The Design Of Inverse Gas Chromatograph System And Its Application In The Study Of The PVC Resin Desorption Performance

PVC is a kind of high molecular synthetic material with high performance cost ratio and wide applications, but its residual VCM is not only harmful to people's health, but also effects the performance of PVC resin, so it has become one of the factors which restrain of the development of PVC. The system of inverse gas chromatography is mainly designed to measure the PVC resin desorption rate for the study of the relationship among polymerization technique, particle structure and desorption properties of PVC, so as to provide statistical proof for the selection of technologcial conditions to composite PVC resin whose monomer is easy to desorb.Based on the two-particles diffusion model, an inverse gas chromatograph control system was designed, with PVC resin filling the chromatograph column, VCM as probe, and N2 as carrier gas. System design tasks included hardware and software system design. First, according to processing technique, the selection and building of hardware was finished, including instrument selection, gas circuit design, chromatography revamping, electrical cabinets, control cabinet circuit design and control equipment configuration; then, The human-computer interface and whole control system was built based on SIMATIC PLC and IFIX which integrated the function of automatic control, acquisition and display of real-time data, model fitting, data storage and inquiry. Finally, after debugging and test several times, the problem of poor reproducibility of data and diverging easily when model fitting was overcome. Experiment result indicates that this system is easy to operate, stable and reliable in performance and it can typify the desorption performance of PVC resin with suitable condition control.PVC resin produced by different polymerization techniques was measured with the designed system.The results showed that:(1) The data obtained after model fitting agreed well with the experimental data, indicating the IGC system based on the two-particles diffusion model had good reliability.(2) Emulsions polyvinyl-chloride had the best desorption performance, followed by Micro suspension polyvinyl-chloride and the Suspension polyvinyl-chloride.(3) In the same conversion rate, with temperature of the polymerization increased, aggregation extent of primary particles within PVC resin particles rose and amount of porosity decreased, causing PVC resin performance reduced.