Posted on 12/09/2022 in Fire Safety 2022
Mechanical recycling of PIN FR epoxy

The PIN FR DOPO is shown to achieve fire and mechanical performance, transparency and recyclability in epoxy. The commercial phosphorus PIN FR 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO) was pre-reacted into DGEBA epoxy before curing. AFD (4-Aminophenyl disulphide) was used as curing agent, resulting in epoxy resin with disulphide bonds. LOI was increased from 24% (neat epoxy) to nearly 30% and peak heat release rate was decreased by nearly 50% at 4% DOPO. UL 94 V-0 (2 mm) was achieved at 3% and 4% DOPO. Good mechanical properties and transparency were maintained. One-cycle mechanical recycling was tested (regrinding then hot pressing at 200°C, without ageing) resulting in limited loss of mechanical properties (90% of initial tensile strength). Fire performance after recycling was not tested.

“Recyclable flame-retardant epoxy composites based on disulfide bonds: Flammability and recyclability”, X. Li et al., Composites Communications 25 (2021) 100754,

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