A: Compostable biodegradable materials fall into two categories, one being bio-based compostable materials and the other being petroleum-based compostable materials. The bio-based compostable material is further divided into materials directly derived from plants, such as pulp, polylactic acid (PLA), aliphatic polyester (PHA), and blends of natural materials with the above two types of polymers. Petroleum-based compostable materials derived from petroleum, such as polybutylene terephthalate (PBAT), polyethylene glycol (PCL) etc.

A: Compostable biodegradable materials also have drawbacks because they are dependent on composting facilities. The most suitable conditions are 60℃ (40℃ - 80℃ can be), 90% humidity conditions can be quickly degraded. However, in the natural environment, although it can still be completely degraded, it will take at least several years. The degradation time needs to be longer under conditions of low temperature, drought or microbial inactivity.

A: Polylactic acid (PLA) is a polymer obtained by polymerizing lactic acid as a raw material, it takes annually renewable resources–corn, cassava and other plants as raw material. After fermentation by microorganisms, lactic acid will be extracted, then PLA will be produced through a process of refining, dehydration polymerization, high temperature pyrolysis and final polymerization. PLA has excellent biodegradable property. After disposal, within one year, it can be degraded into carbon dioxide and water by microorganisms in the soil, and do no harm to our environment. Polylactic acid products are 100% biodegradable in the composting environment after being discarded, and realize the ecological carbon cycle originating from nature and returning to nature. Therefore, it is an ideal green polymer material.

A: Polylactic acid is a relatively mature and widely used fully biodegradable compostable plastic. In addition to the biodegradable properties, this material has several different features.
One of the important characteristics is that polylactic acid is a safer material for food contact. Its monomer is lactic acid, lactic acid is a food additive, and lactic acid is present in yogurt, cosmetics or condiments. Its own level of safety is safer than that made with petroleum monomers. Moreover, polylactic acid was used as a medical material in the 1960s and 1970s for surgical sutures, fixation of bone rods, etc., and later, because of technological breakthroughs and reduced costs, it entered the ranks of civilian use.
Second, polylactic acid is a biobased material derived from plants. The more commonly used raw materials are corn, cassava and sucrose. The corn, cassava and other crops are extracted into starch, fermented into lactic acid, and then chemically polymerized into polylactic acid, which is a

A: In fact, in addition to composting, compostable materials have other treatments, such as burning. Compared with plastics, the products of complete combustion of polylactic acid are carbon dioxide and water, which are not polluted. It can also be landfilled. Although the degradation rate is relatively slow, it does not pollute the groundwater at least, does not damage the plant growth, and does not waste farmland. Of course, it can be recycled, but the cost of recycling is relatively high.

A: If we really have nothing to eat, it is inevitable to ensure food security in advance. It is impossible to do polymer materials first. But from an objective point of view, this worry is superfluous. I will share several sets of data for you.
Global corn production is 1 billion tons / year, 80% of which is used for feed and fuel, fuel ethanol is burned about 50%, feed is about 30%. It is only about 10% used in food, about 100 million tons. Assume that the PLA production is 2 million tons per year, which is 6 million tons of corn, accounting for 0.6%. Our food production is over-supplied, and there are still 200 million tons of grain in China. In addition to corn, other crops, such as cassava, have an annual global production of 300 million tons, 60% of which is used in industry, not human food. These sets of data are sufficient to demonstrate that the use of plant starch to produce polylactic acid materials does not affect the food industry.

A peer-reviewed Life Cycle Impact Assessment of PLA (polylactic acid) has been published that confirms the low carbon footprint of Total Corbion’s PLA at commercial scale.

While bio-based polylactic acid (PLA) thermoplastic is relatively eco-friendly and easily recyclable, composites such as carbon fiber are much stronger.

Nairobi, 11 March, 2018 – The global fight against plastic pollution comes into sharp focus at the Fourth UN Environment Assembly this month in Nairobi, Kenya, with the launch of three reports each addressing different aspects of, and solutions for, the growing impact of plastics on the world’s marine environments.