A Study On The Continuous Preparation Of Polymer Matrix Conductive Composites By SCFNA Method

In recent years,with the advancement of science and technology,polymer composite materials are also developing rapidly.In particular,researchers are particularly concerned about conductive polymer materials.Conductive polymer materials can be used for anti-static,wave absorption and photoelectricity.At present,the conductive fillers studied are mainly carbon-based fillers,but after the occurrence of conductive percolation,the effect will be very poor simply by increasing the content of conductive fillers.Not only will the conductive performance increase become extremely slow,but also it will cause composite material processing performance and mechanics.Spatial confining forced network assembly(SCFNA)is a new method for preparing high-performance conductive composite materials.Its essence is to superimpose the self-assembly force of the filler by the external force,and it restricts the swing freedom of the self-assembly network being subjected to a "forced assembly force" that is much greater than the self-assembly force,forcedly "squeezes away" the polymer between the conductive particles to achieve the densification of the conductive network,which provides the possibility of greatly improving the conductive performance.Using the SCFNA method,the conductivity of the composite material can be increased several times or even orders of magnitude without changing the filler content.However,the SCFNA methods studied by the team in the early stage used non-continuous batch processing technology.Although the processed composite materials have good performance,there are problems of low processing efficiency and poor stability of composite materials during batch processing.(1)In order to improve the productivity and stability of conductive composite materials,based on the research team's early batch method SCFNA process,this article first proposed an extrusion process for continuous SCFNA processing.The process is mainly aimed at thermosetting PDMS(polydimethylsiloxane)and conductive filler system,through raw material pre-mixing,plunger extrusion conveying,self-assembly in extrusion mold and continuous hot-press forced assembly of extrudate process,continuously realize the self-assembly and forced assembly of the filler.The core of the process is to complete the self-assembly of the filler in the extrusion mold to provide a continuous and stable materials for subsequent forced assembly.The subject research verified the feasibility of the process.(2)A set of continuous SCFNA experimental device was designed.This device can adjust the distribution shape of the filler by changing the processing technology conditions,such as raw material pre-mixing conditions,extrusion speed and duration of material's stay in the flow channel,etc.It will appears the fully self-assembled conductive filler in the extrudate at this process and equipment;through the image acquisition window provided on the device,a visual experimental study on the evolution of the distribution of the filler in the continuous flow process was carried out,and the filler self-assembly was obtained.(3)The image analysis software of filler distribution morphology was compiled though the C++,and the collected images were quantified and analyzed.The fuzzy judgment of the image was transformed into a more objective quantitative characterization,which provided useful information for the analysis of the filler self-assembly process.