CN116606184A - TATB/RDX/PVAc/GO composite microsphere and preparation method thereof - Google Patents

Abstract

The invention belongs to the technical field of propellant coating and desensitization, and in particular relates to a TATB/RDX/PVAc/GO composite microsphere and a Pickering emulsion polymerization preparation method thereof. Using solid particle GO as a stabilizer, TATB/RDX/PVAc/GO composite microspheres were prepared by Pickering emulsion polymerization. The composite particles were characterized by SEM, XRD, and DSC, and the impact sensitivity was tested. The results show that the prepared TATB/RDX/PVAc/GO composite microspheres tend to be spherical in shape and have fewer defects; it can be seen from XRD that the TATB/RDX/PVAc/GO composite microspheres have both RDX and TATB and GO The characteristic diffraction peaks of RDX and TATB have not changed; it can be seen from DSC that the activation energy of the two decomposition peaks of RDX and TATB in TATB/RDX/PVAc/GO composite microspheres is higher than that of raw materials RDX and TATB. The thermal stability is improved; compared with the raw material RDX, the impact energy is increased from 4.5J to 55J, the impact sensitivity is obviously reduced, and the safety performance is obviously improved.

Description

A kind of TATB/RDX/PVAc/GO composite microsphere and preparation method thereof

technical field

The invention belongs to the technical field of propellant coating and desensitization, and in particular relates to a TATB/RDX/PVAc/GO composite microsphere and a preparation method for Pickering emulsion polymerization thereof.

Background technique

With the continuous development of science and technology in the world, the military forces of various countries are gradually becoming diversified, with powerful, more accurate, ultra-long-range and intelligent modern weapons emerging one after another. Various catastrophic accidents in the production, processing, use, storage and transportation of ammunition in the past have made low-fragility explosives ready to emerge. In order to improve the combat capability of new weapons and ammunition, explosives should not only have sufficient energy, but also have good safety, which makes the development of high-energy desensitization of weapons and ammunition an inevitable trend.

Polymer bonded explosives (PBX), also known as plastic bonded explosives, are high-energy single-substance explosives as the main body, adding binders, plasticizers and insensitive agents, etc. This kind of particle-filled composite material has high energy density, good molding performance, mechanical properties and high safety performance, and is easy to process and shape. It is suitable for various charging processes and makes the comprehensive index of the medicine far better than the traditional one. The explosives are widely used in the detonation transfer sequence and the main charge. At present, there are many preparation methods for polymer bonded explosives, and the search for new preparation techniques is a hot topic of research by researchers at home and abroad.

Pickering emulsion polymerization technology has increasingly become a hotspot in the preparation of composite materials due to its unique advantages. Pickering emulsions can be summarized as: a class of emulsions in which solid particles replace traditional surfactants as stabilizers. Unlike traditional emulsions, Pickering emulsions reduce the amount of emulsifiers, and even do not use emulsifiers. The prepared latex particles have a smaller size. It is small and has good monodispersity, which saves cost and relatively reduces environmental pollution; it is not easy to generate air bubbles, which minimizes the defects caused by the material when forming a film, and avoids the adverse effects of emulsifiers on the material. In addition, the Pickering emulsion system has higher stability and is not easily affected by changes in the external environment. W. Ramsden first discovered that solid particles of colloidal size can stabilize emulsions, and its stabilization effect is better than that of surfactants. Pickering was the first to conduct comprehensive and systematic research on this kind of emulsion system, and explained the stability mechanism of the emulsion. Therefore, this new type of emulsion is called Pickering emulsion, and this polymerization method is called Pickering emulsion polymerization. Pickering emulsion polymerization is to add polymerizable functional monomers in the preparation of Pickering emulsion, and then initiate polymerization to obtain organic-inorganic composite materials with special structures and functions. The steps are usually to first select suitable solid particles, then add suitable polymerizable monomers to prepare Pickering emulsion, and then use the Pickering emulsion as a template to initiate polymerization. The composite material has the structural characteristics of polymer as the core and nano-solid particles as the shell, and has the advantages of good flexibility and high modulus of polymer materials and high strength, high hardness and heat resistance of inorganic materials. At present, there are many research reports on Pickering emulsion polymerization, most of which use Pickering emulsion as a functional monomer to prepare core-shell nanocomposites, hollow composite microspheres or microcapsules. In a broad sense, composite microspheres and hollow microcapsules also belong to core-shell composite materials. Core-shell structure composite material refers to an applied material composed of at least two substances, one of which forms a core in the center, and another or more substances cover the surface to form a shell, and the core-shell is connected by physical or chemical action. . The surface charge properties of the solid particles in the outer layer of such composite materials can affect the surface properties of the composite materials, and the optical, electrical, magnetic, and catalytic properties of the particles themselves can endow the composite materials with new properties. Therefore, the application of the core-shell structure composite material can be extended to various fields. For example, core-shell composite microspheres have been widely used in the fields of drug delivery and controlled release, disease diagnosis and polymer modification. Zhang et al. used carbon nanotubes as solid surfactants to prepare carbon nanotubes/PSt nanocomposites by Pickering emulsion polymerization. Functionalized carbon nanotubes can be used as effective surfactants for styrene-in-water emulsions, and in this way are uniformly dispersed in polystyrene production as effective nanofillers, and the addition of low-functionalized carbon nanotubes significantly improves polystyrene thermal stability. Chen Zhonghua et al. used graphene oxide (GO) synthesized by improved Hummers method as a stabilizer to prepare Pickering emulsion, and then prepared polystyrene/graphene oxide (PSt/GO) composite emulsion by Pickering polymerization method. When the mass fraction of GO When it is 0.30%, the particle size of PSt/GO composite emulsion is small and the stability is good. The polymerization mechanism of the emulsion with different GO content was discussed, and it was considered that the GO content was small for Pickering emulsion polymerization, and the high GO content was for Pickering suspension polymerization.

The Pickering emulsion polymerization method has unique advantages: first, the operation is simple, and the process is safe and controllable; second, the use of surfactants is reduced, and there are few bubbles generated during the reaction process; third, there is less pollution and it is environmentally friendly. However, no related reports have been seen in the field of energetic materials.

Contents of the invention

On the basis of the existing coating system, the present invention improves the comprehensive performance of RDX, proposes a preparation technology capable of preparing low-sensitivity and high-energy composite microspheres, and successfully applies it in RDX coating, and prepares TATB/RDX/ PVAc/GO composite microspheres, and their morphology, crystal form, thermal properties and sensitivity were analyzed.

The present invention is achieved by the following technical solutions:

A TATB/RDX/PVAc/GO composite microsphere, the components and mass percentages are: the mass fraction ratio of TATB, RDX, PVAc, and GO is: 35-45%: 50-60%: 4%: 1%;

A kind of Pickering emulsion polymerization method prepares the method for TATB/RDX/PVAc/GO composite microsphere, specifically comprises the steps:

(1) Weigh GO and deionized water in a beaker, and place it in an ultrasonic instrument to obtain a uniform dispersion of GO, which is an aqueous phase;

In another beaker, take the binder monomer styrene (VAc) and the initiator APS (based on the monomer mass) of 0.5-1.5wt%, and mix and dissolve it to obtain a uniform oil phase;

Then take TATB, add a dispersant (PVA) with a mass concentration of 3% and deionized water and pour it into a beaker, stir and ultrasonically until the suspension in the beaker is evenly dispersed;

Finally, the water phase and the oil phase are initially mixed in an ultrasonic instrument, poured into the suspension, and immediately ultrasonicated to obtain a Pickering emulsion;

(2) Take RDX and deionized water into a beaker, stir and sonicate for 1 minute, pour it into a four-necked flask equipped with a stirrer and _N2 protection device, place it in a water bath, and control the polymerization temperature at 55-65 °C and the stirring speed is 300～400rad/min, when the temperature of the water bath is raised to the set polymerization temperature, slowly add the Pickering emulsion prepared in step (1) into its flask, while controlling the stirring speed and temperature constant, the reaction 2 Hour;

(3) After the reaction, the product in the bottle was left to stand, filtered and washed, then dried and collected to obtain TATB/RDX/PVAc/GO composite microspheres.

Beneficial effects of the present invention

Compared with the raw material RDX, the TATB/RDX/PVAc/GO composite microsphere prepared by the present invention has a uniform particle size distribution, a spherical shape, an explosive content of 95%, and significantly improved safety performance.

The composite particles were characterized by SEM, XRD and DSC, and the impact sensitivity was tested. The results show that the prepared TATB/RDX/PVAc/GO composite microspheres tend to be spherical in shape and have fewer defects;

It can be seen from XRD that the TATB/RDX/PVAc/GO composite microspheres have the characteristic diffraction peaks of RDX, TATB and GO at the same time, and the crystal forms of RDX and TATB have not changed;

It can be seen from DSC that the activation energy of the two decomposition peaks of RDX and TATB in TATB/RDX/PVAc/GO composite microspheres is higher than that of the raw material RDX and TATB, and the thermal stability is improved; the impact energy is compared with the raw material RDX , increased from 4.5J to 55J, the impact sensitivity is obviously reduced, and the safety performance is obviously improved.

Description of drawings

The present invention has 5 accompanying drawings

Figure 1 is the SEM image of raw material RDX.

Figure 2 is the SEM image of raw material TATB.

Figure 3 is the SEM image of TATB/RDX/PVAc/GO.

Figure 4 is the XRD pattern of RDX, TATB, GO, TATB/RDX/PVAc/GO.

Figure 5 is the DSC spectrum of RDX, TATB, TATB/RDX/PVAc/GO

Detailed ways

The present invention mainly relates to the application of a preparation technology capable of preparing low-sensitivity and high-energy composite microspheres in RDX coating. The Pickering emulsion polymerization method is selected as a new preparation technology to prepare TATB/RDX/PVAc/GO composite microspheres .

The experimental formula was preliminarily determined. The main factors for the formation of TATB/RDX/PVAc/GO composite microspheres were the amount of initiator, polymerization temperature, and stirring speed process parameters.

Table 1 is the experimental formula

The optimal process parameters were obtained through SEM, DSC and impact sensitivity: the amount of initiator was 1wt%, the polymerization temperature was 60°C, and the stirring speed was 350rad/min.

The TATB/RDX/PVAc/GO solid sphere prepared by the present invention; through the impact sensitivity experiment, the impact energy of RDX and TATB/RDX/PVAc/GO increased from 4.5J to 55J, the impact sensitivity was significantly reduced, and the safety performance was significantly improved; through XRD According to SEM analysis, the composite microspheres were successfully prepared, the crystal structure before and after coating did not change, the coating was meticulous, and the surface defects were less. According to DSC analysis, the activation energy of the two decomposition peaks of RDX and TATB in TATB/RDX/PVAc/GO composite microspheres is higher than that of raw materials RDX and TATB, and the thermal stability is improved.

Table 2 Impact Sensitivity Experimental Results

Example 1

A Pickering emulsion polymerization method for preparing TATB/RDX/PVAc/GO composite microspheres, the mass fraction ratio of TATB, RDX, PVAc, and GO is: 40%:55%:4%:1%.

The preparation process is as follows:

(1) Weigh 0.03 g of GO and deionized water into a beaker, place it in an ultrasonic instrument for 30 min, and repeat this three times to obtain a uniform dispersion of GO, which is an aqueous phase. In another beaker, 0.12 g of the binder monomer styrene (VAc) and 1 wt % of the initiator APS (based on the monomer mass) were weighed and mixed and dissolved to obtain a uniform oil phase. Then take 1.2g TATB, add 3% dispersant (PVA) and deionized water into the beaker together, stir and sonicate until the suspension in the beaker is evenly dispersed. Finally, the water phase and the oil phase were initially mixed in an ultrasonic instrument, poured into the suspension, and immediately ultrasonicated for 20 minutes to obtain a Pickering emulsion;

(2) Take 1.65g RDX and 100ml deionized water into a beaker, stir and ultrasonic for 30 minutes, and pour it into a four-neck flask equipped with a condenser, stirrer and _N2 protection device and place it in a water bath to control polymerization The temperature is 60°C and the stirring speed is 350rad/min. When the temperature of the water bath rises to 60°C, slowly add the Pickering emulsion prepared in the above step (1) into its flask, while controlling the stirring speed and temperature. 2 hours;

(3) After the reaction, the product in the bottle was left to stand, filtered and washed, then dried and collected to obtain TATB/RDX/PVAc/GO composite microspheres.

Example 2

The difference from Example 1 is that the temperature in step (2) is 65° C., and the stirring speed is 350 rad/min.

Claims (4)

1. A TATB/RDX/PVAcGO composite microsphere is characterized by comprising the following components in percentage by mass: TATB, RDX, PVAc, GO mass fraction ratio is: 35-45%:50-60%:4%:1%.

2. The method for preparing the TATB/RDX/PVAc/GO composite microsphere according to claim 1, which is characterized by adopting a Pickering emulsion polymerization method, and specifically comprising the following steps:

(1) Weighing GO and deionized water in a beaker, and placing the beaker in an ultrasonic instrument for ultrasonic treatment to obtain a uniform dispersion liquid of GO, wherein the uniform dispersion liquid is a water phase;

weighing binder monomer vinyl acetate (VAc) and 0.5-1.5 wt% of initiator Ammonium Persulfate (APS) in another beaker, and mixing and dissolving to obtain a uniform oil phase;

adding TATB, a dispersing agent (PVA) with the mass concentration of 3% and deionized water into a beaker together, stirring and carrying out ultrasonic treatment until the suspension in the beaker is uniformly dispersed;

finally, primarily mixing the water phase and the oil phase in an ultrasonic instrument, pouring the water phase and the oil phase into suspension, and immediately performing ultrasonic treatment to obtain Pickering emulsion;

(2) RDX and deionized water were taken into a beaker and stirred and sonicated for minutes and poured into a flask equipped with a stirrer and N ₂ Placing the four-neck flask of the protection device in a water bath kettle, controlling the polymerization temperature to be 55-65 ℃ and the stirring speed to be 300-400 rad/min, slowly adding the Pickering emulsion prepared in the step (1) into the flask when the temperature of the water bath kettle is increased to the set polymerization temperature, controlling the stirring speed and the stirring temperature to be unchanged, and reacting for 2 hours;

(3) After the reaction is finished, the product in the bottle is subjected to standing, filtering and washing, and then is dried and collected, so that the TATB/RDX/PVAc/GO composite microsphere is prepared.

3. The process according to claim 2, wherein the initiator APS is used in an amount of 1% by weight in step (1).

4. The process according to claim 2, wherein the polymerization temperature in the step (2) is 60℃and the stirring speed is 350rad/min.