Extrusion foaming of thermoplastic cellulose acetate sheets with HFO‐1234ze and co‐blowing agents

Abstract

Cellulose acetate is a bio‐based plastic which can be used to produce foam sheets through the extrusion process. In this study, different co‐blowing agents (BAs) were added to the foaming process in order to improve the extrusion foaming behavior and cell density of sheets foamed with HFO‐1234ze. The effect of co‐BAs on the melt viscosity was investigated with an inline extrusion rheometer. Furthermore, the resulting cell morphology of foam sheets was studied. While the plasticizing effect of the co‐BA is similar to HFO‐1234ze, the cell density of the foam sheets could be improved by adding co‐BAs in concentrations between 0.04 and 0.16 mol/kg. Adding 0.06 mol/kg of ethanol increased the cell density from approximately 1 to 12 × 105 1/cm³ at an invariant density of ∼130 kg/m³. The density reduction of the foam sheets can be calculated in good agreement from the molar concentration of the BAs. However, high amounts of co‐BA slightly reduce the BA yield. POLYM. ENG. SCI., 58:E182–E188, 2018. © 2018 Society of Plastics Engineers

Modeling flow and cell formation in foam sheet extrusion of polystyrene with CO2 and co‐blowing agents. Part I: Material model

“…The experimental setup and procedure for rheological characterization correspond to the system described in our previous works. [ 54,60 ] A 60 mm single‐screw extruder (type: Barmag 6E4, manufacturer: Oerlikon Textile GmbH & Co. KG, Remscheid) with a process length of 40 L/D was used for all trials. The use of a static mixer with oil temperature control further improves the thermal and material homogeneity of the gas‐loaded melt.…”

Foamability of Cellulose Palmitate Using Various Physical Blowing Agents in the Extrusion Process

“…Cellulose-based thermoplastics are also a promising biopolymer group for replacing synthetic foams in certain foam applications. However, only some results of cellulose-based extrusion foams have been reported [ 28 , 29 , 30 , 31 , 32 , 33 , 34 ]. Cellulose acetate (CA) is one of the cellulose derivatives that have been recognized as suitable for foam extrusion [ 28 , 30 , 32 ].…”

“…However, only some results of cellulose-based extrusion foams have been reported [ 28 , 29 , 30 , 31 , 32 , 33 , 34 ]. Cellulose acetate (CA) is one of the cellulose derivatives that have been recognized as suitable for foam extrusion [ 28 , 30 , 32 ]. Pure cellulose acetate is thermoplastic material with a glass transition close to its thermal decomposition temperature that narrows its processing temperature area.…”

Development and processing of flame retardant cellulose acetate compounds for foaming applications

“…Hence, potential applications for CA foams are, for example, food trays, which are produced by thermoforming of foamed sheets. In this context, investigations have already been done on the foam sheet extrusion of thermoplastic CA with different physical blowing agents (PBA) . The use of environmentally noncritical 1,3,3,3‐tetrafluoropropene (HFO‐1234ze) as PBA and 0.5 wt % talc as nucleating agent resulted in a 10‐fold expansion of the foam sheets.…”