This thesis was conducted in cooperation with a Swedish company that develops and manufactures plastic compounds. An increasing need for identifying material properties is seen within the industry in order to predict the outcome of the extrusion process by using simulations. The purpose of this study was to expand a material database with the results obtained through various measurements of the material parameters in order to enable simulations. The numerical descriptions would be analyzed and validated in relation to the obtained results and conducted methods to enable implementation of the material data into the industry. In order to fulfill the purpose, scientific methods was applied by chosen literature studies, research approaches and experimental research. Machine tests were conducted to collect relevant output data that was compared with the results obtained during the simulation process where the experimentally determined material parameters were applied in a material database. Typical injection molding qualities of PET, POM, PC/ABS, SAN and PA66 has been investigated by conducting measurement methods described by standards of the melt flow rate, specific heats, viscosity, crystallinity and melt- and glass transition temperatures. With exception of the viscosity, the material parameters are considered to have high external validity and high reliability and can be implemented into the industry. The bulk- and melt density was determined by adapted methods that need further investigations. The external validity is reduced until these methods and measurements have been validated. The determined material parameters proved to be able to generate reliable simulation results that indicate of how the extrusion process will turn out based on the output values investigated. The data obtained through machine tests was compared with the results that were achieved through simulations and deviated at most 10.9% from the actual outcomes. The viscosity is considered to be the main factor that affects the differences of the output data between the machine tests and the simulation results.