Study On The Preparation And Properties Of Polyaniline/Ultrapure Taixi Anthracite Composites

Taixi Anthracite as a scarce mineral resource occupies an important position in China’scoal varieties and production. Thus extending its resource life and increasing its utilizationefficiency have become the research focuses. In this paper, ultrapure Taixi anthracite was usedas a template and polyaniline/ultrapure Taixi anthracite conductive composites (PANI/UTXA)were fabricated by the in situ polymerization. The effects of the amount of anthracite, thespecies of doping acid, and the oxidative modification methods of anthracite on the structureand properties of PANI/UTXA waere explored by means of conductivity measurement, SEM,XRD, TG and the BET, etc. Meanwhile, the growth model of PANI/UTXA was presented byusing the fractal theory.First of all, all the conductivity of no external acid, HCl, and TSA doped PANI/UTXAincrease with the increase of aniline content. With the same aniline content, the order of theconductivity of different modified PANI/UTXA composites is: TSA doped PANI/UTXA>HCl-doped PANI/UTXA>no external acid doped PANI/UTXA. There are chemical bondingbetween polyaniline and ultrapure Taixi anthracite and doping occurs mainly in the quinonediimine structure unit. TSA can be effectively doped to the molecule chain of polyaniline, andthe TSA doped PANI/UTXA obtains a high crystallization and well-developed nanowirestructure compared to HCl doped and no external acid doped PANI/UTXA. Additionally,secondary doping does not change the chain structure of PANI/UTXA composites, but lowersthe crystallinity PANI/UTXA. Also, TSA doped PANI/UTXA presents an improved thermalstability. HCl doped PANI/UTXA shows a good electrical conductivity.Secondly, oxidative modification increases the content of COOH and OH groups on thesurface of coal, which facilitate the chemical bonding and doping between coal andpolyaniline to enhance their interface interaction. It also improves the pore structure and poresize distribution of ultrapure Taixi anthracite, plays a role in dredging channels, resulting inmore uniform distribution and more compacted rod structure on PANI/UTXA surface, and increase degree of crystallinity and the thermal stability of the composites. The conductivityof the composites is influenced by the macromolecular skeleton, pore structure, and thecontent of acidic groups. The combining oxidation can easily destroy the macromolecularskeleton structure of ultrapure Taixi anthricate compared to NaClO oxidation. Although thecontent of acidic functional groups increases, it can not make up for the effect of the damageof pore structure and macromolecular skeleton on the conductivity. Therefore, comparedwith combining oxidation, NaClO oxidation can obviously improve the conductivity ofPANI/UTXA composites.Finally, taking advantage of the fractal theory, the growth model of PANI/UTXA ispresented. The results show that the growth of polyaniline particles keeps accordance with theDLA model, and the structure of polyaniline is a branching structure with self-similarity; thefractal growth of polyaniline in the reaction system of PANI/UTXA is affected by theinterfacial interaction and the guiding role. The polymerization growth of polyaniline showsan irregular spherical morphology, layered stack morphology and a rod-like structure inaniline solution, the outer surface of coal, and the limited inner space of coal, respectively.Meanwhile, the polyaniline coating on coal surface is not uniform due to the concentrationdifference.Polyaniline/coal composites as a new functional materials can be widely used asconductive materials, antistatic materials, and anti-corrosion coatings. On the one hand, thehigh cost of polyaniline production can be effectively solved; on the other hand, the industrialchain of Taixi anthracite is further extended and the utilization efficiency of Taixi anthracite isoutstandingly improved.