Facile Preparation of Nickel Phosphide (Ni₁₂P₅) and Synergistic Effect with Intumescent Flame Retardants in Ethylene–Vinyl Acetate Copolymer

In this paper, nanoporous nickel phosphide (Ni₁₂P₅) was synthesized by using a novel hydrothermal method, and its structure was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Then it was used as a synergistic agent with intumescent flame retardant (IFR) in the ethylene–vinyl acetate (EVA) copolymer. With the addition of 2 wt % Ni₁₂P₅ and 28 wt % IFR, the LOI value increased from 30.5 to 34.5. The UL-94 test showed that EVA with 25 wt % IFR burned and had no rating, but with the addition of 2 wt % Ni₁₂P₅ and 23 wt % IFR, it could reach V-0 rating. The CCT results revealed that the Ni₁₂P₅ and IFR system could result in excellent flame retardance. The TGA data indicate that Ni₁₂P₅ can increase the thermal degradation temperature and the charred residues after burning. Moreover, the mechanical and electrical properties of EVA composites are also investigated

Highly Effective P–P Synergy of a Novel DOPO-Based Flame Retardant for Epoxy Resin

A novel flame retardant (FR) DOPO-PEPA, which was synthesized via Atherton–Todd reaction between 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and 1-oxo-4-hydroxymethyl-2,6,7-trioxa-l-phosphabicyclo[2.2.2]­octane (PEPA), was used as an additive-type FR in epoxy resin (EP). The results of the limiting oxygen index (LOI), vertical burning test, and cone calorimeter test indicated that the flame retardance of FR-EP composites is dependent on the chemical structure of phosphorus-based FRs. EP/DOPO-PEPA shows pretty good mechanical properties and a relatively high degree of cross-linking. Furthermore, the synergy as DOPO-PEPA was more efficient than that of DOPO or PEPA alone to flame retardant EP. When the FR additives were 9.1%, the EP/DOPO-PEPA acquired a LOI value of 35%, UL94 V-0 rating, and the lowest peak of heat release rate (PHRR) of 595 kW/m². Furthermore, its continuous and firm char residue layer also reinforced this kind of action

Nacre-Inspired Tunable Electromagnetic Interference Shielding Sandwich Films with Superior Mechanical and Fire-Resistant Protective Performance

With the rapidly increasing development of portable device hardware and flexible electronics, ultrathin electromagnetic interference (EMI) shielding films with a combination of high flexibility and excellent mechanical properties are noticeably required. In addition to minimizing the electromagnetic wave pollution problem, the fire hazards caused by accidental electrical leakage or aging are also a cause of extensive concern. Inspired by nacre and sandwich structure, herein, we fabricated for the first time an electrical insulating sandwich-structured film based on Ca ion cross-linked sodium alginate (SA)–montmorillonite (MMT) and Ti3C2Tx MXene through a step-by-step vacuum-assisted filtration process. This novel design strategy not only maintains the inner EMI shielding network but also can act as an excellent fire-resistant barrier to protect the electronic device in case of accidental fire. Compared with the pure Ti3C2Tx layer, such kind of sandwich film can effectively maintain the EMI shielding performance (50.01 dB), dramatically enhance the mechanical properties (84.4 MPa), and exhibit excellent fire-resistant performance. Especially, compared with the film composed of mixture, the EMI shielding effectiveness value is only 55% that of sandwich films. Besides, it functions well under long-term heat aging test at 80 °C. Therefore, this unique design provides a novel EMI material strategy to facilitate its future applications in flexible electronics

Nacre-Inspired Tunable Electromagnetic Interference Shielding Sandwich Films with Superior Mechanical and Fire-Resistant Protective Performance

With the rapidly increasing development of portable device hardware and flexible electronics, ultrathin electromagnetic interference (EMI) shielding films with a combination of high flexibility and excellent mechanical properties are noticeably required. In addition to minimizing the electromagnetic wave pollution problem, the fire hazards caused by accidental electrical leakage or aging are also a cause of extensive concern. Inspired by nacre and sandwich structure, herein, we fabricated for the first time an electrical insulating sandwich-structured film based on Ca ion cross-linked sodium alginate (SA)–montmorillonite (MMT) and Ti3C2Tx MXene through a step-by-step vacuum-assisted filtration process. This novel design strategy not only maintains the inner EMI shielding network but also can act as an excellent fire-resistant barrier to protect the electronic device in case of accidental fire. Compared with the pure Ti3C2Tx layer, such kind of sandwich film can effectively maintain the EMI shielding performance (50.01 dB), dramatically enhance the mechanical properties (84.4 MPa), and exhibit excellent fire-resistant performance. Especially, compared with the film composed of mixture, the EMI shielding effectiveness value is only 55% that of sandwich films. Besides, it functions well under long-term heat aging test at 80 °C. Therefore, this unique design provides a novel EMI material strategy to facilitate its future applications in flexible electronics

Effect of Rare Earth Hypophosphite Salts on the Fire Performance of Biobased Polylactide Composites

In this work, two kinds of rare earth hypophosphites (REHP), lanthanum hypophosphite (LaHP) and cerium hypophosphite (CeHP), were synthesized and characterized. Subsequently, LaHP and CeHP were added into polylactide to improve its flame retardant properties. Thermal gravimetric analysis was employed to investigate the thermal decomposition behavior of REHP and flame retardant polylactide composites (FR-PLA). The fire performance evaluated by microscale combustion calorimetry and cone calorimeter clearly demonstrated that the addition of LaHP and CeHP resulted in significant reduction of the heat release rate, low total heat release, and compact intumescent char layer. Thermogravimetric analysis–infrared spectrometry testing indicated that the addition of REHP significantly decreased the yields of pyrolysis products. Furthermore, the crystallization behaviors of FR-PLA composites were investigated by differential scanning calorimetry. The char residue of FR-PLA composites after cone calorimeter testing were also be investigated by scanning electron microscope, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy

Graphite-like Carbon Nitride/Polyphosphoramide Nanohybrids for Enhancement on Thermal Stability and Flame Retardancy of Thermoplastic Polyurethane Elastomers

Many efforts have been made to enhance the fire safety of thermoplastic polyurethane elastomers (TPUs) by reducing the heat release rate and smoke emission. Suppressing the emission of smoke and reducing toxic gases generated in the case of TPU burning play a key role to enable TPU meet the eco-friendly and safety requirements. In this work, poly diaminodiphenyl phosphonic methane (PDMPD) with higher thermal stability and catalytic char formation capacity was synthesized; graphitic carbon nitride/PDMPD (CPDMPD) hybrids were fabricated, and their effect on the thermal behavior and flame retardancy of TPU composites was studied. The peak heat release rate (PHRR), the total heat release, the CO yield, and the smoke release of TPU show an obvious reduction on account of addition of CPDMPD hybrids according to the cone tests. TPU/CPDMPD4 is endowed with a reduction of 49.0% of the PHRR. In this work, molecular designing and physical function are integrated to prepare versatile additives of polymers with optimized thermal stability and flame retardancy

Processable Dispersions of Graphitic Carbon Nitride Based Nanohybrids and Application in Polymer Nanocomposites

Graphitic carbon nitride (g-C₃N₄) nanosheets are endowed with extraordinary chemical and thermal stability and good optical and photoelectrochemical properties and are expected to be used in a wide range of fields. The direct dispersion of hydrophobic g-C₃N₄ nanosheets in water or organic solvents without the assistance of dispersing agents is considered to be a great challenge. Here we report novel g-C₃N₄/organic-modified montmorillonite (OMMT) nanohybrids, which were synthesized through electrostatic interaction and then introduced into polystyrene (PS) matrix to fabricate nanocomposites by a simple solvent blending–precipitation method. Hybridizing g-C₃N₄ with OMMT could easily form stable aqueous colloids through electrostatic stabilization. These nanohybrids were evenly dispersed in PS and showed strong interfacial interactions with the polymer matrix. It is noted that the generation of total gaseous products was dramatically inhibited by combining g-C₃N₄ with OMMT. Moreover, flame retardancy was improved upon incorporation of the nanohybrids into PS host. These improvements were due to the strong interactions at interface of ternary systems, synergism between g-C₃N₄ and OMMT, and physical barrier effect of the two components. This work provides a new pathway to manufacture well-dispersed polymeric materials with enhanced fire safety

Nacre-Inspired Tunable Electromagnetic Interference Shielding Sandwich Films with Superior Mechanical and Fire-Resistant Protective Performance

With the rapidly increasing development of portable device hardware and flexible electronics, ultrathin electromagnetic interference (EMI) shielding films with a combination of high flexibility and excellent mechanical properties are noticeably required. In addition to minimizing the electromagnetic wave pollution problem, the fire hazards caused by accidental electrical leakage or aging are also a cause of extensive concern. Inspired by nacre and sandwich structure, herein, we fabricated for the first time an electrical insulating sandwich-structured film based on Ca ion cross-linked sodium alginate (SA)–montmorillonite (MMT) and Ti3C2Tx MXene through a step-by-step vacuum-assisted filtration process. This novel design strategy not only maintains the inner EMI shielding network but also can act as an excellent fire-resistant barrier to protect the electronic device in case of accidental fire. Compared with the pure Ti3C2Tx layer, such kind of sandwich film can effectively maintain the EMI shielding performance (50.01 dB), dramatically enhance the mechanical properties (84.4 MPa), and exhibit excellent fire-resistant performance. Especially, compared with the film composed of mixture, the EMI shielding effectiveness value is only 55% that of sandwich films. Besides, it functions well under long-term heat aging test at 80 °C. Therefore, this unique design provides a novel EMI material strategy to facilitate its future applications in flexible electronics

UV Grafting of a DOPO-Based Phosphoramidate Monomer onto Polyamide 66 Fabrics for Flame Retardant Treatment

A novel DOPO-based phosphorus- and nitrogen-containing monomer named DOPO-DAAM was synthesized and grafted onto the surface of polyamide 66 (PA 66) fabrics via UV grafting in order to improve the flame retardancy. To facilitate the grafting efficiency, the PA66 fabric surface was first modified through the HCl treatment. In the UL-94 vertical burning test, the PA66 fabrics treated with DOPO-DAAM could stop the melt-dripping. Cone calorimetry results showed that a 22% reduction in peak heat release rate was achieved for PA66 fabrics grafted with 20 wt % DOPO-DAAM. Thermogravimetric analysis indicated that the presence of grafted monomer catalyzed the degradation pathway of virgin PA66 fabrics where the initial decomposition temperature was reduced and the char yield was enhanced for all treated fabric samples. Moreover, real time FTIR analysis confirmed that the DOPO-DAAM decomposed ahead of virgin PA66 and catalyzed the formation of char residue

Effect of Functionalized Graphene Oxide with Organophosphorus Oligomer on the Thermal and Mechanical Properties and Fire Safety of Polystyrene

A novel organophosphorus oligomer was synthesized to functionalize graphene oxide. Subsequently, the functionalized graphene oxide (FGO) was incorporated into polystyrene (PS) to enhance the integration properties of the matrix. The effect of FGO on the thermal properties, fire safety, and mechanical properties of PS nanocomposites was investigated. The results showed that the introduction of FGO significantly increased the maximum decomposition temperature (<i>T</i>_max) (25 °C increase), reduced the total heat release (20.8% reduction), and peak heat release rate (38.2% reduction) of PS. In addition, the thermogravimetric analysis/infrared spectrometry analysis results indicated that the amount of organic volatiles and toxic carbon monoxide of PS was remarkably reduced. The physical barrier effect of FGO and the synergistic effects between the organophosphorus oligomer and FGO were the main causations for these properties improvements. Homogeneous dispersion of FGO into the polymer matrix improved the mechanical properties of FGO/PS nanocomposites, as demonstrated by tensile tests results