Study On The Free Radical Polymerization Process Of Polyacrylonitrile-based Carbon Fibers

The structure and properties of the original fibers have a direct impact on the quality of the carbon fiber products,and the properties of the polyacrylonitrile precursors are restricted by various factors in the polymerization process.In the preparation of PAN based carbon fiber,the polymerization process is the key to the performance of carbon fiber products.This paper first introduces the production process of polyacrylonitrile polymerization,such as raw material preparation,polymerization,monomer,deaeration,filtration and neutralization,and the operation process of each process are described in detail.In summary,the main features of the two methyl sulfoxide method for the polymerization of polyacrylonitrile precursor units include:At first,the polymer manufacturing for PAN-based precursor,such as raw material preparation,polymerization,demonomerisation,debubbling,filtration,neutralization are presented.Operation of all the working procedures are described particularly.As a genral rule,polymerization unit of the PAN precursor plant in the DMSO method have some key features as follows:1.Has a long technological process including operations as dissolution,reaction,1.Has a long technological process including operations as dissolution,reaction,phase separation,absorb,filtration,etc.2.Reaction product is macromolecule,a kind of viscous fluid,has special particularities in mass transfer and heat transfer.3.Processes of manufacture and feeding are sensitive to temperature and operating at constant temperature are emphasized.4.Some complicated auxiliary systems or processes are needed.Free-radical copolymerization processes of acrylonitrile(AN)with methacrylate(MA)and itaconic acid(IA)were investigated successionally.Author carried out deeply studies on the polymerization processes of PAN fibers and properties change of PAN spinning dope(acrylonitrile copolymer-dimethyl sulfoxide solution)have been investigated with emphasis.The reaserches on the relationship between raw material,main polymerization and quality performance of spinning dope can provide academic help for the preparation of the high —quality product.Performance parameter involved are The amount of initiator,reaction temperature,monomer feed concentration,bicomponent and tercomponent of solution polymerization,compared the use of recovered solvents.The corresponding relationship between the process parameters and the performance parameters:1.Adding initiator dosage or reaction temperature in a moderate extent has approximative effect on performance parameters.It increases increment speed of conversion rate,but decreases rotary viscosity and intrinsic viscosity of end product observably;2.Adding monomer concentration increases conversion rate,rotary viscosity and intrinsic viscosity in like manner.The preferable extension of process conditions are confirmed according to experimentations before-mentioned of influential factors.After this experiment for bicomponent and tercomponent of solution polymerization and use of recycled solvent,we found that:1.Tercomponent of solution polymerization is more excellen.2.The use of recycled solvent solvent does not cause significant adverse effects on the properties of the product,it is to reduce the cost of technological measures.