Applying the DIPAC Model to Predict the Long-Term Thermal Performance of Extruded Polystyrene Foam

The application of a model to predict long-term thermal perfor mance of extruded polystyrene foam aged under laboratory conditions and tested in laboratory equipment is described. No attempt was made to validate the model using foam aged and measured under service conditions A technique to determine key variables such as the mass extinction coefficient, imtial blowing agent fraction, and blowing agent diffusion rate from fitting data to the aging curves of thin slices is ex plained. Two separate examples are used to show how the model may be used to predict ag ing of extruded polystyrene foam for up to three and one-half years by comparing calculated aging curves with actual behaviour. It was concluded that this model is an excellent research tool, but is too complex to use on a routine basis in its present form.