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Method for improving foaming rate of polylactic acid through pre-isothermal cold crystallization treatment

A polylactic acid foaming and isothermal treatment technology, applied in the field of polymer material processing, can solve problems such as poor melt strength and slow crystallization, and achieve the effects of improving foaming performance, simple process and increasing foaming ratio.

Active Publication Date: 2018-08-17
SHANDONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In view of the problems of slow crystallization and poor melt strength of polylactic acid, the present invention increases the crystallization point and crystallinity in the matrix through pre-isothermal cold crystallization treatment, ensures that more ordered structures are retained in the subsequent saturation process, and forms physical entanglements. network, improve the melt viscoelasticity, and then increase the expansion ratio of polylactic acid

Method used

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  • Method for improving foaming rate of polylactic acid through pre-isothermal cold crystallization treatment
  • Method for improving foaming rate of polylactic acid through pre-isothermal cold crystallization treatment
  • Method for improving foaming rate of polylactic acid through pre-isothermal cold crystallization treatment

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Embodiment 1

[0044] Embodiment 1: the preparation of the pure PLA foaming material of pre-isothermal cold crystallization treatment

[0045] Pure polylactic acid (4032D, Natureworks) particles were dried in a vacuum oven. Using a twin-screw extruder, the dried polylactic acid particles were extruded and air-cooled to prepare an extrusion sample with a diameter of about 3.5 mm. First heat the autoclave to 80°C, then place a certain length of the extruded sample in the autoclave, wait for 15 minutes at the same temperature, and perform pre-isothermal cold crystallization treatment; then take out the sample and quickly place it in ice water to cool; Continue heating the autoclave to 137 °C, and place the treated sample in the autoclave, using low-pressure CO 2 Purging the autoclave, and sealing; filling the CO with a saturation pressure of 2500psi 2 , constant temperature and pressure for 50 minutes; quickly release the pressure, and place the autoclave in ice water to cool and set the shap...

Embodiment 2

[0046] Embodiment 2: the preparation of the pure PLA foaming material of pre-isothermal cold crystallization treatment

[0047] Pure polylactic acid (4032D, Natureworks) particles were dried in a vacuum oven. Using a twin-screw extruder, the dried polylactic acid particles were extruded and air-cooled to prepare an extrusion sample with a diameter of about 3.5 mm. A certain length of the above-mentioned extruded sample was placed in an autoclave, using low-pressure CO 2 Purge the autoclave and seal it; heat the autoclave to 90°C and wait for 15 minutes for pre-isothermal cold crystallization; then continue to heat to 137°C and fill it with CO with a saturation pressure of 2500psi 2 , constant temperature and pressure for 50 minutes; quickly release the pressure, and place the autoclave in ice water to cool and set the shape. The expansion ratio of the polylactic acid foam material obtained after foaming is about 17.7 times, the average cell size is about 18.0 μm, and the cel...

Embodiment 3

[0048] Embodiment 3: the preparation of the pure PLA foaming material of pre-isothermal cold crystallization treatment

[0049] Pure polylactic acid (4032D, Natureworks) particles were dried in a vacuum oven. Using a twin-screw extruder, the dried polylactic acid particles were extruded and air-cooled to prepare an extrusion sample with a diameter of about 3.5 mm. First heat the autoclave to 100°C, then place a certain length of the extruded sample in the autoclave, wait for 15 minutes at the same temperature, and perform pre-isothermal cold crystallization treatment; then take out the sample, and quickly cool it in ice water; Continue heating the autoclave to 137 °C, and place the treated sample in the autoclave, using low-pressure CO 2 Purging the autoclave, and sealing; filling the CO with a saturation pressure of 2500psi 2 , constant temperature and pressure for 50 minutes; quickly release the pressure, and place the autoclave in ice water to cool and set the shape. The...

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Abstract

The invention relates to a method for improving the foaming rate of polylactic acid through pre-isothermal cold crystallization treatment. The method comprises the following steps: (1) preparing polylactic acid or a blend thereof into an amorphous or low-crystalline blank through melt-extruding or hot-pressing; (2) performing pre-isothermal cold crystallization treatment on the blank to obtain a pre-isothermal treatment specimen with certain crystallinity degree and crystallization morphology; (3) performing high-pressure gas swelling and penetrating on the pre-isothermal treatment specimen, and relieving pressure quickly to prepare a foam material. According to the method for improving the foaming rate of the polylactic acid through the pre-isothermal cold crystallization treatment, the technical difficult problems that semi-crystalline polylactic acid melt is low in strength, poor in foamability and low in foaming rate can be effectively solved; a foam structure of a polylactic acidfoaming material is regulated and controlled; moreover, the process is simple; the process is green; the cost is low; the application field of the polylactic acid foaming material can be further expanded.

Description

technical field [0001] The invention belongs to the field of polymer material processing, and in particular relates to a method for increasing the expansion ratio of polylactic acid through pre-isothermal cold crystallization treatment. Background technique [0002] Polymer foam materials have excellent properties such as light weight and material saving, high specific strength, shock absorption and buffering, heat insulation and sound absorption, and high-efficiency adsorption, so they are widely used in automobiles, home appliances, packaging, construction, medicine, aerospace and other fields. However, most of the existing polymer foam materials use petroleum-based plastics such as polystyrene, polypropylene, and polyethylene as the matrix. The large-scale use of these materials will not only consume petroleum resources, but also cause serious depletion of petroleum resources. It is easy to cause ecological and environmental problems such as white pollution. Therefore, i...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08J3/00C08J9/12C08L67/04
CPCC08J3/00C08J9/122C08J2367/04C08J2203/06C08J2201/03C08J2205/044
Inventor 赵国群李博
Owner SHANDONG UNIV