Damping Properties Of Aliphatic Polyurethanes From 4,4'-Dicyclohexylmethane Diisocyanate

Item

Title
Damping Properties Of Aliphatic Polyurethanes From 4,4'-Dicyclohexylmethane Diisocyanate
Report Number
WL-TR-91-3078 Volume III, p. GDF-1 thru GDF-12
Creator
Lee, John D.
Lee, Gilbert F.
Hartmann, Bruce
Corporate Author
Nonmetallic Materials Branch, Code R31, Naval surface Warfare Center
Date
1991
Date Issued
1991-08
Extent
12
Identifier
ADA241313
Format
1 online resource
Abstract
Polyurethanes cover a wide range of damping properties
depending in large part on their two-phase morphology. Hard segment crystallinity was proposed to be the dominant factor in determining these properties. The evidence for this conjecture came from a comparison of a system in which hard segment crystallinity was present with a system where crystallinity was inhibited by using a different chain extender. To verify our assumption, in this work crystallinity was inhibited not by changing the chain extender but by changing the diisocyanate from the aromatic 4,4'-diphenylmethane diisocyanate or MDI to the cycloaliphatic 4,4'-dicyclohexylmethane diisocyanate or H12MDI. Prepolymers of poly{tetramethylene ether glycol) {PTMG) of four different molecular weights {650, 1000, 2000, 2900) with H12MDI were synthesized and chain extended with 1,4 butanediol. Measurements of the dynamic mechanical properties of these materials verified the assumption that hard segment crystallinity is the dominant factor in determining the damping characteristics of polyurethanes. All non-crystalline hard segment systems have very similar properties regardless of the diisocyanate type or the chain extender type.
Description
Polyurethanes cover a wide range of damping properties
depending in large part on their two-phase morphology. Hard segment crystallinity was proposed to be the dominant factor in determining these properties. The evidence for this conjecture came from a comparison of a system in which hard segment crystallinity was present with a system where crystallinity was inhibited by using a different chain extender. To verify our assumption, in this work crystallinity was inhibited not by changing the chain extender but by changing the diisocyanate from the aromatic 4,4'-diphenylmethane diisocyanate or MDI to the cycloaliphatic 4,4'-dicyclohexylmethane diisocyanate or H12MDI. Prepolymers of poly{tetramethylene ether glycol) {PTMG) of four different molecular weights {650, 1000, 2000, 2900) with H12MDI were synthesized and chain extended with 1,4 butanediol. Measurements of the dynamic mechanical properties of these materials verified the assumption that hard segment crystallinity is the dominant factor in determining the damping characteristics of polyurethanes. All non-crystalline hard segment systems have very similar properties regardless of the diisocyanate type or the chain extender type.
Distribution Classification
1
Distribution Conflict
No
DTIC Record Exists
No
Illinois Tech Related
No
Photo Quality
Not Needed
Report Availability
Full text available
Type
article
Is Part Of
Proceedings of Damping '91: 13-15 February 1991 San Diego, California (GCA-1 through JCB-17)
Media
articleGDF

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Items with "Has Part: Damping Properties Of Aliphatic Polyurethanes From 4,4'-Dicyclohexylmethane Diisocyanate"
Title Class
Proceedings of Damping '91: 13-15 February 1991 San Diego, California (GCA-1 through JCB-17)