Another Man’s Trash
Aerogel, one of the lightest solid materials known to man, can now be made from trash. A team of researchers have discovered a technique that can basically turn scrap paper into a highly insulating and incredibly light material.
Typically made from silica, but known to also have been made from materials like gold and graphene, aerogels are also very expensive.
It requires the use of a normal gel, which needs to be very slowly and carefully separated from the liquid so that it leaves behind only the solid structure. The end result is a substance that looks like its original form but feels very light, making it a durable insulator of heat.
To create aerogel from paper waste, scientists from the National University of Singapore used a technique called "cellulose," and it is surprisingly very simple.
It starts with paper being mulched to release cellulose fibers, and then water is added and cross-linked to polymer resin. Finally, they agitate the mixture using high frequency sound. To remove all water from the mixture, it is then frozen at 0 degrees Fahrenheit for 24 hours, free-dried at 144 degrees Fahrenheit for a couple of days, and cured in an oven at 238 degrees for three hours.
The final product is an opaque material that is highly porous—98.2 percent air—but still flexible and fairly strong. Coated with methyltrimethoxysilane, it also becomes hydrophobic. Being highly porous allows it to soak up as much as 90 times its dry weight in crude oil and 99 percent of that can then be wrung so that the material can be reused.
In terms of application, it can be used for home insulation, protective packaging, winter clothing, and even as absorbent layers in diapers. However, despite its commercial viability, it still remains unclear how long before the material hits the market.