| Electromagnetic waves in the ground radar,spy satellites,early warning aircraft and drones and other military detection systems are widely used,at the same time,a variety of electromagnetic pulse bombs,electronic warfare weapons systems to military communications and national defense security also brings a certain threat,so high electromagnetic shielding performance protective materials have been widely concerned and research.Among them,the military tent as the military electromagnetic protection field of more widely used materials,can be in the field conditions to prevent electromagnetic weapons on the field command operations equipment interference and destruction,while preventing command operations equipment leakage of electromagnetic information by the enemy reconnaissance and capture,to provide a safe shelter for combatants and military equipment.The subject relies on a double-layer draping tent structure proposed by the school-enterprise cooperation project to develop an economical and practical,lightweight and high-strength,good shielding performance and flame retardant internal draping shielding fabric.The main work content and research results are as follows:First,according to the target product mechanics,shielding efficiency and other indicators,the silver-plated polyester fiber（100 D/36 f）was selected as the raw material for the product,and the structural characteristics of the same specification of ordinary FDY polyester fiber and the strong extension,electrical conductivity,friction and bending properties of comparative analysis.The experimental comparison shows that the silver-plated polyester fiber not only has similar mechanical properties with polyester,and the resistivity is only 1.42×10-6Ω·m,similar to the conductivity of metal conductors,which provides excellent raw materials for the design and development of lightweight,high-strength,economical and practical fabrics with high shielding properties.Drawing on the theoretical model of wire mesh structure,12 kinds of square fabrics with different arrangement ratios of silver-plated polyester fibers and ordinary polyester fibers were woven in warp-weft bi-directional inlay.The effect of the silver-plated fiber content per unit area,the number of stacked layers and the testing angle on the electromagnetic shielding effectiveness was discussed and analyzed.The results show that the shielding effectiveness of the fabric with 4:4（silver-plated polyester:polyester）is better than that of 2:2 and 1:1 in the range of 30～300 MHz when the fabric silver content is 50%,and the shielding effectiveness of the fabric with 1:1 is higher in the range of 600～1500 MHz when the fabric silver content is33.33%,and the shielding effectiveness of the fabric with 4:4 in the range of 30～100 MHz when the fabric silver content is 33.33%.Within the range of 30～100 MHz,the shielding efficiency of the fabric with the inlay ratio of 4:8 is greater than that of 2:4 and 1:2,and the shielding efficiency of the fabric with the inlay ratio of 1:2 is the best in the range of 500～1500 MHz;the shielding efficiency of the fabric increases with the increase of the silver-plated fiber content per unit area,and when the silver-plated fiber content per unit area increases to 80%,the shielding efficiency exceeds 55 d B;the shielding efficiency of the conductive grid structure Fabric shielding effectiveness with the increase in the number of stacked layers is on the rise,when stacked 2 layers,the average increment of fabric shielding effectiveness of 5～10 d B,stacked 3 layers of fabric shielding effectiveness is not greatly improved.In order to give the shielding fabric flame-retardant performance,firstly,the silver-plated polyester fiber fabric is modified with dopamine,and the dopamine undergoes oxidative polymerization to increase the reactive groups on the fiber surface.Then,through the electrostatic interaction of chitosan and phytic acid,the shielding fabric layers are self-assembled and finished.The results show that as the number of assembled layers increases,the flame retardant performance of the fabric gradually improves,and when assembled with 8layers,the LOI value of the fabric increases to 30.39%,and the phenomenon of renewal and negative combustion does not appear,and its damage length drops to 8.20 cm,which reaches the flame retardant index proposed by the project product.Based on the project index,the raw material cost of the shielding fabric is calculated,and the most economical silver-plated polyester fiber and ordinary polyester fiber arrangement ratio scheme is selected under the condition of a certain shielding effectiveness,and the comprehensive performance of the shielding/flame retardant fabric is evaluated.The results show that when the silver-plated polyester fiber content of the fabric is 80%,that is,the arrangement ratio of silver-plated polyester fiber and ordinary polyester fiber in warp and weft is 4:1,the fabric is more cost-effective,and the shielding efficiency,flame retardant performance and warp/weft breaking strength,tear strength and grammage of the fabric meet the index requirements. |
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