Reactive and Additive Modifications of Styrenic Polymers with Phosphorus-Containing Compounds and Their Effects on Fire Retardance

A flame-retardant and conductive fabric-based triboelectric nanogenerator: Application in fire alarm and emergency evacuation

The fabrics commonly used in architectural decorative materials pose significant fire hazards due to their flammability and rapid fire spread. Moreover, the traditional fire-alarm systems may fail to function properly in complex fire environments owing to power supply disruptions. In this study, we developed a low-cost and eco-friendly flame-retardant conductive fabric-based triboelectric nanogenerator (FCF-TENG) by integrating flame-retardant conductive nylon fabric and polytetrafluoroethylene soaked cotton fabric. This nanogenerator exhibits excellent flame-retardant properties and remarkable energy-harvesting capabilities. The nylon fabric, treated with layer-by-layer self-assembly method, possesses outstanding self-extinguishing capability and melt-dripping resistance. Additionally, the electrical performance of FCF-TENG significantly improves, with a 10-fold boost in conductivity, and the open-circuit voltage increases by 84% to 92 V. Besides, by incorporating the rectifier circuit, the FCF-TENG is capable of completely charging a 1 μF capacitor within 30 s. Furthermore, the FCF-TENG was successfully applied as a self-powered sensor in the fire-alarm system and served as a safety exit indicator for evacuees and fire rescue. This work presents an effective and innovative application of multifunctional smart textiles for energy harvesting and self-powered sensing.

Synthesis and Characterization of a Novel DOPO-Based Flame Retardant Intermediate and Its Flame Retardancy as a Polystyrene Intrinsic Flame Retardant

The research on intrinsic flame retardant has become a hot topic in the field of flame retardant. The synthesis of reactive flame-retardant monomer is one of the effective methods to obtain an intrinsic flame retardant. In addition, in view of the small molecular flame retardant easily migrates from the polymer during the use process, which leads to the gradual reduction of the flame retardant effect and even the gradual loss of flame retardant performance, and the advantages of atom transfer radical polymerization (ATRP) technology in polymer structure design and function customization, we first synthesized reactive flame retardant monomer 6-(hydroxymethyl)dibenzo[c,e][1,2]oxaphosphinine 6-oxide (FAA-DOPO), then synthesized polystyrene bromine (PS148-Br) macromolecular initiator by ATRP technology, and finally obtained block copolymer polystyrene-b-poly{6-(hydroxymethyl)dibenzo[c,e][1,2]oxaphosphinine 6-oxide} (PS-b-PFAA-DOPO) by the polymerization of FAA-DOPO initiated by macromolecular initiator PS148-Br by ATRP technology. The chemical structure of FAA-DOPO was characterized by 1D and 2D NMR (1H, 13C, DEPT 135, HSQC, COSY, NOE, and HMBC) spectra, Fourier transform infrared spectroscopy (FTIR), liquid chromatography-tandem mass spectrometry (LC-MS) and X-ray photoelectron spectroscopy (XPS). The chemical structure and molecular weight of PS-b-PFAA-DOPO were characterized by FTIR and gel permeation chromatography (GPC). The thermal and flame-retardant properties of PS-b-PFAA-DOPO were characterized by thermogravimetry analysis (TG), UL-94, limiting oxygen index (LOI), and microscale combustion calorimetry (MCC). It was found that FAA-DOPO could be used as a monomer for polymerization, although FAA-DOPO had a large steric hindrance from the chemical structure of FAA-DOPO, the UL-94 grade of PS-b-PFAA-DOPO reached the V-0 grade, and the LOI increased by 59.12% compared with PS148-Br.

Gaseous- and Condensed-Phase Activities of Some Reactive P- and N-Containing Fire Retardants in Polystyrenes

Polystyrene (PS) was modified by covalently binding P-, P-N- and/or N- containing fire-retardant moieties through co- or ter-polymerization reactions of styrene with diethyl(acryloyloxymethyl)phosphonate (DEAMP), diethyl-p-vinylbenzyl phosphonate (DEpVBP), acrylic acid-2-[(diethoxyphosphoryl)methylamino]ethyl ester (ADEPMAE) and maleimide (MI). In the present study, the condensed-phase and the gaseous-phase activities of the abovementioned fire retardants within the prepared co- and ter-polymers were evaluated for the first time. Pyrolysis-Gas Chromatography/Mass Spectrometry was employed to identify the volatile products formed during the thermal decomposition of the modified polymers. Benzaldehyde, α-methylstyrene, acetophenone, triethyl phosphate and styrene (monomer, dimer and trimer) were detected in the gaseous phase following the thermal cracking of fire-retardant groups and through main chain scissions. In the case of PS modified with ADEPMAE, the evolution of pyrolysis gases was suppressed by possible inhibitory actions of triethyl phosphate in the gaseous phase. The reactive modification of PS by simultaneously incorporating P- (DEAMP or DEpVBP) and N- (MI) monomeric units, in the chains of ter-polymers, resulted in a predominantly condensed-phase mode of action owing to synergistic P and N interactions. The solid-state ³¹P NMR spectroscopy, Scanning Electron Microscopy/Energy Dispersive Spectroscopy, Inductively-Coupled Plasma/Optical Emission Spectroscopy and X-ray Photoelectron Spectroscopy of char residues, obtained from ter-polymers, confirmed the retention of the phosphorus species in their structures.

Flame Retardant Coatings: Additives, Binders, and Fillers

This review provides an intensive overview of flame retardant coating systems. The occurrence of flame due to thermal degradation of the polymer substrate as a result of overheating is one of the major concerns. Hence, coating is the best solution to this problem as it prevents the substrate from igniting the flame. In this review, the descriptions of several classifications of coating and their relation to thermal degradation and flammability were discussed. The details of flame retardants and flame retardant coatings in terms of principles, types, mechanisms, and properties were explained as well. This overview imparted the importance of intumescent flame retardant coatings in preventing the spread of flame via the formation of a multicellular charred layer. Thus, the intended intumescence can reduce the risk of flame from inherently flammable materials used to maintain a high standard of living.

Thermal and Calorimetric Investigations of Some Phosphorus-Modified Chain Growth Polymers 2: Polystyrene

In this paper, we report on the thermal degradation behaviours and combustion attributes of some polymers based on polystyrene (PSt). Here, both additive and reactive strategies were employed, through the bulk polymerization route, where the modifying groups incorporated P-atom in various chemical environments. These included oxidation states of III or V, and the loading of phosphorus was kept at ca. 2 wt.% in all cases. The characterization techniques that were employed for the recovered products included spectroscopic, thermal, and calorimetric. It was found that the presence of different modifying groups influenced the degradation characteristics of the base polymer, and also exerted varying degrees of combustion inhibition. In all cases, the modification of the base matrix resulted in a noticeable degree of fire retardance as compared to that of the virgin material. Therefore, some of the modifications presented have the potential to be explored on a commercial scale.

The Flame-Retardant Mechanisms and Preparation of Polymer Composites and Their Potential Application in Construction Engineering

Against the background of people's increasing awareness of personal safety and property safety, the flame retardancy (FR) of materials has increasingly become the focus of attention in the field of construction engineering. A variety of materials have been developed in research and production in this field. Polymers have many advantages, such as their light weight, low water absorption, high flexibility, good chemical corrosion resistance, high specific strength, high specific modulus and low thermal conductivity, and are often applied to the field of construction engineering. However, the FR of unmodified polymer is not ideal, and new methods to make it more flame retardant are needed to enhance the FR. This article primarily introduces the flame-retardant mechanism of fire retardancy. It summarizes the preparation of polymer flame-retardant materials by adding different flame-retardant agents, and the application and research progress related to polymer flame-retardant materials in construction engineering.

Mode of Action of Condensed- and Gaseous-Phase Fire Retardation in Some Phosphorus-Modified Polymethyl Methacrylate- and Polystyrene-Based Bulk Polymers

The aspects of fire retardation in some phosphorus-modified polymethyl methacrylate (PMMA) and polystyrene (PSt) polymers are reported in the present paper. Both additive and reactive strategies were employed to obtain the desired level of loading of the phosphorus-bearing compound/moiety (2 wt.% of P in each case). Test samples were obtained using bulk polymerization. The modifying compounds contained the P-atom in various chemical environments, as well as in an oxidation state of either III or V. With a view to gain an understanding of the chemical constitution of the gaseous products formed from the thermal decomposition of liquid additives/reactives, these materials were subjected to GC/MS analysis, whereas the decomposition of solid additives was detailed using the pyrolysis-GC/MS technique. Other investigations included the use of: Inductively-coupled Plasma/Optical Emission Spectroscopy (ICP/OES), solid-state NMR and FT-IR spectroscopy. In the case of PMMA-based systems, it was found that the modifying phosphonate ester function, upon thermal cracking, produced 'phosphorus' acid species which initiated the charring process. In the case of solid additives, it is more likely that the resultant phosphorus- and/or oxygenated phosphorus-containing volatiles acted as flame inhibitors in the gaseous phase. With the PSt-based systems, a probable process involving the phosphorylation of the phenyl groups leading to crosslinking and char formation is feasible.