Multifunctional nucleating agents with simultaneous plasticizing, solubilizing, nucleating and their effect on polyvinyl alcohol foams

Abstract Currently, preparing microcellular polymer foams by supercritical CO2 (Sc-CO2) is a newly trend and challenge. The main limitation of Sc-CO2 used in microcellular foaming industry is its solubility. In this paper, four kinds of amines (formamide, ethylenediamine, polyamide dendrimer (PAMAM) and polyhedral oligomeric silsesquioxane (POSS)) were introduced into polyvinyl alcohol (PVA) to improve the foaming behaviors. The results of differential scanning calorimetry showed that formamide and POSS could plasticize PVA to a certain extent. Through SEM analysis, formamide and ethylenediamine has a nucleating effect and improves the foaming effect. Furthermore, the content of formamide has a great influence on the foaming behavior of PVA. TG-IR analysis showed that -NH2 can react with CO2 to form -HNCOO- at normal temperature and pressure, which contributed to the diffusion of CO2 and improved the uniformity of cell size. With increasing formamide content, the cell density increased from 3.22 × 109 cm−3 to 1.79 × 1010 cm−3.