On the Flammability of the Electron-Beam-Induced Grafting of ABS and SBS Copolymers, Studied by LOI/CONE/XPS

Pre-irradiation of the ABS and SBS copolymers, grafting of monomers (MAA and AA) onto both copolymers (ABS/SBS-g-MAA/AA) and ion exchange of the resulted grafts with cations, such as, Na ⁺ , K ⁺ , Mg ²⁺ , Ca ²⁺ (ABS/SBS-g-MAA/AA-S(Na ⁺ , K ⁺ /Mg ²⁺ , Ca ⁺⁺ ) were involved in grafting. A study has been made using the elevated temperature LOI and CONE in this paper focusing on appraisal of the halogen- and phosphorus-free approach imparting flame retardancy to ABS and SBS copolymers and confirmation of carbon accumulation, extent of cross-linking and onset of charring as functions of temperature by the XPS technique. LOI technique at elevated temperatures and cone calorimetry based on the oxygen consumption principle give parameters definitely associated with the grafting rate (Gr), such as TI,, pk-HRR, SEA, EHC, etc., for each step in grafting. Flammability tests show that the grafting induced by electron beam has led to a large increase in LOI [e.g., ABS-MAA-S(Ca ²⁺ ), +16.5 units], TI [e.g., SBS-g-MAA-S(Mg ²⁺ ), +42.8°C]; cone (25 kW.m ^-2 ): TTI [e.g., ABS-MAA- S(Na ⁺² ), +28%] and dramatic decreases in pk-HRR [e.g., ABS-MAA-S(Na ⁺² ), -67%), pk-MLR [e.g., ABS-MAA-S(Ca ⁺² ), -73%], SEA _F [e.g., SBSMAA-S(Ca ⁺² ), -65%], etc. Most experimental data were studied and confirmed by XPS data.