Study on synergistic enhancement of modified nucleating-blowing agent and its application in foaming polyethylene

Polyethylene (PE) foams are widely used for the advantages of light weight and reducing energy consumption. So, the preparation of environmental friendly and efficient blowing agent is essential. The use of supercritical carbon dioxide (CO₂) as physical blowing agent requires harsh experimental conditions such as high-pressure and temperature. In this study, CO₂ was captured by 1, 2-cyclohexanediamine (TRK) under atmospheric pressure, and reversibly released under heating as a blowing agent with nanosponges (NS) used as the carrier (NS:TRK-CO₂). Furthermore, three ethoxy silane coupling agents were selected to improve the compatibility between heterogeneous nucleating agent (cyclodextrin nanosponges, NS) and PE, so as to improve the nucleation effect of NS and the comprehensive properties of PE composites. Analyses showed that triethoxyvinyl silane (VTES) was a suitable candidate for improving the compatibility of NS and PE. The addition of NS:TRK-CO₂@VTES not only improved the crystallization performance, but also improved the complex viscosity and storage modulus, and enhanced the thermal properties of PE composites. The optimal cell morphology was obtained by introduction of NS:TRK-CO₂@VTES with 5 wt%, the minimum cell diameter was 50 μm, and the maximum cell density was 9.4 × 10⁴ cells/cm³. Compared with the other PE composites, PE/NS:TRK-CO₂@VTES composites showed excellent mechanical, thermal, and sound insulation properties. The maximum impact strength was 7.62 KJ/m², which was two times higher than pure PE. The thermal conductivity was 0.054 W/m k, the sound absorption coefficient was 0.836 at 1500 Hz.