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J. Chruściel


Crosslinking of polydimethylsiloxane-α, ϖ-diols with polymethylhydrosiloxanes

and mechanical properties of resulting silicone rubbers


Polimery 1999, No 9, 586


DOI: dx.doi.org/10.14314/polimery.1999.586


Summary

The chemical structure, selected mechanical properties and applications of silicone rubbers are characterized. When crosslinked with poly(dimethyl-co-methylhydro)siloxanes (PMHS) endowed with a block (Table 2) or with a statistic structure (Table 3), H-siloxanes [Me3SiO(MeHSiO)35SiMe3 and D ], or with tetraethoxysilane in the presence of dibutyltin dilaurate as catalyst, polydimethylsiloxane-α, ϖ-diols (PMMS) yielded silicone rubbers endowed with good mechanical properties. Tensile strength (Rr), elongation at break (εr) and, for certain cured products, Shore A hardness and relative permanent deformation on compression (εs) were measured (Tables 4—10). When used to crosslink, both block and statistical PMHS improved the elasticity of rubbers especially those based on low M (ca. 104) PDMS. As the filler (colloidal silica) proportion was increased, the Rr and ε, of the rubbers examined rose and diminished, respectively. Silica's silanol groups are likely to participate in the reactions with the crosslinking agents. When used as crosslinking agent, PMHS enable thin-film (a few mm thick) solid and large-block microporous cured products to be prepared.


Keywords: silicone rubbers, polymethylhydrosiloxanes, polydimethylsiloxane-α, ϖ-diols, crosslinking, silica filler, mechanical properties

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