Microstrain Study Of SBS Elastic Films

With the continuous upgrading and progress of modern science and technology,thermoplastic elastomer materials are widely used in people’s daily life and in various industries,and researchers have conducted in-depth research on the stress-strain curves of films,the effects of film stretching on the corresponding properties of films,and the effects of varying external conditions on stretching results.However,there is no systematic theoretical system and explanation for the dynamic visualization of strain changes in films at microscopic scales.In this thesis,the tensile properties of SBS film structures of thermoplastic elastomers were investigated,and the effects of film thickness and stretching rate on the microscopic strain behavior of films were investigated by a single-molecule fluorescence imaging system.The main work accomplished in this thesis is as follows.1.Selection and preparation of the substrate film and the film to be tested.In this experiment,PEG dissolved in THF was used as the base film solution,and the prepared base film solution was injected quantitatively into the mold to prepare the base film;SBS dissolved in CHY solution was used as the film solution to be tested,and the prepared film solution to be tested was injected into the mold with the base film in different drop amounts,and the SBS film was immersed in water to dissolve the base film after complete drying to remove the film,and finally the SBS films with different film thicknesses were obtained.2.SBS film stretching experiments.SBS films with fluorescent dye labeling were subjected to uniform stretching experiments through a precision stretching apparatus,and the film stretching information carried by real-time excited fluorescence was recorded using an s CMOS camera to investigate the effects of different film thicknesses and different stretching rates on the tensile strain of SBS films.3.Analysis of SBS tensile experimental results.From the microscopic strain data obtained from 75 sets of tensile experiments,the following conclusions were obtained: at the macroscopic scale,the tensile strain of SBS films showed a linear increase with time;at the microscopic scale,the tensile strain of SBS films showed a nonlinear increase with time when the strain of the films was greater than 7%.Different from the conventional study of stress-strain curves of SBS films,this thesis visualizes and records the microscopic deformation process of films in real time by molecularly labeling the central region of film samples with fluorescent dyes and using a single-molecule fluorescence imaging system to give a strain versus time relationship and to investigate the strain behavior of SBS films on a microscopic scale in depth.The experimental results show that the microscopic strain versus time increases nonlinearly when the strain of the film is greater than7%,and these nonlinear relationships show diversity,and this proves that the microscopic strain behavior is non-homogeneous during the film stretching process,which is different from the homogeneous characteristics of the macroscopic strain of conventional films.