Modelling and simulation of fluorescence in polymer melt strands of polyester resin and polypropylene

• Beam path and attenuation in polymer melt including fluorescent pigments is modelled.
• Simulations compare fluorescence with different pigment distributions.
• Only pigments in outer layers contribute significant fluorescence intensity.

To expand the knowledge of the extrusion process in co-rotating twin-screw extruders, an optical measurement system was previously introduced (Gerstorfer et al., 2013) [1] to acquire residence time density functions. One of the key problems, occurring with the measurement setup, is investigated in this contribution: the penetration depth of the exciting light and the fluorescence intensity at the melt strand surface was previously unknown. Simulations based on Beer–Lambert’s law in combination with experimentally acquired optical parameters of the processed material result in useful assertions. In this paper, the comparison of simulation results for different kinds of material allow to interpret future measurement results more properly.