Long chain branching polylactic resin and preparation method thereof

Abstract

The invention discloses a long chain branching polylactic resin and a preparation method thereof. In the long chain branching polylactic resin, constitutional repeating units of a main chain and branch chains are lactic acid, wherein branch points on the main chain are tertiary carbon atoms in the lactic acid constitutional repeating units of the main chain. The preparation method comprises the steps of uniformly mixing a solution-mixed aid and a linear polylactic resin, and forming a long chain branching structure through internal melt mixing or double-screw reaction extrusion. The branch chain molecular weight Mb is larger than the entanglement molecular weight Me, the molecular weight is obviously improved, low-frequency end storage modulus G' and zero shear viscosity eta 0 are obviously improved during shear flow, the gel content is less than 1 percent, obvious strain hardening characteristic is shown during extensional flow, the requirement for secondary forming processing is met, and the tensile strength is obviously improved to 64MPa. The resin can be applied to the fields such as foaming, melt spinning and the like, and can be expansively applied to the fields such as foam packaging materials and clothing fibers.

Description

technical field [0001] The invention relates to a long-chain branched polylactic acid resin and a preparation method thereof. Background technique [0002] Polylactic acid (PLA) is a thermoplastic aliphatic polyester polymer material with biodegradable properties and good biocompatibility. PLA is derived from nature and is also known as "corn plastic". After it degrades, it decomposes into water and carbon dioxide. It is an environmentally friendly polymer material with good performance. PLA has excellent performance and is widely used, and has been increasingly used in important fields of the national economy such as packaging materials, clothing fibers, and biomedicine. In recent years, with the continuous decline of its price, the advantages of PLA in terms of performance and price are becoming more and more prominent. At present, it has been considered as a strong competitor to replace traditional petroleum-based polymer materials in the future. In recent years, scient...

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Problems solved by technology

The introduction of long-chain branches can usually be achieved by three methods: direct polymerization, reactive extrusion and high-energy irradiation. The introduction of chain branching structure; high-energy irradiation triggers the chemical reaction of the polymer through electron beam or γ-ray irradiation, and introduces long-chain branching structure through the reshoot combination of chain radicals, which has a pure system and a stable structure of the modified product. Good controllability and other characteristics, but this method requires a large investment in equipment, most of which remain in the laboratory stage, and large-scale continuous industrial production is relatively difficult; the basic principle of the reaction is realized by the chemical reaction of chain free radicals initiated by highly active peroxides , the modification process can be completed in the twin-screw extruder, which has the characteristics of simple operation and continuous production, but the process control is relatively difficult

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