Preparation, structure and flame retardancy of poly(butylene terephthalate) with gradient intumescent flame retardant distribution

Abstract

In this manuscript, the content-gradient distributions of an intumescent flame retardant (IFR) island-shaped structure in poly(butylene terephthalate) (PBT) were prepared using compression sintering processing technology inspired by powder metallurgy, to achieve efficient flame retardancy and mechanical properties with low flame retardant dosage. The PBT/IFR master-batch was first prepared by extrusion and then pulverized into powder. At low temperature (20 °C below the melting temperature) and high pressure (≥ 50 MPa) sintering processing conditions, two PBT/IFR powders with different levels of IFR content were fabricated into restricted island-like structure composites. The island with a higher IFR content exhibited flame retardancy, while the island with lower IFR content maintained the mechanics of the matrix. Compared with the uniform dispersion PBT/20 wt% IFR composite, the combustion of the PBT/IFR (25 wt%:15 wt% = 1:1) gradient content composite improved from V-1 to V-0 using a UL-94 test, while the tensile strength increased by 10%. The performance of the flame retardant was improved by periodically changing its distribution in the polymer matrix via restricted island-like structures fabricated using compression sintering processing technology inspired by powder metallurgy.