阅读说明：本技术 一种非均相固化树脂体系的微脱粘试样制备方法 (Preparation method of micro-debonding sample of heterogeneous curing resin system ) 是由 郭妙才 李亚锋 洪旭辉 于 2019-09-29 设计创作，主要内容包括：本发明涉及一种非均相固化树脂体系的微脱粘试样制备方法,尤其适用于具有非均相固化体系的树脂和纤维之间的界面剪切强度的测试,采用树脂预聚合处理的方法,提高树脂内部的均一性分布,控制粘度和微球大小,得到测试稳定性良好的试样,显著提高了测试试样的结果稳定性和准确性,可准确反映该树脂体系和纤维之间的界面结合能力。(The invention relates to a preparation method of a micro-debonding sample of a heterogeneous curing resin system, which is particularly suitable for testing the interfacial shear strength between resin and fiber with the heterogeneous curing system.)

1. A method for preparing a micro-debonded sample of a heterogeneous curing resin system is characterized by comprising the following steps: pre-polymerizing heterogeneous curing resin for 20-90 min at the temperature of 20-50 ℃ lower than the curing temperature of the heterogeneous curing resin, controlling the viscosity of the pre-polymerized resin to be 0.5-8 Pa.s at the temperature, then quickly coating the pre-polymerized resin on a fiber monofilament to form microspheres, curing the microspheres under the curing condition of the heterogeneous curing resin to obtain fiber filaments suspending the cured resin microspheres, and screening the microspheres with the diameter of 40-70 mu m as a micro-debonding sample.

2. The method for preparing a micro-debonded sample of a heterogeneous curing resin system according to claim 1, wherein the average agglomerated particle size of the undissolved components in the pre-polymerized heterogeneous curing resin is less than 3 μm.

3. The method of claim 2, wherein the method of detecting the average agglomerate grain size is laser light scattering.

4. The method for preparing a micro-debonded sample of a heterogeneous curing resin system according to claim 1, wherein the heterogeneous curing resin is any one of an epoxy resin with a latent curing system and a heterogeneous bismaleimide resin.

5. The method for preparing a micro-debonded sample of a heterogeneous curing resin system according to claim 1, wherein the fiber monofilaments are any one of carbon fiber monofilaments, glass fiber monofilaments and aramid fiber monofilaments.

6. The method for preparing the micro-debonded sample of the heterogeneous curing resin system according to claim 4, wherein when the fiber monofilament is a carbon fiber monofilament, microspheres with a diameter of 40-55 μm are selected as the micro-debonded sample.

7. The method for preparing the micro-debonded sample of the heterogeneous curing resin system according to claim 4, wherein when the fiber monofilament is a glass fiber monofilament, microspheres with a diameter of 55-65 μm are selected as the micro-debonded sample.

8. The method for preparing the micro-debonding sample of the heterogeneous curing resin system according to claim 4, wherein when the fiber monofilament is an aramid fiber monofilament, microspheres with the diameter of 55-65 μm are selected as the micro-debonding sample.

9. The method for preparing a micro-debonded sample of a heterogeneous curing resin system according to claim 1, wherein the micro-debonded sample is screened according to the particle size of the microspheres on the fiber monofilaments after the resin is cured and cooled to a temperature below 60 ℃.

Technical Field

The invention relates to the technical field of testing of composite materials, in particular to a preparation method of a micro-debonding sample of a heterogeneous cured resin system.

Background

Compared with the traditional metal material, the continuous fiber reinforced resin-based composite material has lower density, higher specific strength and specific stiffness, and has wider and wider application in the fields of aerospace, petroleum, transportation, sports equipment and the like. For a continuous fiber reinforced resin matrix composite material, the interface of the fiber and the resin plays a role in the connection and stress transfer between the fiber and the resin, and is an important influence factor of the static mechanical property and the fatigue mechanical property of the composite material, the interface shear strength is also one of the most important indexes of the interface property, and how to accurately obtain the interface shear strength is the key of material research and development and performance evaluation.

The micro-debonding method, which was first proposed by Miller, 1987, is a method of vertically embedding fibers in a very small symmetrical resin drop, as shown in fig. 1, and the experimental method is similar to the pulling-out experiment, and the magnitude of the pulling-out force is easily measured, and the adhesion strength r value between the fiber-resin interface is estimated by the adhesion length or the adhesion area. However, the current method has larger test error, and one of the reasons is the control in the sample preparation process. Especially when the resin is a latent-type cured resin system, due to the heterogeneous distribution of the curing agent system, the curing degree inside the micro-debonding sample is seriously uneven, and the finally obtained interfacial shear strength is not only low, but also has great dispersion, so that the data given by the evaluation unit cannot be used as an effective reference.

In view of the above, in order to avoid the above problems, it is necessary to develop a method for preparing a micro-debonded sample of a heterogeneous cured resin system, which can realize a low-error test of the interfacial shear strength.

Disclosure of Invention

(1) Technical problem to be solved

Aiming at the defects of the prior art, the invention provides a preparation method of a micro-debonding sample of a heterogeneous curing resin system, which eliminates a plurality of uncertain factors in the preparation of the micro-debonding sample through prepolymerization and uniformity and viscosity control, and realizes stable and low-dispersion sample preparation and test results.

(2) Technical scheme

The core of the technical scheme of the invention is that the non-uniformity degree of components in a non-homogeneous curing resin system is reduced by controlling the uniformity and viscosity of the resin and a prepolymerization method, so that a plurality of uncertain factors in the preparation of the micro-debonding sample are eliminated, the influence of dispersing agents such as solution and the like on the interface is avoided, and the preparation of the micro-debonding sample with a stable and low-dispersion interface shear strength value is realized.

The preparation method of the micro-debonding sample of the heterogeneous curing resin system comprises the following steps: pre-polymerizing heterogeneous curing resin for 20-90 min at the temperature of 20-50 ℃ lower than the curing temperature of the heterogeneous curing resin, controlling the viscosity of the pre-polymerized resin to be 0.5-8 Pa.s at the temperature, then quickly coating the pre-polymerized resin on a fiber monofilament to form microspheres, curing the microspheres under the curing condition of the heterogeneous curing resin to obtain fiber filaments suspending the cured resin microspheres, and screening the microspheres with the diameter of 40-70 mu m as a micro-debonding sample.

Further, the average agglomerated particle size of undissolved components in the resin after prepolymerization is less than 3 μm.

Further, the method for detecting the average agglomerate grain size is a laser light scattering method

Further, the heterogeneous curing resin is any one of an epoxy resin having a latent curing system and a heterogeneous bismaleimide resin.

Further, the fiber monofilament is any one of a carbon fiber monofilament, a glass fiber monofilament and an aramid fiber monofilament.

Preferably, when the fiber monofilament is a carbon fiber monofilament, microspheres with the diameter of 40-55 mu m are selected as the micro-debonding sample.

Preferably, when the fiber monofilament is a glass fiber monofilament, microspheres with the diameter of 55-65 μm are selected as the micro-debonding sample.

Preferably, when the fiber monofilament is an aramid fiber monofilament, microspheres with the diameter of 55-65 mu m are selected as the micro-debonding sample.

Further, after the resin is cured, the resin is cooled to below 60 ℃, and then the resin is screened according to the particle size of the microspheres on the fiber monofilaments.

(3) Advantageous effects

Aiming at the problem that the error of the data of the shear strength of the interface measured by the micro-debonding method in the prior art is large, and particularly the problem that the shear strength of the interface is difficult to accurately measure by a heterogeneous cured resin system, the method for preparing the micro-debonding sample is provided, and the obtained microsphere debonding sample is used for measuring the shear strength of the interface, so that the error is small, and the real interface shear strength between the fiber and the resin can be reflected better.

By the sample preparation processing method, the dependency relationship between the shearing strength and the diameter disappears, the shearing strength is uniformly distributed in the whole diameter screening range, and the interfacial shearing strength between the fiber and the resin is reflected more truly. The problem of uneven distribution of various substances in the sample is solved through prepolymerization homogenization, the sample keeps in accordance with interface infiltration and substance secondary distribution under the real condition through viscosity control, and errors caused by fiber fracture and microsphere damage are avoided through reasonable fiber diameter screening.

Drawings

FIG. 1 is a schematic diagram of the operation of the micro-debinding process.

FIG. 2 is a graph of the interfacial shear strength of epoxy resins versus microsphere diameter for the dicyandiamide cure systems of example 1 and comparative example 1.

Detailed Description

The embodiments of the present invention will be described in further detail with reference to the drawings and examples. The following detailed description of the embodiments and the accompanying drawings are provided to illustrate the principles of the invention and are not intended to limit the scope of the invention, i.e., the invention is not limited to the embodiments described, but covers any modifications, alterations, and improvements in the parts, components, and connections without departing from the spirit of the invention.

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.