Loss of light stabilizers from polypropylene

Kinetic modelling of phenols consumption during polyethylene thermal oxidation

“…-Values of parameter H for evaporation rate values are also given in literature [20]. Their value may be estimated from kinetics of stabilizer loss under nitrogen [14].…”

Effect of phase transitions on the volatility of UV absorbers from polypropylene

“…Such development of volatility of stabilizers from polymers differs from the evaporation of the pure stabilizers where the dependence of the weight decrease on time is linear20,21 to what corresponds to the kinetic equation of the zero order. The exponential development of the curves of volatility of additives from polymers is already known, 10,15,19,22 and is correlated by the first order kinetic equation. According to Angert15 this dependence is described by analytical equation: (1) c / c , = 1 -exp ( -k t ) where c is the quantity of the substance evaporated in the time t , c, is initial concentration of the additive, and k is a rate constant of the process.…”

The Photooxidative Degradation of Polypropylene. Part II. Photostabilization Mechanisms

“…For example, 2 -hydroxy -4 -met hoxybenzophenone at 0.5 wt %I in PPH film is reduced to c0.02 wt % after only 24 hr of exposure to the heat inside a xenon arc Weather-Ometer (-35°C); the 4-dodecyloxy derivative persists for over 500 hr [20]. Durmis et al [98] have quantitatively compared the rates of evaporation at close to room tempeiature for a series of substituted 2-hydroxybenzophenones and 242' -hydroxpphenyl)benzotriazoles.…”