Investigating the impact of operating conditions on the extent of additive mixing during thermoplastic polymer extrusion

Abstract

Abstract. Adequate dispersion of the additive in polymer composites is vital to their performance. Dispersion occurs via rupture, erosion and collision induced mechanisms. Organophosphorus salt/PET nanocomposites were manufactured on a co-rotating fully intermeshing pilot scale twin screw extruder to determine the impact of operating conditions on the mixing achieved in order to understand the level of control available over the process. The effect on key dispersion mechanisms is discussed. Dispersion was found to increase with decreasing throughput, increasing screw speed and increasing molecular weight of the polymer. Linear relationships between calculated parameters including specific mechanical energy, degree of fill and specific throughput were also observed. A need for a compromise between achieving the desired level of mixing and maintaining the molecular weight of the polymer is established.

Pigmentation and Degradative Activity of TiO2 on Polyethylene Films Using Masterbatches Fabricated Using Variable-Frequency Ultrasound-Assisted Melt-Extrusion

“…The energy required to optimize the dispersion of TiO 2 pigment in polymers is related to the attraction forces between particles and affinity between components [ 11 ]. Dispersion of TiO 2 into polymers is commonly obtained during melt-extrusion (ME) and depends on the mix processes, equipment (such as extruder type single, twin-screw extruder, co-rotating or counter-rotating, intermeshing or non-intermeshing) and screw design [ 12 ]. Even the melt-flow index of the polymer matrix is another factor that plays an important role to enable the transmission of dispersion energy [ 13 ].…”

Investigations Concerning the Residence Time Distribution of Twin-Screw-Extrusion Processes as Indicator for Inherent Mixing

“…This is the potential to balance out local concentration gradients of single components. This type of mixing is classified as distributive mixing and has to be considered separately from dispersive mixing [19], which is the ability to even particle sizes during processing. Overall, the RTD is a suitable measure in terms of material traceability for TSE and continuous manufacturing in general [20].…”

Compounding of Short Fiber Reinforced Phenolic Resin by Using Specific Mechanical Energy Input as a Process Control Parameter

“…Their simulation results showed that the blocks of the kneading discs and the filled section prior to that are responsible for most of the energy input into the material. Stratiychuk-Dear et al [18] found a linear correlation between the SME and the dispersion quality of additives in polymer composites. Dreiblatt and Canedo [14] confirmed by numerical simulation that the main mechanical energy input happens in the first kneading zone, in which the polymer is melted.…”