Replacing Harmful Flame Retardants with Biodegradable Starch-Based Materials in Polyethylene Formulations
Author:
Carvalho Bárbara O.1, Gonçalves Luís P. C.1, Mendonça Patrícia V.1, Pereira João P.2, Serra Arménio C.1, Coelho Jorge F. J.1
Affiliation:
1. Centre for Mechanical Engineering, Materials, and Processes, Advanced Production and Intelligent Systems (ARISE), Department of Chemical Engineering, University of Coimbra, Rua Sílvio Lima-Polo II, 3030-790 Coimbra, Portugal 2. Componit Lda, Estr. Real 3, 2070-621 Vila Chã de Ourique, Portugal
Abstract
The addition of toxic flame retardants to commercially available polymers is often required for safety reasons due to the high flammability of these materials. In this work, the preparation and incorporation of efficient biodegradable starch-based flame retardants into a low-density polyethylene (LDPE) matrix was investigated. Thermoplastic starch was first obtained by plasticizing starch with glycerol/water or glycerol/water/choline phytate to obtain TPS-G and TPS-G-CPA, respectively. Various LDPE/TPS blends were prepared by means of melt blending using polyethylene graft maleic anhydride as a compatibilizer and by varying the content of TPS and a halogenated commercial flame retardant. By replacing 38% and 76% of the harmful commercial flame retardant with safe TPS-G-CPA and TPS-G, respectively, blends with promising fire behavior were obtained, while the limiting oxygen index (LOI ≈ 28%) remained the same. The presence of choline phytate improved both the charring ability and fire retardancy of starch and resulted in a 43% reduction in fire growth index compared to the blend with commercial flame retardant only, as confirmed by means of cone calorimetry. Standard UL 94 vertical tests showed that blends containing TPS exhibited dripping behavior (rated V2), while those with commercial flame retardant were rated V0. Overall, this work demonstrates the potential of starch as a natural flame retardant that could reduce the cost and increase the safety of polymer-based materials.
Funder
FEDER funds national funds CEMMPRE funding ARISE funding FEDER—European Regional Development Fund Rede Nacional de Ressonância Magnética Nuclear FCT—Fundação para a Ciência e a Tecnologia
Subject
Polymers and Plastics,General Chemistry
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