Homogeneous functions Terms Links

Fractionation of natural organics is required to link characteristics to treatment behaviour. Leenheer et al. (1989) expressed an urgent need to separate the complex mixture of HSs into more homogeneous fractions in order to understand its nature and properties. The fractionation of HS in terms of IVW, functional groups, elemental composition, and other characteristics, is limited by methods and patience (Swift (1985)). 

It is known that the efficiency of catalysts is not only a function of the kind of active site, but also dependent on the constimtion of the carbon support, that will influence the overall electronic properties of the catalyst material [96, 107-109]. For platinum-based catalysts, it was shown that by nitrogen doping of the carbon support, the platinum particles are stronger linked to the support material compared to the not-modified carbon. The resultant smaller particles with a more homogeneous distribution enabled higher ORR activity and an improved long-term stability [107, 110]. 

The rate at which initiator molecules decompose, and hence the rate of cross-linking, is a function of their chemical stability and the temperature to which they are subjected. The decomposition of organic peroxides is an approximately first-order reaction, its rate increasing exponentially as a function of temperature. The rate of spontaneous decomposition of an initiator at any temperature is typically characterized in terms of its half-life. The approximate half-lives of some commonly used peroxide intiators are listed in Table 1. Initiator molecules for cross-linking polyethylene are selected with respect to the temperature at which the resin must be processed. The goal is to homogenize and mold the resin into the desired shape below the temperature at which peroxide decomposition becomes significant premature decomposition of the peroxide is known as... 

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