Experimental Study on Thermal and UV-enhanced Gas-Solid Chlorination of High-Density Polyethylene.

The dynamic process of gas-solid chlorination of high-density polyethylene (HDPE) was revealed using a vibrated-bed reactor, where a UV-Vis measurement system was used to record the kinetics of chlorination online. Thermal and UV-enhanced chlorination at fixed temperature below the melting point (Tm) of HDPE were firstly investigated. It was observed that UV irradiation could accelerate the reaction rate. However, all of the prepared chlorinated polyethylene (CPE) products had unchlorinated crystal structures and a limitation of chlorine content. Multi-stage chlorination was hence designed for more homogeneous chlorination and decreasing the residual crystallinity. The differential scanning calorimetry (DSC) results showed effective decrease of the melting enthalpy (ΔHm) while the final reaction temperature was beyond Tm. Meanwhile, the presence of -CH = CH- bonds in the polymer chain revealed by solid-state nuclear magnetic resonance (S-NMR) indicated that the final reaction temperature should not be higher than 150 °C. [ABSTRACT FROM AUTHOR]