Continuous Preparation Of PDMS/SCF Conductive Composites By SCFNA Method

Polymer-based conductive composites have excellent properties such as controllable conductivity range,low density,and easy processing,and are widely used in antistatic,electromagnetic shielding,and conductive sealing materials.Self-assembly of conductive fillers is the main preparation method of polymer-based conductive composites.By increasing the volume fraction of conductive fillers to the percolation threshold,the conductive particles form a self-assembled conductive network within the polymer matrix,which can make the composites obtain a strong conductivity.However,due to the low conductivity of the selfassembled network,it is difficult to obtain composites with high conductivity by increasing the volume fraction of conductive filler alone.Moreover,the high content of conductive fillers can seriously weaken the mechanical properties and processability of the composites.Spatial Confining Forced Network Assembly method(SCFNA)is capable of spatially confined extrusion and interfacial micro-and nanomechanical assembly of polymer-conductive filler systems by mechanical means,thus exerting a "forced assembly force" on the functionally dispersed phase that is much larger than the self-assembly force,forcing the polymer between the conductive particles to "extrude" to obtain a dense conductive network,offering the possibility of preparing highly conductive composites.At present,the preparation of conductive composites by SCFNA method is mainly realized by processing processes such as doubleplate hot embossing or injection compression,which has problems such as discontinuous production and low preparation efficiency.In order to achieve high efficiency and continuous preparation of high-performance conductive composites,this paper combines the SCFNA method with the continuous roll pressing process and proposes a new method for the preparation of conductive composites by Continuous Rolling Spatial Confining Forced Network Assembly technique(CRSCFNA).The polymer-conductive filler system is rolled using low-modulus elastic rolls to achieve densification of the conductive network,thus meeting the requirement of continuous preparation of high-performance conductive composites.In addition,continuous rolling enables the conductive filler to be oriented and oriented in the direction of the roll,resulting in better conductivity and mechanical properties of the composite in the direction of the roll.The main research of this paper is:(1)Based on the principle of preparing conductive composites by SCFNA method,a CRSCFNA process model in the form of roll-to-plate was established.The modulus of elasticity of the press roll material is the key factor affecting the compacting effect of the conductive network and the thickness uniformity of the composite by theoretical calculation.An experimental setup for the preparation of conductive composites using the CRSCFNA process was designed,and the main structural components of the setup were optimized and calibrated to determine the number of screw steps as a function of roll pressure,average contact surface pressure and contact surface pressure distribution.(2)The PDMS/SCF conductive composites were prepared by the CRSCFNA process,and the experimental method of controlled variables was used to study the influence of process parameters in the CRSCFNA process on the conductivity,material thickness and surface quality of the products,and to determine the optimal process parameters applicable to the preparation of PDMS/SCF conductive composites by the CRSCFNA device.(3)PDMS/SCF conductive composites were prepared using the comingled self-assembly method,SCFNA method and CRSCFNA process,and the conductive properties,mechanical properties and micromorphology of the composites prepared by the three methods were analyzed.PDMS/SCF-Bolting Cloth conductive composites were prepared using the CRSCFNA process,and the effects of screen mesh number,screen placement and rolling method on the conductive properties,mechanical properties and filler distribution of the composites were investigated.(4)A preliminary scheme for the continuous preparation of PDMS/SCF conductive composites by CRSCFNA process was proposed,and some structures of the roll press system and hot press curing system were designed and improved,and the feasibility of continuous production of PDMS/SCF conductive composites by CRSCFNA process in industry was initially verified by simulating the continuous preparation of PDMS/SCF conductive composites.