Starch-Derived Absorbent Could Help Reduce Diaper Garbage

November 15th 2023

Biodegradable super absorbent polymer made from starch.

A scientist here says he has developed an inexpensive, biodegradable super absorbent polymer (SAP) derived from starch that could help resolve the growing environmental problem concerning disposable diapers.

The starch and a natural organic compound that can be found in such items as lemons are mixed with a tiny amount of water to perfect the SAP, which can be broken down by micro-organisms, he said.

Biodegradable super absorbent polymer made from starch.

The technology of Hiroshi Uyama, a polymer chemistry professor at Osaka University, can absorb water and artificial urine up to 20 times the original weight of the substance.

“I previously tested other materials, but their costs were 100 times or so higher,” Uyama said. “The latest achievement was a result of me becoming accustomed to handling starch.”

At his lab featuring an electron microscope, a specialized camera, a strength analyzer and other instruments, Uyama showed how the whitish solid powder takes in so much fluid.

The mesh-like structure of the SAP quickly soaked up a drop of water.

“I have succeeded in creating better interstices,” Uyama said about the SAP’s porous design. “That was fortunate.”

The production method is kept secret, as Uyama is seeking a patent for the technology.

But the relatively easy technique could lead to the efficient mass production of the new SAP variant, he said.

SAP, an essential absorbent for paper diapers, is often fashioned from polyacrylic acid, a non-biodegradable chemical.

According to the Environment Ministry, disposable diapers accounted for 5.2 percent to 5.4 percent of general waste in fiscal 2020. The ratio is expected to reach 6.6 percent to 7.1 percent by fiscal 2030, given the graying of society.

Uyama’s lab, which has been cooperating with private businesses and other entities to produce biodegradable plastics and films from starch, is using its expertise to tackle the diaper problem.

Researchers from around the world are developing new bioplastics and other articles at the laboratory.

The lab’s objective is to make disposable diapers exclusively from biodegradable ingredients. These diapers could be fully composted instead of being incinerated alongside ordinary trash.

“The problem of waste from paper diapers has emerged as a serious concern in society,” Uyama said. “I hold out hope we can help reduce the volume.”


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