A century-old white terror - plastic

Non-degradable plastic products break down into microplastics that harm animal and human health

Plastic bags, bottles, packaging and other plastic products that have not been recycled are inevitably causing serious damage to the natural environment and the survival of wildlife when they are abandoned on land or thrown into the ocean. After being abandoned, plastic products gradually become fragile in nature and begin to decompose slowly due to sunlight exposure, oxidation, physical friction or animal feeding. For non-degradable plastics, the decomposition process will continue forever. The size of the plastic fragments becomes very small as they continue to break down, eventually becoming microplastic forms.

Microplastic substances are not degradable. Because of its extremely small size, it may be dispersed to all corners of nature with weather changes, animal feeding, etc., i.e. into water resources, soil and even into the air, causing direct pollution to the natural environment and also affecting the survival of animals due to intake by wild animals and fish. Scientific studies have proved that microplastics are found in the digestive system of deep-sea fish, and the microplastics in the digestive system may move to the muscle tissue. Some fish with microplastics in their bodies are commonly caught commercially, and microplastics in fish muscle tissue may eventually be ingested by humans. Therefore, non-biodegradable plastic products not only cause serious pollution to the natural environment, but also endanger human health in the form of food chain movement.

Performance comparison of commonly used degradable materials

Starch-based plastics have the lowest overall performance, and the performance of biodegradable plastics is close to that of ordinary plastics

Starch-based plastics with poor mechanical properties and low transparency are the least comprehensive biodegradable materials; PLA (polylactic acid), PHA (polyhydroxy fatty acid ester), PBS (polybutylene succinate), PBAT (polybutylene adipate/butylene terephthalate) and other later developed biodegradable plastics have better performance than starch-based plastics.

For different downstream applications (films, plastic bags, cups, etc.), the heat resistance, mechanical and processing properties of different materials should be considered. Among them, the modulus has a greater impact on the softness and hardness of the material. From the perspective of making hard products, PLA has high hardness and high transparency, and is an ideal material for transparent containers and tubes, but has poor hydrolysis resistance; from the perspective of making soft products, PBAT has the characteristics of both PBA (polybutylene adipate) and PBT (polybutylene terephthalate), and its performance is close to that of traditional petroleum-based plastics, with good ductility and elongation at break. PHA has good degradability and does not require harsh conditions such as industrial composting. From a comprehensive point of view, the performance of PBAT and PLA is close to that of ordinary consumer grade plastics.

Degradable Environmental Conditions

Degradable materials do not form a natural closed loop in nature and can only be fully degraded if certain environmental conditions are met. According to external environmental factors, degradation methods mainly include water degradation, soil degradation and photodegradation, and the degradation time and conditions are different under different methods.

Analysis of the degradation environment of biodegradable materials

In view of the different raw materials and structures, different biodegradable materials degrade in different ways and at different rates under different environmental conditions, which affects the realization and length of the whole life cycle of environmental protection, and thus affects the future prospects of the use of different materials.

According to the relevant research, 83% of the disposable biodegradable plastic products currently on the market are compostable degradable plastics, which need to be degraded under industrial composting conditions, such as PLA and PBS, which cannot be rapidly degraded under natural conditions. However, at present, biodegradable materials in China are in the initial stage, composting plants and other back-end treatment facilities are not popular, and the treatment methods are still mainly landfill and incineration, and effective recycling is not realized.