关键词导电纸 纸 导电复合材料 层压导电复合材料 面发热材料 炭纤维导电纸
Carbon fiber (CF) electrically conductive composites consisting of electrically conductive paper, facial-heating materials laminated FR-4 brominated epoxy resin and flexible facial-heating materials laminated rubber have been studied in order to develop and apply carbon fiber functional composites. The relationships between the CF volume fraction and the resistance ratio of electrically conductive paper, which were made by short carbon fiber mixing with natural lignocellulose through general wetting-making paper method, were investigated. A sharp drop in resistance ratio was observed in the case after a critical concentration of fiber reached, which was called percolation threshold (about 0.376vo1％) mainly depended on carbon fiber geometry and structure. The relationship for the resistance ratio of electrically conductive paper and the volume fraction of carbon fiber presents as follow: ρ=ρ〓 (Φ+0.62) 〓. The pressure-sensitive characteristics of the electrically conductive paper filled with carbon fiber have been also studied. The results suggested that the electrical conductivity of the composites depends on the pressure critically. In the range of the experimental pressure, the resistance ratio reduces constantly with the increase of the pressure, which is called"Negative Pressure Coefficient of resistive (NPCR) "effect. The press-sensitivity of the electrical resistance and the behavior of electrical resistance wriggle shown under the same pressure at different time are associated with the reformulation and the destruction of the conductive network under a certain strain. A three dimension conductive network structural model for the electrically conductive composites was presented on the basis of the research of its electrical properties and pressure-sensitive characteristics and the observation of its microstructure. It can well be applied to the thermal history experiment of the paper and the facial heating-board laminated with resin. A conductive mechanism model called "conductive network combined with thermal expansion model"was also pointed out.
The electrical properties of carbon fiber facial heating-sheet made by carbon fiber conductive paper laminated with FR-4 brominated epoxy prepreg glass cloth have been studied in this paper. The results showed that the curing of FR-4 prepreg influenced the changes of electrical properties. Different kinds of conductive paper samples had different decrease ratios. The resistance and temperature (R-T) relationship of facial heating sheet during the heating and cooling recycling process presented some difference between the heating curve and the cooling curve. The samples exhibited PTC or NTC effect, but the room temperature resistance kept stable after several times of heat treatment. Resistance of facial heating sheet decreased slightly and kept stable after use for several hours. This kind of facial heating sheet had constant power under long use. Power density and surface temperature curve showed linear behavior. The electrical properties、the character of far infrared radiation and the power properties for carbon fiber facial heating voltage-board for wool textile finishing were studied further. It can be widely used as a new kind of carbon fiber facial heating voltage-board based on the application at some wool textile factories.
The electrical properties of laminated rubber/carbon fiber paper facial heating-sheet were investigated. The results show that the vulcanization process had direct effect on the resistance of conductive paper and facial-heating board, and the sheets in different sizes had different resistance decay rates during vulcanization. Heating-sheets possessed good heat circle stability, and the room temperature resistance kept constant after several heat circles. The linear relationships of voltage-current and power density-surface temperature relationships existed. It also can keep constant power for long time use on the basis of the formation of interconnecting continuous conducting networks in electrically conductive carbon fiber paper. It can be widely used as a new kind of low temperature facial heating material for livestock and other uses.
Activated carbon fiber paper (ACFP) was made through wetting-making-paper technology. The effect of dispersing agent and the ratio of activated carbon fiber to cellulose fiber on permeability, tensile strength, BET surface area and microporosity of ACFP was investigated. The results show that dispersing agent can increase the tensile strength of ACFP and has little influence on the permeability of ACFP. The permeability of ACFP increases and the tensile strength of ACFP decreases while increasing the percent of ACF in ACFP. ACFP has similar pore size and pore size distribution to ACF. Both of them have the similar nitrogen adsorption isotherm plot, i. e. I type isotherm plot. The adsorption mechanism of ACF and ACFP is micropore filling. The structure of ACFP is randomly arranged.
Secondly, surface treatment of ACF by anode oxidation using 〓 electrolyte has beeen carried out. The results indicated that the concentration of electrolyte is much more important than the other factors and the better condition of anode oxidation treatment is as follows: the concentration of electrolyte 3％ (wt％) , the electric current intensity 1. 6A, oxidation time 150s. The structure between as-received ACF and oxidized ACF was characterized by AFM, XPS, XRD, SEM, BETSSA and PSD methods. The different structure of ACF and oxidized ACF indicated that OACF has higher adsorption capacity than ACF and the mechanical properties of ACFP by surface treatment were improved. In the course of anode oxidation, amorphous carbon atoms were etched under the suitable conditions at first, then, crystallitic carbon atoms would be etched as the surface treatment conditions becoming more rigorous.