Raw material explanation of degradable materials

In the new century, more and more serious energy and environmental problems have made people realize the seriousness of protecting the environment, especially the huge amount of packaging materials, and major cities in the world are plagued by white waste. Therefore, the development of degradable plastic packaging materials is even more important. Countries around the world have done a lot of work in this field and achieved gratifying results. There are many ways to realize biodegradable materials, such as processing with natural ingredients; adding starch and other substances to the resin to make the material decomposed by bacteria; developing hydrolyzable polymers.

Synthetic polymer degradable plastics are actually chemically synthesized biodegradable plastics, which mainly include aliphatic polyesters (PCL), polyamides, polysaccharide copolymers, polylactic acid, etc. Many biodegradable synthetic high Molecular materials include polylactic acid (PLA), polyvinyl alcohol (PVA), polycaprolactone (PCL) and other polymers. PLA is polymerized by lactic acid monomer. Lactic acid is transformed into starch by special strains. PLA is expensive and is currently the most important biodegradable material on the market.

Aliphatic polyester (such as polycaprolactone PCL) has good biodegradability, and has good compatibility with other widely used plastic resins, but has poor heat resistance and physical strength. Aromatic polyesters, such as ethylene terephthalate, have a high melting point and high mechanical strength, but are poorly degradable. Using anhydrous zinc carbonate as a catalyst, the copolymer can be synthesized by miscibility under nitrogen flow. This type of copolymer prepared by the indirect transesterification not only has good biodegradability, but also has strong heat resistance and mechanical strength.

Polylactide is a kind of biodegradable plastic that can be used as a packaging material in recent years and has broad application prospects. The raw material of polylactide is lactic acid. The lactic acid molecule has both hydroxyl and carboxyl functional groups, which has high reactivity and is easy to be dehydrated and condensed into polylactic acid under appropriate conditions. The synthesis of polylactide has two methods: direct polycondensation and ring-opening polymerization of lactide. Either synthetic polylactide or fermented glucose, maltose, cereal sweet juice or potato starch can be used to prepare biodegradable materials. The composted polylactide is degraded in about a month and can be absorbed by microorganisms in seawater.

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