The effect of the chemical and physical properties of carbon black on the thermal and photooxidation of polyethylene

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Abstract
The antioxidant and UV stabilizing effect of different carbon blacks on parafin oil model compound with and without additional stabilizers was investigated. The thermal and photooxistabilities of the samples were characterized by the induction period of the oxygen consumption which was measured volumetrically in a closed system filled with oxygen. A relationship was established between the induction periods of the thermal oxistability curves and the distributions of oxygen content within the active groups of the blacks.Determining the stabilities of the polymer‐black‐antioxidant systems, synergistic and antagonistic phenomena were observed. These effects were explained by taking nto account the quality and amount of the active sites of the blacks.The photooxidation experiments corroborated the double role of the black as UV stabilizer. Primarily it acts as a UV screen, its effectiveness being proportional to its specific surface. In addition to this, the synergism and antagonism observed in the ternary systems suggested that the carbon was also involved in the photooxidation as a chain terminating and peroxide decomposing agent.