The Trommsdorff effect is a non-linear autoacceleration phenomenon in bulk free radical polymerizations. It is undesired in processes of industrial scale, as it causes hot spots and erratic behavior. In this paper a rheokinetic investigation of the Trommsdorff effect is performed with a helical barrel rheometer. This rheometer can be considered a small-scale model of large reactors, particularly extruders. The rheokinetic measurements show that the Trommsdorff effect can be reduced when the polymerization is performed at a high rotational velocity of the screw. This confirms a previous study performed with a cone and plate rheometer and is encouraging with a view to designing better-controlled bulk free radical polymerization processes of industrial scale.