阅读说明：本技术 一种含磷超支化聚硅氧烷及其制备方法与改性环氧树脂体系 (Phosphorus-containing hyperbranched polysiloxane, preparation method thereof and modified epoxy resin system ) 是由 蔡浩鹏 胡娟 王钧 于 2020-03-02 设计创作，主要内容包括：本发明属于化工和材料技术领域,具体涉及一种含磷超支化聚硅氧烷及其制备方法与改性环氧树脂体系。所述含磷超支化聚硅氧烷通过如下方法制备：首先,在氮气气氛保护下,偶氮二异丁腈的作为催化剂,乙烯基三乙氧基硅烷与9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物发生加成反应生成含磷硅烷；然后,使用氢氧化钡作为催化剂,合成的含磷硅烷与一缩二丙二醇发生反应,同时蒸馏排出乙醇；最后,过滤氢氧化钡得到所述含磷超支化聚硅氧烷。本发明制备的含磷超支化聚硅氧烷主要应用于提高环氧树脂及其复合材料的低温韧性和液氧相容性,拓展树脂基复合材料在液氧贮箱等低温领域应用。(The invention belongs to the technical field of chemical engineering and materials, and particularly relates to phosphorus-containing hyperbranched polysiloxane, a preparation method thereof and a modified epoxy resin system. The phosphorus-containing hyperbranched polysiloxane is prepared by the following method: firstly, under the protection of nitrogen atmosphere, taking azobisisobutyronitrile as a catalyst, and carrying out addition reaction on vinyl triethoxysilane and 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to generate phosphorus-containing silane; then, reacting the synthesized phosphorus-containing silane with dipropylene glycol by using barium hydroxide as a catalyst, and distilling to discharge ethanol; and finally, filtering the barium hydroxide to obtain the phosphorus-containing hyperbranched polysiloxane. The phosphorus-containing hyperbranched polysiloxane prepared by the invention is mainly applied to improving the low-temperature toughness and the liquid oxygen compatibility of epoxy resin and composite materials thereof and expanding the application of resin-based composite materials in the low-temperature fields of liquid oxygen storage tanks and the like.)

1. The phosphorus-containing hyperbranched polysiloxane is characterized by having a structural formula as follows:

wherein:

2. the preparation method of the phosphorus-containing hyperbranched polysiloxane is characterized by comprising the following steps:

(1) uniformly mixing 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and vinyl triethoxysilane according to the molar ratio of 1: 0.8-1.2, adding a certain amount of catalyst azodiisobutyronitrile, heating to 70-90 ℃ under the protection of nitrogen, keeping the temperature for reacting for 6-9 hours after the DOPO is dissolved and the system becomes clear and transparent, and then cooling to room temperature to obtain phosphorus-containing silane;

(2) uniformly mixing phosphorus-containing silane obtained in the first step with dipropylene glycol according to a molar ratio of 0.3-0.6: 1, adding a certain amount of barium hydroxide catalyst, under the protection of nitrogen, firstly heating to 60-90 ℃, when the system becomes clear and transparent, continuously heating to 110-140 ℃, starting to react for 10-30 min, generating distillate, continuously reacting for 1-5 h until no distillate is generated, and then cooling to room temperature;

(3) filtering to remove the catalyst barium hydroxide to obtain light yellow liquid, namely the phosphorus-containing hyperbranched polysiloxane.

3. The method according to claim 2, wherein the amount of azobisisobutyronitrile added as a catalyst in step (1) is 0.6 to 1.0% by mass based on the total mass of DOPO and vinyltriethoxysilane.

4. The method according to claim 2, wherein the amount of the barium hydroxide catalyst added in the step (2) is 0.5 to 0.8% of the total mass of the dipropylene glycol and the phosphorus-containing silane.

5. A modified epoxy resin system is characterized by comprising an epoxy resin matrix and phosphorus-containing hyperbranched polysiloxane accounting for 2-25% of the mass of the epoxy resin matrix, wherein the phosphorus-containing hyperbranched polysiloxane is the phosphorus-containing hyperbranched polysiloxane of claim 1.

6. Use of the modified epoxy resin system of claim 6 in a low temperature liquid oxygen storage tank.

Technical Field

The invention belongs to the technical field of chemical engineering and materials, and particularly relates to phosphorus-containing hyperbranched polysiloxane, a preparation method thereof and a modified epoxy resin system.

Background

With the further development of aerospace science and technology, the liquid oxygen storage tank is used as a propellant of a main structure of an aerospace vehicle and is characterized by large volume and high occupied weight ratio, and the liquid oxygen storage tank occupies about 70-80% of the total volume. Therefore, in order to further improve the carrying capacity of the aircraft, the weight of the aerospace aircraft must be reduced, and at present, the traditional liquid oxygen storage tank is made of metal or alloy materials, the net weight ratio of the metal storage tank is as high as 0.097, but if the resin-based composite material is adopted, the weight of the liquid oxygen storage tank can be obviously reduced, for example, the graphite fiber/epoxy resin composite material is reduced by 27% compared with the alloy material.

The epoxy resin has high mechanical strength, good manufacturability and good chemical corrosion resistance, and is a common fiber reinforced composite material matrix. However, the epoxy resin is inflammable, so that the epoxy resin is incompatible with liquid oxygen, and meanwhile, the low-temperature toughness is poor, so that the application of the epoxy resin in low-temperature and liquid oxygen environments such as aerospace, ships and warships is limited. Epoxy resin is used as a resin matrix of a carbon fiber reinforced resin matrix composite material, and the compatibility with liquid oxygen and low-temperature toughness need to be improved.

Because liquid oxygen has strong oxidizing property and low temperature, and according to the free radical theory and the hot spot theory of liquid oxygen compatibility, the incompatible reaction of the polymer and the liquid oxygen is basically consistent with the oxidizing combustion of the polymer and the liquid oxygen in oxygen, and the improvement of the thermal stability and the flame retardant property of the resin is beneficial to the improvement of the liquid oxygen compatibility of the epoxy resin. A common method for improving the liquid oxygen compatibility of epoxy resins is to add flame retardants. The halogen flame retardant generates toxic gas to pollute the environment when burning, and limits the industrial application of the halogen flame retardant. The common non-halogen flame retardant containing elements such as phosphorus, bromine, nitrogen and the like has good flame retardant effect, can obviously improve the liquid oxygen compatibility of the epoxy resin, but can deteriorate the toughness of the epoxy resin. Therefore, it is urgently required to develop an epoxy resin capable of improving liquid oxygen compatibility and low-temperature toughness.

Disclosure of Invention

The invention provides the phosphorus-containing hyperbranched polysiloxane, the preparation method thereof and a modified epoxy resin system for solving the technical problems, and the phosphorus-containing hyperbranched polysiloxane can improve the liquid-oxygen compatibility of the epoxy resin and the composite material thereof and improve the low-temperature toughness of the epoxy resin and the composite material thereof.

In order to achieve the purpose, the technical scheme of the invention is as follows:

a phosphorus-containing hyperbranched polysiloxane has a structural formula as follows:

wherein:

a preparation method of phosphorus-containing hyperbranched polysiloxane comprises the following steps:

(1) uniformly mixing 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and vinyl triethoxysilane according to the molar ratio of 1: 0.8-1.2, adding a certain amount of catalyst azodiisobutyronitrile, heating to 70-90 ℃ under the protection of nitrogen, keeping the temperature for reacting for 6-9 hours after the DOPO is dissolved and the system becomes clear and transparent, and then cooling to room temperature to obtain phosphorus-containing silane;

(2) uniformly mixing phosphorus-containing silane obtained in the first step with dipropylene glycol according to a molar ratio of 0.3-0.6: 1, adding a certain amount of barium hydroxide catalyst, under the protection of nitrogen, firstly heating to 60-90 ℃, when the system becomes clear and transparent, continuously heating to 110-140 ℃, starting to react for 10-30 min, generating distillate, continuously reacting for 1-5 h until no distillate is generated, and then cooling to room temperature;

wherein:

(3) filtering to remove the catalyst barium hydroxide to obtain light yellow liquid, namely the phosphorus-containing hyperbranched polysiloxane.

In the scheme, the adding amount of the catalyst azodiisobutyronitrile in the step (1) is 0.6-1.0% of the total mass of DOPO and vinyltriethoxysilane.

In the scheme, the addition amount of the barium hydroxide catalyst in the step (2) is 0.5-0.8% of the total mass of the dipropylene glycol and the phosphorus-containing silane.

A modified epoxy resin system comprises an epoxy resin matrix and phosphorus-containing hyperbranched polysiloxane accounting for 2-25% of the mass of the epoxy resin matrix, wherein the phosphorus-containing hyperbranched polysiloxane is the phosphorus-containing hyperbranched polysiloxane of claim 1.

The modified epoxy resin system is applied to a low-temperature liquid oxygen storage tank.

Compared with the prior art, the invention has the following beneficial effects: the phosphorus-containing hyperbranched polysiloxane prepared by the invention contains two flame retardant elements of silicon and phosphorus, and the synergistic effect of silicon and phosphorus can effectively improve the thermal stability and flame retardant property of epoxy resin, thereby improving the liquid oxygen compatibility of the epoxy resin; meanwhile, the toughness and the mechanical property of the epoxy resin can be improved due to the existence of a large number of flexible silicon-oxygen bonds, so that the epoxy resin modified by the phosphorus-containing hyperbranched polysiloxane can be better applied to a liquid oxygen environment. Meanwhile, the method for preparing the phosphorus-containing hyperbranched polysiloxane is simple in process and convenient to control.

Drawings

FIG. 1 is a comparison graph of an infrared spectrum of a hyperbranched polysiloxane containing phosphorus provided by the present invention.

FIG. 2 is a comparison graph of nuclear magnetic resonance hydrogen spectra of the hyperbranched polysiloxane containing phosphorus provided by the present invention.

FIG. 3 is a scanning electron microscope image of the phosphorus-containing hyperbranched polysiloxane-modified epoxy resin provided by the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. The invention is described in detail below with reference to the figures and examples.