Effect of antioxidants and latex vulcanising agents on the environmental degradation of latex films.

The role of antioxidants and latex vulcanising agents on the environmental degradation of NR latex gloves and films was studied. In soil burial tests, acetone-treated glove pieces degraded significantly more than the untreated + samples after 24 weeks, whereas polychloroprene and nitrile pieces remained unaffected. This solvent-induced rapid degradation rate of NR glove pieces was due to the leaching out of the organic antioxidants and dithiocarbamate accelerators. Under the + scanning electron microscope, the particulate-structured surface of the treated NR samples displayed wide cracks and cavities in the degraded areas which indicates bulk disintegration in the film. In agar plate culture studies, more than 80% of bacteria + could grow at the highest level (10 000 µg/mL) of the phenolic antioxidants (Irganox®, Wingstay L®). With the dithiocarbamate accelerators, ZDEC was more inhibitory than ZDBC as 50% of the bacteria grew at the highest level of ZDBC (10 000 µg/mL) but + only 16% grew on ZDEC. The growth of fungi except yeast was unaffected by the presence of the antioxidants or accelerators. When latex films of varying curing systems were used, increasing the level of crosslink concentrations increased their resistance + to environmental degradation. As a group, the non-sulphur prevulcanised films degraded much faster than the sulphur-vulcanised films. The singular presence of sulphur, ZDEC, ZnO or Irganox® did not significantly affect the resistance of the non-sulphur + prevulcanised films to environmental degradation whereas the combined effect of these additives did. The study confirmed that antioxidants and accelerators affect the rate of latex film degradation via their role in influencing the crosslink efficiency + of the rubber.The role of antioxidants and latex vulcanising agents on the environmental degradation of NR latex gloves and films was studied. In soil burial tests, acetone-treated glove pieces degraded significantly more than the untreated samples after+ 24 weeks, whereas polychloroprene and nitrile pieces remained unaffected. This solvent-induced rapid degradation rate of NR glove pieces was due to the leaching out of the organic antioxidants and dithiocarbamate accelerators. Under the scanning + electron microscope, the particulate-structured surface of the treated NR samples displayed wide cracks and cavities in the degraded areas which indicates bulk disintegration in the film. In agar plate culture studies, more than 80% of bacteria could + grow at the highest level (10 000 µg/mL) of the phenolic antioxidants (Irganox®, Wingstay L®). With the dithiocarbamate accelerators, ZDEC was more inhibitory than ZDBC as 50% of the bacteria grew at the highest level of ZDBC (10 000 µg/mL) but only 16% + grew on ZDEC. The growth of fungi except yeast was unaffected by the presence of the antioxidants or accelerators. When latex films of varying curing systems were used, increasing the level of crosslink concentrations increased their resistance to + environmental degradation. As a group, the non-sulphur prevulcanised films degraded much faster than the sulphur-vulcanised films. The singular presence of sulphur, ZDEC, ZnO or Irganox® did not significantly affect the resistance of the non-sulphur + prevulcanised films to environmental degradation whereas the combined effect of these additives did. The study confirmed that antioxidants and accelerators affect the rate of latex film degradation via their role in influencing the crosslink efficiency + of the rubber.