CN109721728B - A kind of polyamide 6/fluorescein composite material and preparation method thereof - Google Patents

Abstract

The application belongs to the technical field of polymer composite materials in material science, and particularly relates to a polyamide 6/fluorescein composite material and a preparation method thereof. The material is prepared by adopting an in-situ polymerization method, and in the preparation process, fluorescein is used as a filler, and adipic acid is used as a catalyst. During preparation, firstly, heating the system to 190-210 ℃, and heating, melting and refluxing for reaction; after the reaction is finished, releasing water vapor, then raising the temperature of the system to 210-230 ℃, and then gradually raising the temperature of the system to 260 ℃; finally, the vacuum is pumped and the pressure is gradually reduced to-0.08 MPa. The polymer composite material provided by the application is added with fluorescein, so that the performance of the polymer material is greatly improved, and the application range of the polyamide polymer material is widened due to the addition of the fluorescein, so that the polymer composite material has good practical value and popularization and application significance.

Description

Polyamide 6/fluorescein composite material and preparation method thereof

Technical Field

The application belongs to the technical field of polymer composite materials in material science, and particularly relates to a polyamide 6/fluorescein composite material and a preparation method thereof.

Background

The polymer composite material is one of the research hotspots in the field of the existing material science, and is an important way for exploring high-performance and multifunctional composite materials because the material has the characteristics of organic and inorganic materials and can generate more new excellent performances through the interaction between the organic and inorganic materials.

In the prior art, there are various methods for preparing polymer composite materials, and four methods are commonly used: melt blending, sol-gel, intercalation, and in situ polymerization. However, since the requirements for the applicable materials and the performance of the polymer composite material are different, different preparation methods have advantages and disadvantages, and an optimal preparation method needs to be properly selected and determined according to the specific performance requirements and the performance characteristics of different raw materials for the polymer composite material.

Polyamide 6, commonly known as Nylon 6, is one of the most important engineering plastics, and the yield is the top of five general engineering plastics, and because of its excellent properties, such as high strength, strong flame retardant property, good rigidity and wear resistance, and easy processing, it is widely used in the fields of automobiles, machinery, electronic and electrical appliances, communication equipment, instruments and meters, buildings, etc. With the development of modern scientific technology and practical application, people have higher demand on polyamide 6, especially on the aspects of strength, heat resistance, cold resistance and the like. These inherent disadvantages of polyamide 6, such as "poor dimensional stability and high water absorption", are important factors limiting its application. In order to improve the mechanical properties of polyamide 6, it is often necessary to add inorganic or organic fillers as modifiers to improve the overall properties of polyamide 6. In the prior art, based on different performance requirements, more technical improvements based on the technical thought are carried out, and better technical effects are obtained. However, in general, due to the different requirements of technical properties, there is still a need for further exploration of new material designs and new property improvements based on polyamide 6.

Disclosure of Invention

The application aims to provide a polyamide 6/fluorescein composite material, so that the composite material can play a certain role in the fields of safety emergency (such as marks of fire-fighting safety equipment, life-saving equipment, emergency evacuation marks, emergency indication lighting and the like), transportation (such as traffic marks) and the like.

The technical solution adopted in the present application is detailed as follows.

A polyamide 6/fluorescein composite material is prepared by an in-situ polymerization method, wherein fluorescein is used as a filler and acid is used as a catalyst in the preparation process, and the preparation process comprises the following steps:

(1) adding epsilon-caprolactam, water (for example, distilled water), an acid catalyst and fluorescein into a reaction container, sealing, heating the system to 190-210 ℃ from room temperature, heating to melt, and performing reflux reaction for 2-4 hours to perform full reaction;

in the reaction process, in order to ensure that the reaction is sufficient, stirring can be performed in a magnetic stirring mode to ensure that the reaction is sufficient;

the acid catalyst can be inorganic acid or organic acid, and specifically, adipic acid, acetic acid, sulfuric acid, phosphoric acid, aminocaproic acid and the like are used;

taking adipic acid as an example of the catalyst, the specific dosage of each material is, by mass volume ratio, epsilon-caprolactam: water: adipic acid: fluorescein = 50-100 g: 1-3 mL: 1-2 g: 0.1-1.5 g;

specific dosage is for example: epsilon-caprolactam: water: adipic acid: fluorescein =100 g: 2 mL of: 1 g: 0.1-1.5 g;

(2) after the reaction in the step (1) is finished, releasing water vapor, raising the temperature of the system to 210-230 ℃ within 0.5-1 h, and then gradually raising the temperature of the system to 260 ℃ within 1.5-2 h (note that the temperature raising speed is not too fast, and the temperature raising speed is too fast, so that the stability of the product quality is not facilitated), namely the polyamide 6/fluorescein composite material; to ensure the quality of the final product, the preferred procedure is to maintain this temperature (260 ℃), gradually reduce the vacuum to-0.08 Mpa and then vent it;

and finally, casting and forming the product according to the shape and type of the product as required.

When the cast molding is carried out, a dumbbell-shaped sample can be cast for testing the tensile strength of the material, or a V-shaped notch sample can be cast for testing the impact strength of the material.

The polyamide 6/fluorescein composite material is applied to fluorescent indicating products, such as marks of safety facility equipment in safety emergency, marks of lifesaving equipment, emergency evacuation marks, emergency indication lighting, or traffic marks in traffic transportation.

In the application, the polymer and the fluorescein are compounded to form the novel polymer composite material, so that the excellent performances of light weight, good toughness, high strength and the like of the polymer can be embodied, and the novel characteristics of the polymer are also endowed. After the prepared composite material is characterized by using instruments and equipment such as an X-ray diffractometer (XRD)/a thermogravimetric analyzer (TGA), the test and analysis results show that: with the addition of the fluorescein filler, the crystal structure of the polyamide 6 matrix tends to be gamma crystal; with the addition of the fluorescein, the performance parameters of the polymer composite material, such as the tensile strength, the impact toughness and the like, are greatly improved, and a better performance improvement effect is shown; the fluorescein in the polymer still has the fluorescent characteristic, so the fluorescein can be better used in the fields of safety emergency (such as the marks of fire-fighting safety equipment, life-saving equipment, emergency evacuation marks, emergency indication lighting and the like), transportation (such as traffic marks) and the like which need fluorescence and can play a role.

In general, although the preparation method of the polymer composite material provided by the application is relatively conventional, the performance of the polymer material is greatly improved through the addition of fluorescein, and the application range of the polyamide polymer material is widened due to the addition of the fluorescein, so that the polymer composite material has relatively good practical value and popularization and application significance.

Drawings

FIG. 1 is an image of polyamide 6 and a polyamide 6/fluorescein composite material under ultraviolet light, wherein A (left drawing) is the polyamide 6/fluorescein composite material, and B (right drawing) is the polyamide 6;

FIG. 2 is an XRD pattern of polyamide 6 and a polyamide 6/fluorescein composite;

FIG. 3 is a graph of the thermal weight loss of polyamide 6 and a polyamide 6/fluorescein composite;

FIG. 4 shows the tensile strength and impact toughness of polyamide 6 and polyamide 6/fluorescein composites.

Detailed Description

The present application is further illustrated by the following examples. Before describing specific embodiments, some experimental materials, experimental instruments, etc. in the following embodiments will be briefly described as follows.

Experimental materials:

epsilon-caprolactam (CP, chemically pure), manufactured by BASF corporation (Zhengzhou, China),

adipic acid (AR, analytical grade), Penny chemical industries (Zheng, China),

fluorescein (AR), shanghai crystal purifyation science and technology ltd (shanghai, china);

the main apparatus is as follows:

x-ray diffraction Analyzer (X-PertPro), Philips Inc. of the Netherlands,

thermogravimetric analysis (TGA), Shanghai Yokogaku instruments and meters Co., Ltd,

microcomputer controlled electronic universal tester (WDW-10D), Jinan Proc group Limited,

pendulum impact test (ZBC-1400-2), Shenzhen, New Miss Material detection, Inc.

Examples

The polyamide 6/fluorescein composite material provided by the embodiment is prepared by an in-situ polymerization method, wherein fluorescein is used as a filler and adipic acid is used as a catalyst in the preparation process, and the specific preparation process is as follows:

(1) adding 100 g of epsilon-caprolactam, 2 mL of distilled water, 1.0 g of adipic acid and fluorescein (the using amount of the fluorescein is 0.1g, 0.3g, 0.5g, 0.7g and 0.9g respectively) into a three-neck flask, heating to melt, magnetically stirring, raising the temperature of the system from room temperature to 190 ℃, and carrying out reflux reaction for 3 hours;

(2) after the reaction in the step (1) is finished, releasing water vapor, raising the temperature of the system to 230 ℃ within 0.5h, and then gradually raising the temperature of the system to 260 ℃ within 1.5 ℃;

keeping the temperature, vacuumizing to gradually reduce to-0.08 MPa, emptying, and casting into dumbbell-shaped samples for testing the tensile strength of the material and V-shaped notch samples for testing the impact strength of the material.

It should be noted that, the dumbbell sample, V notch sample, refer to the requirements in the national standards GB/T1040-.

Comparative example

As a comparative example, the preparation method and the material amount were the same as those of the above example except that no fluorescein was added; also, a dumbbell sample and a notch sample of "V" shape were cast separately.

The samples prepared in the above examples and comparative examples were subjected to material characterization and performance measurement, respectively. It should be noted that all samples were dried in an oven at 80 ℃ for 24 hours prior to testing to eliminate the effect of moisture on the material properties. Specific results are presented below.

(I) characterization of materials

(1) Fluorescent characteristics

The inventor determines whether the fluorescein in the polyamide 6/fluorescein composite material still has the fluorescence characteristic under the ultraviolet ray, and the result is shown in fig. 1 (fig. 1 is the test result of the material of some examples).

As can be seen from FIG. 1, the polyamide 6/fluorescein composite material still has the fluorescence characteristics of fluorescein under the irradiation of ultraviolet light, and the fluorescence is uniform, and the result shows that the preparation method of the application can uniformly disperse the fluorescein in the matrix material, and the original structure of the fluorescein is not destroyed in the process of synthesizing the composite material, so that the composite material still has the fluorescence characteristics of the fluorescein.

(2) X-ray diffraction analysis

The crystal structures of polyamide 6 (comparative example) and a polyamide 6/fluorescein composite material (material with fluorescein content of 0.5%) and the existence state of fluorescein in a polyamide 6 matrix were measured by an X-ray diffractometer. The test parameters are:

the current is 30 mA, the voltage is 40 kV, the scanning speed is 2 degrees/min, the scanning range is 5 degrees to 85 degrees, and the scanning interval is 0.03 degrees.

The XRD pattern is shown in figure 2. Analysis shows that due to the addition of fluorescein, the polyamide 6 not only has an alpha crystal form structure, but also has a gamma crystal form. Specifically, the XRD curve of polyamide 6 showed, in addition to α characteristic diffraction peaks at 20.1 ° and 24.1 °, a γ diffraction peak at 22.2 °; compared with pure polyamide 6, the diffraction peak of the alpha crystal form of the composite material added with the fluorescein is weakened, namely the fluorescein promotes the polyamide 6 to have a crystal structure inclined to the gamma crystal form. The analysis considers that: after the fluorescein is added, the agglomeration phenomenon is difficult to avoid, so that the movement of polyamide 6 molecules is hindered, and a gamma crystal form is prone to be generated.

(3) Thermogravimetric analysis

Thermogravimetric analyzers were used to measure the thermogravimetric curves of polyamide 6 (comparative example) and polyamide 6/fluorescein composite (material with 0.5% fluorescein) respectively. During testing: the temperature range is 20-700 ℃, and the heating rate is 20 ℃/min.

The thermogravimetric curve is shown in fig. 3. Analysis shows that the polyamide 6/fluorescein composite material and pure polyamide 6 have similar thermal decomposition process, the decomposition speed is slower below 400 ℃, the decomposition speed is accelerated above 430 ℃, but the thermal decomposition temperature of the composite material is still increased due to the addition of fluorescein. Specifically, the thermal decomposition temperature of polyamide 6 was 415 ℃ and after adding fluorescein, the thermal decomposition temperature was 432 ℃. Generally, the thermal decomposition temperature of a composite material has a close relationship with the degree of crosslinking thereof, and in some cases, the thermal decomposition temperature increases as the degree of crosslinking increases. Therefore, after the fluorescein is added, the molecular chain structure of the polyamide is changed through the polymerization reaction of the fluorescein and the amino group of the polyamide, so that the thermal decomposition temperature of the polyamide is increased.

(II) mechanical Property test

The tensile strength and impact toughness of the polyamide 6 and the polyamide 6/fluorescein composite material are respectively determined by referring to corresponding national standard standards (GB/T1040-.

Analysis shows that the mechanical property of the composite material shows a trend of increasing and then decreasing with the increase of the addition amount of the fluorescein. When the content of the fluorescein is 0.5%, the tensile strength of the system is the maximum, reaches 43.26MPa, and is improved by 38.9 percent compared with pure polyamide 6; the maximum impact strength of the composite material is 0.5 percent and reaches 15.36MPa, which is 49.3 percent higher than that of pure polyamide 6.

Analysis shows that, for the change of the tensile strength of the system, when the content of the fluorescein is 0.5 percent, the fluorescein is dispersed in the polyamide 6 system more uniformly; when the content of the fluorescein derivative exceeds 0.5%, the viscosity of the system is increased, so that the dispersion difficulty of the fluorescein is increased, the fluorescein may be partially aggregated, and the tensile strength of the composite material is reduced. And for the reasons of the change in impact toughness of the system: when the content of the fluorescein is 0.5%, the fluorescein is uniformly dispersed in the polyamide 6 matrix, so that the plastic deformation of a composite system is improved, the impact stress of the material can be dispersed, more impact energy can be absorbed, and the impact strength of the composite material is greatly enhanced.

In summary, the inventors believe that when the polyamide 6/fluorescein composite material is prepared by in-situ polymerization, the structure of fluorescein is not destroyed and good fluorescence performance is imparted to polyamide 6, but when the amount of the fluorescein is not more than 0.5%, the fluorescein can be dispersed in the matrix material more uniformly, and some series of physical and chemical properties such as tensile strength, thermal decomposition temperature, maximum impact strength and the like of the composite material can be improved to a good extent. Based on the performance improvement and the fluorescent characteristic of the new material, the polyamide 6/fluorescein composite material and the product thereof can be used for the aspects of safety and emergency, such as the marks of fire-fighting safety equipment, lifesaving equipment, emergency evacuation, emergency indication lighting and hidden lighting of military equipment; in the field of transportation for traffic signs; in the aspect of building decoration, the building decorative paint can be used for decorating and beautifying indoor and outdoor environments, is simple, convenient and visible, and saves electric energy; and the method can also be used for indication of instrument panels and decoration of daily consumer goods, thereby having better application prospect.

Claims (3)

1. a polyamide 6/fluorescein composite material, is characterized in that, this material adopts in-situ polymerization to prepare, takes fluorescein as filler in the preparation process, takes adipic acid as catalyzer, and this composite material passes through the following steps Prepare to obtain: (1) Add ε-caprolactam, water, adipic acid and fluorescein into the reaction vessel, seal it, raise the system to 190~210°C, heat and melt and reflux for 2~4 h; The specific dosage of each material is, ε-caprolactam: water: adipic acid: fluorescein = 100 g: 2 mL: 1 g: 0.3 g; Or, ε-caprolactam: water: adipic acid: fluorescein = 100 g: 2 mL: 1 g: 0.5 g; Or, ε-caprolactam: water: adipic acid: fluorescein = 100 g: 2 mL: 1 g: 0.7 g; (2) After the reaction in step (1) is completed, release water vapor, then raise the temperature of the system to 210-230°C within 0.5-1h, and then gradually increase the temperature of the system to 260°C within 1.5-2h; Maintain this temperature and gradually reduce the vacuum to -0.08MPa. 2. the preparation method of the described polyamide 6/fluorescein composite material of claim 1, is characterized in that, comprises the steps: (1) Add ε-caprolactam, water, adipic acid and fluorescein into the reaction vessel, seal it, raise the system to 190~210°C, heat and melt and reflux for 2~4 h; (2) After the reaction in step (1) is completed, release water vapor, then raise the temperature of the system to 210-230°C within 0.5-1h, and then gradually increase the temperature of the system to 260°C within 1.5-2h; Maintain this temperature and gradually reduce the vacuum to -0.08MPa. 3. The polyamide 6/fluorescein composite material of claim 1 is used in a fluorescent indicator product.

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