Long-Term Temperature Influence

Behavior under short-term temperature exposure is generally characterized hy mechanical properties as a function of temperature (heat distortion temperature, see Section 2.4.1). Long-term temperature influence is seen in chemical aging processes leading to crosslinking, cyclization, thermal-oxidative degradation, and others. 

Regarding the operational use of thermoplastics, we generally have to distinguish between short-term and long-term temperature influence, respectively. 

For plastic materials, the thermal-oxidative aging behavior determines the effect of long-term temperature influence. Therefore, tests and testing criteria are focused on thermal oxidative aging behavior. 

The correlation coefficients between a 10 year monthly mean time series of volatilisation rates and SST, 1 Om wind speed and pollutant concentration are used to elucidate which of the parameters drives the volatilisation rate changes and causes the deviations from the long term mean. All of the parameters do not vary independently. Since both SST and wind speed influence the volatilisation rate in a nonlinear manner, it is not intuitive whether an increase in wind speed leads to an increase in volatilisation rate. A raise in wind speed that coincides with a decrease of the sea surface temperature can lead to a negative linear correlation coefficient between volatilisation rate and wind speed. For that reason the partial correlation coefficient is calculated in addition to the simple linear correlation coefficients. It explains the relation between a dependent and one or more independent parameters with reduced danger of spurious correlations due to the elimination of the influence of a third or fourth parameter, by holding it fixed. One important feature of the partial correlation coefficient is, that it is equal to the linear correlation coefficient if both variables... 

The annual mean water percolation Qie,zb is determined by the long-term mean annual temperature (mainly determining the potential evapotranspiration, Epol) and precipitation (mainly influencing the actual evapotranspiration, act) according to... 

The realization of the extraordinary properties of these new ligands stimulated research in this area and many imidazole-2-ylidenes have been synthesized in the last 10 years [8]. The 1,3-diadamantyl derivative 1 of the imidazole-2-ylidenes is stable at room temperature and the 1,3-dimesityl-4,5-dichloroimidazole-2-ylidene [9] is reported to be even air-stable. A variety of stable carbenes has been synthesized in between and it could be shown that steric bulk is not a requirement for the stability (the 1,3-dimethylimidazoline-2-yhdene can be distilled without decomposition [10]), although it certainly influences the long-term stability by preventing dimerization. 

The behavior of wax in these oils can sometimes be influenced by temperature cycling and long-term storage. As the wax melts and recrystallizes through repeated cycles of heating and cooling, the pour point of the oil may be affected. If the pour... 

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