Correlation of the melt rheological properties with the foaming behavior of immiscible blends of poly(2,6‐dimethyl‐1,4‐phenylene ether) and poly(styrene‐co‐acrylonitrile)

Abstract

Immiscible blends of poly(2,6-dimethyl-1,4-phenylene ether)/poly(styrene-co-acrylonitrile) (PPE/SAN) were batch-foamed using CO 2 as a blowing agent as a function of foaming temperature, foaming time, and blend composition. Evaluation of the resulting cellular morphology revealed an enhanced foamability of SAN with PPE contents up to 20 wt% as indicated by a similar volume expansion but a significantly reduced mean cell size. This behavior is related to a heterogeneous nucleation activity by the dispersed PPE phase. A further increasing PPE content, however, leads to increasing foam densities as well as nonuniform foam morphologies. The changes in the foaming behavior can be correlated with the melt rheological properties and the corresponding blend morphology. Shear-rheological investigations revealed an onset of percolation of the dispersed PPE phase between 20 and 40 wt%, and a transition towards cocontinuity at 60 wt%. The materials response under uniaxial elongational flow, as assessed by Rheotens measurements, revealed an increase in elongational viscosity scaling with the PPE content, similar to the shear data. However, the strain hardening behavior was reduced by increasing PPE contents and, at 20 wt%, the drawability revealed a significant drop-both phenomena limiting the foamability of polymers. In summary, the present study discusses fundamental aspects of foaming immiscible PPE/SAN blends.

Morphology and physical properties of composite foams based on low‐density polyethylene and ground tire rubber

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Effect of β‐tricalcium phosphate on the thermal foaming behavior of poly(vinyl alcohol)/water system

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“…The cell size distribution and the average cell size were measured by using the Nano Measurer software (Fudan University, China), each data was a statistic of 100 cells in the SEM photo. The cell density was calculated using the following equation where N is the cell density, n is the number of cells in the SEM photo, M is the magnification factor of the SEM photo, A is the corresponding area of the photo.…”

Microcellular silicone rubber foams: The influence of reinforcing agent on cellular morphology and nucleation

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