Experimental studies of siloxane polymers and their elastomeric networks
Siloxane polymers have been investigated systematically for the purpose of a greater understanding of the structure-property relationships in terms of their synthesis, polymer blends and rubber elasticity of their crosslinked networks. This study includes a variety of topological structures: linear, cyclic and crosslinked networks of poly(dimethylsiloxane) (PDMS) and poly(dimethylco-methylphenylsiloxane) copolymers. Siloxane polymers with a narrow molecular weight distribution were prepared by a series of well-characterized organometallic polymerizations. The reaction conditions and mechanisms for preparing polyorganosiloxane chains and networks using organotin catalyst and promoters were discussed. Experimental evidence shows that formamide was one of the best additives to improve the reactivity of the tin dicarboxylate catalyst, which seems to suggest that the nucleophilic function of the additive was on the Sn atom. Since the PDMS and PMPS are immiscible under most conditions, the miscibility and phase behavior of siloxane blends were studied by a static light scattering t technique. THe influence of molar mass, the topological effect of cyclic and linear structures, the end-group effect, and the configurational isomerism effect on miscibility were examined. Silicon networks of PDMS, PMPS and their copolymers were prepared at room temperature using the crosslinked siloxane homopolymer and copolymer networks at equilibrium swelling in organic solvents and in liquid siloxane oligomers were investigated as function of crosslinking density and composition variation. The resulting interaction parameters for PDMS and PMPS from the swollen siloxane networks in siloxane oligomers individually were compared with those from measurements of the corresponding blend systems. Moreover, the stress-strain behavior of the siloxane polymer networks undergoing uniaxial deformation were evaluated by a stress-strain experiment.
- Research Organization:
- Cincinnati Univ., OH (United States)
- OSTI ID:
- 111315
- Resource Relation:
- Other Information: TH: Thesis (Ph.D.); PBD: 1992
- Country of Publication:
- United States
- Language:
- English
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