Research of Polymer Manufacturing for PAN-based Precursor
|School||East China University of Science and Technology|
|Keywords||Polyacrylonitrile Spinning Dope Dimethyl Sulphoxide Polymerization Process|
The structure and properties of original fiber directly impact on carbon fiber’s quality,and the polymerization process will impact the performance of the PAN precursor.As the first step of whole manufacturing process, polymerization technics is the key factor which determine the quality of polyacrylonitrile(PAN)-based carbon fibers during the preparation of carbon fibers.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. Not only two key working procedures,polymerization and de-monomer,were illustrated in detail,but alse the whole manufacturing course of polymer was demonstrated as far as possible.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, 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 conversion rate, rotary viscosity, intrinsic viscosity and molecular weight characteristic; Material and process conditions involved are initiator dosage and adding time; principal reaction temperature and polymerization time; monomer concentration; the content of oxazole in moncmcr; the application of recuperated solvent.We find that:good coincidence relations as follows exist between process conditions and performance parameters.1. prolonging polymerization time increases conversion rate and rotary viscosity,but with different rate of accretion;2.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;3.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,experimentations concerning molecular weight characteristic are put in practice. We find that:1. Planing initiator adding time at the end of heatingup for polymerization obtains copolymer with better molecular weight characteristic.2. High dosage of oxazole in monomer results in wider distribution of molecular weight.It should be confined.At last, the application impact of recuperated solvent was tested and proved that the performances of product don’t worsen be consequent upon it usage.It’s considerd to be the most effective technics means of cost cutting.