Emulsion copolymerization of vinyl acetate-ethylene in high pressure reactor-characterization by inline FTIR spectroscopy

The objective of this research was to investigate the effect of temperature, pressure, initiator concentration and agitation rate, in ethylene-vinyl acetate emulsion copolymerization, on copolymer composition. The inline React-IR ATR system was used to monitor the reaction as well as to determine residual free vinyl acetate. Pressure, temperature and agitation rate have great influence on mass transfer of ethylene monomer to the reaction sites. The vinyl acetate was introduced in semi-batch mode as well as ethylene since the copolymerization was carried out under a constant pressure of ethylene. The higher temperature results in lower content of ethylene incorporated in copolymer. Increase of pressure has a direct effect on the ethylene content in the copolymers through increasing solubilization of ethylene monomer which in turn increases ethylene content in the copolymers. Copolymers of up to 15 wt.% of ethylene content have been synthesized at an ethylene pressure of 30 bar and a temperature of 75 °C. Analytical methods, such as differential scanning calorimetry, nuclear magnetic resonance, thermogravimetric analysis, and infrared spectroscopy were used for characterization of copolymers.