TENSILE STRENGTH OF RUBBERS.
PRINCETON UNIV N J FRICK CHEMICAL LAB
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A current theory of the tensile strength of rubbers invokes large scale crosslink interchange at room temperature to explain the high tensile strengths of networks crosslinked with weak linkages. This mechanical lability of certain crosslinks has been assumed from their known thermal lability at higher temperatures. Relaxation of stress experiments at various elongations were performed at room temperature on networks crosslinked with both weak and strong linkages. The purpose was to detect mechanically-induced crosslink slippage. No evidence was found of any mechanical lability of weak crosslinks at room temperature. A hypothesis is presented which explains the high tensile strengths of rubbers crosslinked with weak linkages as resulting from an internally relaxed network formed by the thermal lability of the crosslinks at the vulcanization temperature. This theory is shown to be consistent with some previously unexplained experimental results. Author
- Physical Chemistry
- Elastomers and Rubber