Microscopic fibers produced from grasses enable the production of thinner and stronger condoms, when added to latex. If commercially viable, the discovery could bolster the struggling quest for more popular condoms, increasing usage vastly. The same process could also make possible latex gloves that are less tiring to wear – an important consideration for extended surgery.
Spinifex is the popular name for grasses that, according to Dr. Nasim Amiralian of the University of Queensland, "cover 30 percent of Australia." They are different from the coastal genus true Spinifex, common on three continents. Evolutionary pressure from harsh semi-desert conditions has made spinifex grasses rich in nanocellulose, tiny fibers that help them retain water and fend off the harsh sun.
For her PhD, Amiralian demonstrated that the uniquely long and thin nanofibrils in spinifex can be extracted more cheaply and easily than their equivalents from other plants as well as making stronger products.
Now Amiralian has integrated the fibers into latex materials. "We tested our latex formulation on a commercial dipping line in the United States and conducted a burst test that inflates condoms and measures the volume and pressure, and on average got a performance increase of 20 percent in pressure and 40 percent in volume compared to the commercial latex control sample," said Professor Darren Martin, head of Amiralian's lab, in a statement.
Latex strengthened with spinifex nanofibers gets stretch tested. Australian Institute for Bioengineering and Nanotechnology. The University of Queensland
"We were able to get down to about 45 microns on our very first commercial dipping run, which is around the width of the hair on your head," said Martin. He expects that, "Rather than looking at increasing the strength, companies would be looking to market the thinnest, most satisfying prophylactic possible." However, for some other uses extra strength latex might be preferred.
Spinifex is so widespread across Australia that the supply of raw material is cheap and almost unlimited. To produce the fibers Amiralian said, "You would firstly hedge the grass, and then it would be chopped up and pulped with sodium hydroxide -- and at that stage it just looks like paper pulp. Then you hit it with mechanical energy to force it through a very small hole under high pressure to peel the nano-fibers apart from the pulp, into nanocellulose happily suspended in water and ready to add to things like water-based rubber latex."
As elaborate as the process sounds, Martin noted that the fact that 30 percent less latex is required could ultimately mean that condoms and gloves produced this way are cheaper, as well as more pleasurable to use.
The team were inspired to investigate Spinifex because of its traditional use by Indigenous Australians. "The knowledge of its properties goes back thousands of years," Amiralian told IFLScience in an interview. The University of Queensland has recognised the contribution made by this knowledge by providing equity to the Dugalunji Aboriginal Corporation (DUC) in any commercial products made from commercialization of their nanocellulose extraction technology. There are also plans for spinifex harvesting and processing to be conducted by the DUC, creating much-needed jobs in remote indigenous communities.