Supercritical COSubscript2/Subscript assisted

Authors: Jia Wang Li Zhang Jinbiao Bao

Publish Date: 2016/05/21

Volume: 34, Issue: 7, Pages: 889-900

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Abstract

The opencell structure foams of linear lowdensity polyethylene LLDPE and linear lowdensity polyethylene LLDPE/multiwall carbon nanotubes MWCNTs composites are prepared by using supercritical carbon dioxide scCO2 as a foaming agent The effects of processing parameters foaming temperature saturation pressure and depressurization rate and the addition of MWCNTs on the evolution of cell opening are studied systematically For LLDPE foaming the foaming temperature and saturation pressure are two key factors for preparing opencell foams An increase in temperature and pressure promotes both the cell wall thinning and cell rupture because a high temperature results in a decrease in the viscosity of the polymer and a high pressure leads to a larger amount of cell nucleation Moreover for the given temperature and pressure the high pressurization rate results in a high pressure gradient favoring cell rupture For LLDPE/MWCNTs foaming the addition of MWCNTs not only promotes the cell heterogeneous nucleation but also prevents the cell collapse during cell opening which is critical to achieve the opencell structures with small cell size and high cell densityThis work was financially supported by the National Natural Science Foundation of China Nos 21306090 and 51403110 Scientific Research Fund of Zhejiang Provincial Education Department Nos Y201430774 and Y201327472 and KC Wong Magna Fund in Ningbo University

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