Title page for ETD etd-08012012-040558


Type of Document Master's Thesis
Author Kim, Regina H.
URN etd-08012012-040558
Title Siloxane modified polyurea and polyurethane urea segmented copolymers
Degree Master of Science
Department Materials Engineering
Advisory Committee
Advisor Name Title
McGrath, James E. Committee Chair
Spencer, Chester W. Committee Member
Wightman, John P. Committee Member
Wilkes, Garth L. Committee Member
Keywords
  • Surface active agents
Date of Defense 1989-08-15
Availability restricted
Abstract

High molecular weight polyether urea copolymers were synthesized using perfectly difunctional aromatic amine terminated poiypropylene oxide (PPO) (2800 ) prepared via aluminum porphorin initiated coordination polymerization. The resulting segmented copolymer showed much higher tensile strength and better thermal stability than polyureas based on commercial PPO which contains some terminal unsaturation. This was attributed to the achievement of both higher molecular weight and to more extensive microphase separation between the segments. ln addition, the surface structure of segmented polyether urea and polyurethane urea copolymers were modified in two ways: siloxane urea segmented copolymers were synthesized and physically blended into the system, and siloxane oligomers of controlled molecular weight and composition were incorporated into the copolymer backbone as a part of the soft segment. X-ray photoelectron spectroscopy (XPS) was used to obtain surface compositional information, while differential scanning calorimetry (DSC) and stress-strain analysis were used to characterize the bulk properties. In general, the surface enrichment of siloxane was observed in both solvent cast blends and siloxane incorporated systems. The surface siloxane concentration showed a small increase with siloxane segment length, content, and surface sensitive angle. Surface segregation of these systems was suppressed to a certain extent due to phase mixing within the copolymer bulk and by the anchoring of both ends of the siloxane segment with urea components. The bulk properties of these copolymer systems were not affected greatly when small amounts of siloxane ureas were added or when small amounts of siloxane blocks were incorporated.

Files
  Filename       Size       Approximate Download Time (Hours:Minutes:Seconds) 
 
 28.8 Modem   56K Modem   ISDN (64 Kb)   ISDN (128 Kb)   Higher-speed Access 
[VT] LD5655.V855_1989.K42.pdf 4.51 Mb 00:20:52 00:10:44 00:09:23 00:04:41 00:00:24
[BTD] next to an author's name indicates that all files or directories associated with their ETD are accessible from the Virginia Tech campus network only.

Browse All Available ETDs by ( Author | Department )

dla home
etds imagebase journals news ereserve special collections
virgnia tech home contact dla university libraries

If you have questions or technical problems, please Contact DLA.