PE/PET Non-woven Based Electromagnetic Shielding Film And Its PET Component Depolymerization Study

The rapid innovation of electromagnetic wave technology promotes the rapid development of science,technology and industry,but it also causes the problem of electromagnetic pollution.For example,electromagnetic wave will cause electromagnetic interference.In addition,long-term exposure to electromagnetic wave environment will also cause serious harm to human physical and mental health.Based on this background,it is urgent to develop effective electromagnetic shielding materials to shield unnecessary electromagnetic waves.At present,the ideal electromagnetic shielding materials are committed to meeting the comprehensive requirements of“thin(thin thickness),light(light weight),wide(wide shielding band)and strong(strong shielding efficiency)”.At the same time,the bending resistance,fire resistance,durability and other characteristics of the material should also be comprehensively considered.In this paper,the“thin and light”polyethylene/polyethylene terephthalate(PE/PET)two-component non-woven fabric is used as the base material for research.Because PE/PET non-woven fabric is insulated and does not have electromagnetic shielding function,Ti₃C₂T_x material with high conductivity in MXene material family is selected as the functional coating to composite with PE/PET non-woven fabric,and the electromagnetic shielding composite film for practical application scenarios is designed and developed.In addition,considering the needs of sustainable development and recycling,PE/PET non-woven alcoholysis reaction process is also explored,which is committed to the decomposition and polymerization of PET components in PE/PET non-woven substrate into monomer ethylene terephthalate(BHET)for recycling,and the physical separation and recycling of PE components.The main contents of this paper are as follows:1.Study on PE/PET loaded MXene self-reinforced electromagnetic shielding film and its properties.Firstly,polydopamine(PDA)was used to modify PE/PET non-woven substrate to enhance its interfacial compatibility.Subsequently,the non-woven substrate was repeatedly dipped into Ti₃C₂T_x suspension(10 mg/mL),and the Ti₃C₂T_x functional components were uniformly loaded on its surface.Finally,combined with hot pressing process,the PE component in PE/PET substrate is melted,and the interfacial bonding properties between the components are enhanced.The results show that when PE/PET is dip coated for 4 times,the 2D Ti₃C₂T_x component achieves uniform load,the load is?2.3 mg/cm~2,and the electromagnetic shielding effectiveness(EMI SE)can reach 47.17dB.More importantly,the EMI SE of the film material obtained by further hot pressing is increased to 50.44 dB.In addition,hot pressing causes PE components to melt and flow out,which increases the surface hydrophobicity of the material,and forms a“glue”effect by self-bonding,which enhances the force between components of the composite membrane and significantly improves its mechanical properties.2.Flame retardant functional PE/PET loaded MXene electromagnetic shielding film and its properties.Based on the first part of the work,we used PDA modified PE/PET non-woven fabric as the substrate,and first deposited polyethyleneimine(PEI)/ammonium polyphosphate(APP)alternately on its surface to realize flame retardant functionalization.Subsequently,Ti₃C₂T_x was loaded onto the flame-retardant non-woven fabric in combination with the dip coating process in the previous chapter.Finally,hot pressing was carried out to melt PE and enhance the adhesion between components.The results show that the load of Ti₃C₂T_x is?1.48 mg/cm~2 and the EMI SE is36.04 dB,the flame retardant experiment shows that the limiting oxygen index of the composite film is 35.5%,which has good flame retardant and self-extinguishing properties,and expands the flame retardant application scenarios of its electromagnetic shielding properties.3.Preliminary exploration on alcohol depolymerization process of PET components of PE/PET non-woven fabric.This part of the research is based on PE/PET non-woven substrate,and is committed to separating and recycling PE components and recycling PET components.The effects of reaction time and catalyst content on the yield were investigated.The results showed that the PE component did not participate in the depolymerization reaction,and the efficient recovery was realized(yield?96%).When the catalyst content was 2 wt%and the depolymerization time was 3h,higher BHET yield(82.56%)could be achieved.Finally,the separation products and target products were characterized by NMR,IR,TG and DSC,which provided a certain research basis for the chemical recovery and recycling of PET based two-component non-woven materials.