New aspects of the problem of the ageing and stabilisation of polymers

Diffusion coefficients of sodium dodecyl sulfate in water swollen cross-linked polyacrylamide membranes

“…The diffusion of solutes in hydrogels has applications in a wide variety of processes and systems, such as its use in biosensors [1], purification procedures [2], etc. Particular reference can be made to the application of hydrogels based on polyacrylamide and the anionic surfactant sodium dodecyl sulfate (SDS) in the electrophoretic separation of biological macromolecules (PAGE systems, see for example [3]).…”

The Effect of Red Pigment and Photo Stabilizers on the Photo Degradation of Polypropylene Films

“…Other types of additives can act either (i) reducing the rate of degradation by limiting the oxygen diffusion into the product or blocking the passage of ultraviolet light 3 or even acting chemically with the degradation mechanism 4 or (ii) promoting chemical degradation. The latter occurs when the additive molecules act as source of free radicals 5 or when they contain active sites for chemical reactions 6,7 .…”

Study by Differential Thermal Analysis and Thermogravimetric Analysis of the Heat Stability of Polyethylene Stabilised with Gossypol Derivatives

“…As shown in Figure 1, the obtained series of values makes it possible to plot the dependence in the coordinates of equation (1). Figure 1 gives the dependences obtained for the high-temperature stages of degradation in Dlog dW/dt -Dlog W r coordinates.…”

“…At the foundation of modern ideas concerning increase in the heat stability of polymers, along with numerous attempts to synthesise new heat-resistant polymers, a great deal of attention is being paid to the stabilisation of industrially produced polymeric materials with different organic and inorganic stabilising additives. The importance of this question has prompted numerous investigations of chemical aspects of the stabilisation of polymers, which have been systematised in a number of monographs [1,2]. However, physical aspects of this problem have generally been investigated insufficiently.…”

“…In the present work, on the basis of a study of the kinetics of thermal degradation of stabilised polymers, the effective kinetic parameters were calculated from TGA data using the Freeman-Carroll method [4]. The breakdown rate of the polymer is equal to dW/dt = (A 0 /RH)e -E/RT W n (1) where RH is the heating rate, W is the weight of the polymer sample, A 0 is the pre-exponential factor, n is the effective order of the reaction, and E is the effective activation energy of thermal degradation of the polymer. From the graphic dependence in the logarithmic coordinates of the equation, the order of the reaction n is found from the slope tangent, and the effective activation energy of thermal degradation is found from the segment intercepted on the ordinate axis.…”