The structure of polymers significantly influences its mechanical properties and temperature stability. Structure formation of polymers is frequently investigated by DSC. However, the cooling and heating rate range that can be applied by DSC are in many cases not representative for actual processing conditions. Therefore, as an example, the impact of fillers or nucleation agents on the crystallization behavior cannot be investigated under relevant processing conditions. Also, reorganization processes prevent the analysis of the structure of a polymer product, if the applied heating rate is not above a critical, usually quite high heating rate. To overcome these limitations of conventional DSC, chip calorimeters allowing scan rates of several 10'000 K/s have been developed. In this contribution, we present some basic principles of chip calorimetry. We then illustrate the general methodology to study structure formation in polymers. Finally, we investigate the impact of additives (filler, nucleation agents) on the crystallization behavior measured under relevant processing (using chip calorimetry). These results will be compared with data obtained by conventional DSC measurements.