Tensile-elongation properties under varied climatic conditions

There is little well-founded knowledge on material fatigue processes for viscoelastic materials such as leather or material composites based on synthetic polymers (e.g. plastic films, coated textiles). These materials are subject to sometimes drastic material stress both during manufacture and during use. In addition to static and dynamic-mechanical stress (e.g. tensile/pressure loads, elongation, etc.), the materials are exposed to different climatic stress scenarios depending on the intended use. Exposure to relatively high temperatures as well as frequent changes in temperature and humidity can lead to temporary and/or permanent changes in the material properties, which may severely restrict the usability.

Information on physical-mechanical material properties is generated in standardised test procedures. These tests are carried out on universal material testing machines and are usually carried out under normal climatic conditions (23 °C, 50 % relative humidity) in an appropriately climatised environment. However, in most cases the results generated from this cannot be transferred to the material behaviour in constant or alternating climates. Consequently, only a partial aspect of the material-specific ageing process can be mapped in the form of a subsequently obtained, statistical material response within the framework of this procedure.

In the future, the new testing system can be used to make more realistic statements about the properties and more accurate predictions about material fatigue or ageing of viscoelastic materials. First of all, a standardised procedure for testing, including identification of the necessary system settings (temperature-humidity regime, rates for temperature control, humidification and dehumidification, compressed air requirements), duration of pre-tempering/pre-conditioning of individual test specimens, insertion and removal of test specimens, will be developed for selected climate scenarios.