9—THE EFFECT OF TEMPERATURE AND HUMIDITY ON THE BENDING MODULUS OF SOME MONOFILAMENT MATERIALS

Experiments axe described in which the bending modulus of several monofilament materials was determined at different constant humidities and varying temperature and at different constant temperatures and varying humidity. It was found that the bending modulus of a thermoplastic monofilament decreased with increasing temperature by an amount dependent on the temperature and the thermodynamic properties and history of the material and decreased with increasing humidity, provided that the material was hydrophilic, by an amount that was again dependent on the temperature. It is shown that the effect of chants in temperature and humidity on the behaviour of fibres can be predicted from the observations on coarse monofilaments and that these changes are important in the assessment of handle.