VietNamNet Bridge - Accidentally discovering that the finest flour can create a thin film with tensile strength, two female students from Hue City flattened starch into film to make biodegradable bags.


{keywords}




The bag was created by Nguyen Cam Binh Minh and Nguyen Cam Kieu Khanh from the Hue High School for the Gifted.

The materials used included 100 ppm silver nano solution, pure polyvinyl alcohol (PVA) powder, cassava starch and 99 percent glycerol.
Accidentally discovering that the finest flour can create a thin film with tensile strength, two female students from Hue City flattened starch into film to make biodegradable bags.

“One year ago, when making banh bot loc (a small, clear-looking, chewy tapioca dumpling), I accidentally discovered that the finest flour could create a thin film with tensile strength. I thought of flattening starch into thin film,” Khanh said.

The two girls consulted with Le Dai Vuong, a teacher at the school, and got permission to use the laboratory to develop their idea.

The flat-ribbed starch elements rearrange and interact directly through hydrogen bonds and indirectly through water molecules. PVA is capable of creating pockets helping to create tensile strength.

In addition, the two girls use necessary additives such as glycerol to make film from silver nanoparticles and cassava starch to increase starch processing capabilities.

The product was completed in early 2017, though many shortcomings still existed.

According to Minh, biological antibacterial bags can be used to wrap vegetables and fruits and can partially replace PE, PVC and PP in wrapping high-end food.

Experiments show that the bags have the ability to absorb moisture over time. The thickness of the bags should be 0.038 mm.

The tests against E. coli and Salmonella bacteria with an antibacterial ring method showed that the bag had good antibacterial capability.

They also investigated the biodegradability of the bag by burying the bag in the soil and monitoring the weight loss. They found that the decomposition time in the soil decreased day by day and did not affect the environment. The production cost of one bag is VND400.

A Ministry of Natural Resources and the Environment (MONRE) report showed that one consumer uses at least one plastic bag a day, which means that at least 90 million plastic bags are used every day in the country.

Plastic bags need 500 years or longer to disintegrate.

In related news, the environmental protection tax on plastic bags are expected to increase from VND30,000-50,000 to VND40,000-200,000 per kilo. The new tax rates would help change consumption habits and offer opportunities to biodegradable bag manufacturers.


RELATED NEWS

Finance Ministry proposes tax hikes on petrol, plastic bags

HCM City attempts to cut use of plastic bags


Kham Pha