Carbon black surface energy effect

Plastics can be protected against UV radiation in three ways. One possibility is the addition of molecules or pigments, which extensively absorb UV radiation and convert the radiation energy directly into heat energy. The particular effectiveness of fine carbon black has already been discussed. Carbon black not only absorbs UV radiation but also binds free radicals through a number of organic compounds adsorbed on the carbon black surface. Absorbent light-protective substances, such as carbon black, display their full effectiveness only when a certain thickness of the exposed layer is available. 

Effect of Surface Energy on Dispersibility of Carbon Black.937... 

Composite-based PTC thermistors are potentially more economical. These devices are based on a combination of a conductor in a semicrystalline polymer—for example, carbon black in polyethylene. Other fillers include copper, iron, and silver. Important filler parameters in addition to conductivity include particle size, distribution, morphology, surface energy, oxidation state, and thermal expansion coefficient. Important polymer matrix characteristics in addition to conductivity include the glass transition temperature, Tg, and thermal expansion coefficient. Interfacial effects are extremely important in these materials and can influence the ultimate electrical properties of the composite. 

Mackor (1951) was perhaps the first to endeavour to calculate the free energy of repulsion between sterically stabilized particles. This work was instigated after van der Waarden (1950 1951) had shown experimentally that aromatic molecules with long-chain aliphatic substituents could have a profound effect on the stability of carbon black particles dispersed in a paraffin (see Section 2.4.2). For this reason, Mackor adopted a model in which he assumed that the aromatic nuclei were adsorbed onto the carbon black particles in a flat configuration, thus anchoring the alkyl chains to the surface. These chains were assumed to project into the dispersion medium and were modelled as rigid rods, of length L, flexibly attached to the particle surfaces by ball joints. 

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