Effect of inorganic particles on the foaming and anti-shrinkage behav-ior of thermoplastic polyamide elastomers and the mechanism of for-mation of an open-cell structure
Effect of inorganic particles on the foaming and anti-shrinkage behav-ior of thermoplastic polyamide elastomers and the mechanism of for-mation of an open-cell structure
Thermoplastic polyamide elastomer(TPAE)/inorganic particle microcellular foams with low shrinkage and high expansion ratio have been prepared using supercritical CO2 as a blowing agent.The effects of inorganic particles on the foaming and anti-shrinkage behavior of TPAE were studied using scanning electron microscopy,con-tact angle measurements,rotary rheometry,true density measurements,and intermittent foaming experiments.The results show that compared with Talc as a standard,calcium silicate(CaSiO3),calcium carbonate(CaCO3),and wollastonite(WI)all have higher interfacial tension with TPAE,showing apparent thermodynamic incompatibility and improving the melt viscoelasticity of TPAE.Analysis of the mechanism of formation of the open-cell structure of the composite foams shows that their open-cell content increases with the increasing interfacial tension between the inorganic particles and the TPAE matrix,the diameter of inorganic particles,and the distribution density.The for-mation of an open-cell structure can accelerate the exchange rate of CO2 and air,and reduce the shrinkage of the TPAE foams.Therefore,the introduction of inorganic particles not only improves the cell density and uniformity of the cell structure of TPAE foam but also endows the TPAE foam with an open-cell content of more than 90％,an expansion ratio of 20,and a shrinkage ratio of less than 5％,which significantly enhances the dimensional stability.
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