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MORPHOLOGICAL BEHAVIOR OF SEGMENTED POLYURETHANE BLOCK COPOLYMERS (MDI/BD, SMALL ANGLE X-RAY, POLYETHER-BASED, DSC).

Record Type:	Electronic resources : Monograph/item
Title/Author:	MORPHOLOGICAL BEHAVIOR OF SEGMENTED POLYURETHANE BLOCK COPOLYMERS (MDI/BD, SMALL ANGLE X-RAY, POLYETHER-BASED, DSC)./
Author:	LEUNG, LOUIS MAN LAY.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 1985,
Description:	388 p.
Notes:	Source: Dissertations Abstracts International, Volume: 46-07, Section: B.
Contained By:	Dissertations Abstracts International46-07B.
Subject:	Polymers. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=8509637
ISBN:	9798205847667

MORPHOLOGICAL BEHAVIOR OF SEGMENTED POLYURETHANE BLOCK COPOLYMERS (MDI/BD, SMALL ANGLE X-RAY, POLYETHER-BASED, DSC).
LEUNG, LOUIS MAN LAY.

MORPHOLOGICAL BEHAVIOR OF SEGMENTED POLYURETHANE BLOCK COPOLYMERS (MDI/BD, SMALL ANGLE X-RAY, POLYETHER-BASED, DSC). - Ann Arbor : ProQuest Dissertations & Theses, 1985 - 388 p.

Source: Dissertations Abstracts International, Volume: 46-07, Section: B.

Thesis (Ph.D.)--Princeton University, 1985.

This item must not be added to any third party search indexes.

I. A series of polyether-based segmented polyurethane block copolymers is characterized by small angle x-ray (SAXS) and neutron scattering analyses. The materials contain hard segments formed from 4-4' diphenylmethane diisocyanate and butanediol, and range in hard segment content from 20 to 80 weight percent. Scattering results provide evidence for a transition from discrete to continuous microdomain morphology as the hard segment content is increased above ca. 40 percent by weight. The hard domain structure is found to be lamellar for all hard segment compositions. Measured interdomain spacings, specific interfacial areas, and electron density variances show that the hard segment sequences, though rigid, are not fully extended. The thickness of the hard microdomain corresponds roughly to 3 to 4 hard segment repeat units. II. The thermal behavior of the same series of copolymers is studied in detail by Differential Scanning Calorimetry (DSC). Thermal annealing, quench mixing and isothermal crystallization studies are used to ascertain the morphological origin of the observed multiple endotherms. Three distinct endotherms are detected above the pure hard segment glass transition temperature and are attributed to the different hard microdomain structures. III. The microdomain structure and degree of phase mixing for the same series of copolymer prepared under different conditions are studied. By combining the DSC and SAXS results and applying thermodynamic relations between the soft microphase glass transition temperature and its composition, the individual microphase compositions for the hard and soft microphases are determined. IV. The temperature dependence of mechanical properties for the series of polyether-based polyurethanes is investigated. Results from dynamic mechanical analysis indicate that a hard phase alpha relaxation peak, related to the hard phase glass transition process, is observed only after the sample has been heated above its highest melting temperature. Two alpha relaxation peaks are observed for samples with hard segment contents above ca. 30 weight percent confirming the existence of a two-phase morphology for these copolymers.

ISBN: 9798205847667Subjects--Topical Terms:

535398
Polymers.

MORPHOLOGICAL BEHAVIOR OF SEGMENTED POLYURETHANE BLOCK COPOLYMERS (MDI/BD, SMALL ANGLE X-RAY, POLYETHER-BASED, DSC).
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020 $a 9798205847667
035 $a (MiAaPQ)AAI8509637
035 $a AAI8509637
040 $a MiAaPQ $c MiAaPQ
100 1 $a LEUNG, LOUIS MAN LAY. $3 3687481
245 1 0 $a MORPHOLOGICAL BEHAVIOR OF SEGMENTED POLYURETHANE BLOCK COPOLYMERS (MDI/BD, SMALL ANGLE X-RAY, POLYETHER-BASED, DSC).
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 1985
300 $a 388 p.
500 $a Source: Dissertations Abstracts International, Volume: 46-07, Section: B.
500 $a Publisher info.: Dissertation/Thesis.
502 $a Thesis (Ph.D.)--Princeton University, 1985.
506 $a This item must not be added to any third party search indexes.
506 $a This item must not be sold to any third party vendors.
520 $a I. A series of polyether-based segmented polyurethane block copolymers is characterized by small angle x-ray (SAXS) and neutron scattering analyses. The materials contain hard segments formed from 4-4' diphenylmethane diisocyanate and butanediol, and range in hard segment content from 20 to 80 weight percent. Scattering results provide evidence for a transition from discrete to continuous microdomain morphology as the hard segment content is increased above ca. 40 percent by weight. The hard domain structure is found to be lamellar for all hard segment compositions. Measured interdomain spacings, specific interfacial areas, and electron density variances show that the hard segment sequences, though rigid, are not fully extended. The thickness of the hard microdomain corresponds roughly to 3 to 4 hard segment repeat units. II. The thermal behavior of the same series of copolymers is studied in detail by Differential Scanning Calorimetry (DSC). Thermal annealing, quench mixing and isothermal crystallization studies are used to ascertain the morphological origin of the observed multiple endotherms. Three distinct endotherms are detected above the pure hard segment glass transition temperature and are attributed to the different hard microdomain structures. III. The microdomain structure and degree of phase mixing for the same series of copolymer prepared under different conditions are studied. By combining the DSC and SAXS results and applying thermodynamic relations between the soft microphase glass transition temperature and its composition, the individual microphase compositions for the hard and soft microphases are determined. IV. The temperature dependence of mechanical properties for the series of polyether-based polyurethanes is investigated. Results from dynamic mechanical analysis indicate that a hard phase alpha relaxation peak, related to the hard phase glass transition process, is observed only after the sample has been heated above its highest melting temperature. Two alpha relaxation peaks are observed for samples with hard segment contents above ca. 30 weight percent confirming the existence of a two-phase morphology for these copolymers.
590 $a School code: 0181.
650 4 $a Polymers. $3 535398
690 $a 0495
710 2 $a Princeton University. $3 645579
773 0 $t Dissertations Abstracts International $g 46-07B.
790 $a 0181
791 $a Ph.D.
792 $a 1985
793 $a English
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=8509637