Self-destructing plastic beads from Polyolephin waste and biodegradable packaging

The benefits that plastic materials bring are undeniable. However, along with these benefits, plastic waste after use causes serious problems for the environment. To overcome and solve the above problem, it is necessary to have an effective plastic waste treatment and recycling technology, in parallel with the research to improve plastic materials in the direction of producing biodegradable plastic with short-time decomposition in order to meet the demand for using plastic materials, especially plastic packaging and bags; and at the same time overcome the environmental pollution caused by plastic waste.

In Vietnam, the utilization of waste plastic in combination with oxygen decomposition technology to produce useful products has received little attention. Waste plastic recycling facilities in some craft villages are mainly spontaneous, lack planning, and have outdated equipment and technology, causing environmental pollution and significantly affecting the health of people in the surrounding area.

Stemming from the practical needs of society, along with the requirement to develop methods of recycling and processing plastic waste into useful products, contributing to reducing environmental pollution, the research team of Dr. Trung Duc, Institute of Chemistry, was assigned to carry out the project "Research on technology to produce self-destructing garbage bags from waste plastic".

Waste polyolephin is an abundant source of recyclable material, by using an appropriate oxidation promoter, the polyolephin plastic waste can be completely used as background plastic of the self-destructing polymer films. Self-destructing plastic beads often have reduced physical and mechanical properties compared to primary plastic beads, resulting in the finished film being brittle and easily broken when used. Therefore, the scientists mixed with mLLDPE plastic (metaloxene low-density linear polyethylene) to increase the toughness of the film. Furthermore, by adjusting the total amount of oxidants available in the plastic waste to some specific value, based on the hematological relationship of the autolysis time to the oxidizing promoter concentration, it can be easily to adjust the self-destruction time relatively according to the oxidizing promoter concentration.

Self-destructing waste plastic beads are extruded and processed in a blown extruder to create a film, then welded to create a self-destructing bag. This self-destructing bag is able to be designed to a set self-destructing time.

The project has built the technological process and equipment line for the production of self-destructing garbage bags from waste HDPE plastic at a scale of 30 kg/hour and evaluated their biodegradability according to TCVN standards 9493. Produced 500 kg of 3 types of self-destructing garbage bags (160 kg of blue self-destructing garbage bags, 160 kg of yellow self-destructing garbage bags, 180 kg of black self-destructing garbage bags) with corresponding self-destructing time are 12, 24 and 36 months.  The project's self-destructing garbage bags were granted a certificate of environmentally friendly plastic bags by the General Department of Environment under the Ministry of Natural Resources and Environment, No 74/CN-TCMT on May 28, 2018.

Japan's SJ-45 series single-screw extruded and blown equipment used in the production of self-destructing garbage bags

Photograph of the process of burying samples in the soil, (a): preparing soil samples and bags, (b): placing soil and samples in bags, (c): Burying sample bags in trenches, (d): Filling trenches

Decomposition in the soil

Research results of the project "Process to produce self-destructing plastic beads from waste Polyolephin and self-destructing packing bags made from self-destructing plastic beads" has been granted a patent by the National Property Office of Vietnam for Utility Solution No 2603 April 25, 2021.

Translated by Tuyet Nhung
Link to Vietnamese version

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