Composite aluminum foil processing process
How the rolling and annealing process gives aluminum foil, which is produced by rolling between successive steel rollers, excellent barrier properties. Each set of rollers squeezes the foil thinner. The final stage of rolling reduces the thickness of the foil to thousandths of an inch or even thinner. The problem is that such thin foil tears too easily during the final rolling stage, where the two foils are placed face to face and passed together through the final set of rollers. Because the steel rollers are highly polished, the foil side in contact with the rollers is also embossed into a highly shiny surface.
After rolling, the resulting sheets are separated from each other. The surface of each foil facing each other has a matte texture because they are simply pressed against each other rather than a polished roller. What makes it the material of choice for a variety of packaging and insulation applications?
Most metals are fairly impermeable. Rolling and annealing the princess will break down the crystal size. Some aluminized plastics use vacuum vapor deposition to obtain thinner layers.
As for insulation, aluminum itself is a good conductor of heat, good insulation only applies to the reflection and retention of radiation, and in the case of a survival bag to prevent evaporative cooling.
