TECHNOLOGY FOCUS - POLYMERS - Preferred Composition: The sealant composition further includes a molecular sieve included in an amount greater than about 2.5% by weight of the total composition. It exhibits a water break through time of greater than 5 hr and a steady state moisture vapor transmission rate of less than 40 g-m2/day for a 0.030 inch thick sample of the sealant composition tested at 85 degrees C and 100% relative humidity. The sealant composition exhibits a water break through time of greater than 10 hr and a steady state moisture vapor transmission rate of less than 30 g-m2/day for a 0.030 inch thick sample of the sealant composition tested at 85 degrees C and 100% relative humidity. Combination of the calcium oxide and the molecular sieve is included in an amount greater than about 10% by weight and the sealant composition exhibits a water break through time of greater than 5 hours and a steady state moisture vapor transmission rate of less than 40 g-m2/day for a 0.030 inch thick sample of the sealant composition tested at 85 degrees C and 100% relative humidity. Combination of the calcium oxide and the molecular sieve is included in an amount greater than about 10% by weight and the sealant composition exhibits a water break through time of greater than 10 hours and steady state moisture vapor transmission rate of less than 30 g-m2/day for a 0.030 inch thick sample of the sealant composition tested at 85 degrees C and 100% relative humidity. The sealant composition also includes at least one of a clay, a calcium sulfate, and a silica gel, and where the sealant composition exhibits exhibit a water break through time of greater than 5 hours and a steady state moisture vapor transmission rate of less than 40 g-m2/day for a 0.030 inch thick sample of the sealant composition tested at 85 degrees C and 100% relative humidity. It further includes at least one of a clay, a calcium sulfate, and a silica gel, and where a combination of the calcium oxide, the molecular sieve, and the sealant composition exhibits a water break through time of greater than 10 hours and steady state moisture vapor transmission rate of lesser than 30 g-m2/day for a 0.030 inch thick sample of the sealant composition tested at 85 degrees C and 100% relative humidity. Combination of the calcium oxide and the molecular sieve is included in an amount from about 10% to about 40% by weight of the total composition. Combination of the calcium oxide and the molecular sieve is included in an amount from about 20% to about 40% by weight of the total composition. Combination of the calcium oxide and the molecular sieve is included in an amount from about 25% to about 35% by weight of the total composition. The olefinic polymer is included in an amount from about 30% to about 60% by weight of the total composition, the silane modified polyolefin is included in an amount from about 10% to about 25% by weight of the total composition, the carbon black is included in an amount from about 2% to about 20% by weight of the total composition, the filler is included in an amount from about 20% to about 60% by weight of the total composition, the calcium oxide is included in an amount from about 2.5% to about 25% by weight of the total composition, and the aging resistor is included in an amount from 0% to about 2% by weight of the total composition. It is included in an amount from about 20% to about 40% by weight of the total composition, the silane modified polyolefin is included in an amount from about 10% to about 20% by weight of the total composition, a combination of the carbon black and the filler is included in an amount from about 30% to about 40% by weight of the total composition, the calcium oxide is included in an amount from about 10% to about 30% by weight of the total composition, and the aging resistor is included in an amount from 0% to about 2% by weight of the total composition. The sealant composition includes a molecular sieve included in an amount from about 2.5% to about 25% by weight of the total composition. The sealant composition exhibits less than about 15 gm/((m2)-day) moisture vapor transmission rate at steady state for a 0.030 inch thick sample of the sealant composition tested at 85 degrees C and 100% relative humidity. Sealant composition includes balanced properties that keep swelling of the sealant to a predetermined amount upon reaction of the calcium oxide with water. The calcium oxide does not substantially react with or corrode other components of the sealant. Olefinic polymer includes at least one of a polyethylene, a polypropylene, a polybutene, a polyisobutene, a butyl rubber (polyisobutene-isoprene), styrene block copolymers, and modified forms of styrene block copolymers, where the olefinic polymers have a number average molecular weight of 100-700000 Da, where the silane modified polyolefins include at least one of an amorphous poly alpha olefin, a silane grafted PE, a moisture curing catalyst, an alkoxy silane, and an amino silane, where the fillers include at least one of a ground chalk, a precipitated chalk, a silicate, a silicon oxide, calcium carbonate (CaCO3), calcium hydroxide (Ca(OH)2), and titanium dioxide, and where the silicate is selected from talc, kaolin, mica, silicon oxide, silicas, and calcium or magnesium silicates, and where the aging resistors include at least one of hindered phenols, hindered amines, thioethers, mercapto compounds, phosphorus esters, benzotriazoles, benzophenones, and antizonants. Preferred Compound: In the sealing compound, the olefinic polymer includes a polyisobutylene in an amount from about 30% to about 60% by weight of the total composition, the at least one of the silane modified APAO and the silane modified polyisobutylene is included in an amount from about 2% to about 35% by weight of the total composition, the filler is included in an amount from about 3% to about 47% by weight of the total composition, a combination of the molecular sieve and the calcium oxide is included in an amount of about 10% to about 40% by weight of the total composition, and the aging resistor is included in an amount from 0.1% to about 3% by weight of the total composition.