Two methods of copolymerization were evaluated. The first method simply involved adding liquid CPD at a variety of feed ratios to molten sulfur at 140 ºC through a reflux condenser (Fig. ). At a scale of 3.0 g of molten sulfur, the CPD had to be added in 150 µL portions every three minutes or the sulfur would cool too rapidly, crystallize, and interfere with stirring. The condenser was effective in recycling the volatile CPD and returning it to the polymerization vessel.