Abstract: Reactive stabilizer compounds, to be used in the stabilization of organic polymers, contain a sterically hindered, N-substituted piperidinic, morpholinic or pyrrolidinic group, and at least a hydrolysable silicic function.Such compounds give rise, by hydrolysis of the silicic function, to complex resinous structures endowed with stabilizing properties.The reactive stabilizer compounds can spontaneously hydrolyse inside the polymer, or they can be stably supported on a solid support, or they can be chemically linked to the polymeric chain to be stabilized.

Abstract: Stabilizing inorganic fillers or pigments having simultaneous reinforcing effect and stabilizing effect on organic polymers are obtained by a process comprising the following stages:(a) bringing the inorganic filler or pigment into contact with a solution, in an inert organic solvent, of a sterically hindered amine comprising one or more alkoxysilane groups in its molecule;(b) maintaining the obtained mixture at higher than ambient temperature (20.degree.-25.degree. C.) for a period of at least 0.5 hours;(c) removing the solvent, treating at a temperature of 120.degree.-200.degree. C. and recovering the stabilizing filler or pigment obtained.