Rheological and thermal properties of externally plasticized cellulose acetate for physical foaming

The influence of plasticizers on thermoplastic processing, rheological and thermal properties of CA necessary for foam sheet extrusion were investigated by rotational and capillary rheometer, rheotens test, melt flow rate (MFR) and differential scanning calorimetry (DSC)

Surface roughness and foam morphology of cellulose acetate sheets foamed with 1,3,3,3-tetrafluoropropene

Cellulose acetate (CA) is a bio-based polymer suitable to replace foamed polystyrene (PS) in packaging applications. Foam trays can be produced by thermoforming of extruded sheets foamed with physical blowing agents. In this paper, the effects of various process settings and the calibration of the sheet on foam morphology and surface quality of extruded CA sheets are presented. Different contact cooling options were applied in order to investigate their influence on surface roughness, density, and morphology of the sheets. By adjusting cooling parameters, blowing agent formulation, and process settings, smooth foam sheets with a surface roughness below 10 µm and a density in the range of 150 kg m−3 were produced

Influence of physical blowing agent and talc content on the foam extrusion behaviour and foam morphology of externally plasticized cellulose acetate

Today, foam extrusion is a well established polymer processing technology. Generally oil-based polystyrene (PS) is one standard material used for producing thermoformable extruded foam sheets with physical blowing agents (PBA). PS is non-biodegradable polymer based on non-renewable resources. Contrary, cellulose acetate (CA) is biodegradable and bio-based polymer which exhibits similar properties to PS. This contribution presents recent results of foam extrusion of externally (physically) plasticized CA using different types of PBAs and different amount of talc as nucleating agent. Generally, the density of CA decreased of about 12-times. The PBA as well as the talc have a significant influence on the foaming behaviour, the physical foam properties and consequently on the foam morphology. With an increase in PBA and talc content the foaming behaviour is significantly improved and the foam morphology becomes more homogeneous with higher cell densities. Depending on the type and concentration of the PBA, a closed cell structure can be observed

Regiocontrolled Rearrangement of Isobenzofurans

The regioselective alkylation and oxidative rearrangement of isobenzofurans has been achieved to generate substituted 4,8-dihydroxyisochromanones in good yields and with complete regiocontrol