CN109810260A - A method of polylactic acid crystal is controlled by alternating electromagnetic field - Google Patents
A method of polylactic acid crystal is controlled by alternating electromagnetic field Download PDFInfo
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- CN109810260A CN109810260A CN201810939152.6A CN201810939152A CN109810260A CN 109810260 A CN109810260 A CN 109810260A CN 201810939152 A CN201810939152 A CN 201810939152A CN 109810260 A CN109810260 A CN 109810260A
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Abstract
The invention discloses a kind of methods for controlling polylactic acid crystal by alternating electromagnetic field, belong to polylactic acid crystal technical field of modification.Method includes the following steps: evenly spreading in polylactic acid using solution blending or melt-mixing method by ferroso-ferric oxide particle first and obtaining polylactic acid/ferriferrous oxide composite material；Then polylactic acid/ferriferrous oxide composite material sample is placed on to keep the temperature in alternating electromagnetic field and is crystallized, by the frequency and intensity for controlling alternating electromagnetic field, it may be implemented to be accurately controlled polylactic acid molecule chain movement, and then control crystallization shape, crystallinity, this is that the method that other adjust polylactic acid crystal is not accomplished, in addition, magnetic field strength required for this method is low, a kind of method for promising to be widely applied control polymer crystallization.
Description
Technical field
The present invention relates to polylactic acid crystal technical field of modification, and in particular to one kind controls polylactic acid by alternating electromagnetic field
The method of crystallization.
Background technique
Polylactic acid (polylactic acid, PLA) is also known as polylactide, and there is excellent reproducibility, biology can drop
Xie Xing, biocompatibility, machinability and environment friendly, petroleum resource consumption is continuously increased, environmental pollution is got worse
Instantly, polylactic acid is paid close attention to by researcher.Since the difference synthesizing polylactic acid of lactic acid optical activity is there are three types of spatial configuration: dextrorotation
Polylactic acid (PDLA), l-lactic acid (PLLA), ploy DL lactic caid (PDLLA).Common PLLA is a kind of hemicrystalline high score
Son, crystalT mIt is 160-180 DEG C, crystalline rate is slow and crystallinity is low etc. keeps its heat resistance and mechanical performance poor, limits
The extensive use of PLA.In order to solve this problem, it is adjusted about PLA crystallization condition, out-phase induction nucleation, molecular chain structure etc.
The research of control means is always the hot spot of polymer crystallization research field.
It is formed for the nucleus during polylactic acid crystal with two stages of crystal growth, the method for accelerating its crystallization is main
Have, first is that heterogeneous nucleation agent is added, reduces the free energy barrier of nucleating surface, promote its rapid crystallization in the cooling condition；Second is that plus
Enter plasticizer, improve strand migration, reduces energy required for chain folding in crystallization process.Although plasticizer can promote
Polylactic acid crystal, but the effect is unsatisfactory, and a large amount of additions of plasticizer, so that the mechanical strength of polylactic acid and modulus are substantially
Degree reduces.In contrast, addition heterogeneous nucleation agent is method maximally efficient and economical and practical in polylactic acid crystal regulation.It is common
Nucleating agent can be divided into two classes: inorganic nucleator and organic nucleating agent.Inorganic nucleator mainly has talcum powder, calcium sulfate, carbon
Sour calcium, titanium dioxide, barium sulfate and montmorillonite etc.；Organic nucleating agent mainly has fatty acid amide, stearmide, benzoyl hydrazine
Compound and biodegradable high molecular material (such as polyglycolide, poly 3-hydroxy butyrate, polycaprolactone) etc..It is just poly-
It is in fact exactly the process of molecular chain movement for the essence for closing object crystallization, but the inorganic nucleator of routine, organic nucleating agent are all only
It is the movement for passively influencing strand, accurate active control can not be carried out to the movement of polymer molecular chain, thus, to poly-
The influence of lactic acid crystallization is very limited.
Ferroso-ferric oxide (Fe3O4) belong to inverse spinel structure in cubic system, due to special magnetic conductance tropism,
Superparamagnetism can also be used as the heterogeneous nucleation agent of polylactic acid.Alternating electromagnetic field (hereinafter electromagnetic field) is by alternating current
The magnetic field of generation.Intensity, direction and the frequency of variation of induced magnetic field can be controlled by changing input current.If will
The nFe3O4 of superparamagnetic is put into electromagnetic field, it will generate vibration, and the frequency and intensity of vibration can be defeated by electromagnetic field
The size and frequency of the alternating current entered and easily control.Further, if nFe3O4/ polymer composites are put into electricity
In magnetic field, the nFe of vibration3O4Polymer molecular chain will be made to generate forced vibration.It is known that when external force frequency compares chain
When the inverse of section sports relaxation time is much smaller (ω≪1/τ), sub-chain motion gets caught up in the variation of alternation external force completely, usual
Suitable polymer crystallization at a temperature of, sub-chain motion is the (electromagnetism for getting caught up in the variation for the alternation external force that we use completely
The frequency range of field is 50-500Hz, by taking PLLA as an example: at 80 DEG C, according to the 1/ of the PLLA segment of WLF equation calculationτIt is 7.5
×104Hz, and at 100 DEG C, 1/τThen it is up to 5.2 × 107Hz), that is to say, that the movement of strand can be with nFe3O4Vibration
The variation of frequency and intensity and change, do not lag, in this way, we can adjust electromagnetic field parameters control polymer point
The size (being controlled by electromagnetic field intensity) and frequency (being controlled by electromagnetic field frequency) of son movement, and then study different molecular chain movement
Influence of the mode to polymer Isothermal crystallization behavior.Energy of electromagnetic field required for present invention regulation polymer crystallization is low, favorably
In realization greenization production.
Summary of the invention
The present invention is in order to improve the mechanical property of existing polylactic acid, and overcomes the shortcomings of its crystalline modified technology, uses
While nano ferriferrous oxide filling-modified polylactic acid, using the crystallization behavior of alternating electromagnetic field control polylactic acid, to obtain
Obtain polylactic acid/ferriferrous oxide composite material that crystallinity, crystallization shape, mechanical property are well combined.
To achieve the above object, the present invention is realized by following measures:
A method of polylactic acid crystal being controlled by alternating electromagnetic field, this method comprises the following steps:
(1) ferroso-ferric oxide particle is distributed in polylactic acid using solution or melt-mixing method, obtains polylactic acid/tetra- oxidations
Three iron composite materials, wherein mass percent of the ferroso-ferric oxide particle in polylactic acid/ferriferrous oxide composite material is 1-
3%；
(2) polylactic acid/ferriferrous oxide composite material prepared by step (1) is warming up to 80-170 in alternating electromagnetic field
It DEG C is crystallized, and the frequency and intensity by controlling alternating electromagnetic field control the crystallization of polylactic acid, the frequency of Electromagnetic Field
Rate is 50 ~ 500 hertz, and intensity is 0 ~ 5 milli tesla.
Preferably, a kind of method that polylactic acid crystal is controlled by alternating electromagnetic field as described above, four in step (1)
The partial size of Fe 3 O nanoparticle is 3 ~ 10 nanometers.
Preferably, a kind of method that polylactic acid crystal is controlled by alternating electromagnetic field as described above, it is poly- in step (1)
Lactic acid is any one of l-lactic acid, racemic polylactic acid.
Compared with prior art, the present invention has the following advantages:
(1) the accurate control of active, conventional nucleating agent can be carried out to the molecular chain movement of polylactic acid by alternating electromagnetic field
Strand crystallization behavior can only passively be influenced.
(2) cheap and easy to get as the ferroso-ferric oxide of magnetic fillers, the alternating magnetic field intensity of control ferroso-ferric oxide vibration
Small, low energy consumption, is advantageously implemented greenization production.
(3) parameters such as the morphology and size of polymer crystallization, crystallinity can easily be controlled, this is that other methods are done
Less than.
(4) it has broad application prospects and promotional value to the use scope for expanding polylactic acid.
Detailed description of the invention
Fig. 1 is the POM photo that 1 gained polylactic acid of embodiment/ferroso-ferric oxide crystallizes in alternating electromagnetic field.
Fig. 2 be 1 gained polylactic acid of embodiment/ferroso-ferric oxide frequency be 165 hertz, 0.64 mT of intensity, observe temperature
Alternating electromagnetic field schemes the POM that spherocrystal pattern influences when changing between 110 ~ 130 DEG C.
Fig. 3 is that 2 gained ferroso-ferric oxide particle of embodiment is dispersed in TEM photo in polylactic acid.
Fig. 4 is the DSC heating curve of embodiment 1, embodiment 2, embodiment 3.
Specific embodiment
Below in conjunction with attached drawing, embodiments of the present invention is further illustrated, to make the purpose of the present invention, technical solution and excellent
Point is clearer, below technical solution in the present invention be clearly and completely described, it is clear that described embodiment is this
Invention a part of the embodiment, instead of all the embodiments.Based on the embodiments of the present invention, those of ordinary skill in the art exist
Every other embodiment obtained under the premise of creative work is not made, shall fall within the protection scope of the present invention.
Embodiment 1
A method of polylactic acid crystal being controlled by alternating electromagnetic field, this method comprises the following steps:
(1) it weighs 0.99g l-lactic acid (4032D, U.S. Nature works) to be dissolved in 10 milliliters of chloroforms, 0.01g is added
Ferroso-ferric oxide particle (3 ~ 10 nanometers) stirs evenly, and drips to solvent flashing on glass slide, it is multiple to obtain polylactic acid/ferroso-ferric oxide
Close thin-film material；
(2) polylactic acid/ferriferrous oxide composite material of step (1) 123 DEG C are warming up to crystallize in alternating electromagnetic field,
By the intensity and frequency of adjusting alternating electromagnetic field, (intensity is 0 ~ 0.64mT；Frequency is 60 ~ 200 hertz) exist to control polylactic acid
Isothermal crystallization behavior at 123 DEG C.Control frequency is 165 hertz first, adjusts alternating magnetic field intensity and becomes between 0 ~ 0.64 mT
Change, obtains isothermal crystal POM photo of the polylactic acid at 123 DEG C；Then control magnetic field strength is 0.48 milli tesla, control frequency
Rate changes between 60 ~ 200 hertz, obtains the POM photo of isothermal crystal 30min of the polylactic acid at 123 DEG C.What test obtained
POM photo is as shown in Figure 1.
Controlling alternating magnetic field frequency is 165 hertz, 0.64 mT of intensity, magnetic when observation temperature changes between 110 ~ 130 DEG C
Influence of the field to spherocrystal pattern, as a result as shown in Figure 2.
The crystallinity under different electromagnetic field parameter is tested by DSC method, crystallinity X a when without externally-applied magnetic field；165
The crystallinity X b of 30min is crystallized under hertz, 0.64 milli tesla in 123 DEG C；165 hertz, tie in 123 DEG C under 0.16 milli tesla
The crystallinity Xc of brilliant 30min the results are shown in Table 1 and Fig. 4.
Embodiment 2
A method of polylactic acid crystal being controlled by alternating electromagnetic field, this method comprises the following steps:
(1) it weighs 0.97g l-lactic acid to be dissolved in 10 milliliters of chloroforms, be added 0.03g ferroso-ferric oxide particle (3 ~ 10 nanometers)
It stirs evenly, drips to solvent flashing on glass slide, obtain polylactic acid/ferriferrous oxide composite material；
(2) polylactic acid/ferriferrous oxide composite material of step (1) is warming up to 123 DEG C of crystallizations in alternating electromagnetic field
30min, the intensity for adjusting alternating electromagnetic field is 0.16 milli tesla and frequency is the crystallization behavior of 165 hertz of control polylactic acid.
Its crystallinity is tested by DSC method, the results are shown in Table 1 and Fig. 4.
The TEM photo that the embodiment prepares composite material is shown in Fig. 3, by figure it can be seen that ferroso-ferric oxide divides in polylactic acid
It dissipates uniform.
Embodiment 3
A method of polylactic acid crystal being controlled by alternating electromagnetic field, this method comprises the following steps:
(1) 97g racemic polylactic acid is weighed, 3g ferroso-ferric oxide particle (3 ~ 10 nanometers) are added and stir evenly, in twin-screw extrusion
Melt blending squeezes out on machine, obtains polylactic acid/ferriferrous oxide composite material；
(2) it polylactic acid/ferriferrous oxide composite material will be obtained is warming up to 123 DEG C in alternating electromagnetic field carrying out crystallization 30min,
The intensity for adjusting alternating electromagnetic field is 0.48 milli tesla and frequency is the crystallization behavior of 130 hertz of control polylactic acid.
Its crystallinity is tested by DSC method, the results are shown in Table 1 and Fig. 4.
The DSC result of 1 embodiment 1 ~ 3 of table
| Crystallization temperature (DEG C) | Melting peak temperature (DEG C) | Crystallization enthalpy (J/g) | Crystallinity (%) | |
| Embodiment 1-Xa | 123 | 166 | 41.3 | 45.1 |
| Embodiment 1-Xb | 123 | 165 | 36.7 | 40.6 |
| Embodiment 1-Xc | 123 | 166 | 56.8 | 60.2 |
| Embodiment 2 | 123 | 166 | 57.2 | 61.3 |
| Embodiment 3 | 123 | 166 | 54.6 | 58.6 |
By above embodiments it can be concluded that the ruler of the suitable alternating electromagnetic field state modulator crystal of adjusting can be passed through
Very little and crystallinity.
Claims (3)
1. a kind of method for controlling polylactic acid crystal by alternating electromagnetic field, it is characterised in that: this method comprises the following steps:
(1) ferroso-ferric oxide particle is distributed in polylactic acid using solution or melt-mixing method, obtains polylactic acid/tetra- oxidations
Three iron composite materials, wherein mass percent of the ferroso-ferric oxide particle in polylactic acid/ferriferrous oxide composite material is 1-
3%；
(2) polylactic acid/ferriferrous oxide composite material prepared by step (1) is warming up to 80-170 in alternating electromagnetic field
It DEG C is crystallized, and the frequency and intensity by controlling alternating electromagnetic field control the crystallization of polylactic acid, the frequency of Electromagnetic Field
Rate is 50 ~ 500 hertz, and intensity is 0 ~ 5 milli tesla.
2. a kind of method for controlling polylactic acid crystal by alternating electromagnetic field as described in claim 1, it is characterised in that: step
(1) partial size of the ferriferrous oxide nano-particle in is 3--10 nanometers.
3. a kind of method for controlling polylactic acid crystal by alternating electromagnetic field as described in claim 1, it is characterised in that: step
(1) polylactic acid in is any one of l-lactic acid, racemic polylactic acid.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110354528A (en) * | 2019-08-21 | 2019-10-22 | 贺剑 | Solution crystal system and the method for promoting solution crystallization |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101787113A (en) * | 2010-01-21 | 2010-07-28 | 上海大学 | Method and device for improving crystallizing performances of polyactic acid by pulse magnetic field |
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2018
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Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101787113A (en) * | 2010-01-21 | 2010-07-28 | 上海大学 | Method and device for improving crystallizing performances of polyactic acid by pulse magnetic field |
Non-Patent Citations (2)
| Title |
|---|
| DONG ZHANG ET AL.: ""Analysis of crystallization property of LDPE/Fe3O4 nano-dielectrics based on AFM measurements"", 《J MATER SCI: MATER ELECTRON》 * |
| RYOSUKE KUSUMI ET AL.: ""Crystal Orientation of Poly(L-Lactic Acid) Induced by Magnetic Alignment of a Nucleating Agent"", 《POLYMERS》 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110354528A (en) * | 2019-08-21 | 2019-10-22 | 贺剑 | Solution crystal system and the method for promoting solution crystallization |
| CN110354528B (en) * | 2019-08-21 | 2021-11-19 | 贺剑 | Solution crystallization system and method for promoting crystallization of solution |
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Application publication date: 20190528 |