Progress on interfacial debonding of basalt fiber-reinforced polymer composites
Release Date：
2022-12-23
Basalt fiber is a kind of high performance fiber material prepared from basalt ore by using melt drawing process, which has the advantages of non-toxic, excellent mechanical properties and corrosion resistance, etc. It is used to prepare fiber reinforced polymer composites (FRP) and is quite valuable in the fields of transportation and construction. In FRP, the area formed between the fiber surface and the matrix is called the interface, whose main function is to transfer the external load from the polymer matrix to the fiber through the interface, so that the macroscopic properties of FRP can be significantly enhanced. The structure and nature of the interface are especially important for the stress transfer process, and the interfacial debonding between the fiber and the matrix is the main factor leading to the structural damage of FRPs, so it is important to establish the early warning and monitoring technology for the interfacial debonding of FRP materials to evaluate the life and service behavior of the materials.
Recently, the Research Laboratory of Environmental Science and Technology, Xinjiang Institute of Physical and Chemical Sciences, Chinese Academy of Sciences, established a new method for monitoring the study of interfacial debonding of basalt fiber-reinforced polymer composites. The researchers researched the literature and found that the organic small molecule tetra-(4-nitrophenyl)ethylene (TPE-4N), which has an aggregation-induced luminescence (AIE) effect, has a fluorescence "switching" property: the material barely emits light when it exists in the crystalline form, but emits strong green fluorescence when it is ground and transformed into the amorphous state. The molecules have excellent film-forming properties on glass, metal and other surfaces. Based on the above phenomenon, basalt fibers coated with TPE-4N were prepared by a simple dip-coating process. The researchers observed the surface morphology of the fiber and found that TPE-4N molecules could form a uniform coating on the fiber surface, at which time the fiber emitted bright green fluorescence; when the fiber was heat treated at 150 degrees, the TPE-4N coating on its surface underwent a phase transition from the amorphous state to the crystalline state, and the fluorescence was almost completely burnt out. After studying the basalt fiber specimens after tensile heat treatment, it was found that the specimens were basically fluorescence-free before stretching, but when the fibers were partially fractured under stress, the TPE-4N crystalline coating coated on the fiber surface was damaged and transformed into the amorphous state at this time, which caused the specimens to emit obvious green fluorescence again (Figure A).
The researchers prepared basalt fiber-reinforced FRP specimens (BFRP) by encapsulating the above fibers in a flexible polymer matrix (polydimethylsiloxane, PDMS) matrix and investigated their fluorescence behavior under tensile conditions. It was shown that the debonding strain (6.29%) of the TPE-4N/BFRP specimens was essentially the same as that of the BFRP specimens (6.93%) (Figure B), indicating that the introduction of TPE-4N at the interface had less effect on the mechanical properties of BFRP. the TPE-4N/BFRP specimens showed an abrupt change in the gray value when the tensile strain reached 5.25% (Figure C), which earlier than the strain at its complete debonding (to 6.29%), indicating that TPE-4N can be used for early warning detection of interfacial debonding in BFRP materials. The method provides a new way to predict the life time of BFRP materials in real time by detecting the intensity of the fluorescence signal and evaluating the health of the corresponding material.
The related research results were published in Composites Communications, and the research work was funded by Xinjiang Natural Science Foundation.
Using TPE-4N molecules with AIE effect for health monitoring of basalt fiber-reinforced composites (A, fluorescence signal changes of basalt fibers coated with TPE-4N molecules under different stress conditions; B, stress-strain curves of different BRFRP materials; C, fluorescence signal changes of TPE-4N and BFRP under different strain conditions)
