Evaluation of the melting behavior and the melt penetration into the solid bed using a model experiment

Activity: Talk or presentationOral presentation


This work deals with the melting of polymeric materials and the melt penetration into the solid bed utilizing a model experiment that simulates the melting process in single screw plasticating units. Polymer granules are pressed onto a heated rotating shaft. The thickness distribution of the resulting melt film is measured according to the principle of optical triangulation (light intersection). This new method and the measurement of the density of bulk using a piston position measurement were presented earlier by the authors. The combination of these different principles allows the determination of the melt penetration into the solid bulk as it takes place in single screw plasticating units. A defined mass of the bulk material is filled into the sample chamber. During the experiment the optical measurement determines the amount of molten material which is transported out of the sample chamber, while the remaining material (bulk and melt) is still inside of the sample chamber. The piston position measurement and the previous measured density of the bulk are used to calculate the mass of bulk material in the sample chamber. The difference between these two values is the melted material which has penetrated the bulk. The packing density and the density of the melt are used to determine the melt penetration depth. The melting behavior of spheroidal and cylindrical shaped polypropylene-homopolymer (PP-H) bulk solids is analyzed at different applied pressure. Spheroidal bulk solids show significant advantages compared to cylindrical shaped granules which melt much slower, particularly at higher pressures. The melt clearly penetrates deeper into the spheroidal bulk compared to cylindrical bulk. The reason for that could be that spheroidal bulk has coherent voids, whereas cylindrical bulk solids can form a very closely spaced orientation. Another possible reason is that the diameter of the spherical virgin material (about 5 mm) is much bigger than that of the cylindrical shaped pellets (1.9 to 2.3 mm, length 6 mm).
Period22 Sept 2015
Event titlePolymer Processing Society Conference 2015
Event typeConference
LocationGraz, AustriaShow on map