Measurements at controlled relative humidity
The Humidity option consists of a special humidity chamber, a circulating heating bath and a humidity generator. It allows you to perform measurements under optimum conditions in every deformation mode. Special readjustment is not necessary after installing the humidity chamber.
Effect of Relative Humidity
Ethylene-Vinyl Alcohol (EVOH) copolymer is often used in packaging films for foodstuffs because of its excellent barrier properties toward oxygen and water vapor.
Since EVOH is hygroscopic and water acts as a plasticizer, the barrier properties of a film are influenced by its water content. Isothermal DMA measurements at 50 °C show that an increase in relative humidity leads to a decrease in the storage modulus. The
peak in the tan delta curves is due to the decrease of the glass transition temperature with increasing relative humidity. Since the glass transition is frequency dependent, the peak measured at lower frequency appears at lower relative humidity.