Butyl samples with different degrees of branching and molecular weight were prepared in batch and continuous polymerization experiments. Branching was achieved using a bifunctional monomer. Molecular weight was controlled by the addition of a strong chain transfer agent. Samples were compounded with black filler and their processability was determined using cold flow, green strength, green stress decay, mill shrinkage, capillary viscometry, die swell and extrusion rate measurements. The effect of long chain branching on these properties was quantified. Key processing properties of the samples could successfully be described using stress relaxation measurements. Cold-flow, apparent viscosity and die swell were successfully correlated to the stress relaxation properties of the samples. These correlations appeared to be independent of the structure of the polymer.