来源网址：http://www.rsoau.com 2019-02-28 16:04:25
Entering the new century, more and more serious energy and environmental problems make people realize the seriousness of environmental protection, especially the huge amount of packaging information, the world's major cities are plagued by white waste.
Therefore, the development of packaging materials for degradable plastics is more important. Many countries in the world have done a lot of work in this field and achieved gratifying results.
There are many ways to complete biodegradable data, such as using natural ingredients to process, taking part in starch and other substances in resin to make the data differentiated by bacteria, and developing hydrolyzable polymers.
Composition of biodegradable polymer plastics is actually chemical composition of biodegradable plastics, which mainly includes aliphatic polyesters (PCL), polyamides, polysaccharide copolymers, polylactic acid, etc. Many biodegradable polymer data have been announced, including polylactic acid (PLA), polyvinyl alcohol (PVA), polycaprolactone (PCL) and other polymers.
PLA is polymerized from lactic acid monomers, and lactic acid is produced from starch by special bacteria. PLA is expensive and is mainly used in medicine.
Aliphatic polyesters (such as polycaprolactone PCL) have good biodegradability, excellent compatibility with other widely used plastic resins, but poor heat resistance and physical strength. Aromatic polyesters, such as ethylene terephthalate, have high melting point.
The copolymers can be formed by mixing anhydrous zinc carbonate as catalyst under nitrogen flow. The copolymers prepared by transesterification between polymer chains have excellent biodegradability, heat resistance and mechanical strength.
Polylactide is a kind of biodegradable plastic which can be used as packaging material in recent years. It has broad application prospects. The raw material of polylactide is lactic acid, which has both hydroxyl and carboxyl functional groups in the molecule of lactic acid and has high reactivity.
Polylactic acid can be easily dehydrated and condensed under appropriate conditions. The composition of poly (lactide) includes direct polycondensation and ring opening polymerization of lactide. Biodegradable materials can be prepared from either polylactide or fermented glucose, maltose, sweet cereal juice or potato starch. The compost polylactide is degraded in about a month and can be absorbed by microorganisms in seawater.
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