This work deals with the material parameters of bulk solids in the solid conveying zone. New measurements show that the coefficient of friction of polypropylene-Homopolymer (PP-H) bulk material is clearly dependent on the frictional distance. Furthermore, a new mathematical model for the bulk density regarding the pressure and the temperature is presented. This model considers the melting point and the pvT-data and needs only three parameters to approximate the bulk density depending on pressure and temperature. The model fits experimental data from room temperature up to the melting point. There is a smooth crossover to the pvT-data at the melting point. These are clear advantages compared to existing models. The same approach approximates the pressure anisotropy sufficiently as well. Experimental results of the measurements of the external coefficient of friction, the bulk density and the pressure anisotropy of PP-Homopolymer (PP-H) utilizing model experiments are presented. The bulk density and the pressure anisotropy coefficient were measured in dependence of pressure and temperature using a special measuring device. The external coefficient of friction was measured dependent on frictional distance, pressure, temperature and the sliding velocity using a unique tribometer. Furthermore the influence of these dependencies is shown by applying these models to a segmented calculation of the solids conveying zone, regarding different models like that of Schöppner, Schneider, Hyun, Campbell as well as the classical one of Darnel and Mol. The results are compared to extrusion experiments.