmentioning

confidence: 99%

Preparation and study of block copolymers with ordered structures

Gallot

Structure and Properties of Polymers

109

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X-ray investigations concerning the physical structure of cross-linking in urethane elastomers. II. Butanediol as chain extender

Cited by 245 publications

References 6 publications

Tensile properties of segmented block copolymers with monodisperse hard segments

Tensile properties of segmented block copolymers with monodisperse hard segments

Preparation and properties of segmented thermoplastic polyurethane elastomers with two different soft segments

Preparation and study of block copolymers with ordered structures

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