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Polymers 2016, 8(8), 313;

Silica Treatments: A Fire Retardant Strategy for Hemp Fabric/Epoxy Composites

Department of Chemical Materials and Industrial Production Engineering (DICMaPI), University of Naples Federico II, P.le Tecchio 80, Naples 80125, Italy
Department of Applied Science and Technology, Politecnico di Torino, Viale Teresa Michel 5, Alessandria 15121, Italy
Centro Interdipartimentale di Ricerca sulla Risonanza Magnetica Nucleare per l’Ambiente, l’Agroalimentare e di Nuovi Materiali (CERMANU), Via Università 100, Naples 80055, Italy
Author to whom correspondence should be addressed.
Academic Editor: Abderrahim Boudenne
Received: 6 July 2016 / Revised: 30 July 2016 / Accepted: 8 August 2016 / Published: 22 August 2016
(This article belongs to the Special Issue Recent Advances in Flame Retardancy of Textile Related Products)
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In this paper, for the first time, inexpensive waterglass solutions are exploited as a new, simple and ecofriendly chemical approach for promoting the formation of a silica-based coating on hemp fabrics, able to act as a thermal shield and to protect the latter from heat sources. Fourier Transform Infrared (FTIR) and solid-state Nuclear Magnetic Resonance (NMR) analysis confirm the formation of –C–O–Si– covalent bonds between the coating and the cellulosic substrate. The proposed waterglass treatment, which is resistant to washing, seems to be very effective for improving the fire behavior of hemp fabric/epoxy composites, also in combination with ammonium polyphosphate. In particular, the exploitation of hemp surface treatment and Ammonium Polyphosphate (APP) addition to epoxy favors a remarkable decrease of the Heat Release Rate (HRR), Total Heat Release (THR), Total Smoke Release (TSR) and Specific Extinction Area (SEA) (respectively by 83%, 35%, 45% and 44%) as compared to untreated hemp/epoxy composites, favoring the formation of a very stable char, as also assessed by Thermogravimetric Analysis (TGA). Because of the low interfacial adhesion between the fabrics and the epoxy matrix, the obtained composites show low strength and stiffness; however, the energy absorbed by the material is higher when using treated hemp. The presence of APP in the epoxy matrix does not affect the mechanical behavior of the composites. View Full-Text
Keywords: hemp/epoxy composites; waterglass treatments; solid-state NMR; flame retardancy; cone calorimetry tests; three-point bending tests; vacuum bag molding hemp/epoxy composites; waterglass treatments; solid-state NMR; flame retardancy; cone calorimetry tests; three-point bending tests; vacuum bag molding

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

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Branda, F.; Malucelli, G.; Durante, M.; Piccolo, A.; Mazzei, P.; Costantini, A.; Silvestri, B.; Pennetta, M.; Bifulco, A. Silica Treatments: A Fire Retardant Strategy for Hemp Fabric/Epoxy Composites. Polymers 2016, 8, 313.

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