Internal mixer model

The mixer was Moriyama internal mixer, model D3-75, with a 3 litre capacity. The fill factor was 0.7, and the rotor speeds were 72.2 rpm for the front rotor and 52.1 rpm for the back rotor. Also, a laboratory size Banbury mixer was used to assure the similarity of mixing performance. 

Ghoreishy, M. H. R. and Nassehi, V., 1997. Modelling the transient flow of rubber compounds in the dispersive section of an internal mixer with slip-stick boundary conditions. Adv. Poly. Tech. 16, 45-68. 

Nassehi, V. and Ghoreishy, M. H. R., 2001. Modelling of mixing in internal mixers with long blade tips. Adv. Polym. TechnoL 20, 132-145. 

The devolatilization of a component in an internal mixer can be described by a model based on the penetration theory [27,28]. The main characteristic of this model is the separation of the bulk of material into two parts A layer periodically wiped onto the wall of the mixing chamber, and a pool of material rotating in front of the rotor flights, as shown in Figure 29.15. This flow pattern results in a constant exposure time of the interface between the material and the vapor phase in the void space of the internal mixer. Devolatilization occurs according to two different mechanisms Molecular diffusion between the fluid elements in the surface layer of the wall film and the pool, and mass transport between the rubber phase and the vapor phase due to evaporation of the volatile component. As the diffusion rate of a liquid or a gas in a polymeric matrix is rather low, the main contribution to devolatilization is based on the mass transport between the surface layer of the polymeric material and the vapor phase. 

There have been several attempts at models incorporating breakup and coalescence. Two concepts underlie many of these models binary breakup and a flow subdivision into weak and strong flows. These ideas were first used by Manas-Zloczower, Nir, and Tadmor (1982,1984) in modeling the dispersion of carbon black in an elastomer in a Banbury internal mixer. A similar approach was taken by Janssen and Meijer (1995) to model blending of two polymers in an extruder. In this case the extruder was divided into two types of zones, strong and weak. The strong zones correspond to regions... 

Manas-Zloczower, I., Nir, A., and Tadmor, Z., Dispersive mixing in internal mixers—a theoretical model based on agglomerate rupture. Rubber Chem. Tech 55, 1250-1285 (1982). 

The mastication equipment most commonly employed is standard rubber instrumentation such as roll mills, internal mixers, extruders or laboratory devices modeled on them (e.g., a single-rotor internal masticator described by Wilson and Watson (43), die model improved by Kargin and coworkers (11) and the Brabender plastograph). 

I. Manas-Zloczower, A. Nir, and Z. Tadmor, Dispersive Mixing in Internal Mixers - A Theoretical Model Based on Agglomerate Rupture, Rubber Chem. Technol., 55, 1250-1285 (1982). 

Campanelli et al (2004) discuss a model of rubber mixing in an internal mixer based on kinetic, thermodynamic and rheological equations that is used to determine the extent of dispersion, batch temperature and relative batch viscosity over time. The chemoviscosity model is complex in that a model must be developed for the compaction zone, the incorporation zone and the size-reduction zone, as defined by the mixing-time zones in Figure 6.21. 

NMR / TGA / MS / IV / model smdies / kinetics / also data from solution reactions thermal redistribution in internal mixer at 240°C or SSE at 250°C / DSC / selective solvent extraction / SEC / FTIR / SEM vs. time / rheology / mechanical properties / DMTA low degree of thermal redistribution in internal mixer at 240-250°C / torque vs. time, temperature / DSC / solvent extraction... 

PA-6 (70) / EP (0-30) / EP-g-MA (0-30) internal mixer at 240°C / SEM / effects of adding phthahc anhydride to consume amine end-groups / model reactions to assess roles of amine- vs. amide-anhydride reactions Marechal et al., 1995... 

PETG (90-80) / EVAc (10-20) internal mixer at 210°C / SEM / NMR model study / rheology / DMA / interfacial tension measurements by breaking thread method / dibutyl tin oxide catalyst (0-1%) Lacroix et al., 1996 a, b... 

Copolymer formation by miscellaneous reactions Hourston et al. [1991] have prepared compositions of 60-0 parts PBT and 16-40 parts EPDM in the presence of 0-60 parts copolymer of PBT with maleate ester (3.5% maleate) using a TSE at 255°C. A compatibilizing copolymer resulted from the crosslinking reaction between maleate olefinic groups and EPDM olefinic groups. Blends were characterized by mechanical properties and TEM. Model studies were performed to understand the crosslinking process. Blends were also prepared using an internal mixer at 250°C. 

The behaviour of elastomers in internal mixers reflects consequently a combination of shear and extensional responses. Any model of the mixing process has to take account of both shear flow and transitory extensional flow, since for the latter the steady state cannot be achieved. Therefore the response of the elastomers in the earlier times of an elongational process gives information about the mixing behaviour. Using a high rate extensometer,... 

Cha, J. and White, J. L. 2001. Maleic anhydride modification of polyolefin in an internal mixer and a twin-screw extruder Experiment and kinetic model. Polymer Envineerin and Science 41 1227-1237. 

PA-6 (80-20)/PC (20-80) Internal mixer at 240 °C/selective solvent extraction/NMR/TGA/MS/IV/model studies/kinetics/also data from solution reactions Montaudo et al. 1994... 

PET (75)/PBT (25)/various phosphite condensing agents (0-5 %) Internal mixer at 275-280 °C/GPC/DSC/ torque rheometry/viscometry/selective solvent extraction/phosphoms analysis/ effect of PET end-group concentrations/ FTIR for end-groups concentration/effect of phosphite structure/model study with OH -t COOH-terminated acrylic polymer/ detailed mechanistic study Jacques et al. 1993, 1996a, b, 1997... 

PC (50-30)/imidized acrylate copolymer (77 % glutarimide, 19 % MMA, 3 % MAA, 2 % glutaric anhydride) (70-50) Internal mixer at 260-270 °C or solution casting/ETlK/optical microscopy/SEM/ TEM/SEC/model reactions/selective solvent extraction/comparison to blends with PMMA or with imidized acrylate copolymer cmitaining different imide levels, or no acid or anhydride/details of reaction mechanism Debier et al. 1995, 1997a, b... 

PBT (50-10)/EVAc (9 % or 28 % VAc) (50-90) Internal mixer at 230 °C/selective solvent extraction/NMR/FTIR/SEM/model reactions/dibutyltin oxide catalyst (0-1 %)/blends optionally -1- PE Pesneau et al. 1997... 

---