CN112279561A

CN112279561A - Wet-process gel dispersion millimeter-grade short fiber composite blank and preparation method thereof

Info

Publication number: CN112279561A
Application number: CN202011247178.8A
Authority: CN
Inventors: 刘应军; 沙建军; 沙如意; 祖宇飞; 代吉祥
Original assignee: Dalian University of Technology
Current assignee: Dalian University of Technology
Priority date: 2020-11-10
Filing date: 2020-11-10
Publication date: 2021-01-29
Anticipated expiration: 2040-11-10
Also published as: CN112279561B

Abstract

The invention belongs to the field of fiber toughened composite materials, and particularly relates to a wet-process gel dispersion millimeter-sized short fiber composite material blank and a preparation method thereof. The invention has the advantages that: the uniform dispersion of the millimeter-sized short fibers is realized, the fibers are firmly fixed in the gel, the defect of the composite material caused by fiber settlement and agglomeration is avoided, the fibers are not damaged by machinery and are not corroded by chemistry, and the strengthening and toughening effect of the short fiber composite material is improved; in addition, the method has low cost and is easy to realize industrial production.

Description

Wet-process gel dispersion millimeter-grade short fiber composite blank and preparation method thereof

Technical Field

The invention belongs to the field of fiber toughened composite materials, and particularly relates to a wet gel dispersion millimeter-sized short fiber composite material blank and a preparation method thereof.

Background

The fiber has the advantages of high specific modulus and high specific strength, and can be widely applied to various composite materials. Fiber-composites can be classified into short fiber-composites and continuous fiber-composites according to fiber length. Continuous fiber-composites possess high stiffness, high strength characteristics, but have a high degree of directionality, such as: the load perpendicular to the fiber direction is mainly carried by the fiber, so that the strengthening and toughening effect in the direction is obvious, and the load parallel to the fiber direction is carried by the matrix of the composite material, so that the mechanical property in the direction is poor. The short fiber-composite material has small anisotropy, good comprehensive mechanical properties in all directions and wide application prospect.

The problem of short fiber dispersion is involved in the preparation of short fiber-composite materials, and the general short fiber dispersion method mainly comprises the following steps: ball milling dispersion, dispersion using a surfactant, colloidal dispersion, and the like. For ball milling dispersion, the continuous impact and friction of the milling balls cause severe mechanical damage to the fiber surface and the length of the fiber can be shortened or even changed into fiber powder with the increase of the ball milling time, which is not favorable for improving the performance of the composite material. For dispersion using a surfactant, such as a silane coupling agent, hydroxyethyl cellulose, and the like, short fibers can be uniformly dispersed, but only micron-sized short fibers can be uniformly dispersed and the problem of fiber settlement and agglomeration after standing for a period of time often occurs. For colloid dispersion, such as a phenolic resin-polyethyleneimine system, the problem of standing, settling and agglomeration after uniform dispersion of fibers is solved, but the length of short fibers capable of being dispersed is only 50-500 um. Once the length of the short fiber reaches the millimeter level, the purpose of uniform dispersion is difficult to achieve under the condition of ensuring that the fiber is not damaged by adopting the prior art.

However, for short fiber-composite materials, the breaking energy absorbed by longer short fibers through mechanisms such as fiber extraction, fiber debonding, fiber bridging and the like is more; in particular, the fiber draw mechanism dissipates more energy the longer the fiber is drawn for the same fiber-matrix interface strength. The length of the short fiber is increased from micron level to millimeter level, and the strengthening and toughening effect of the short fiber on the composite material is expected to be improved by several times.

The millimeter-sized short fiber-composite material prepared by the prior art has poor fiber dispersion effect and poor strengthening and toughening effect. Therefore, in the present stage, the method for uniformly dispersing carbon fibers is limited by the fiber length, the toughening effect of the short fiber-composite material has reached the bottleneck, and in order to further improve the toughening effect, a method for uniformly dispersing millimeter-sized short carbon fibers must be developed.

Disclosure of Invention

In order to solve the technical problems, the invention aims to provide a wet gel dispersion millimeter-sized short fiber composite blank, which overcomes the problem of difficult dispersion of millimeter-sized short fibers and is used as a basis for preparing a composite material with high strengthening and toughening effects.

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

a method for preparing a millimeter-sized short fiber composite blank body by wet gel dispersion comprises the steps of preparing gel by using amylose and amylopectin, uniformly dispersing millimeter-sized short fibers and composite material matrix powder under continuous stirring by utilizing the shear rheology and the blocking and positioning characteristics of the gel, injecting the gel into a mold, and drying to obtain the millimeter-sized short fiber composite blank body, wherein the specific steps comprise:

1) adding amylose and amylopectin into deionized water under ultrasonic oscillation and mechanical stirring to prepare 5-80mg/mL gel precursor dispersion, wherein the mass ratio of the amylose to the amylopectin is 0.1-0.9, the degree of polymerization of the amylose is 800-5000, and the chain length of the amylopectin is 10-30;

2) metering the total volume of the millimeter-sized short fibers and the composite material matrix powder as 100 parts, adding 5-50 parts by volume of the millimeter-sized short fibers into the gel precursor dispersion liquid obtained in the step 1), heating to 60-100 ℃, keeping for 10-60min for gelation, and continuously mechanically stirring for 20-120min to obtain fiber gel;

3) adding composite material matrix powder with the volume part of 50-95 into the fiber gel obtained in the step 2), continuously stirring for 20-120min, and finally injecting into a mold for drying to obtain a millimeter-grade short fiber composite material blank; the composite matrix powder comprises: zirconium diboride, zirconium disilicide powder.

The invention has the following beneficial effects:

1) the invention uses amylose and amylopectin to prepare gel, and utilizes the shear rheology and the barrier positioning characteristic of the gel to uniformly disperse millimeter-sized short fibers and composite material matrix powder under continuous stirring. By the method, the uniform dispersion of the millimeter-sized fibers is realized, the uniformly dispersed millimeter-sized short fiber composite material blank is obtained, and a foundation is laid for preparing the composite material with excellent performance.

2) The invention firmly fixes the fibers in the gel, avoids the defects of the composite material caused by fiber settlement and agglomeration, prevents the fibers from mechanical damage and chemical corrosion, and improves the strengthening and toughening effect of the short fiber-composite material;

3) the wet gel dispersion adopted by the invention has the advantages of low cost and easy realization of industrial production.

Drawings

FIG. 1 is a schematic diagram of a wet-process gel-dispersed millimeter-sized short fiber composite blank manufacturing process according to an embodiment.

Detailed Description

The invention is further illustrated with reference to the following specific examples, without limiting the scope of the invention thereto.

In the embodiment, a millimeter-sized short fiber toughened zirconium diboride-based composite material blank with the volume part of 20 is prepared, wherein T700 of east Nippon is used as the fiber, and the length of the fiber is 1-5 mm. The preparation process comprises the following steps:

as shown in fig. 1, amylose and amylopectin with a mass ratio of 20:80 are added into deionized water under ultrasonic assistance and continuous stirring to prepare a gel precursor dispersion liquid with a concentration of 60 mg/mL; wherein the polymerization degree of amylose is 2000, and the chain length of amylopectin is 24;

and then, measuring the total volume of the millimeter-sized short fibers and the composite material matrix powder as 100 parts, adding the millimeter-sized short fibers with the volume part of 20 parts under continuous stirring, keeping the mixture at the temperature of 95 ℃ for 20min for gelation, and uniformly dispersing the mixture under continuous stirring for 60min to obtain the fiber gel.

And finally, measuring by taking the total volume of the millimeter-sized short fibers and the composite material matrix powder as 100 parts, adding 80 parts by volume of zirconium diboride and zirconium disilicide powder after the fiber gel is cooled, continuously stirring for 100min, injecting into a mold, and drying to obtain a 20 parts by volume of the millimeter-sized short fiber toughened zirconium diboride-based composite material blank.

In conclusion, the wet-process gel-dispersed millimeter-scale short fiber composite blank disclosed by the invention realizes uniform dispersion of the millimeter-scale short fibers, avoids the defects of the composite material caused by fiber settlement and agglomeration, prevents the fibers from being damaged mechanically and corroded chemically, and lays a foundation for preparing the composite material with excellent performance. And the method has low cost and is easy to realize industrial production.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. It is not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and its practical application to enable one skilled in the art to make and use various exemplary embodiments of the invention and various alternatives and modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims and their equivalents.

Claims

1. The preparation method of the wet gel dispersion millimeter-sized short fiber composite blank is characterized in that amylose and amylopectin are used for preparing gel, millimeter-sized short fibers and composite material matrix powder are uniformly dispersed under continuous stirring by utilizing the shear rheology and the separation positioning characteristics of the gel, then the gel is injected into a mold and dried to obtain the millimeter-sized short fiber composite blank, and the specific steps comprise:

2. A wet-process gel-dispersed millimeter-sized short fiber composite blank, characterized in that the wet-process gel-dispersed millimeter-sized short fiber composite blank is prepared by the method of claim 1.