Fig. 7. A plot of normalized force against temperature for a sample of Araneus MA silk held at an extension of 36%. The intercept of the uncorrected plot is 0.2, indicating that for this sample approximately 20% of the force is due to enthalpy. When corrected for the effects of thermal swelling, the slope of the force–temperature plot decreases, and the intercept rises to 0.30 for this silk sample, indicating that approximately 30% of the force is due to bond energy.