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Method for controlling crystallization of polylactic acid through alternating electromagnetic field

An alternating electromagnetic field and polylactic acid technology, which is applied in the field of polylactic acid crystallization modification, can solve the problems of affecting molecular chains, limited influence of polylactic acid crystallization, and inability to actively control polymer molecular chains, etc. The effect of low consumption

Inactive Publication Date: 2019-05-28
HUBEI UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

As far as the essence of polymer crystallization is concerned, it is actually the process of molecular chain movement, but conventional inorganic nucleating agents and organic nucleating agents only passively affect the movement of molecular chains, and cannot accurately control the movement of polymer molecular chains. Active control, thus, has limited influence on PLA crystallization

Method used

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  • Method for controlling crystallization of polylactic acid through alternating electromagnetic field
  • Method for controlling crystallization of polylactic acid through alternating electromagnetic field
  • Method for controlling crystallization of polylactic acid through alternating electromagnetic field

Examples

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Effect test

Embodiment 1

[0023] A method for controlling polylactic acid crystallization by an alternating electromagnetic field, the method comprising the steps of:

[0024] (1) Weigh 0.99g of L-polylactic acid (4032D, Nature works, USA) and dissolve it in 10ml of chloroform, add 0.01g of ferric oxide particles (3-10nm) and stir evenly, drop it onto a glass slide to evaporate the solvent, and get Polylactic acid / ferric oxide composite film material;

[0025] (2) Heat the polylactic acid / ferroferric oxide composite material in step (1) to 123°C in an alternating electromagnetic field for crystallization, by adjusting the intensity and frequency of the alternating electromagnetic field (the intensity is 0~0.64mT; ~200 Hz) to control the isothermal crystallization behavior of PLA at 123 °C. First, the frequency is controlled to 165 Hz, and the intensity of the alternating magnetic field is adjusted between 0 and 0.64 mT to obtain the isothermal crystal POM photo of polylactic acid at 123 °C; then the m...

Embodiment 2

[0029] A method for controlling polylactic acid crystallization by an alternating electromagnetic field, the method comprising the steps of:

[0030] (1) Weigh 0.97g of L-polylactic acid and dissolve it in 10ml of chloroform, add 0.03g of iron ferric oxide particles (3~10nm) and stir evenly, drop it onto a glass slide to evaporate the solvent, and obtain polylactic acid / ferric iron tetroxide composite materials;

[0031] (2) Heat the polylactic acid / ferroferric oxide composite material in step (1) to 123°C in an alternating electromagnetic field to crystallize for 30 minutes, adjust the strength of the alternating electromagnetic field to 0.16 millitesla and the frequency to 165 Hz to control the polylactic acid crystallization behavior.

[0032] Test its crystallinity by DSC method, the results are shown in Table 1 and Figure 4 .

[0033] The TEM photograph that this embodiment prepares composite material sees image 3 , it can be seen from the figure that ferric oxide i...

Embodiment 3

[0035] A method for controlling polylactic acid crystallization by an alternating electromagnetic field, the method comprising the steps of:

[0036] (1) Weigh 97g of racemic polylactic acid, add 3g of ferric oxide particles (3-10 nanometers) and stir evenly, and melt, blend and extrude on a twin-screw extruder to obtain polylactic acid / ferric oxide composite material;

[0037](2) The obtained polylactic acid / iron tetroxide composite material was heated to 123°C in an alternating electromagnetic field for crystallization for 30 minutes, and the intensity of the alternating electromagnetic field was adjusted to 0.48 millitesla and the frequency was 130 Hz to control the crystallization behavior of polylactic acid .

[0038] Test its crystallinity by DSC method, the results are shown in Table 1 and Figure 4 .

[0039] The DSC result of table 1 embodiment 1~3

[0040]

[0041] The following conclusions can be drawn from the above examples: the size and crystallinity...

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Abstract

The invention discloses a method for controlling the crystallization of polylactic acid through an alternating electromagnetic field and belongs to the technical field of polylactic acid crystallization modification. The method comprises the following steps: firstly, uniformly dispersing ferroferric oxide particles into the polylactic acid by adopting a solution blending or melt blending method, so as to obtain a polylactic acid / ferroferric oxide composite material; then putting a polylactic acid / ferroferric oxide composite material sample into the alternating electromagnetic field and carrying out heat insulation and crystallization; the movement of a polylactic acid molecular chain can be accurately controlled through controlling the frequency and strength of the alternating electromagnetic field, so that the crystallization morphology and the crystallization degree are controlled, and cannot be controlled through other methods for regulating the crystallization of the polylactic acid; furthermore, the strength of the electromagnetic field needed by the method is low and the method hopefully becomes one method which is widely used for controlling the crystallization of polymers.

Description

technical field [0001] The invention relates to the technical field of polylactic acid crystallization modification, in particular to a method for controlling polylactic acid crystallization through an alternating electromagnetic field. Background technique [0002] Polylactic acid (PLA), also known as polylactide, has excellent renewability, biodegradability, biocompatibility, processability and environmental friendliness. It is increasingly used in petroleum resource consumption and environmental pollution. At present, polylactic acid has attracted the attention of researchers. Due to the difference in the optical activity of lactic acid, there are three stereo configurations of polylactic acid synthesized: D-polylactic acid (PDLA), L-polylactic acid (PLLA), and poly-lactamic lactic acid (PDLLA). The common PLLA is a semi-crystalline polymer whose crystalline T m The temperature is 160-180°C, the slow crystallization rate and low crystallinity make the heat resistance a...

Claims

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Application Information

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IPC IPC(8): C08J3/00C08L67/04C08K3/22
Inventor 龚兴厚王博成程成
Owner HUBEI UNIV OF TECH
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