Foaming Polystyrene with a Mixture of CO2 and Ethanol

Abstract

Use of mixtures of blowing agents in thermoplastic foam extrusion has been an industrial practice for a long time. However, it has gained renewed interest in the past few years due to the introduction of difficult-to-process alternative gases, targeted as potential replacement for the banned ozone-depleting blowing agents. Reasons for blending physical foaming agents (PFA) are numerous. The incentives may be economical, environmental, or technical. With respect to that latter factor, blending suitable PFAs is often regarded as providing a better control of processing conditions. For example, a specific PFA could be selected for its inflation performance and blended with other co-blowing agents chosen for their stabilizing role. Although a considerable amount of work has been done in that area, very little information has been disclosed in open literature. Carbon dioxide (CO2) has been reported as an interesting candidate for low-density polystyrene (PS) foaming, although the required concentrations are associated with high processing pressures due to the low solubility of the gas. Thus, stable processing conditions are difficult to achieve. This work studies the effect of blending CO2 with ethanol (EtOH) as a co-blowing agent for PS foaming. Extrusion foaming performance of this mixture is discussed, with respect to its solubility (i.e., degassing conditions) and rheological behavior. The function of each blowing agent during the process is analyzed with respect to the plasticization, nucleation, expansion, and stabilization phases. Attention is also paid to the interaction involving the two PFA components.

Study of solubility and swelling ratio in polymer‐CO2 systems using the PC‐SAFT equation of state

“…CO 2 is also considered as a potential blowing agent in polymeric foaming processes after chlorofluorocarbon gases (such as CFC‐11, CFC‐12) are prohibited. When CO 2 penetrates into a polymer, the polymer properties such as glass transition temperature, melting temperature, surface tension, and viscosity are altered . Thus, the solubility data of CO 2 in polymers is important for optimal design in polymeric foaming process.…”

New challenges in polymer foaming: A review of extrusion processes assisted by supercritical carbon dioxide

“…Several CO 2 -based mixtures have also been used as blowing agent. For instance, Champagne et al used ethanol and 1,1,1,2-tetrafluoroethane (HFC-134a) as a co-blowing agent for the foaming of PS [64] and PE [65], respectively.…”

Catalytic Molecular Logic Devices by DNAzyme Displacement

“…Zur Validierung des Simulationsmodells unter produktionstechnisch relevanten Bedingungen wird der Extrusionsprozess von physikalisch geschäumtem Polystyrol betrachtet. Das Verfahren ist für die Herstellung von Hartschaumplatten zur thermischen Dämmung von wesentlicher Bedeutung 18. Die Experimente wurden an einer Tandem‐Schaumextrusionsanlage der Firma Reifenhäuser durchgeführt.…”