Spin-Label Investigation of Polyurethane Networks

1974 ◽  
Vol 47 (5) ◽  
pp. 1160-1174
Author(s):  
T. C. Ward ◽  
J. T. Books
Keyword(s):  
Mechanical Properties ◽  
Spin Label ◽  
Amorphous Polymers ◽  
Diphenylmethane Diisocyanate ◽  
Label Technique ◽  
Spin Resonance ◽  
Soft Segments ◽  
Polyurethane Networks ◽  
Hard Block ◽  
Very High

Abstract Two types of polyurethane networks were examined using the spin-label technique. Nitroxide free radicals which are stable under moderate conditions were covalently attached to the network chains of amorphous polymers based on (1) poly(tetramethylene glycol), p,p′-diphenylmethane diisocyanate (MDI), trimethylolpropane, and (2) ethylene glycol, MDI, glycerine. Polymer (1) had very low “hard block” content, polymer (2) a very high content. Mechanical properties and differential thermal analysis measurements were made on polymer (1). Electron spin resonance spectra of the samples were obtained in the unstrained, strained, and swollen states. Large differences in the spectra were observed, depending on chemical composition, temperature, and state of swelling. Transitions from “frozen” to “rapid motion” type of spectra occurred at 70° for polymer (1), at −10° for polymer (1) swollen to equilibrium, and were unobserved up to 150° for polymer (2). Since the nitroxide label was necessarily adjacent to MDI units, was present in very small concentrations, and experienced no alterations in environment as “soft segments” did, then it is suggested that the spin-label technique is a valuable tool for analyzing microstructure of pseudoamorphous systems.

Influence of Diisocyanates on Dynamic Mechanical Properties of Castable Polyurethane Elastomers

2012 ◽  
Vol 217-219 ◽  
pp. 563-566
Author(s):  
Xiao Dong Chen ◽  
Yu Hua Yi
Keyword(s):  
Mechanical Properties ◽  
Dynamic Mechanical Analysis ◽  
Dynamic Mechanical Properties ◽  
Mechanical Analysis ◽  
Toluene Diisocyanate ◽  
Diphenylmethane Diisocyanate ◽  
Analysis Method ◽  
Polyurethane Elastomers ◽  
Dynamic Mechanical ◽  
Soft Segments

A series of castable polyurethane elastomers, based on polytetramethylene glycol as soft segments and toluene diisocyanate, 4, 4’-diphenylmethane diisocyanate, P-phenylene diisocyanate as diisocyanates respectively, were synthesized. The dynamic mechanical analysis method was utilized to determine tan delta property (tanδ). Also the influence of diisocyanates on the dynamic mechanical properties of castable polyurethane elastomers was analyzed. It can be concluded that the P-phenylene diisocyanate system elastomers have the most excellent dynamic mechanical properties.

UNS A97075

Alloy Digest ◽  
1986 ◽  
Vol 35 (7) ◽  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Aluminum Alloy ◽  
High Strength ◽  
Heat Treating ◽  
Good Resistance ◽  
Temperature Performance ◽  
Structural Applications ◽  
Structural Parts ◽  
Very High

Abstract UNS No. A97075 is a wrought precipitation-hardenable aluminum alloy. It has excellent mechanical properties, workability and response to heat treatment and refrigeration. Its typical uses comprise aircraft structural parts and other highly stressed structural applications where very high strength and good resistance to corrosion are required. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and shear strength as well as fatigue. It also includes information on low temperature performance as well as forming, heat treating, and machining. Filing Code: Al-269. Producer or source: Various aluminum companies.

KAISER ALUMINUM ALLOY 7050

Alloy Digest ◽  
2000 ◽  
Vol 49 (1) ◽  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Tensile Strength ◽  
Aluminum Alloy ◽  
Heat Treating ◽  
High Fracture Toughness ◽  
High Fracture ◽  
Kaiser Aluminum ◽  
Structural Parts ◽  
Very High

Abstract Kaiser Aluminum Alloy 7050 has very high mechanical properties including tensile strength, high fracture toughness, and a high resistance to exfoliation and stress-corrosion cracking. The alloy is typically used in aircraft structural parts. This datasheet provides information on composition, physical properties, hardness, tensile properties, and shear strength as well as fracture toughness and fatigue. It also includes information on forming, heat treating, machining, and joining. Filing Code: AL-366. Producer or source: Tennalum, A Division of Kaiser Aluminum.

TIMKEN 16-15-6

Alloy Digest ◽  
1963 ◽  
Vol 12 (12) ◽  
Keyword(s):  
Mechanical Properties ◽  
Creep Resistance ◽  
Elevated Temperatures ◽  
Roller Bearing ◽  
Heat Treating ◽  
Resistant Steel ◽  
Heat Resistant Steel ◽  
Corrosion And Oxidation ◽  
Very High ◽  
High Creep Resistance

Abstract Timken 16-15-6 is a non-magnetic, austenitic, corrosion and heat resistant steel having high creep resistance at elevated temperatures and good corrosion and oxidation resistance. It age-hardens at elevated temperatures after solution quenching, and possesses very high mechanical properties. This datasheet provides information on composition, microstructure, hardness, and tensile properties as well as creep. It also includes information on forming, heat treating, machining, and joining. Filing Code: SS-150. Producer or source: Timken Roller Bearing Company.

scholarly journals Recyclable Self-Healing Polyurethane Cross-Linked by Alkyl Diselenide with Enhanced Mechanical Properties

Polymers ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 773 ◽  
Author(s):  
Yuqing Qian ◽  
Xiaowei An ◽  
Xiaofei Huang ◽  
Xiangqiang Pan ◽  
Jian Zhu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Room Temperature ◽  
Amide Bond ◽  
Self Healing ◽  
Healing Efficiency ◽  
Polyurethane Networks ◽  
Combined Action ◽  
Cross Linker ◽  
Dynamic Structures ◽  
External Interventions

Dynamic structures containing polymers can behave as thermosets at room temperature while maintaining good mechanical properties, showing good reprocessability, repairability, and recyclability. In this work, alkyl diselenide is effectively used as a dynamic cross-linker for the design of self-healing poly(urea–urethane) elastomers, which show quantitative healing efficiency at room temperature, without the need for any catalysts or external interventions. Due to the combined action of the urea bond and amide bond, the material has better mechanical properties. We also compared the self-healing effect of alkyl diselenide-based polyurethanes and alkyl disulfide-based polyurethanes. The alkyl diselenide has been incorporated into polyurethane networks using a para-substituted amine diphenyl alkyl diselenide. The resulting materials not only exhibit faster self-healing properties than the corresponding disulfide-based materials, but also show the ability to be processed at temperatures as low as 60 °C.

Processing of Nanoporous Gold by Dealloying and its Morphological Control

2007 ◽  
Vol 561-565 ◽  
pp. 1657-1660 ◽  
Author(s):  
Masataka Hakamada ◽  
Mamoru Mabuchi
Keyword(s):  
Mechanical Properties ◽  
Thermal Treatment ◽  
Acid Treatment ◽  
Nanoporous Gold ◽  
Anisotropic Structure ◽  
Ideal Strength ◽  
Pore Characteristics ◽  
Very High ◽  
Ligament Size ◽  
The Ideal

Nanoporous gold was fabricated by dealloying and their pore characteristics were further modified by thermal or acid treatment. The fabricated nanoporous gold had a ligament size of approximately 5 nm. Thermal treatment on the nanoporous gold increased the ligament size to approximately 500 nm. During the thermal treatment, ligaments are bonded across the cracks which had been generated during the dealloying. Acid treatment also increased the ligament size to approximately 500 nm; however, the acid treatment had a different effect on the pore characteristics from the thermal treatment. As a result, nanoporous gold prism microassembly with anisotropic structure was spontaneously fabricated by the acid treatment. The mechanical properties of nanoporous gold were also examined. It is estimated that the yield strength of nanosized ligaments in nanoporous gold is very high and close to the ideal strength of gold.

scholarly journals Dynamic Molecular Structure of DPPC-DLPC-Cholesterol Ternary Lipid System by Spin-Label Electron Spin Resonance

2004 ◽  
Vol 87 (4) ◽  
pp. 2483-2496 ◽  
Author(s):  
Yun-Wei Chiang ◽  
Yuhei Shimoyama ◽  
Gerald W. Feigenson ◽  
Jack H. Freed
Keyword(s):  
Molecular Structure ◽  
Electron Spin Resonance ◽  
Electron Spin ◽  
Spin Label ◽  
Spin Resonance ◽  
Lipid System
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