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Method for rapidly forming polylactic acid stereocomplex

A technology of stereocomplexes and polylactic acid, applied in the field of rapid formation of polylactic acid stereocomplexes, can solve problems such as inability to eliminate polylactic acid homogeneous crystals, inability to suppress polylactic acid homogeneous crystals, and low rate of stereocomplexes , to achieve the effect of fast speed, strong mobility and small size

Active Publication Date: 2015-09-23
JIANGNAN UNIV
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  • Abstract
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Problems solved by technology

Patent JP2003192884 effectively increases the formation rate of polylactic acid stereocomplexes by adding a phosphate metal salt, but this nucleating agent cannot inhibit the appearance of polylactic acid homogeneous crystals
Patent JP189888327A prepares polylactic acid stereocomplex by blending polylactic acid stereoblock copolymer and xylylene bisstearyl urea, which can increase the rate and content of stereocomplex formation, but cannot eliminate polylactic acid homogeneity. quality crystal
[0005] The above patents mostly use the method of adding talcum powder or metal compounds to L-PLA and D-PLA to promote the formation of stereocomplexes. These methods introduce non-bio-based and non-biodegradable components to a certain extent. Even metal ions, and the resulting stereocomplex has a small rate and low content of stereocomplex after melting, thus limiting its application range

Method used

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  • Method for rapidly forming polylactic acid stereocomplex
  • Method for rapidly forming polylactic acid stereocomplex
  • Method for rapidly forming polylactic acid stereocomplex

Examples

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Embodiment 1

[0041] A method for rapidly forming a polylactic acid stereocomplex, the method comprising the following steps:

[0042] (1) Dissolve D-polylactic acid and nanocellulose-grafted L-polylactic acid with a comb-like structure in chloroform at room temperature according to a weight ratio of 33:67 to obtain a mixture; The optical purity of lactic acid is 99%;

[0043] (2) removing the solvent from the mixture at 40° C. to obtain a polylactic acid / cellulose nanocomposite material, that is, to obtain the polylactic acid stereocomplex of the present invention;

[0044] Gained polylactic acid stereocomplex DSC cooling process crystallization curve and the XRD spectrogram after crystallization are as follows image 3 As shown, the crystallization curve of the polylactic acid stereocomplex at 175°C in the DSC isothermal process is shown in Figure 4 , the polarizing microscope photo of isothermal crystallization of polylactic acid stereocomposite at 175°C Figure 5 As shown, the atomi...

Embodiment 2

[0056] A method for rapidly forming a polylactic acid stereocomplex, the method comprising the following steps:

[0057] (1) Dissolve D-polylactic acid and nanocellulose-grafted L-polylactic acid with a comb-like structure in chloroform at room temperature according to a weight ratio of 30:70 and stir thoroughly to obtain a mixture; The optical purity of lactic acid is 99.5%;

[0058] (2) removing the solvent from the mixture at 40° C. to obtain a polylactic acid / cellulose nanocomposite material, that is, to obtain the polylactic acid stereocomplex of the present invention;

[0059] refer to figure 1 , the preparation method of the nanocellulose grafted L-polylactic acid is:

[0060] (1) first nanocellulose and L-lactide are uniformly dispersed in xylene respectively according to the weight ratio of 1:25, and the solution is blended to obtain a uniform mixture;

[0061] (2) Add catalyst tin protochloride (1.5% for the weight fraction of L-lactide) in the mixture again, reac...

Embodiment 3

[0065] A method for rapidly forming a polylactic acid stereocomplex, the method comprising the following steps:

[0066] (1) Dissolve the L-polylactic acid and the nanocellulose-grafted D-polylactic acid with a comb-like structure in a weight ratio of 40:60 at room temperature in dichloromethane to obtain a mixture; The optical purity of polylactic acid is 98%;

[0067] (2) removing the solvent from the mixture at 50° C. to obtain a polylactic acid / cellulose nanocomposite material, that is, to obtain the polylactic acid stereocomplex of the present invention;

[0068] The preparation method of the nanocellulose grafted D-polylactic acid is:

[0069] (1) first nanocellulose and D-lactide are uniformly dispersed in xylene respectively according to the weight ratio of 1:25, and the solution is blended to obtain a uniform mixture;

[0070] (2) Add the catalyst stannous octoate (3% of the weight fraction of D-lactide) in the mixture again, the reaction temperature is 80 DEG C, re...

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Abstract

The invention discloses a method for rapidly forming a polylactic acid stereocomplex. The method comprises the following steps of performing solution mixing on poly-D-lactic acid and nanocellulose-grafted poly-L-lactic acid with a comb structure or on poly-L-lactic acid and poly-D-lactic acid with a comb structure in parts by weight, and removing a solvent to prepare the polylactic acid stereocomplex. A high-content polylactic acid stereocomplex can be rapidly formed at 130 to 200 DEG C after the stereocomplex is molten at 230 to 260 DEG C, the components of the polylactic acid stereocomplex are renewable resources, and the method is simple in process and easy to industrialize.

Description

technical field [0001] The invention relates to the technical field of polymer materials, in particular to a method for grafting left-handed (right-handed) polylactic acid with nano-cellulose to rapidly form a polylactic acid stereocomplex through a blending and melting process. Background technique [0002] Polylactic acid is a renewable biodegradable material. Due to its non-toxic, degradable and renewable characteristics, it meets the requirements of environmental protection and sustainable development, so it has attracted extensive attention. However, the heat resistance of polylactic acid is poor, the crystallization rate is slow, and the crystallinity is low. The heat distortion temperature of the product obtained by injection molding is only about 55°C, which greatly limits the application range of polylactic acid. The polylactic acid stereocombination technology developed in recent years has opened up a new direction for the improvement of the physical and mechanical...

Claims

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Application Information

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IPC IPC(8): C08L67/04C08L1/08C08G63/664C08B15/06
Inventor 马丕明蒋龙禹子骅余鳗漫吕培东为富陈明清
Owner JIANGNAN UNIV
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