| This paper put forward a new kind of activation method for chemical plating textiles based on Molecular Self-assembly technology.Activation layer can be obtained successfully on the surface of textile to initiate chemical plating nickel-phosphorus alloy by such activation method.It improved the traditional technology which included roughening,sensitization and activation process and the amount of palladium was reduced.The new method had much better catalytic ability when applying to polyester and polyamide fabrics,the metalized fabric with high fastness and excellent electromagnetic performance can be acquired.Since the chemical plating is the main stream technology for preparing electromagnetic shielding material,the study of the pretreatment process had broad applying prospects and important theoretical consequences.The main process of the activation method included that,first of all,chitosan-supported layer was deposited on the fabric surface to introduce amino group and hydroxyl group by impregnation or padding method,then the self-assembly palladium membrane can be formed based on the coordination reaction between palladium ions and activated groups when dipping in palladium activation solution.The electromagnetic shielding fabric was finally obtained after chemical plating nickel-phosphorus alloy.Chitosan was used as a carrier on polyester fabric surface to study the absorption properties of palladium ion.The research of adsorption kinetics indicated that the adsorption correlated well with the second-order kinetic model and the adsorption velocity constant was 0.1743min-1 at room temperature.The adsorption was well fitted by the Langmuir isotherm equation which can be considered as monolayer adsorption,and the activation energy was 18.84KJ/mol.The study of the adsorption thermodynamics showed that the process carried on spontaneously and increasing temperature can improve the effect.The C2-NH2,C3-OH,C6-OH polar functional groups of chitosan and palladium ion undergo a coordination reaction according to the analysis of infrared spectroscopy and the potential reaction mechanism was proposed in this study. The polyamide and polyester fabric has been used as the materials to discuss the forming conditions of activation layer and the effects of factors during the activation process by orthogonal and single-elemental experiments.The optimum conditions came out in terms of activation effects judging by the surface resistances of the electromagnetic shielding fabric and the mass-increase rates.Polyamide fabric:concentration of C S 12g/L,concentration of acetic acid 1%,concentration of chloride palladium 10mL/L,concentration of palladium chloride 45mg/L,activated treatment time 30～40min and activated treatment temperature 50℃.Polyester fabric:concentration of CS 10g/L,concentration of acetic acid 3%,concentration of formaldehyde 10mL/L,concentration of palladium chloride 45mg/L,chitosan dipping time 10 min,padder pressure 3kg/cm2,activated treatment time 30～40min and activated treatment temperature 50℃.The fabric after the best activation processing was characterized by XRD,XPS,SEM and ATR-FTIR.The XRD Spectrogram indicated that the uniform palladium layer was formed,and the palladium particles arranged orderly on the surface of fabric.The sizes were about 40nm by SPM observation,and the results of SEM,micro-image also supported this conclusion.It can be speculated that the catalytic layer made by the activation method was thin and uniform,because the ATRFTIR spectra of the activated fabric surface only showed the characteristic peaks of fabric.The chemical plating fabrics were tested by resistant rubbing and fastness before application. The good fastness and rubbing-resistant properties of electromagnetic shielding material which is processed by this activation method had been indicated.Electromagnetic shielding effectiveness of metalized fabric was calculated above 30dB based on Schelkunoff theory was,which meant 96.0 percent of the electromagnetic wave or more being shielded.The metalized fabric obtained by this activation method can meet the demand of electromagnetic protection of civilian supplies.
|
PDF Full Text Request