Can degradable plastic bags be completely degraded?
With the increasing popularity of "plastic reduction order", it is proposed that "degradable plastic" can be used as an alternative material in the future. So, can degradable plastic bags be completely degraded?
First of all, according to the different materials and characteristics, we can simply divide the common plastics into the following four types. We often say "degradable plastics" mainly refers to the general term of "bio based biodegradable plastics".
Among these "degradable plastics", polylactic acid (PLA) is the most common. PLA is polymerized from lactic acid produced by starch fermentation, and the raw materials are from plants. Compared with other degradable materials, the production technology of PLA is more mature and the cost is lower, so it is often mistaken as an excellent environmental protection material.
However, the biodegradability of PLA needs to meet two conditions: 50% - 60% humidity and 50-70 ℃ temperature. Under these conditions, it is possible for microorganisms to decompose PLA gradually after several months or even longer. However, it is difficult for the natural environment to reach the necessary temperature for degradation. If PLA plastic bags are discarded at will, they cannot be degraded.
In addition, studies have shown that the degradation rate of PLA in fresh water and seawater is almost the same as that of ordinary plastics. The European Plastics Association also said that biodegradable plastics cannot be considered more environmentally friendly than traditional non biodegradable plastics. If the degradation conditions are not met, there is no difference between "degradable plastics" and ordinary plastics, which will also pollute the ocean and water.