DURABILITY AND TESTING

Three factors were considered when assessing the durability of the AeroBarrier

sealant – flexing, aging, and compatibility of the material.

• Flexing is an important characteristic, because most joints within the

building enclosure expand and contract due to changes in temperature

and/or moisture, which requires that the sealant material accommodate

that movement.

• Aging is very important for the building industry because some materials

can break down over time due to leaching of plasticizers or other low-

molecular-weight volatiles, causing them to embrittle.

• Compatibility is important with all building products because the sealant

shouldn’t chemically react with or leach into other building materials.

• Flexing: The AeroBarrier material was aerosolized and deposited on

a 1/8-inch-wide wood joint. The joint was designed such that it would

contract by 20% at high temperature (180°F) and expand by 20% at low

temperature (-30°F). These temperatures were chosen as the worst-case

climatic extremes that could be experienced on a wall/roof assembly in North

America (high temperature includes the effect of solar heating). The joint

was cycled through this temperature range fifty times in an environmental

chamber to simulate the worst-case full range of joint movement over a fifty-

year period.

• Aging: The aging over that fifty-year period was simulated with an Arrhenius

relationship to accelerate any chemical degradation in the material with

temperature. During the fifty temperature cycles in the environmental

chamber, the duration at the high temperature (180°F) was extended for

each cycle to simulate the equivalent of fifty years of service life at the

sealant’s expected service temperature.

• Sealing Performance: The air permeance of the 1/8-inch-wide wood joint

was measured before and after the flexing and aging conditioning described

above (75 Pa pressure differential).

• Compatibility: The sealant was exposed to 41 different building materials

that were then conditioned in a warm, humid environment (120°F/95%

RH) for 10 days, followed by magnified inspection of the sealant-substrate interface.