At present, the degradable raw materials in degradable packaging bags on the market are mainly starch-based plastics. Because the cost of starch-based packaging is much lower than that of PLA or PBAT, many manufacturers choose starch-based plastics as raw materials to produce degradable packaging bags.
How is starch-based plastic synthesized?
When starch is used in plastic processing and production, it generally needs to be modified, and then processed or blended with other polymers.
Natural starch can be obtained from the tubers or seeds of plants such as potatoes, tubers, corn, rice, wheat and oats. The starch-based plastic starch used in most degradable packaging bags is mainly corn starch. The composition of corn starch granules mainly includes moisture, ester compounds, nitrogenous substances, ash, phosphorus, etc. The content of amylose is about 26%. The inherent water content is 9%~15%. When remanufacturing the starch base of degradable packaging bags, it is often necessary to treat the starch to improve the following shortcomings of untreated starch: poor compatibility with polyethylene and other polymers; poor dispersion; due to hydrophilicity affecting the finished product Dimensional stability; poor thermal stability, processing temperature can not be higher than 230 ℃, or even lower. There are many starch treatment methods used to produce degradable packaging bags, including simple surface treatment, gelatinization treatment, various denaturation treatments, and graft modification of starch.