Natural weathering of textiles used in agricultural applications

In-field research was carried out on five agrotextiles which were exposed to natural weathering for 5 years. Prior to weathering and each subsequent year of exposure, samples were taken to evaluate tensile strength, strain at break, thickness and mass per unit surface. The results show that the effect of weathering is material dependent. The two polyvinyl chloride (PVC)-coated polyester materials exhibited a distinct decrease in tensile strength, especially after the first year of exposure, whereas the three other polyethylene materials, which were ultraviolet (UV) stabilised, showed only a continuously slight decrease in tensile strength with exposure time. Strain at break presented more or less the same tendency as the tensile strength. Material thickness was not affected by weathering. A decrease in mass was only observed for the two PVC-coated materials, whereas weathering had no effect on the mass of the UV-stabilised materials. The tensile data led to a logarithmic-model to predict the long-term weathering behaviour. However, the tensile properties prior to exposure do not fit with this model unless it is assumed that they do not change during the early stages of weathering. Three short periods of exposure with duration of, respectively, 15 days, 7 days and 1 day, within which it was assumed that the initial tensile properties remained unaltered, were used to investigate the effect of this assumption on the long-term prediction of the tensile properties. The accepted period was, however, of crucial importance to the long-term prediction and could not be determined unequivocally. Therefore, it was decided to exclude the initial values prior to exposure in deriving the logarithmic-model.