PROTECTING POLYMERS AGAINST DAMAGE FROM GAMMA-RADIATION

The sensitivity of polymers to oxidation and chain scissioning during exposure to high energy radiation is mitigated by the use of radical trapping stabilizers of the hindered phenol and hindered amine classes. The stabilizers undergo oxidative transformations in the process and, in the case of hindered phenols, yield colored products with conjugated pi-electrons, which contribute to the discoloration of the polymers. Hindered amine stabilizers, in combination with trivalent phosphorus melt processing stabilizers, are the stabilizers of choice to protect polymers against gamma radiation since they are effective in protecting polymer properties and since they are usually much less discoloring than hindered phenolic stabilizers.