Preparation And Properties Of Polypyrrole/Carbon Fiber Paper-based Electrothermal Composites

As electric heating materials slowly enter people's daily life,people's requirements for electric heating materials have been advanced to everhigher levels,so researchers are actively looking for heating materials with excellent heating effects and beneficial to human health.Carbon fiber conductive paper and polypyrrole?PPY?have good conductive heating effect,and the far infrared generated by carbon fiber conductive paper heating can promote human blood circulation,but it is difficult to achieve uniform heating and high heating temperature.Therefore,the purpose of this paper is to use a small amount of carbon fiber?CF?and other fibers to prepare a carbon paper precursor?CPP?with uniform carbon fiber dispersion,then evenly distribute PPY on the CPP,finally it can obtain an electric heating with uniform heating and a higher heating temperature paper-based composite materials.In this paper,the carbon paper precursor?CPP?with uniformly dispersed carbon fiber was obtained by wet papermaking technology,The hydrogen bond was formed due to the imine bond of the pyrrole?PY?monomer and the amide bond of the aramid pulp in liquid phase polymerization method and the gas phase polymerization method.Then under the action of oxidant and dopant,PY polymerizes on CPP for obtain liquid-phase polypyrrole/carbon fiber?LPPY/CF?paper-based composite materials and gas-phase polypyrrole/carbon fiber?GPPY/CF?paper-based composite materials.And their best preparation process was discussed in order to get their lowest resistivity.The results showed that when the carbon fiber?CF?content was 10 wt%,the best effect of CPP was made by papermaking.CPP was prepared through 90 wt%aramid pulp?AR?and 10 wt%CF,and when ammonium persulfate?APS?as oxidant,anthraquinone-2-sulfonate?AQS?as dopant,a concentration of pyrrole?PY?was 0.75 mol/L,the prepared LPPY/CF paper-based composite had the lowest resistivity of 0.152?·cm.When 90 wt%aramid pulp?AR?and 10 wt%CF were used to prepare CPP,and the concentration of ferric trichloride?FeCl₃?was 1.2 mol/L,the resistivity of the obtained GPPY/CF paper-based composite reaches a minimum value of0.139?·cm.It can be seen from the results that the conductivity of the obtained GPPY/CF paper-based composite was better than that of LPPY/CF paper-based composite.This was because the PY monomer was basically converted to PPY in the gas-phase polymerization method,and a part of it was not converted in the liquid-phase polymerization method,resulting in a slightly lower resistivity of the paper-based composite material obtained.In order to compare the performance of LPPY/CF paper-based composite and GPPY/CF paper-based composite,the mechanical properties,conductive and thermal properties,environmental stability of LPPY/CF paper-based composite and GPPY/CF paper-based composite were tested.In terms of mechanical properties:Compared with CPP,LPPY/CF paper-based composite increased the tension index by 40.08%,the tear index by 46.49%,and the tear index by 24.64%,while GPPY/CF paper-based composite increased the tension index by 93.83%,the tear index by 115.21%,and the tear index by 87.41%.It can be seen that the mechanical properties of LPPY/CF paper-based composite materials and GPPY/CF paper-based composite materials had been improved,but that of GPPP/CF paper-based composite materials had been more improved.From the aspect of conductive heating performance:the comparison between GPPP/CF paper-based composite materials and LPPY/CF paper-based composite materials,not only the minimum resistivity of GPPY/CF paper-based composite materials was lower than LPPY/CF,but also the uniformity and conductive heating performance LPPY/CF paper-based composite material.From the aspect of environmental stability:LPPY/CF paper-based composite and GPPY/CF paper-based composite work better under weak acid or neutral conditions,and had low requirements for environmental temperature,but the storage durability and environmental humidity resistance of LPPY/CF paper-based composite were better.This was due to the fact that the PPY produced by the polymerization of GPPY/CF paper-based composites was more and more uniform,and the combination of PY and aramid pulp produces more hydrogen bonds,which makes the amorphous region in CPP change more to the crystalline region,so the mechanical properties,Uniformity and conductive heating performance were better than LPPY/CF paper-based composite materials;However,as the dopant of LPPY/CF paper-based composite was AQS,and AQS was the large molecule dopant,it was difficult to escape from the molecular chain of PPY,the PPY in the material had a low degree of corrosion,so its storage durability was better.In order to improve the storage durability of GPPY/CF paper-based composite materials and to be able to work for a long time,GPPY/CF paper-based composite materials were impregnated with phenolic resin at a concentration of 15%,and then obtained the gas-phase polypyrrole/carbon fiber resin?GPPY/CFRP?paper-based composite material was optimal with the conditions of 160°C and 6MPa hot pressing,the mechanical properties,electrothermal properties and environmental stability of GPPY/CFPR paper-based composites were tested.Due to the crosslinking between phenolic resin and fiber after hot pressing and curing,a layer of resin film is formed,which makes the material have high hydrophobicity and can effectively isolate O₂ and H₂O in the air.Compared with GPPY/CF paper-based composite material,its mechanical properties and storage durability are greatly improved,but the conductive heating effect was basically the same.It is known that GPPY/CFRP composite material has better mechanical processing performance and can be used for a long time,so it has a broader application prospect.