AbstractThe magnitude of the thermal stresses generated among the polymeric constituents in highly grafted ABS‐samples during cooling down from the melt can be calculated by means of the ‘double emulsion model’. The effect of these stresses on the location of the rubber maximum in the loss modulusvstemperature plot can be derived from literature data regarding the pressure dependence of mechanical relaxation times.The results are in good agreement with those of torsion pendulum tests on a series of ABS‐samples prepared by blending a grafted rubber with various amounts of SAN‐resin. A continuous shift of the rubber loss peak to lower temperatures with decreasing rubber content is observed.Samples of low rubber content show a split damping peak at low temperatures. The area under the extra peak can be reversibly enlarged or reduced by varying the rate of cooling of the sample in the high temperature region, which indicates that real fracturing of graft molecules cannot be held responsible for this splitting of the peak.Especially at low rubber contents it has been found that the relative increase in rigidity with decreasing temperature is smaller in ABS‐resins than in the pure SAN‐copolymer. This decrease in relative modulus can also be correlated with the absolute value of the thermally induced hydros