| abstract |
PLASTICS MATERIALS SUITABLE FOR USE IN PACKAGING ARE PROVIDED, WHICH PHOTODEGRADE UPON EXPOSURE TO DIRECT SUNLIGHT, BUTT WHICH HAVE INDEFINITE STORAGE LIFE OTHERWISE. THE MATERIALS ARE POLYMERS OF COMMON VINYLIDENE MONOMERS SUCH AS ETHYLENE, STYRENE AND METHYL METHACRYLATE, CONTAINING 0.1-5 MOLE PERCENT OF KETO CARBONYL GROUPS LOCATED IN SIDE CHAINS BUT ADJACENT THE MAIN CHAIN OF THE POLYMER. THESE KETO GROUPS ABSORB U.V. RADIATION AND CAUSE PHOTODEGRADATION OF THE POLYMER. |