Polyisocyanuratoesters: Renewable linear polyesters with high flame retardancy

Abstract

Biobased urea nowadays attracts increasing attention as a biomass resource with giant potential, which benefits from the development of biobased ammonia and ecological sanitation system. Urea is an ideal feedstock for chemical industry and developing new urea-based polymer materials can take advantage of the urea resource. In this work, a class of renewable linear polyesters, namely polyisocyanuratoesters (PICEs) were synthesized from a urea-based monomer bis(2-carbomethoxyethyl) isocyanurate and biobased aliphatic diols. Compared with conventional aliphatic polyesters, PICEs containing isocyanurate rings in the polymer chain backbone exhibit outstanding flame retardancy that both PICE-4 (the number ‘4’ refers to the number of methylene in diols, e.g. 4 for butylene and 6 for hexylene) and PICE-6 have high limiting oxygen index values over 30%. In the UL 94 tests, PICE-6 reaches V-1 rating; while V-2 is found for PICE-10. All PICEs exhibit similar pyrolysis behavior that the temperatures of 5% weight loss are around 320°C. PICEs are found to have glass transition among 20°C-45°C. No crystallization behavior is observed without annealing except for PICE-10, which can crystallize even at room temperature.