Co-chlorination of low-density polyethylene in paraffin: An intensified green process alternative to conventional solvent-based chlorination

Abstract

This study experimentally demonstrates the potential of co-chlorination as a green process alternative to conventional independent chlorination of polyolefins, which involves the use of non-environment-friendly solvents like carbon tetrachloride (CCl4). Low-density polyethylene (LDPE) was used as a representative polymer in this study and co-chlorinated with paraffin. Apart from being a reactant, the paraffin also acts as a solvent, thus eliminating the need for using CCl4 during the reaction. Test runs were first conducted to measure LDPE-paraffin solution viscosities at different LDPE concentrations to investigate the solubility of LDPE in paraffin. Co-chlorination experiments were then carried out covering a range of temperatures (100–130°C), chlorine flow rates (150–350 mL·min-1), LDPE concentrations in paraffin (10–30%) and agitation speeds (100–400 rpm). The chlorinated LDPE and paraffin products were subsequently characterized post separation using FTIR/1H NMR spectroscopy and differential scanning calorimetry. Specific properties of these two co-chlorinated products were compared with independently chlorinated LDPE and paraffin. The co-chlorinated products were found to compare well in terms of chlorine content and quality. A preliminary comparative study from a process perspective between co-chlorination and conventional chlorination of LDPE is also reported. The results obtained confirm the potential of co-chlorination as an environmentally friendly alternative.