Abstract
Hindered amine light stabilizers (HALS) possess many functions unlike other additives and are frequently used to extend the service life of polymeric materials, but show particular compatibility with certain other additives. However, combination does not always show synergistic actions, but sometimes has antagonistic effects. Most previous research into the interaction of HALS with other additives has focused on qualitative high synergism to high antagonism, and no common understanding has been reached. HALS and homologs have many derivatives which are classified here as "good" HALS and "bad" HALS, including a new HALS derivative, HALS nitrosonium. The investigation of the antagonism of HALS with other additives has been based on only "good" HALS. The present study discusses the chaotic interactions of HALS with other additives kinetically and thermodynamically by separately considering the synergism of "good" HALS and the antagonism of "bad" HALS. This approach has lead to a new technique for unified evaluation of the interaction semi-quantitatively. The results summarized here clarify the complex and diverse characteristics of HALS and present the possibility that the action mechanism of HALS alone and together with other additives can be discussed based on a unified mechanism. Such united ideas can determine additive formulation much more easily and facilitate the development of new additives, resulting in more stable and functional polymeric materials.
