Preparation and Properties of Thermoplastic Low-Smoke Halogen-Free Flame Retardant Polypropylene Insulating Materials for 450/750 V and below Wires and Cables

In order to solve the shortcomings of traditional cross-linked polyolefin insulated cable materials for 450/750 V and below wires and cables, which have poor heat resistance and cannot be recycled, thermoplastic low-smoke halogen-free flame retardant polypropylene insulated cable materials were prepared by mixing and plasticizing using polypropylene resin and ethylene-butadiene block copolymer as a base, adding halogen-free flame retardant, antioxidant, lubricant and other auxiliaries. Effects of tougheners, antioxidants and flame retardants on properties of cable materials were investigated. And property verification of material samples was carried out after formula optimization, as well as property comparison between trial cables and cross-linked polyethylene insulated cables. Results showed that the selection of styrene-butadiene block copolymer (SBS) as a toughening agent had the best toughening effect on polypropylene insulating materials, with optimal tensile strength and elongation at break. In antioxidant system, when the ratio of antioxidant 1010 and antioxidant 168 was 3∶1, aging properties of polypropylene insulating material were optimal. In flame retardant system, nitrogen-based flame retardant and aluminum hydroxide were used to compound polypropylene insulating materials, which had good flame retardant effect and low smoke generation. The properties of material samples and cable samples could meet the requirements of cross-linked polyolefin insulating materials for 450/750 V and below wires and cables with a temperature resistance of 125 °C, and wear resistance of polypropylene insulating materials was better than that of similar cross-linked polyolefin products. Results in the paper could provide a reference for the development of polypropylene insulated cable materials for low-voltage wires and cables.