Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

A New Perspective on Hydrogen Chloride Scavenging at High Temperatures for Reducing the Smoke Acidity of PVC Cables in Fires. IV: The Impact of Acid Scavengers at High Temperatures on Flame Retardance and Smoke Emission

Version 1 : Received: 6 June 2023 / Approved: 7 June 2023 / Online: 7 June 2023 (09:22:56 CEST)

A peer-reviewed article of this Preprint also exists.

Bassi, I.; Delchiaro, F.; Bandinelli, C.; Mazzocchetti, L.; Salatelli, E.; Sarti, G. A New Perspective on Hydrogen Chloride Scavenging at High Temperatures for Reducing the Smoke Acidity of PVC Cables in Fires, IV: The Impact of Acid Scavengers at High Temperatures on Flame Retardance and Smoke Emission. Fire 2023, 6, 259. Bassi, I.; Delchiaro, F.; Bandinelli, C.; Mazzocchetti, L.; Salatelli, E.; Sarti, G. A New Perspective on Hydrogen Chloride Scavenging at High Temperatures for Reducing the Smoke Acidity of PVC Cables in Fires, IV: The Impact of Acid Scavengers at High Temperatures on Flame Retardance and Smoke Emission. Fire 2023, 6, 259.

Abstract

In PVC compounds, hydrogen chloride plays a fundamental role in .H and .OH radical trapping lowering the flame energy during combustion. Furthermore, it yields actual Lewis acids promoting the cross-linking of the polyene sequences from PVC degradation and bringing a char layer, protecting PVC items from flames. Therefore, PVC is inherently flame retarded. However, plasticized PVC requires flame retardants and smoke suppressants to enhance fire performance. Low smoke acidity PVC compounds contain potent acid scavengers capable of acting at high temperatures. They react with hydrogen chloride in the condensed phase, making it unavailable in the gas and even in the condensed phase, compromising the reaction to fire and enhancing the smoke produced during the combustion. The effect of the sequestration of hydrogen chloride in PVC compounds for cables by potent acid scavengers has been studied in this paper through measurements of oxygen index, heat release, and smoke production. It is shown that potent acid scavengers strongly affect parameters like fire growth rate in cone calorimetry, specific (total) heat capacity, and specific heat of combustion of fuel gases in micro combustion calorimetry. They neutralize the action of antimony trioxide and Lewis acid precursors commonly used as flame retardants and smoke suppressants in PVC items, making them prone to ignite, release smoke, and spread flame. A new generation of flame retardants and smoke suppressants is necessary to keep low smoke acidity and high fire performances together in PVC items

Keywords

PVC; Cables; smoke acidity; acid scavengers

Subject

Chemistry and Materials Science, Polymers and Plastics

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