ISSN:
1435-1536
Keywords:
Polyurethane elastomers
;
segmented block copolymers
;
poly(N-alkylurethane)
;
hard segment
;
chain folding
;
dynamic mechanical properties
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract Segmented polyetherurethanes with distinctively different morphologies, i.e., with chain-extended or chain-folded crystallized hard segments, could be created by small constitutional changes in the hard segment architecture. The different superstructure was achieved by building-in specially designed constitutional units in the middle of the otherwise regularly built hard segment which for flexibility or sterical reasons allowed an adjacent reentry chain-folded and/or chain-extended crystallization of the hard phase forming polyurethane segments. The material properties of the thermoplastic elastomers correlated systematically with the hard domain superstructure which was determined by the primary structure of the macromolecule and could be reversibly altered by the thermal history in the case of the flexible center unit. The softening temperature was determined by the hard domain height of the chain-folded lamellar or the chain-extended cylindrical domains; variation of the modulus in the elastomeric region could be related to imperfections in the hard segment packing which affected the effective hard domain filler.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00652349
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