On the mechanism of strain energy storage in silica reinforced silicone elastomers

J of Applied Polymer Sci

1970

SynopsisLight-scattering and optical microscope observations of silica-reinforced silicone rubber have shown that the filler is dispersed in a complex manner. Much of the original material appears agglomerated into particles several microns in size. These particles apparently further cluster to form agglomerates of about 20 p in diameter. I n an earlier paper in this series it was shown that the thermodynamic function fe/f (the fraction of the retractive force due to internal energy changes) was a measure of the reinforcement level. It is now proposed that the corresponding physical mechanism of reinforcement may have its origin in the large amounts of energy required to deform the filler particle agglomerates.

Morphology and structure of silica agglomerates in silica‐reinforced silicone rubber

Galanti

J of Applied Polymer Sci

1970

Rubber elasticity of poly(n‐butyl acrylate) networks formed with multifunctional crosslinkers

Yeo

J of Applied Polymer Sci

Thomas

1981

SynopsisThe rubber elasticity characteristics of poly(n-butyl acrylate) networks crosslinked with tetrafunctional (EGDM and TEGDM), hexafunctional (TMPTM), and octafunctional (PETMA) vinyl crosslinkers were investigated. Both gel-sol analyses and crosslinking efficiency theories were used to evaluate the chemical crosslink contribution v, and the entanglement contribution up to the elastically effective network chains ve, and the effect of the crosslink junction functionality f on the front factor g. The front factors obtained were in the range of 0.50-0.92, depending upon the network system and the counting method for v,. The relationship of g = [(f -2)/f]/(r*)/(r2)~ seems reasonable in the case of the tetrafunctional and hexafunctional networks, but deviates in the case of the octafunctional network.

Relationship between thermoelasticity and reinforcement in elastomers: Silica filled silicone elastomers

Galanti

Polymer Engineering & Sci

1970

Increases in modulus, tensile strength, and swelling caused by reinforcing silicone rubber with silica filler were correlated with the thermoelastic parameter, fe/f. A new semiempirical equation of state, containing a generalized front factor, was derived to explain the experimental results. While the retractive force in pure gum elastomers is largely entropic in origin, reinforcement in silicone rubber‐silica systems appears to arise by greatly augmenting the deformational free energy change stored in energetic modes.