They are convenient, water resistant and cheap. These qualities make plastic bags second to none as the packaging of choice for most products. However, they have huge disadvantages especially in how friendly they are to the environment. They are made from non-renewable sources – oil and gas – and they are not biodegradable, as it takes them between 500 and 1,000 years to decompose in natural conditions. Scientists, therefore, have long been trying to create biodegradable plastic (or bioplastic) as a solution.
As part of the country’s efforts to reduce the use of plastic bags, some local companies have imported technologies producing bioplastic from other countries like the United States and Canada for hundreds of thousand of dollars. Recently, research scientists from the Ho Chi Minh City-based University of Sciences have developed a material to make biodegradable plastic bags (or bioplastic bags) with several advantages over the imported ones.
According to the result of a project initiated four years ago, the material not only can degrade fully in land within a short time but also make the cost of bags produced with it much cheaper, says Truong Phuoc Nghia, the group’s leader.
He says the material, known as nanocomposite, is a mix of thermoplastic starch (made from starch), polyvinyl alcohol (PVA), a kind of polymer clay, and some food additives, adding that it is made with nanotechnology.
Associate Professor Ha Thuc Huy, who directs the group, says this allows the material to be fully biodegradable in landfill where microorganisms will eat it up within a short time – between one to six months.
PVA costs less than VND 30,000 (US $1.75) per kilogram if imported in bulk, while polypropylene (PP) and polyethylene (PE), which are components in bioplastic produced with foreign technologies, cost some VND 40,000 ($2.33) per kilogram, according to Nghia. This plus starch from the locally abundant wheat and cassava allows them to produce bags from the material at a much lower cost just 30 percent or so of foreign-produced ones, Nghia says.
Tests have shown that the material’s ductility and elasticity are the same as common plastics. The material, in fact, can become a redoubtable competitor to the common plastic, which is rarely reusable, according to the scientists.
“Nanocomposite bags can be re-used many times, if they do not come into contact with water,” Nghia says. However, Nghia says to make bags from the material, it is necessary to invest in machinery to make it into plastic grains and then process and sharpen it.
Huy, meanwhile, says if the group receives adequate sponsorship to do more research on industrial production, products made of the new material can be launched in the market within a year. A project proposal has been submitted to the HCMC Department of Science and Technology for sponsorship to continue their research, Nghia says. If this does not go through, they may cooperate with a foreign partner, he adds.
Nghia says Vietnam uses about half a million tons of polymer to make plastic bags and the figures is increasing year by year. HCMC residents discard over 6,000 tons of waste a month, up to 7.5 percent of which is made up of plastic bags, according to statistics from the city’s Department of Environment and Natural Resources released last year.
Reprinted with permission from Thanh Nien News Published: 08 January, 2009, 14:29:17 (GMT+7)
Photo caption: The material in the process of degrading after three months in landfill.