The objective of the work reported here was to determine the influence of UV radiation and environmental temperature on the strength and rheological characteristics of multilayer agricultural packaging foils. The transmission properties of the experimental foils were tested in 286–363.5 nm range. The analysis of transmission properties of the foils showed that the maximum transmission was 10 % and 45 % with the experimental violet foils having 20 % and 5 % UV inhibitor in them, respectively. However, the transmission was higher than 80 % with the white foils of 5 % and 20 % inhibitor.The effect of the temperature on the tensile stress of commercial foils was investigated gated in the −20 ≤
≤ 50 °C temperature range. The measured relaxation curve was found to have a close correlation both for −10°C and 45°C with the calculated results. The highest reduced strength decreased as the function of the temperature according to the σ= −0,1861
+19,107 [MPa] equation. Therefore, the probability of the break of the foils in cold weather is definitely higher than under warm weather conditions.
Authors:Ferenc Safranyik, Attila Csatár, and Attila Varga
The phenomenon of friction reduces efficiency of almost all machines in practice. In order to reduce the deficits, we have to understand this phenomenon and have to take it into consideration during design in all cases. Nevertheless, in certain cases describing of a friction process is very difficult, because it depends on a lot of parameters. In case of polymers, granular materials or in geology, the rate and state dependent friction have great importance. In this paper, velocity and time dependent friction is examined with the help of a direct shear apparatus, which was developed in our earlier work.