A Study of Phosphorus-Containing Antioxidants in Polyolefins

  • Parmode Sharma

Student thesis: Doctoral ThesisDoctor of Philosophy


Metal dithiophosphonates (Ni, Zn, Fe, Co, Cu) and the
corresponding sulphide, TPS, were examined as potential
antioxidants in polypropylene. All the dithiophosphonates
were very good melt stabilisers when compared to commercial
controls. Their effectiveness as thermal antioxidants varied
considerably from CuDiBuPn which was poor to NiDiBuPn which
was excellent and appears to be better than Irganox 1076, a
commercial antioxidant. The photostabilising activity of
these compounds also varied considerably. The NiDiBuPn was
found to be the most outstanding photostabiliser when
compared to the other phosphonates both on a molar and
weight basis and its activity was found to be highly
dependent on concentration, alkyl substituent and processing
severity. NiDiBuPn and CuDiBuPn were both found to synergise
effectively with the U.V. absorber HOBP and their
effectiveness was found to increase when an excess of the
U.V. absorber was used.

The dithiophosphonates were shown to be effective
radical traps (oxygen absorption) and peroxide decomposers
(hydroperoxide decomposition). Mechanistic studies of
NiDiBuPn also showed the complex to be highly stable to
thermolysis and photolysis. The lp NMR studies of NiDiBuPn
and TBH showed that the major transformation products are
the corresponding sulphides, the acidic species, the
phosphorus esters and some highly oxygenated inorganic
Date of Award1988
Original languageEnglish
SupervisorSahar Al-Malaika (Supervisor)


  • Thiophosphonates
  • Antioxidants
  • U.V. Stabilisers
  • Sulphur-containing Antioxidants

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