Good Flame Resistance Research Articles

Lewis-basic nitrogen-rich covalent organic frameworks enable flexible and stretchable solid-state electrolytes with stable lithium-metal batteries

Designing flexible and stretchable solid-state electrolytes (SSEs) holds promise but challenge in flexible all-solid-state lithium-metal batteries (LMBs) owing to their insufficient ion conductivity and mechanical strength. Herein, we develop nitrogen-rich covalent organic frameworks (NCOF) with abundant Lewis-basic N atoms as lithiophilic sites to incorporate Lewis-acidic Li+ into its inner order structure for fabricating flexible and stretchable PEO-LI+@NCOF SSEs with the crosslinking of polyethylene oxide (PEO). The SSE film displays high mechanical strain (2.2 MPa), Young's modulus (689 MPa), stretchability (1000 %), ion conductivity (2.4 × 10–4 S cm-1), good flame resistance, and wide electrochemical window (4.8 V). Owing to the rich Lewis-basic N atoms with strong Li+ adsorption energy, orderly nanochannels, and negative charge environment within NCOFs, the SSE film endows orderly and rapid ion migration, low Li-ion diffusion barrier, and significantly enhanced ion conductivity for uniform lithium plating/stripping and suppressing Li-dendrite growth. The crosslinking of Li+@NCOF with PEO greatly enhances the mechanical stretchability, flame resistance, and electrochemical window of PEO-based SSEs. Consequently, the Li/PEO-LI+@NCOF/Li symmetrical cell exhibits stable cycling without short-circuiting for 1200 h at 0.1 mA cm-2/0.1 mAh cm-2. The LiFePO4/PEO-LI+@NCOF/Li battery exhibits a 500-cycle long lifespan at 1 C (78 % capacity retention), and its pouch cell verifies promising applications in flexible all-solid-state LMBs. Therefore, introducting Lewis-basic N-rich COFs verifies an effective strategy to design a flexible and stretchable SSE film with high mechanical strength, superior ion conductivity and flame resistance.

PVDF–HFP@Nafion-based quasisolid polymer electrolyte for high migration number in working rechargeable Na–O2 batteries

Rechargeable sodium-oxygen (Na-O2) battery is deemed as a promising high-energy storage device due to the abundant sodium resources and high theoretical energy density (1,108 Wh kg-1). A series of quasisolid electrolytes are constantly being designed to restrain the dendrites growth, the volatile and leaking risks of liquid electrolytes due to the open system of Na-O2 batteries. However, the ticklish problem about low operating current density for quasisolid electrolytes still hasn't been conquered. Herein, we report a rechargeable Na-O2 battery with polyvinylidene fluoride-hexafluoropropylene recombination Nafion (PVDF-HFP@Nafion) based quasisolid polymer electrolyte (QPE) and MXene-based Na anode with gradient sodiophilic structure (M-GSS/Na). QPE displays good flame resistance, locking liquid and hydrophobic properties. The introduction of Nafion can lead to a high Na+ migration number (tNa+ = 0.68) by blocking the motion of anion and promote the formation of NaF-rich solid electrolyte interphase, resulting in excellent cycling stability at relatively high current density under quasisolid environment. In the meantime, the M-GSS/Na anode exhibits excellent dendrite inhibition ability and cycling stability. Therefore, with the synergistic effect of QPE and M-GSS/Na, constructed Na-O2 batteries run more stably and exhibit a low potential gap (0.166 V) after an initial 80 cycles at 1,000 mA g-1 and 1,000 mAh g-1. This work provides the reference basis for building quasisolid state Na-O2 batteries with long-term cycling stability.

P/N/Si-rich and flexible coating imparting polypropylene excellent flame retardancy without compromising its inherent mechanical properties

In general, the addition of flame retardants may lead to the degradation of the mechanical properties of polymers, despite enhancing their flame retardancy. However, flame-retardant coatings have the potential to provide good flame resistance to polymers without compromising their inherent mechanical properties. In this study, we applied highly adhesive and flexible polysiloxane flame-retardant coatings (196 μm) to polypropylene, resulting in reductions of 74.9 %, 58.0 %, 80.0 %, and 56.4 % in peak heat release rate, peak smoke production rate, fire growth rate, and mass loss, respectively. By incorporating the lab-synthesized DOPO-modified polysiloxane (APID), the flame-retardant efficiency of ammonium polyphosphate (APP) was greatly enhanced. The primary film-forming agent, (3-aminopropyl) triethoxysilane (APTES), played a key role in maintaining the compatibility of APP and APID with the coating, as well as facilitating the formation of a robust SiOSi crosslinked network structure that strengthened the resulting char layer. The interactivity between the various components, including hydrogen bonds and crosslinked network structures, contributed to improved uniformity, thermal stability, and adhesion of the coatings. Moreover, the coatings exhibited resistance to ultraviolet radiation and water. Our findings suggest that highly flexible and adhesive flame-retardant coatings hold significant potential for applications in polymer protection. These promising results provide a viable pathway for improving the fire protection of polymers through the use of high-adhesive intumescent flame-retardant coatings.

Ecofriendly and durable flame-retardant cotton fabric based on alkyl/N/B/P modified meglumine with high efficiency

Flame retardants for textiles have increasing tendency towards high efficiency and environmental protection. Herein, a series of efficient and ecofriendly alkyl/N/B/P modified meglumine (CmNBPM) were prepared by boric/phosphoric acid esterification of meglumine and then hydrophobic modification by N-alkylamine. Durable flame-retardant cotton fabric was fabricated by using CmNBPM as flame retardant. The results showed that carbon chains of alkylamine in CmNBPM structure should be controlled in range from C3 to C8. CmNBPM attained the best flame resistance at molar ratio of meglumine to boric acid 1: 4 and at molar ratio of phosphoric acid to n-propylamine 1: 0.8. In comparison with the untreated cotton fabric, LOI value of C3NBPM flame-retardant cotton fabric reached the maximum 38.4 % and improved by 1.18 times. pHRR, THR, and FGR of C3NBPM flame-retardant fabric were minimized among different N-alkylamine modification, which decreased by 84.5 %, 47.1 %, and 93.5 %, respectively. C3NBPM achieved high flame resistance at low dosage for the treatment of cotton fabric. Compared with NBPM fabric treated at the same concentration, LOI values of C3NBPM fabric treated in C3NBPM solution from 25 g/L to 200 g/L increased by 4.4– 17.7 %. Furthermore, C3NBPM fabric maintained good flame resistance after 30 laundry cycles.

Application of Neural Network for the Prediction of Loss in Mechanical Properties of Aramid Fabrics After Thermal Aging

Aramid fabrics are used to produce most of the flame resistant protection clothes to fulfil the protection requirements. Even though aramid fibers have good thermal stability and flame resistance properties, fabrics used in protective clothing age and loss some of their essential functions under various environmental and operational conditions during their lifetime. These conditions cause serious limitations in the use of clothing. In this study, various woven fabrics produced from aramid (Nomex, Kevlar) fabrics were exposed to accelerated aging tests under varying temperature and time period in order to construct Neural Network models to predict weight loss and tensile strength loss percentages of the fabrics. The results of Artificial Neural Network models demonstrate that regression values are 0.98405 for weight loss percentages and 0.99935 for tensile strength loss percentages of the fabrics. Accordingly, the proposed Artificial Neural Network models are correctly constituted and the losses in determined fabric properties is successfully predicted.

Bifunctional modification of graphene by phosphorus/nitrogen‐containing silane compounds for smoke suppression and flame retardancy of epoxy resins

AbstractEnhancing the flame retardancy with minimal impact on the mechanical and thermal performances of polymers remains a challenge. This study synthesized a phosphorus/nitrogen‐containing silane compound (D) using polyformaldehyde, KH‐550, and 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) as raw materials through the Kabachnik‐Fields reaction. After that, D was grafted onto the surface of graphene after hydrothermal treatment to obtain a nano hybrid flame retardant (D‐GR). And D‐GR/EP composites exhibited good flame resistance (LOI = 30.1% and UL‐94 reaches the V‐1 rating) even if the load on D‐GR was 1 wt%. Indeed, the total heat release, the peak heat release rate (PHRR), and the total smoke release of 1% D‐GR/EP dropped by 13.54%, 28.62%, and 44.32%, respectively, in comparison to pure EP. The mechanical performance of 1% D‐GR/EP was effectively maintained, as indicated by the results of impact, tensile and flexural tests. A systematic evaluation indicated that the accession of D‐GR effectively inhibited smoke and heat releases that are ascribed to the synergistic effect of phosphorus/nitrogen‐containing silane compound and graphene. In this study, a facile method was provided for the synthesis of halogen‐free flame‐retardant epoxy composites with superior performances. The combustion products of the as‐prepared composites complied with green and environmental protection standards.

Ionic Liquids Endowed with Novel Hybrid Anions for Supercapacitors.

The synthesis of a novel class of ionic liquids (ILs) with sulfimide-type anions is presented herein. [Py14][PTSNTF] (N-butyl-N-methylpyrrolidinium p-tosyl(trifluoromethyl)sulfonimide) shows that the maximal electrochemical window is as high as 5.3 V, higher than that of most reported ILs. In addition, thermogravimetry analysis, differential scanning calorimetry, and the flammability test were also carried out for its thermal stability and practical safety. Impressively, these ILs exhibited good flame resistance and demonstrated an admirable intrinsic safety, in sharp contrast to ordinary electrolytes. Furthermore, the electrostatic potential of ILs was calculated theoretically, and the distribution of surrounding charge is intuitively understood. Cyclic voltammetry, galvanostatic charge–discharge tests, and cycling stability measurement were performed to evaluate the potential as the electrolyte for supercapacitors. The insights obtained from the study of novel anions provide new ideas for the design of novel IL electrolytes for energy applications.

Oyster-inspired organic-inorganic hybrid system to improve cold-pressing adhesion, flame retardancy, and mildew resistance of soybean meal adhesive

Soy protein adhesives have aroused widespread interest as a replacement for traditional formaldehyde synthetic resins in the wood industry. However, how to improve the poor cold-pressing adhesion to the industrial level while retaining decent integrated performances is a bottleneck of soy protein adhesives for practical applications. Inspired by the strong wet adhesion of marine oysters, we propose a novel strategy for developing excellent adhesion performance soybean meal (SM) adhesive based on an organic-inorganic hybrid system. The introduction of poly (vinyl alcohol) (PVA) and hydroxyapatite-tannin acid (HT) nanohybrids construct a densely-crosslinked coacervate network through non-covalent interactions to enhance the adhesion and cohesion of the adhesives, which penetrated the wood interfacial water layer. Compared with the pristine SM adhesive, the cold-pressing bonding strength of the novel adhesive increased from 167.3 kPa to 557.0 kPa. The adhesive possessed excellent toughness of 4.99 MJ/m3 because the multiple non-covalent bonds provided sacrificial interactions that dissipated the fracture energy. Moreover, due to the synergistic effect of the inorganic components and phenolic components, the adhesive also displayed good flame resistance and mildew resistance, which stored for 15 days without mildew formation and showed self-extinguishing behavior during combustion tests. This work demonstrates a novel and effective method for developing other wood adhesives with high performance.

Mechanically strong, thermostable, and flame-retardant composites enabled by Brown paper made from bamboo

We design a facile strategy to manufacture a high-performance composite of polyvinyl chloride (PVC) made from brown paper and PVC film. Brown paper with little fiber damage is prepared using bamboo pulping via a moderate method, and a high content of lignin enhances the lipophilicity of the fibers. The "layer-network" porous paper provides “green” framework support. When hot and cold pressing of the stacks of paper sheets and PVC films is performed, PVC resin fills the pores of the framework support, and then, strong mechanical interlocking structures are established, similar to the vastly distributed microscale "mortise riveting". Then, a dense and lightweight paper/PVC composite is produced. The composite exhibits strong mechanical properties in terms of tensile strength (132.65 MPa), flexural strength (183.45 MPa), flexural modulus (10.44 GPa), and internal bonding strength (2.6 MPa), with good thermal stability and flame resistance. The strength is 5- to 10-fold that of commercial artificial boards, substantially surpassing that of bamboo, PVC, and other PVC composite resin profiles. Additionally, PVC replaces adhesives that contain or release formaldehyde, and a high percentage (>60 wt%) of green cellulose fibers is used. The simple technology directly uses existing manufacturing methods of papermaking, film stretching, and press laminating systems. Therefore, the high-performance paper/PVC composite is environmentally sustainable and more cost-effective than PVC composites prepared with other fillers. The new materials have great potential prospects for the development of high-strength materials and the implementation of carbon neutrality in prefabricated houses, furniture, vehicles, ships, containers, and color steel plates.

An integrate and ultra-flexible solid-state lithium battery enabled by in situ polymerized solid electrolyte

Searching for ultra-safe flexible electrolytes is crucial to the exploitation of flexible solid-state batteries and wearable devices. However, it is very challenging to simultaneously conquer the issues of the elastic electrolyte, including low ionic conductivity, inferior electrolyte/electrode interface compatibility, and unsatisfying cycling stability of the assembled cell. Herein, we developed an elastic PEL electrolyte using poly(butyl acrylate) cross-linked polyethylene glycol and EMIMTFSI with an ultrahigh elongation of 1000%. The PEL-0.1 electrolyte delivers an ionic conductivity of 1.19 × 10−4 S cm−1 and good flame resistance. The superior interface compatibility between electrodes and electrolyte is realized by the in situ polymerized PEL on cathode and contact stability towards metallic lithium, which facilitates the ion conduction in the solid-state cell and accommodate the electrode volume changes during the charge/discharge processes. The Li/PEL-0.1/Li cell can stable cycle for 300 h at 50 mV. The little difference in the impedance of the tabulate and wire-shaped solid-state batteries at various deformation states demonstrates the good shape conformability and feasibility of flexible PEL electrolyte. The integrated LiFePO4/PEL-0.1/Li batteries show excellent cycling stability at all the temperatures of 25 °C, 40 °C and 60 °C. A series of destructive operations on the working pouch cell confirms the superior safety and practicability of the designed electrolyte. The study proposed a promising ultrasafe and flexible electrolyte with outstanding electrochemical performance in the applications of the next-generation flexible solid-state lithium batteries and wearable devices.

Mechanical Properties of Sugar Palm (Arenga pinnata Wurmb. Merr)/Glass Fiber-Reinforced Poly(lactic acid) Hybrid Composites for Potential Use in Motorcycle Components.

This research aims to determine the mechanical properties of sugar palm fiber (Arenga pinnata Wurmb. Merr) (SPF)/glass fiber (GF)-reinforced poly(lactic acid) (PLA) hybrid composites for potential use in motorcycle components. The mechanical (hardness, compressive, impact, and creep) and flammability properties of SPF/GF/PLA hybrid composites were investigated and compared to commercially available motorcycle Acrylonitrile Butadiene Styrene (ABS) plastic components. The composites were initially prepared using a Brabender Plastograph, followed by a compression molding method. This study also illustrated the tensile and flexural stress–strain curves. The results revealed that alkaline-treated SPF/GF/PLA had the highest hardness and impact strength values of 88.6 HRS and 3.10 kJ/m2, respectively. According to the results, both alkaline and benzoyl chloride treatments may improve the mechanical properties of SPF/GF/PLA hybrid composites, and a short-term creep test revealed that the alkaline treated SPF/GF/PLA composite displayed the least creep deformation. The findings of the horizontal UL 94 testing indicated that the alkaline-treated SPF/GF/PLA hybrid composites had good flame resistance. However, alkaline-treated SPF/GF/PLA composites are more suitable materials for motorcycle components.

Thermally insulating robust carbon composite foams with high EMI shielding from natural cotton

• Conversion of biomass, medical-grade cotton and sucrose, into carbon foams by filter-pressing. • Foams exhibit density in the range of 0.06 to 0.31 g cm −3 . • Foams possess reasonable compressive strength in the range 5 kPa to 1.4 MPa. • Foams possess partial compressibility. • Low thermal conductivity (0.069 to 0.185 W m − 1 K −1 ) and good flame resistance. • carbon composite foams are amenable to machining using conventional machines and tools. • CCFs materials showed good electrical and EMI shielding properties. • The rigid CCFs showed shielding effectiveness in the ranges of 21.5 to 38.9 dB with adsorption dominant shielding properties. Thermally insulating and fire-resistant carbon composite foams are prepared by consolidating natural cotton fibre dispersed in aqueous sucrose solution by filter-pressing followed by drying and carbonization. The compressive strength (5 kPa to 1.4 MPa) and thermal conductivity (0.069 to 0.185 W m − 1 K − 1 ) depend on the foam density (0.06 to 0.31 g cm −3 ) which is modulated by varying the sucrose solutions concentration (100 to 700 g L − 1 ). Partially flexible to the rigid transition of the carbon composite foams occurs at sucrose concentration above 200 g L − 1 . The tubular carbon fibre formed from cotton is welded at their contact points by the amorphous carbon produced from sucrose leading to partial flexibility at low sucrose concentration and advancement of fibre- to- fibre bonding area at higher sucrose concentration results in rigid foam. The porosity in the inter-fibre space and lumen of the carbonized cotton fibre contributes to the low thermal conductivity. The carbon composite foams prepared at a sucrose solution concentration of 500 g L − 1 and above are amenable to machining using conventional machines and tools. The rigid carbon foams show EMI shielding effectiveness and specific shielding effectiveness in the ranges of 21.5 to 38.9 dB and 108–138 dB cm 3 g − 1 , respectively.

Perspective on High‐Concentration Electrolytes for Lithium Metal Batteries

Nonaqueous electrolytes play important roles in determining the performance of lithium‐ion batteries. However, the high flammability, poor thermal stability, narrow electrochemical window, and slow electrode reaction kinetics seriously hinder the application of batteries. Compared with traditional electrolytes, high‐concentration electrolytes (HCEs) have a higher ion transfer number, wider electrochemical window, higher thermal stability, low volatility, good flame resistance, and passivation of Al current collector at high potential. The HCEs can effectively overcome the shortcomings of traditional electrolytes, and provide a new direction for the development of next‐generation batteries. Therefore, it is very timely to write a perspective on HCEs for directing future research. Herein, the recent development of HCEs is described.

Polymer-based electrolytes for all-solid-state lithium–sulfur batteries: from fundamental research to performance improvement

With the increasing demand for a higher energy density and a lower cost energy storage system, lithium–sulfur batteries have become one of the promising candidates to replace current Li-ion batteries. However, in liquid electrolyte systems, the lithium dendrite growth and the shuttle effect cause severe safety hazard as well as capacity decay, which hinders the commercialization of practical lithium–sulfur batteries. Polymer-based electrolytes provide a promising solution to these challenges. This type of electrolyte, including polymer and composite polymer electrolytes, demonstrates the capabilities to prevent polysulfide dissolution and suppress lithium dendrite growths, while ensuring good surface contact and high flame resistance. This review summarizes the most recent progress of polymer-based all-solid-state lithium–sulfur batteries (ASSLSB), which revealed mechanisms and challenges of electrolyte ionic conductivity, reaction mechanism, anode/electrolyte interface, and cathode/electrolyte interface. Based on these revealed principles, possible solutions to these challenges such as the addition of inorganic fillers, interface modification, utilization of different types of lithium salt and polymers are introduced. In addition, the state-of-the-art approaches with great performance improvement are highlighted in this review. Finally, we provide perspectives on research directions that can further the understanding and development of polymer-based ASSLSB.

Synthesis, characterization and finite element analysis of polypropylene composite reinforced by jute and carbon fiber

In recent scenario, polymer hybrid composites are in growing demand over conventional natural fiber, or synthetic fiber reinforced polypropylene composite in automobile and aerospace industries. These hybrid composites have good properties like light weight, good strength, high stiffness, sound absorbing capacity good creep and flame resistance etc. In this study, natural fiber (NF) has been blended with carbon fiber (CF) to fabricated jute-carbon fiber reinforced polypropylene composites. Compression molding process with volume fraction of 0.20 has been used to fabricate the composite. Jute fibers have been arranged in bidirectional manner to add strength and good surface finish to the composite. For characterization, tensile test, flexural strength test, impact test and hardness test have been investigated followed by water absorption test. It has been observed that stacking sequence of CJC reinforced polymer composite has resulted in maximum tensile strength of 92.336 MPa, Rockwell hardness number 103.65, flexural strength of 44.771 MPa and impact strength of 2.65 ± 0.5 J as compared to JCJ reinforced polymer composite.

New deep eutectic solvents based on ethylene glycol - LiTFSI and their application as an electrolyte in electrochemical double layer capacitor (EDLC)

Deep eutectic solvents (DESs) have been considered the existing alternatives that are analog and cheap to ionic liquids for their favorable properties (e.g., chemical stability, low flammability, and low vapor pressure). In the present study, the physical and electrochemical properties of ethylene glycol (EG) and lithium bis[(trifluoromethyl)sulfonyl] imide (LiTFSI)-based DESs were comprehensively analyzed. According to the results of the differential scanning calorimetry (DSC) measurement, the formation of DESs was confirmed with a low melting point from −23 to −26 °C. Besides, the DESs were confirmed to be formed by the variations in the intermolecular interactions of two solid precursors observed under the Infrared spectroscopy (IR). By Vogel-Tamman-Vulcher (VTF) fitting equation, the temperature dependencies of ionic conductivity and the viscosity of these DESs were correctly expressed. The synthesized DESs exhibited superior properties (e.g., high electrochemical window (~4.5 V vs Li+/Li), high thermal stability (~200 °C), good flame resistance, as well as relatively high ionic conductivity about 3 mS cm−1 at 30 °C). Lastly, DES-based electrolytes were added to the activated carbon electrochemical double-layer capacitor (EDLC). The performance of the EDLC was assessed by Cyclic Voltammetry and Galvanostatic charge/discharge tests at ambient temperature. As revealed from the preliminary results, the overall performance of the DESs could address the main challenges in supercapacitor applications, i.e., limited operating voltage range and safety problems.

Synthesis and characterization of semi-aromatic polyamides containing heterocyclic 1,3,5 s-triazine and methylene spacer group for thermally stable and colloidal property

ABSTRACT A new aromatic diacid (II) was synthesized and Characterized by Spectroscopic techniques namely, FT-IR, 1 H and 13 C NMR, etc. A series of aromatic aliphatic polyamides containing phenoxy s-triazine ring with methylene spacer group was synthesized from diacid (II) and various aromatic diamines by using Yamazaki Phosphorylation method. These polyamides were obtained in good yields and characterized by solubility in common organic solvent, inherent viscosity, FT-IR, X-ray diffraction analysis. All of these polyamides were found to be amorphous in morphology as indicated by XRD to posses outstanding solubilities, and to be easily dissolved in amide-type polar aprotic polar solvents. Polyamides with moderate inherent viscosity in the range 0.21 to 0.41 dL/g in N,N,dimethyl formamide solvent (DMF) at 30 ± 0.1° C. The Thermal properties of the polyamides were evaluated by Thermogravimetric analysis and Differential scanning calorimetery. These polymer shows good thermal stability with glass transition temperature (Tg) of 143–223°C and their (Tmax) weight loss temperature were around 426–455°C, confirming their good thermal stability. The char yields of these polymers were given their limiting oxygen index LOI 32.3 to 37.5 5% values of polyamides; indicate these polymers also show good flame resistance. The NPs were negatively charged with a zeta potential of −24.2 to −37.9 mV indicating a good colloidal stability against aggregation.

On the bending behaviour and the failure mechanisms of grid-reinforced aluminium foam cylinders by using an experimental/numerical approach

Metal foams are attracting interest in both aerospace and automotive industries due to their intriguing properties such as high stiffness coupled with low specific weight, good absorbing energy capabilities and flame resistance. To date, many researchers are trying to develop innovative solutions for the improvement of the mechanical properties of metal foams keeping the light-weight condition, with the scope to extend their potential application field. In this scenario, an advanced solution was here proposed; in particular, an innovative manufacturing process was presented for the production of steel grid–reinforced closed-cell aluminium foam cylinders in one single step by using the powder compact melting technique. The bending properties of plain, as well as reinforced, foam systems were experimentally tested and extensively discussed. An original finite element model was developed and validated for the analysis of the bending behaviour and the synergistic action of each component constituting the hybrid system, with a special focus on the failure mechanisms occurring under specified load conditions. The outcomes showed an increase of the mechanical properties of the reinforced systems due to the action of the light-weight mesh grid reinforcement that delays the failure of the structure. The solution proposed shows promises of being a useful method to expand the industrial applications of metal foams.

Enhanced mechanical property and flame resistance of graphene oxide nanocomposite paper modified with functionalized silica nanoparticles

Graphene oxide (GO) paper with outstanding integrated multiple functionalities (good mechanical performance, thermal stability and flame resistance, etc.) is strongly needed for numerous potential applications in cutting-edge fields. In this work, we report a facile and green process to fabricate GO-based nanocomposite papers via introducing functionalized silica (f-SiO2) nanoparticles. The results reveal that addition of f-SiO2 produces simultaneous improvements in mechanical strength, stiffness and flame resistance for GO paper. With incorporation of 10 wt% f-SiO2, the tensile strength, elastic modulus and toughness of the GO/f-SiO2 nanocomposite papers can be increased by about 51%, 317%, and 69%, respectively. Various characterizations disclose that hydrogen bonds and covalent interactions between GO sheets and f-SiO2 mainly contribute to the effective load transfer and energy dissipation between them, and thus leading to the improvements of mechanical properties. Based on the structural observation and analysis, the improved flame resistance of the GO/f-SiO2 papers should be attributed to the formation of rGO/SiO2 protective char, which are derived from the decomposition and redeposition of the grafted silane molecules and inorganic SiO2 and thermal reduction of GO into rGO. Our results suggest that the mechanical and thermal properties of GO papers can be tuned by introducing inorganic/organic f-SiO2, providing a new route for the rational designing and development of mechanically flexible and flame-retardant GO-based nanocomposite paper materials.

Rational design of modified fluororubber-based quasi-solid-state electrolyte for flexible supercapacitors with enhanced performance

The poly(vinylidene fluoride-co-hexafluoropropylene) rubber (FKM) is a perfect matrix of organic quasi-solid-state polymer electrolyte (oQPE) due to its outstanding chemical stability, excellent elasticity, and non-flammability. However, the poor adhesion to electrodes limits its practical application. Herein, the porous FKM grafted poly(butyl acrylate) membranes (pFKM-g-PBA), prepared through a template pore-forming and γ-ray radiation grafting method, is reported. The corresponding oQPE (pFKM-g-PBA/Et4NBF4-AN) shows superior stretchability (the retention of 96.3% after 1000 stretching cycles at 100% strain), high ionic conductivity (8.1 × 10−3 S cm−1), and good flame resistance. Benefit from the considerable increase in adhesiveness, the pFKM-g-PBA/Et4NBF4-AN oQPE adhere firmly to the carboxylated multiwall carbon nanotubes-supported poly(1,5-diaminoanthraquinone) (cMWCNT@PDAA) flexible electrodes. The as-assembled flexible supercapacitor (cMWCNT@PDAA//pFKM-g-PBA/Et4NBF4-AN//cMWCNT@PDAA) delivers a high energy density of 65.2 Wh kg−1 at a power density of 0.67 kW kg−1 and retains specific capacitance of 87% after 10,000 charge-discharge cycles which is better than that of the raw FKM-based device (75%).