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Morphological Failure Mechanisms in Tensile Tests of Crosslinked Polyurethanes With Poorly Developed Domain Structure
Author(s) -
Stribeck Norbert,
Li Xuke,
Kogut Igor,
Moritz HansUlrich,
Eling Berend,
Goerigk Günter Johannes,
Hoell Armin
Publication year - 2015
Publication title -
macromolecular materials and engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.913
H-Index - 96
eISSN - 1439-2054
pISSN - 1438-7492
DOI - 10.1002/mame.201500007
Subject(s) - materials science , small angle x ray scattering , polyurethane , ultimate tensile strength , microstructure , composite material , crystallography , scattering , physics , chemistry , optics
Macroscopic failure of polyurethane materials of 30 wt.‐% hard‐segment content is related to microstructure evolution mechanisms. Topology and functionality ( f = 2 … 4) of the polyols are varied. Samples are strained and small‐angle X‐ray scattering (SAXS) patterns are recorded. Only material PU‐I ( f = 2) passes the tensile test. Material PU‐Hs – a H‐shaped ( f = 4) polyol with short arms – is not nanostructured. PU‐Hl has long arms. It contains few hard domains placed at random. PU‐Hl survives longer (strain: 1.8) than the other short‐lived materials. Its isolated hard domains are not destroyed during straining. PU‐X ( f = 4, star‐shaped) develops microfibrils: one‐dimensional (1D) correlations among hard domains, as deduced from a chord distribution function (CDF) analysis. PU‐I and PU‐Y are based on 2‐ and 3‐functional polyols. They contain many well‐separated hard domains with one‐dimensional (3D) connectivity. Their arrangement of hard domains evolves identically, but not the population density. In PU‐I (and PU‐X) hard domains fail during straining, in PU‐Y the interdomain soft phase density decreases.