Views:18 Author:Site Editor Publish Time: 2019-11-18 Origin:Site
4 Things You Should Know About Biodegradable Plastics
The emergence of biodegradable plastics is seen as a tool to deal with plastic pollution, especially the environmental pollution of plastic food contact materials such as disposable straws. “Automatically disappear without treatment” is a general perception or expectation of biodegradable plastics.
However, in November 2015, the United Nations Environment Program published the report “Biodegradable Plastics and Marine Waste: Misunderstandings, Concerns and Impacts on the Marine Environment”, calling for the elimination of misunderstandings caused by “biodegradable plastics” labels. The widespread use of products labeled with "biodegradable" labels does not significantly reduce the amount of plastics entering the ocean or reduce the physical and chemical risks of plastics to the ocean. Food plastic packaging labeled "degradable", "100% degraded", etc. is easily misunderstood by consumers, resulting in increased behavior of random purchase and disposal, which may exacerbate the problem of plastic contamination.
In April 2019, "Environmental Science & Technology" published a recent study by the University of Plymouth, UK, which indicated that some biomarkable plastic bags could still be used after three years of placement under different natural environmental conditions; Oxo-degradable or biodegradable plastic bags do not show better degradation than traditional plastic bags. The article has once again triggered concerns about the role of biodegradable plastics. The European Bioplastics Association, which represents the industry, questioned the scientific nature of the study and claimed that the study misled the value of biodegradable plastics and compostable plastics.
The biodegradable packaging bag can be used normally after 3 years of seawater immersion.
It is true that the role of biodegradable plastics in the control of plastic pollution has been debated for a long time. In addition to the uncertainties of policies, unsound standards, and disputes in scientific research, the public and industry who with unclear and chaotic concepts to biodegradable plastics are also an important cause, resulting in misuse, misuse of biodegradable signs, and even false publicity. Some typical misunderstandings include:
Equivalent to biobased plastics as biodegradable plastics;
Biodegradable is considered to be fully biodegradable;
Biodegradable under industrial composting conditions is considered to be biodegradable in the natural environment.
1. Is bio-based plastic a biodegradable plastic?
Not all bio-based plastics a biodegradable plastic! Some bio-based plastics are biodegradable plastics, and some are not.
Biobased plastics are plastics produced under the action of microorganisms based on natural substances such as starch. Biomass for bio-based plastic synthesis can be derived from corn, sugar cane or cellulose
Biodegradable plastics is defined under natural conditions (such as soil, sand, seawater, etc.) or under specific conditions (such as composting conditions, anaerobic digestion conditions or aqueous culture fluids), by microorganisms (such as Bacteria, molds, fungi, algae, etc.,) which cause degradation, and eventually completely degrade into carbon dioxide, water, methane, mineralized inorganic salts and new materials.
So bio-based plastics are defined and divided based on the origin of material; biodegradable plastics are classified from the perspective of end of life. In other words, 100% bio-based plastics may not be biodegradable, such as bio-based-PET and bio-based-PE, and their chemical structure is same as traditional petroleum-based PET or PET; some traditional petroleum-based plastics can be biodegradable, such as polybutylene terephthalate (PBAT) and polycaprolactone (PCL).
2. Is degradable same as biodegradable?
Plastic Degradation refers to the process of significant changes in structure and loss of performance under the influence of environmental conditions (temperature, humidity, moisture, oxygen, etc.). Specifically, it can be divided into mechanical degradation, bio degradation, photo degradation, thermal oxygen degradation and photo-oxidation degradation.
Whether a certain plastic will completely biodegrade is affected by many factors, including crystallinity, additives, microorganisms, temperature, humidity, pH and time. In the absence of these conditions, many degradable plastics are not only unable biodegrade completely, but may also have a negative impact on the environment and human health. For example, Oxo-degradable plastics, under the action of additives, only break up the material and degrade into plastic particles that are invisible by eye.
3. Compostable plastic = biodegradable plastic?
No! compostable plastics are a class of biodegradable plastics. Biodegradable plastics also include plastics that can be biodegraded in an anaerobic manner.
Compostable Plastics refers to plastics that can be converted into carbon dioxide, water, mineralized inorganic salts and new biomass in a certain period of time under the conditions of composting. And finally, heavy metal content, toxicity test, residual debris, etc (which they degrade) should pass the relevant standards. Compostable plastics can be further divided into industrial compost and home compost. Most of the compostable plastics on the market today are biodegradable plastics under industrial composting conditions.
Because compostable plastics are biodegradable under certain conditions, if the compostable plastics are discarded in the natural environment (such as seawater, mud), these plastics degrade very slowly in the natural environment and cannot be completely degraded into carbon dioxide and water, etc in a short time. its adverse effects on the environment are same as traditional plastics. In addition, Research have indicated that biodegradable plastics, such as those incorporated into other recyclable plastics, can degrade the properties of the recycled materials. For example, starch in polylactic acid may cause defects such as pores and spots in the film made of recycled plastic.
4. How to regulate the identification of biodegradable plastics?
There are no mandatory standards or regulations for biodegradable plastics in China. The relevant standard is GB/T20197-2006 "Definition, Classification, Marking and Degradation Performance Requirements for Degradable Plastics", which stipulates that the degradable plastic mark should contain the main raw materials and composition information of the product, the degradation type or degradation mode of the plastic. And the standard number. The requirements of the GB/T 20197 standard for identification do not refer to the identification mark, the degradation evaluation standard number, whether it can be recycled, etc.
The European Bioplastics Association recommends in its published guidelines that when a product claims to be biodegradable, the product should state what degradation criteria (certification instructions and labeling) it meets, when it can be completely degraded, and state its location/condition of the degradation process. In North Carolina and Alabama of the United States, in 2013 (HB 315, Senate Bill 298): plastic products marked with degradable, biodegradable or compostable should be marked as "non-recyclable, not recycled" to avoid Mix in other recyclable plastic products. The figure below shows a standard degradable logo.
Faced with the challenge of environmental hazards of plastic waste and marine micro-plastics, the application of biodegradable plastics in food contact materials has been more and more respected and concerned. China's biodegradable food contact materials industry is facing a good development prospect. However, biodegradable plastics are not a panacea for solving plastic pollution. Responsible use can play its advantages and functions. Clear definition of biodegradable plastics, standard labeling, and effective public education are key measures to promote the healthy development of biodegradable food packaging industry, develop circular economy, and promote effective treatment of plastic pollution.
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