COMPATIBILITY OF HALS-NITROXIDES WITH POLYOLEFINS

The solubilities and diffusion coefficients of some nitroxy derivative s of hindered amine light stabilizers (HALS-NO) have been measured in polypropylene (PP), high density polyethylene (HDPE), low density PE ( LDPE) and linear low density PE (L-LDPE). The results are compared wit h the values for the corresponding HALS and it is shown that nitroxide s are always less soluble than the parent amines. Quantitative measure ment of non-extractable stabilizer indicates that 1-2% of the stabiliz er is bonded to the polymer chains after thermal aging (60-80-degrees- C). The diffusion behaviour of nitroxides is strongly dependent on the polyolefin type and differences of up to two orders of magnitude have been observed between PP and LDPE.