Rubbery Ormosils

1990 ◽  
Vol 180 ◽  
Author(s):  
Young J. Chung ◽  
Su-Jen Ting ◽  
John D. Mackenzie
Keyword(s):  
Nmr Spectroscopy ◽  
Structural Model ◽  
Rubber Elasticity ◽  
New Technique ◽  
Polydimethyl Siloxane ◽  
Gelation Process ◽  
Organically Modified Silicates ◽  
Organically Modified ◽  
A New Technique

ABSTRACTA new technique which permits the successful preparation of ORMOSILS (Organically Modified Silicates) with rubbery elasticity has been developed. Common alkoxides were reacted with polydimethyl siloxane (PDMS) and the microstructures were carefully controlled. Large monoliths of the porous rubbery ORMOSILS have been prepared. Gelation process was studied by 29Si liquid NMR spectroscopy. A structural model for rubber elasticity of ORMOSILS was proposed.

Ormosils of High Hardness

1994 ◽  
Vol 346 ◽  
Author(s):  
Takashi Iwamoto ◽  
John D. Mackenzie
Keyword(s):  
Theoretical Model ◽  
Nmr Spectroscopy ◽  
Ultrasonic Irradiation ◽  
Vickers Hardness ◽  
Liquid State ◽  
High Hardness ◽  
Experimental Results ◽  
Organically Modified Silicates ◽  
Organically Modified ◽  
Hardness Values

ABSTRACTOrganically modified silicates (ormosils) of high hardness were prepared by the reactions of tetraethoxysilane (TEOS) and polydimethylsiloxane (PDMS) aided by ultrasonic irradiation. The mechanisms leading to the hard ormosil formation were investigated by liquid state 29Si NMR spectroscopy. PDMS chains were found to be broken into shorter chains and/or 4-membered siloxane rings during the reaction and finally, all PDMS chains were chemically incorporated as short chains into silica networks. Vickers hardnesses of the hard ormosils were measured and compared with those of the hardest transparent plastics. Whereas the hardest transparent plastics have Vickers hardness values of less than 25 kg/mm2, the hard ormosils have Vickers hardnesses up to higher than 150 kg/mm2. A theoretical model was developed for the calculation of Vickers hardnesses of the hard ormosils and agreed well with experimental results. Predictions based on this theory indicate that even harder ormosils can be made when Al2O3, ZrO2 and TiO2 are substituted for SiO2. Results based on these new ormosils are also presented.

Spatial and chemical-shift-encoded excitation. SPACE, a new technique for volume-selected NMR spectroscopy

1986 ◽  
Vol 68 (2) ◽  
pp. 367-372 ◽  
Author(s):  
David M Doddrell ◽  
William M Brooks ◽  
J.Mark Bulsing ◽  
James Field ◽  
Michael G Irving ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Chemical Shift ◽  
New Technique ◽  
A New Technique

Discrete isolation from gradient-governed elimination of resonances. DIGGER, a new technique for in vivo volume-selected NMR spectroscopy

1986 ◽  
Vol 70 (2) ◽  
pp. 319-326 ◽  
Author(s):  
David M Doddrell ◽  
J.Mark Bulsing ◽  
Graham J Galloway ◽  
William M Brooks ◽  
James Field ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
New Technique ◽  
A New Technique

Structure-Related Mechanical Properties of Ormosils by SOL-GEL Process

1992 ◽  
Vol 271 ◽  
Author(s):  
Yi Hu ◽  
John D. Mackenzie
Keyword(s):  
Mechanical Properties ◽  
Reaction Temperature ◽  
Fracture Strength ◽  
Modulus Of Elasticity ◽  
Sol Gel ◽  
Acid Catalyst ◽  
Polydimethyl Siloxane ◽  
Organically Modified Silicates ◽  
Sol Gel Process ◽  
Organically Modified

ABSTRACTThe mechanical properties corresponding to the different structures of organically modified silicates (Ormosils) prepared by the sol-gel process were studied. Tetraethoxysilane (TEOS) and polydimethyl siloxane (PDMS) were used as the inorganic and polymeric components, respectively. Large variations in the microstructure of the Ormosils were found by changing the reaction temperature, and the content of PDMS, acid catalyst (HCI),and water. The structure of the Ormosils and the mechanical properties were correlated by the edge connectivity. Modulus of elasticity and fracture strength were used to study their relations Ormosils structures.

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