Measurement of the Tensile Failure of Gels

Various methods of probing the tensile failure characteristics of both extensible and brittle gels using the Instron machine were evaluated. The true strain of the gels at failure determined from high speed video camera recording and the corresponding true stress were used as the reference. When the ratio of the test length to the length of the end‐pieces of a dumbbell shaped specimen exceeds 10:1, the effect of the end‐pieces was negligible and the measured stress and strain at failure by the Instron machine represent the true values in the test sector of the gel. Experimental data from tensile testing using the above method suggest that both extensive and brittle gels were weaker in tension than in compression.