高分子受阻胺光稳定剂存在下聚丁二烯的单线态氧氧化

用粘度法、ESR、IR、GPC等方法研究了三种商品高分子受阻胺存在下聚丁二烯的单线态氧氧化,结果表明,高分子受阻胺抑止聚丁二烯的单线态氧氧化,其效率是944>PDS>770>622。用Monroe方法测定了受阻胺对单线态氧的猝灭速率常数,K_q~(-O_2),它们是944(3.2×10~6M~(-1)s~(-1)),PDS(8.2×10~5M~(-1)s~(-1)),622,770为2×10~5M~(-1)s~(-1),ESR研究表明,在本实验条件下,944和PDS能够产生稳定的氮氧自由基No,而622则不产生。用GPC研究还发现,在本实验条件下,PDS具有对聚丁二烯的接枝——交联效应,提出了这种接枝交联效应的机理。

SINGLET OXYGEN OXIDATION OF cis-1,4-POLYBUTADIENE IN PRESENCE OF POLYMERIC HINDERED AMINE LIGHT STABILIZER

The singlet oxygen (¹O₂) oxidation of polybutadiene (PB) in presence of polymeric hindered amine light stabilizer (HALS) was studied by determination of viscosity, ESR., lR., GFC.. The results show that polymeric HALS can inhibite ¹O₂ oxidation of PB and the effectiveness is 944 > PDS > 770 > 622. The quenching rate constants of ¹O₂ by HALS were determined by Monroe's method(19) They are:944(3.2×10⁶),PDS(8.2×10⁵),622 and 770 < 2×10⁵M^-1S^-1.The determination of ESR. shows that 944 and PDS can produce stable nitroxy free radi-cal in this experimental condition and 622 does not. This is associated with the steric effect of 622. The determination of GPC also shows that PDS possesses an effect of grafting-crosslin-king to PB in this experimental condition. The mechanizm of grafting-crosslinking has be-en proposed.