In recent years, carbon dioxide (CO 2 ) has proven to be an environmentally friendly foaming agent for the production of polymeric foams. Until now, extrusion is used to scale-up the CO 2 -based foaming process. Once the production of large foamed blocks is also possible using the CO 2 -based foaming process, it has the potential to completely replace the currently used foam production process, thus making the world-wide foam production more sustainable. This review focuses on the polymer-CO 2 -foaming process, by first addressing the principles of the process, followed by an overview of papers on nucleation and cell growth of CO 2 in polymers. The last part will focus on application of the process for various purposes, including bulk polymer foaming, the production of bioscaffolds and polymer blends.

The physics and chemistry of nonlinearly oscillating acoustic cavitation bubbles are strongly influenced by the dissolved gas in the surrounding liquid. Changing the gas alters among others the luminescence spectrum, and the radical production of the collapsing bubbles. An overview of experiments with various gas types and concentration described in literature is given and is compared to mechanisms that lead to the observed changes in luminescence spectra and radical production. The dissolved gas type changes the bubble adiabatic ratio, thermal conductivity, and the liquid surface tension, and consequently the hot spot temperature. The gas can also participate in chemical reactions, which can enhance radical production or luminescence of a cavitation bubble. With this knowledge, the gas content in cavitation can be tailored to obtain the desired output.

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A stator–rotor–stator spinning disc reactor is presented, which aims at intensification of convective heat‐transfer rates for chemical conversion processes. Single phase fluid‐rotor heat‐transfer coefficients hr are presented for rotor angular velocities ω=0−157 rad s−1 and volumetric throughflow rates ϕnormalv=15−20·10−6 m3s−1. The values of hr are independent of ϕnormalv and increase from 0.95 kWm−2K−1 at ω = 0 rad s−1 to 34 kWm−2K−1 at ω = 157 rad s−1. This is a factor 2–3 higher than values achievable in passively enhanced reactor‐heat exchangers, due to the 1–2 orders of magnitude larger specific energy input achievable in the stator–rotor–stator spinning disc reactor. Moreover, as hr is independent of ϕnormalv, the heat‐transfer rates are independent of residence time. Together with the high mass‐transfer rates reported for rotor–stator spinning disc reactors, this makes the stator–rotor–stator spinning disc reactor a promising tool to intensify heat‐transfer rates for highly exothermal chemical reactions. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2307–2318, 2015