Test method applying compressing load and stretching load in vertical direction and horizontal direction simultaneously

Abstract

The invention provides a test method applying compressing load and stretching load in the vertical direction and the horizontal direction simultaneously, belongs to the technical field of polymer-based shape memory material training methods and solves the problems of poor shape memory effect and limited application range caused by the unidirectional training method at present. The test method comprises the steps that firstly, a polymer-based shape memory material is prepared and processed into a cross test piece, and the cross test piece is mounted and fixed in a clamp; compressing load is applied under the condition that the temperature is higher than the glass-transition temperature of the test piece, compressing stress and stretching stress are produced simultaneously in the vertical direction and the horizontal direction of the test piece simultaneously, heating is stopped when the test piece is deformed to a designed value, the compressing load is kept unchanged, the test piece is cooled naturally to the room temperature and the load is removed, and a sample with a shape memory function is prepared; the shape memory effect, molecular orientation, internal stress and structure change of the sample are inspected finally, and the shape memory of the sample is studied. With adoption of the convenient training method, the two-dimensional training difficulty of the polymer-based shape memory material is reduced, the shape memory effect is improved, and the engineering application range is enlarged.

Description

technical field [0001] The invention relates to a test method for simultaneously applying compressive and tensile loads in vertical and horizontal directions, and belongs to the technical field of training methods for polymer-based shape memory materials. Background technique [0002] Stimuli-responsive polymers refer to a class of polymers that can respond to subtle physical or chemical changes in the external environment, such as changes in molecular configuration or solubility, or even the formation or breaking of chemical bonds. The subtle changes in environmental conditions include temperature, electric field, pH value, magnetic field, ionic strength, enzyme protein and glucose, etc., while polymer-based shape memory materials change their original shape through external environmental stimuli, thus becoming an important Stimuli-responsive polymers are widely used in daily life, aerospace, civil engineering, etc. [0003] Shape memory polymers and their composite materi...

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Problems solved by technology

[0005] Researchers at home and abroad have used uniaxial loading methods to study the thermodynamic properties of shape memory polymer matrix composites, and analyzed the shape memory effects such as the fixation rate and recovery rate of shape memory materials. However, this unidirectional stretching or compression training method can only Make the molecular orientation of the shape memory material in a certain dimensional direction, endow the material with a one-dimensional shape memory function, and cannot give the shape memory effect to the shape memory polymer base material in the vertical and horizontal two-dimensional directions at the same time, so that the shape memory polymer base material materials are subject to certain limitations in practical applications

[0006] It can be seen that at present, the unidirectional stretching or compression training method is mainly used to endow the material with shape memory effect. This method can only make the molecular orientation of the material in a certain direction. At the same time, the shape memory polymer-based material has a shape memory function, so that the material has a low fixation rate and recovery rate, and the shape memory effect is poor.

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