DEPAL synergists in TPE cable sheaths

Aluminium diethylphosphinate with synergists achieves UL-94 V0 (3 mm) and reduced smoke in thermoplastic elastomer. The phosphorus PIN FR aluminium diethylphosphinate (DEPAL), from Clariant (pinfa member), was tested in thermoplastic elastomer (TPE: 60% SEBS, 20% POE, 20% PPO), at 0 – 30% phr DEPAL loading and at 25% DEPAL with 5% of three different synergists: zinc borate, melamine cyanurate and organic montmorillonite (OMMT). 30% DEPAL increased LOI from 18.5 (neat TPE) to 25.2, reduced PHRR peak heat release rate by over 50% and achieved UL-94 V-2 (3 mm). With 25% DEPAL and 5% zinc borate or 5% OMMT, UL-94 V-0 (3 mm) was achieved, LOI further increased to >28 and PHHR further reduced to <40% compared to neat TPE. On its own, DEPAL increased smoke density compared to neat TPE, but this effect was mitigated by zinc borate, and with OMMT the smoke density was significantly lower than for neat TPE. Tensile strength and elongation at break were not significantly deteriorated. The authors conclude that these PIN synergists with DEPAL can achieve high fire performance in TPE cable materials and reduce dangers from reduce smoke emission.

“Study on the flame retardancy of thermoplastic elastomers composites applied for cable sheath”, L. Wang et al., Progress in Rubber, Plastics and Recycling Technology 2025, https://doi.org/10.1177/14777606241313075  Image: Wikipedia Edgar181