into the desired surrounding structures by procedures such as extrusion blow molding as described in dupont magazine 1949 the invention also has the advantage that the termination of protection is indicated by a color change for example as the copper particles in the polymer scavenger sulfur entities from the permeating environment a chemical reaction is induced that produces a black material thus a substantial decrease in protection is indicated by development of a black color on the outside of the bag and the total loss of efficacy is indicated by the development of a dark black color both on the outside and inside surfaces of the bag similarly the interaction of aluminum with the environment produces a yellow color change the following examples are illustrative of the conditions employed in the use of the invention pellets of low density polyethylene were prepared having various loading levels of 7 u03bcm diameter copper powder the loading levels utilized were 25 35 and 45 weight percent of copper the pellets were then utilized to form polymer bags utilizing a braybender extrusion apparatus the bags were extruded to a thickness of 2 mils u00b1 15 percent were approximately 51 2 inches wide and cut and heat sealed every 7 inches a silver lead frame for an integrated circuit chip carrier was placed in each bag the bags were then heat sealed at each end three times to ensure proper sealing several bags made from each level of copper loaded material were placed in a chamber the chamber was evacuated and.