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Flame-retardant foamed PP prepared by Ningbo Institute of Materials Science Author/Source: China Chemical Industry News Date: 2019-02-22 Clicks: 1 Polypropylene (PP) is a flammable material, making it particularly important to modify it to make it flame-retardant. Recently, the team led by Researcher Zheng Wenge from the Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, developed an ultra-light, ultra-strong, and highly flame-retardant polypropylene foam by using supercritical carbon dioxide foaming technology in combination with unidirectional drawing, building on the foundation of preparing polypropylene materials with high flame-retardant properties. The polypropylene foam prepared by this team has a unique structure with significant anisotropy. Polypropylene foam has a density of only 0.08 g/cm3, yet it can support a weight equivalent to about 30,000 times its own weight; its specific strength is as high as 1813 MPa/g·cm3, which is far higher than that of polymer foams reported in existing literature. Not only that, but this polypropylene foam also possesses excellent flame-retardant properties due to the use of evenly dispersed intumescent flame retardants, enabling it to extinguish itself within 2 seconds of being exposed to a flame in horizontal combustion tests. Furthermore, the research team also used supercritical carbon dioxide foaming technology to further investigate the effect of various biaxial stretching forces generated during bubble growth on the flame retardant in the matrix. Based on this, the team successfully prepared polypropylene materials with excellent flame-retardant and mechanical properties using hot-press defoaming technology. Currently, halogen-free, low-smoke, drip-resistant intumescent flame retardants remain the main additives for flame-retardant polypropylene materials. However, due to the opposite polarities of the intumescent flame retardant and the polypropylene matrix, compatibility is poor; as a result, severe agglomeration of the intumescent flame retardant occurs within the polypropylene matrix, compromising the material’s flame-retardant and mechanical properties. Therefore, how to effectively improve the dispersion of intumescent flame retardants in polypropylene matrices has always been a major challenge for both the academic community and the industry.