Sugar’s Greater Potential

The wily ways of the biggest petrochemical companies have been a concern since we started this platform, and when something seems like big news, but turns not to be so big, we share what we find.  We have previously shared a story or two about sugar’s potential as an energy source, but in its recent edition The Economist weighs in on what may be sugar’s bigger than big potential:

Better disposable coffee cups

They can be made with the waste from sugar cane

Sugar cane contains around 10% sugar. But that means it contains around 90% non-sugar—the material known as bagasse (pictured) which remains once the cane has been pulverised and the sugar-bearing juice squeezed out of it. World production of cane sugar was 185m tonnes in 2017. That results in a lot of bagasse.

At the moment, most of this is burned. Often, it fuels local generators that power the mills, so it is not wasted. But Zhu Hongli, a mechanical engineer at Northeastern University in Boston, thinks it can be put to better use. As she and her colleagues describe in Matter this week, with a bit of tweaking bagasse makes an excellent—and biodegradable—replacement for the plastic used for disposable food containers such as coffee cups.

Dr Zhu is not the first person to have this idea. But previous attempts tended not to survive contact with liquids. She thought she could overcome that by spiking the sugar cane pulp with another biodegradable material. She knew from previous research that the main reason past efforts fell to pieces when wet is that bagasse is composed of short fibres which are unable to overlap sufficiently to confer resilience on the finished product. She therefore sought to insert a suitably long-fibred substance.

Bamboo seemed to fit the bill. It grows quickly, degrades readily and has appropriately long fibres. And it worked. When the researchers blended a small amount of bamboo pulp into bagasse, they found that the result had a strong interweaving of short and long fibres. As a bonus, they also discovered that the hot pressing used as part of the process had mobilised some of the lignin in the fibres, and that this stiff, water-repelling material was now acting as an adhesive that bound the fibres together…

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