Bulk free‐radical polymerization of styrene on a spinning disc reactor

Abstract

The bulk free-radical polymerization of styrene was carried out on a spinning disc reactor (SDR) with prepolymer feeds previously prepared in a stirred batch reactor at 70 C. The SDR significantly enhanced the reaction rate when the conversion of the prepolymer feed was about 50%. There was an optimal disc rotation speed, that is, 1500 rpm, at which the conversion enhancement was maximized. Increasing the disc rotation speed up to 1500 rpm increased the conversion, but a further increase beyond this speed caused the conversion enhancement to decrease. This behavior could be attributed to the dual effect of the disc speed (controlling both the residence time and the effective radial mixing of the reaction media) on the disc. On the other hand, the multipass disc feeding mode was used as an approach to increase the residence time and evolution of the conversion of the reacting mixture in the SDR. Surprisingly, a maximum conversion change of about 40% was achieved for a prepolymer feed of 50% after three passes across the rotating disc. Furthermore, the effect of multipass disc feeding on the molecular characteristics of the SDR products was investigated. In comparison with the results obtained at a feed conversion of 30%, the weightaverage molecular weight, the z-average molecular weight, and the polydispersity index of the three-pass SDR products prepared with a 50% feed conversion at a rotation speed of 1500 rpm were lower than those of the one-pass products. This behavior could be attributed to probable chain scission of long polymer chains as a result of the high shear and elongation forces that arose on the disc surface.

Free-Radical Polymerization of Styrene: Kinetic Study in a Spinning Disc Reactor (SDR)

“…Same Figure 4 demonstrates time savings of up to 50 min (depending on prepolymerized feed conversion) gained by a single pass on a SDR and evaluates utilization of nine passes on a SDR, whereby a time saving of 2 hours appears achievable. A multi-pass SDR study conducted by Moghbeli et al (2009) showed that considerable increases in conversion were indeed observed, but molecular weights and PDI slightly decreased, most probably due to chain scission of the long polymer chains subjected to the high shear forces. As previously mentioned, on the surface of the SDR thin, highly sheared films are formed, which are associated with high mixing intensities, high shear rates as well as plug flow characteristics.…”

Online conductivity measurement of residence time distribution of thin film flow in the spinning disc reactor

“…Spinning disc reactors (SDRs) have received considerable attention as an intensified reactor technology which can produce highly sheared thin films with enhanced heat and mass transfer characteristics [1][2][3][4][5][6]. As a consequence the SDR has been shown to be suitable for exothermic reactions [7][8][9], and to be very effective as continuous-flow mixers which can offer important benefits over traditional batch processing equipment for intrinsically fast reactions [1].…”

Optimising a vortex fluidic device for controlling chemical reactivity and selectivity

“…Microfluidics also encompasses dynamic fluidic thin films generated centrifugally by passing liquids over rotating surfaces, as in spinning disc processors (SDPs)3456789101112131415161718 and horizontally aligned rotating tube processors (RTPs) with open ends18192021222324. These processors are effective in controlling chemical reactions34567891011121322, probing the structure of self organised systems14, and exfoliation and scrolling of graphite and hexagonal boron nitride ( h -BN)318192021222324. However, the volumes of liquid required for maintaining constant shear intensity in the fluids flowing over the rotating surfaces, coupled with finite residence times and high cost of construction, can limit the scope of their applications.…”

“…SDP has feed jets directed close to the centre of a rapidly rotating disc where there is intense micro-mixing, with residence times of typically less than a second, depending on the size of the disc, spinning speed, surface texture of the disc itself, viscosity of liquid and flow rates10. With respect to applications in organic synthesis, the SDP has been used to isomerize α-pinene7, control polymerization reactions368, and prepare 1,5-diketones as an entry to 2,4,6-triaryl pyridines9. Intriguingly, for the latter, several passes are required to move beyond the chalcone intermediate to form significant quantities of the desired 1,5-diketone9.…”