Development Of Pahs-based Carbon Fibers

Mesophase pitch-based carbon fiber has high modulus,high thermal conductivity and other characteristics,is a modern national defense,electronics and other fields of urgent demand for a high-performance materials.Traditionally,the raw materials chosen for intermediate phase asphalt are industrial oil refining or coking by-products,whose complex and variable components and structures have limited the industrial development and performance improvement of the final fibers to a certain extent.This paper explores the feasibility of using chemically synthesized polycyclic aromatic hydrocarbons(PAHs)as precursors to prepare carbon fibers,and provides a research basis for developing new high modulus and high thermal conductivity carbon fibers.The main contents of the paper are as follows.1.Naphthalene was used as the raw material and anhydrous aluminum chloride was used as the catalyst to synthesize PAHs,the infection of different reaction conditions about structure of products was investigated,and the mechanism of chemical synthesis was explored.The study showed that the catalytic polymerization reaction of naphthalene at room temperature could produce trimers or tetramers;the products were tested and analyzed by mass spectrometry,nuclear magnetic hydrogen spectrometry and carbon spectrometry,etc.It was found that the polymerization reaction was in accordance with the Scholl reaction mechanism,and the prolonged reaction time was beneficial to increase the polymerization degree of the products,while the excessive reaction time would reduce the aliphatic branched structure in the naphthalene multimer products;the addition of iron trichloride would The addition of iron trichloride will promote the formation of aliphatic ring structure and improve the regularity of the catalytic product carbon microcrystals.Finally,we chose to extend the reaction time and add a small amount of ferric chloride as the reaction conditions for naphthalene catalysis.2.Different alkylating reagents(ethanol,xylene,dichloroethane,o-xylene)were added to the catalytic synthesis of PAHs compounds to improve the viscosity-temperature properties.The results showed that the introduction of all four alkylation reagents could effectively reduce the softening point of the PAHs compounds,and the softening point temperature decreased significantly with the increase of the amount of alkylation reagents.By studying the melt spinning performance of the four alkylation products,it was found that the products containing polar groups were less spinnable,while the hydrocarbon ratio of the o-xylene catalyzed alkylation products was close to that of naphthalene,and the spinnability performance was better.(3)The PAHs products were carbonized at 600℃,and the apparent graphene-like structure with a thickness of 4-5 nm and a band width of more than 4 e V was tested by UV absorption spectroscopy,which is expected to be a new type of broad-band semiconductor material.(4)Five different PAHs-based carbon fibers were prepared under suitable spinning conditions by melt spinning of naphthalene alkylation products with suitable softening points,and PAHs-based carbon fibers were obtained by non-melting and high temperature carbonization.The strength of the PAHs-based carbon fibers is more than 600 Mpa.