Melamine Formaldehyde Foam Research Articles

Efficient As(V) removal by NiFe-LDHs and NiFe2O4 in situ growth on 3D porous carbon foam fabricated from waste melamine–formaldehyde foam

The utilization of waste melamine-formaldehyde foam to produce value-added carbon foam has been identified as a promising approach to polymer recycling. Nickel-Iron layered double hydroxides (NiFe-LDHs) and its complex oxides (NiFe2O4) were synthesized in this study through a hydrothermal method, growing in situ on the above-mentioned carbon foam substrate. Comparative analysis revealed that CF@NiFe2O4 exhibited superior removal efficiency compared to CF@NiFe-LDHs. Furthermore, arsenate adsorption on CF@NiFe-LDHs and CF@NiFe2O4 conformed more to the pseudo-second-order model; meanwhile, the isothermal adsorption characteristic fitted the Langmuir isothermal model better. The negative ΔG (free energy changes, <-37.68 kJ/mol) and positive ΔH (enthalpy change, 7.64 kJ/mol) indicate that it is spontaneous and endothermic for As(V) to adsorb on CF@NiFe2O4. Potential mechanisms such as surface complexation, electrostatic interaction, and hydrogen bonding were suggested. This innovative approach offers a novel method for utilizing LDHs-based adsorption materials and recycling waste polymers.

Three-terminal high-output triboelectric nanogenerator to achieve alternating current/direct current collaborative output by coupling three-dimensional porous structure, triboelectrification and corona discharge

Nowadays, the comprehensive consideration of output performance, durability, and industrial environmental recycling has been the focus of triboelectric nanogenerator (TENG) research in recent years. Herein, the melamine formaldehyde (MF) foam with the feature of three-dimensional porous structure, soft contact and eco-friendly is used to design a novel three-terminal high-output TENG (TH-TENG) to efficiently harvest rotating mechanical energy based on the coupling of electrostatic induction, triboelectrification and corona discharge. The simplified sliding TENG model has been demonstrated to have excellent electrical output of 532.81 μA m−2, with the outstanding resistance to heat and humidity of the output for maintaining 95.1 % and 82.1 % under the condition of 40 ℃ and 60 % RH, 20 ℃ and 80 % RH after 100 k cycles, respectively. Furthermore, the TH-TENG achieves efficient collaborative output of DC and AC through persistent directional movement and reciprocating movement with alternant connection of electrodes, where the upper-sided and lower-sided TENGs achieve DC with power density of 3.54 and 4.97 W m−3 Hz−1, and middle-sided TENG achieves AC with power density of 0.66 W m−3 Hz−1, respectively. The TH-TENG can drive 2540 LEDs and 8 incandescent lamps, and continuously power 36 hygrothermographs in parallel for smart farm. This work has enriched charge density enhancement strategy through the industrial recyclable MF foam.

Differences in ingestion and biodegradation of the melamine formaldehyde plastic by yellow mealworms Tenebrio molitor and superworms Zophobas atratus, and the prediction of functional gut microbes

Plastics biodegradation by insect larvae is considered as a new strategy for plastic wastes treatment. To uncover the biodegradation of a more complex chemical polymer of melamine formaldehyde (MF) by insect larvae, two worm species of yellow mealworm Tenebrio molitor and superworm Zophobas atratus were fed on MF foam as sole diet for 45 days with sole bran diet as control. Although the MF foam consumption by yellow mealworms of 0.38 mg/d/g-larvae was almost 40% higher than that by superworms of 0.28 mg/d/g-larvae, a similar decrease of survival rates in both species were obtained at about 58%, indicating the adverse effects on their growth. Depolymerization and biodegradation of MF foam occurred in both larval guts, but was more extensive in yellow mealworms. MF foam sole diet influenced gut bacterial and fungal microbiomes of both larvae species, which were assessed by Illumina MiSeq on day 45. Compared to the bran-fed group, both gut bacterial and fungal communities significantly changed in MF-fed groups, but differed in the two larvae species. The results demonstrated a strong association between the distinctive gut microbiome and MF foam degradation, such as unclassified Enterobacteriaceae, Hyphopichia and Issatchenkia. However, sole MF foam diet negatively influenced worms, like lower survival rates and gut abnormalities. In summary, MF foam could be degraded by both yellow mealworms and superworms, albeit with adverse effects. Gut microbes were strongly associated to MF foam degradation, especially the gut fungi.

Preparation of Melamine Formaldehyde Foam and a Melamine-Formaldehyde-Organo-Clay Nanocomposite and Hybrid Composites

Mineral fillers can be added to thermoset polymers to improve thermal conductivity and deformation behavior, shrinkage, impact strength, dimensional stability and molding cycle time. This study aims to prepare various hybrid composites (MFHCs) using melamine formaldehyde foam (MF), a melamine formaldehyde organo-clay nanocomposite (MFNC) and also pumice as primary filler, and gypsum, kaolinite and a hollow glass sphere as secondary filler. It also focuses on the study of some mechanical properties and thermal conductivities, as well as their microscopic and spectroscopic characterization. For this, firstly, organo-clay was prepared with the solution intercalation method using montmorillonite, a cationic surfactant and long-chain hydrocarbon material, and then was produced using a melamine formaldehyde nanocomposite with in situ synthesis using a melamine formaldehyde pre-polymer and organo-clay. Finally, hybrid composites were prepared by blending various minerals and the produced nanocomposite. For morphological and textural characterization, both FTIR spectroscopy and XRD spectra, as well as SEM and HRTEM images of the raw montmorillonite (MMT), organo-montmorillonite (OMMT), pure polymer (MF) and prepared hybrid composites, were used. Spectroscopic and microscopic analyses have shown that materials with different textural arrangements and properties are obtained depending on effective adhesion interactions between polymer–clay nanocomposite particles and filler grains. Mechanical and thermal conductivity test results showed that melamine-formaldehyde-organo-clay nanocomposite foam (MFCNC) exhibited a very good thermal insulation performance despite its weak mechanical strength (λ: 0.0640 W/m K). On the other hand, among hybrid composites, it has been determined that the hybrid composite containing hollow glass beads (MFCPHHC) is a material with superior properties in terms of thermal insulation and mechanical strength (λ: 0.642 W/m K, bulk density: 0.36 g/cm3, bending strength: 228.41 Mpa, modulus of elasticity: 2.22 Mpa and screw holding resistance: 3.59 N/mm2).

Preparation of Porous Silver Nanowires‐Melamine Formaldehyde Hybrid Composite Materials and Their Electromagnetic Shielding and Flame‐Retardant Properties

Along with the booming development of communication technology and electronic equipment, higher requirements of flame‐retardant and EMI shielding performances for electromagnetic interference (EMI) shielding materials are put forward. Herein, the ultralight and porous silver nanowires (AgNWs)‐melamine formaldehyde (MF) hybrid composite with unique micro‐/nanostructure is developed by a facile dip‐coating method, which uses the AgNWs as 1D conductive coating and MF foam (MF foam) as 3D skeleton template. Benefiting from the unique porous micro‐/nanostructure, the resultant hybrid composite displays low density, excellent EMI shielding performances, and superior flame‐retardant property. The EMI shielding effectiveness (SE) and specific EMI SE (SSEt) of the hybrid composite in X‐band (8.2–12.4 GHz) can be up to 77 dB and 26971.4 dB cm−2 g−1, respectively. At the same time, the hybrid composite also passes the vertical burning test and shows an increased LOI value of 40.6%. The combination of flame‐retardant and EMI shielding performances for EMI shielding materials makes the AgNWs‐MF hybrid composite great application potential in civil and military fields. This work provides a new guide for the design of multifunctional high‐performance EMI shielding materials.

Trimethylsilylethynyl-Substituted Pyrene Doped Materials as Improved Fluorescent Sensors towards Nitroaromatic Explosives and Related Compounds

The well-known fluorophore, namely 1,3,6,8-tetrakis[(trimethylsilyl)ethynyl]pyrene, has been studied profoundly as a fluorescent sensor toward nitroaromatic compounds in solutions and vapor phase. Three prototypes of fluorescent materials for vapor sensing were prepared via electrospinning and drop-casting onto the melamine formaldehyde foam with the fluorophore as a pure solid or as a dopant in the polystyrene matrix. It has been shown that this fluorophore and solid fluorescent materials based on it have high detection limits toward nitroaromatic compounds within the range of 10−8 to 10−9 M in acetonitrile solution and within the up to ppb range in the vapor phase. The model, expanding on Frisch’s permeation model, was utilized to characterize the fluorescence response of materials relative to vapor concentration and duration of exposure to vapor. All prototypes can be used as sensor materials exhibiting a good sensitivity and selectivity for the original hand-made sniffer for detecting nitro-containing explosives in the vapor phase for real-time application.

Constructing 3D Tent-Like frameworks in melamine hybrid foam for superior microwave absorption and thermal insulation

Taking serious electromagnetic pollution and practical application requirements into consideration, it’s imperative to develop multifunctional microwave absorption materials. In this work, the phenol–formaldehyde resin (PF) successfully adheres to melamine–formaldehyde foam (MF) as three-dimensional (3D) porous frameworks, and subsequently the substrate anchors few-layered MXene nanosheets by dripping-squeeze-drying procedures. According to the results, the hollow tent-like structure of MXene/PF@MF (MPM) shows a significant effect on microwave absorption capability, including extending heterogeneous interfaces for polarization relaxation and prolonging microwave propagation paths for energy dissipation. Based on the synergy of multiple components and rational structure, MPM exhibits a minimum reflection loss (RLmin) value of −58.8 dB at 2.2 mm and achieves an effective absorption bandwidth (EAB) of 6.74 GHz covering the entire Ku band. The microwave absorption mechanism reveals that the superior microwave absorption capability results from high conduction loss, polarization relaxation, multiple attenuations, and appropriate impedance matching. Furthermore, the MPMs possess lightweight features (32.7–48.7 g cm−3) and low thermal conductivity (0.0309–0.0318 W m−1 K−1) benefitting the unique 3D porous structure. Meanwhile, the low thermal conductivity endows MPMs with infrared stealth, which broadens the application in military fields. This work proposes a facile strategy for constructing highly efficient microwave absorbers with multiple functions.

An efficient and mild recycling of waste melamine formaldehyde foams by alkaline hydrolysis

Melamine formaldehyde foam (MFF) generates many poisonous chemicals through the traditional recycling methods for organic resin wastes. Herein, a high MFF degradation ratio of ca. 97 wt.% was achieved under the mild conditions (160 °C) in a NaOH–H2O system with ammelide and ammeline as the main degradation products. The alkaline solvent had an obvious corrosion effect for MFF, as indicated by scanning electron microscopy (SEM). The reaction process and products distribution were studied by Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and 13C nuclear magnetic resonance (NMR). Besides, the MFF degradation products that have the similar chemical structures and bonding performances to those of melamine can be directly used as the raw material for synthesis of melamine urea-formaldehyde resins (MUFs). Moreover, the degradation system demonstrated here showed the high degradation efficiency after reusing for 7 times. The degradation process generated few harmful pollutants and no pre- or post-treatments were required, which proves its feasibility in the safe removal or recovery of waste MFF.

FLUORESCENT DETECTION OF NITROBENZENE VAPORS VIA FLUOROPHORE-DOPED POLYSTYRENE MATERIALS

Integration of fluorescent substances into polymeric matrices can improve their sensory properties and photostability. In this work, fluorescent materials based on fluorophore-doped polystyrene were obtained and characterized as sensors towards the ecotoxicant nitrobenzene in gas phase. Melamine-formaldehyde foam has been proposed as a permeable substrate for the sensor material deposition applicable for gas-phase measurements. The effect on sensor properties of the porous material surface obtained via Breath Figure pore generation technique was investigated. Limits of detection and calibration relationships of obtained materials towards nitrobenzene were evaluated by materials exposure to low concentrations of nitrobenzene vapors. The sorption properties of polystyrene allow the retention of the quencher near the fluorophore, leading to improved detection limits compared with pure fluorophores. Obtaining a porous surface of the polymer material by the Breath Figure technique increases the scale of its fluorescence quenching by vapors. Detection limits (down to 0.45 ppm) and detectable concentration ranges (0.5 - 371.6 ppm) have been experimentally established. The relative standard deviations of the fluorescent signal of polymer materials do not exceed 13.3 % for a number of concentrations in the detectable range. The applicability of the calibration linear relationship of the logarithm of the fluorescent signal on the logarithm of the nitrobenzene vapor concentration is shown. Fluorescence signal measurements were performed using the original sensor element and the luminescence detector employing an array of fluorescent materials. The developed device is simple in application, portable, automated, and in combination with the used polymeric materials allows detection of nitrobenzene vapors in concentrations 2.5 times lower than the maximum permissible level.

Green triboelectric nanogenerator based on waste polymers for electrophoretic deposition of titania nanoparticles

Nowadays, with the development of electronic devices and the internet of things (IoT), there is a growing demand for an available, eco-friendly and endless power supply. Triboelectric nanogenerator (TENG), which converts wasted mechanical energy to electricity, is an alternative to batteries for power generation. TENGs are usually fabricated from polymers, and there are already great quantities of waste polymers in the environment that concern animals, wildlife and humans. Therefore, in this work, several eco-friendly, simple and low-cost TENGs were crafted using waste polymers like polyurethane foam (PU), expanded polystyrene (PS), polypropylene (PP), polyethylene foam (PE) and melamine formaldehyde foam (MF) without performing any physical or chemical functionalization on them. Finite element analysis was performed for each TENG and simulation results supported our experimental findings. Among these TENGs, voltage and power density of 1830 V and 96.68 mW/cm2 were achieved over a 3 × 3 cm2 area of M-TENG. This TENG could turn on 100 commercial blue light LED. The TENG with Melamine formaldehyde foam as a tribo-positive layer (M-TENG) also showed high mechanical robustness and its output did not change after 10,000 contact and separation cycles. To examine M-TENG utilization for high voltage practical application, M-TENG was used as a power source of electrophoretic deposition. The obtained high-quality titanium dioxide coating was uniform with no microcracks.

A salt-rejecting solar evaporator for continuous steam generation

Recently, great efforts have been focused on solar evaporators because they can localize solar heat on the air-water interface resulting in enhanced photothermal conversion efficiency. However, to prevent salt accumulation during evaporation while maintaining high evaporation rates is still a challenge. In this work, a salt-rejecting solar evaporator was fabricated for continuous seawater desalination. The evaporator was composed of a top layer of carbon black (CB) nanoparticles for solar absorbance, an interlayer of superhydrophilic melamine formaldehyde (MF) foam for both seawater and concentrated brine delivery, and an outlayer of expandable polyethylene (EPE) foam for floating and heat insulation. The superhydrophilic MF foam could offer a channel for rapid exchange of the concentrated brine with the solution beneath, thereby preventing salt accumulation in the evaporator. It was demonstrated that the salt-rejecting solar evaporator produced a high water evaporation rate of 1.24 kg·m−2·h−1 under 1 kW·m−2 solar irradiance, which was 3.2 times higher than that of the pristine simulated seawater (3.5 wt% NaCl solution). Furthermore, the salt-rejecting evaporator displayed an excellent stability as the water evaporation rate remained constant even after 16-cycles of use within 20 days.

Synthesis and Preparation of Hydrophobic CNTs-Coated Melamine Formaldehyde Foam by Green and Simple Method for Efficient Oil/Water Separation

Hydrophobic porous polymeric materials have attracted great interests recently as potential candicate for oil-water separation due to their high selectivity and sorption capacity. Herein, we present a green, simple and cost-effective method to change hydrophilic melamine formaldehyde (MF) foam to hydrophobic carbon nanotubes (CNTs) coated MF foam through an immersion process. The MF foam was produced from the MF resin which was synthesized in a laboratory by a condensation reaction between melamine and formaldehyde under alkaline condition with a molar ratio of melamine to formaldehyde of 1:3. The MF foam has an open-cell structure with the average pore diameter of 350 m, density of 25 kg •m-3 and porosity of 98 %. The as-prepared CNTs-coated MF foam exhibits high sorption capacity (23–-66 g/g) for oils and organic solvents, good recyclability and high selectivity.

Flexible 3D Cu/C Scaffolds As Lithium Host for Dendrite-Free Lithium Metal Battery

Lithium (Li) metal has been considered as one of the most attractive anode materials in Li battery due to its high theoretical capacity (3860 mAh g-1) and low electrochemical potential (-3.04 V vs SHE). However, large volume change and fibrous or needle-like dendrites formation during battery operation hinders its commercialization. Here, a Cu/C foam Li host was designed for the first time based on pyrolysis of melamine-formaldehyde foam and followed by Cu deposition. The Cu/C foam with C as backbone and Cu as shell exhibits excellent flexibility and superior conductivity. The cross-linked flexible fiber network, as well as high surface area, enables a dendrite-free Li metal anode due to its self-adapted structure and reduced local current density. A high coulombic efficiency of 99.5% is achieved after 300 plating/stripping cycles (~1200 hours). Significantly, it can last for more than 170 cycles at a high current of 5 mA cm-2 for symmetric cell cycling test. Furthermore, the full cell with lithium iron phosphate (LFP) as cathode exhibits a long cycling life at a high current of 1C.

Selective cationic dye sorption in water by a two-dimensional zinc-carboxylate coordination polymer and its melamine-formaldehyde foam composite

A new two-dimensional zinc(II) coordination polymer of 5-aminoisophtalic acid (H2AIP), namely [Zn(AIP)(DMSO)]n (Zn-CP), has been successfully prepared via conventional heating at 100 ​°C in a (2:1) dimethyl sulfoxide/ethanol solvent mixture. The compound has been characterized by FT-IR spectroscopy, elemental and thermogravimetric analyses, powder and single-crystal X-ray diffraction techniques. Crystal structure of Zn-CP shows the presence of neutral layers of composition Zn(AIP) and 63-hcb topology, which are decorated only on one side with dangling DMSO molecules. Moreover, the composite Zn-CP@Foam has also been fabricated growing Zn-CP crystals on the 3D porous structure of a melamine-formaldehyde foam (MF) by immersion of pieces of MF in the precursor solution of the coordination polymer. Both Zn-CP and Zn-CP@Foam materials have been studied for the adsorption in water of cationic dyes, such as Crystal Violet (CV), Victoria Blue (VB) and Malachite Green (MG), and anionic dyes, such as Sunset Yellow (SY), Congo Red (CR) and Aniline Blue (AB). Results show selective sorption of cationic dyes only, with faster and larger adsorption capacity observed for the porous composite material which has an adsorption capacity for Victoria Blue (VB) (102 ​mg ​g−1) more than twice larger than that found for pristine Zn-CP powder (48 ​mg ​g−1). This selectivity towards cationic dyes is attributed to electrostatic interactions between the cationic dye molecules and the negatively charged surface of the zinc coordination polymer, which shows a zeta potential of −13.7 ​mV. Moreover, dye adsorbed Zn-CP and Zn-CP@Foam can be regenerated by immersion in a water/acetic acid solution (1:1) and reused with almost the same efficiency.

Preparation of cellular SiBOC foams by precipitating methylvinylborosiloxane oligomers within melamine formaldehyde foam scaffold

SiBOC cellular ceramic foams were realized by precipitating methylvinylborosiloxane (MVBS) oligomers within reticulated poly(melamine-formaldehyde) (PMF) foam followed by drying and ceramization. The conventional method of impregnation-squeezing-drying exhibited MVBS starvation at the foam-core as the MVBS oligomers migrate to the surface due to its high solubility in ethanol and small cell size (200 ppi) of the PMF foam. In contrast, the precipitation of the MVBS oligomers on the web of the PMF foam prevents their migration to the surface. Ceramization by heat treatment at 1500 °C in inert atmosphere resulted in amorphous SiBOC cellular foams with cells in the size range of 20–400 μm. The density, compressive strength and thermal conductivity of the SiBOC foams were modulated in the ranges of 0.18−0.39 gcm−3, 0.3 to 0.87 MPa and 0.08−0.13 Wm-1 K-1, respectively, by using MVBS solution of concentrations in the range of 37–73 wt.%. The SiBOC foams remain amorphous up to 1600 °C beyond which extensive crystallization and phase separation occurs. Exposure of the SiBOC foam bodies at 1300 °C in air atmosphere showed negligible (∼ 0.2 wt.%) weight gain due to oxidation, indicating its potential as thermal protection material in oxidizing atmosphere.

Facile Synthesis of Ultralight and Porous Melamine-Formaldehyde (MF) Resin-Derived Magnetic Graphite-Like C3N4/Carbon Foam with Electromagnetic Wave Absorption Behavior

Society demands effective electromagnetic wave (EMW) absorbers that are lightweight, with a broad absorption band and strong absorption, to solve excessive electromagnetic radiation. Herein, ultralight magnetic graphite-like C3N4/carbon foam (MCMF) was fabricated via impregnating polymerized melamine formaldehyde (MF) foams in Fe3O4 nanoparticle solution, followed by in situ pyrolysis at 1000 °C. MCMF possesses porous architectures consisting of graphitic C3N4/carbon and CFe15.1. The magnetic particles (α-Fe, Fe3O4 and Fe3C) were formed and modified on the internal skeleton surface. The EMW absorption capacity of MCMF is better than the that of carbonized MF foam without Fe3O4 (CMF), possessing excellent absorption behavior, with a minimum RL value of −47.38 dB and a matching thickness as thin as 3.90 mm. The corresponding effective absorbing bandwidth is as broad as 13.32 GHz. Maxwell–Wagner–Sillars (MWS) polarization and the residual loss are proved to be beneficial for such superior absorption behavior. Besides, graphitic C3N4 enriches the interface polarization effect and the electromagnetic matching effect. The microporous structures are beneficial for increasing EMW propagation, resulting in internal multiple reflections and scatterings, which are also beneficial for EMW attenuation.

Efficient Solar Evaporation by [Ni(Phen)3 ][V14 O34 Cl]Cl Hybrid Semiconductor Confined in Mesoporous Glass.

Efficient utilization of solar energy for water evaporation is an advanced and environmentally friendly technology to address the crisis of global drinking water shortages. This study concerns an efficient solar vapor generator comprised of a light-absorbing and photothermal hybrid compound [Ni(Phen)3 ][V14 O34 Cl]Cl (NiV14 ) confined in mesoporous and hydrophilic glass (meso-glass). The generator is floated in water by supporting it on a domestic melamine-formaldehyde (MF) foam to ensure evaporation at the water-air interface. The porous structures and poor thermal conductivities of the meso-glass and MF foam contribute to enabling a consistent water supply, strong solar thermal localization, and less heat dissipation and convection. Associated with the strong photothermal role of NiV14 , these synergistic effects lead to a water evaporation rate of 14.38 kg m-2 h-1 with total water evaporation efficiency of 111.4% under 6 suns and a daily solar water purification yield of 42.00 L m-2 under 1 sun irradiation. This solar evaporation system shows great promise for high-efficiency water purification application.

Micro-nano surface structure construction and hydrophobic modification to prepare efficient oil-water separation melamine formaldehyde foam

A superhydrophobic melamine formaldehyde foam (SMF) was fabricated via a simple green solution-dipping method in polyvinyl alcohol (PVA) aqueous solution and polydimethylsiloxane (PDMS) ethanol one respectively. The resulted phase-separated PVA during transferring MF from aqueous solution to ethanol one, can form micro-nano structure on MF skeleton, thus endowing the foam surface with considerable roughness. Along with the crosslinking of PDMS, hydrophobic coating on the surface was formed. The modified foam exhibited superhydrophobicity (water contact angle at 157° and water sliding angle at 7°). Its absorption capacity to different organic solvents was evaluated. Meanwhile, a simple device for oil-water separation by connecting the modified foam block with a vacuum system was designed to testify the oil-water separation efficiency. In addition to excellent oil-water separation ability, the modified foam also showed good compressive performances including excellent corrosion resistance with pH of solutions ranging from 1 to 13, remarkable recyclability (up to 150 cycles), improved mechanical properties and high flame retardancy. Compared with the conventional porous superhydrophobic absorbents involving complicated methods and nanomaterials, such efficient SMF fabricated via a simple, low-cost and eco-friendly way shows promising prospect in dealing with oil spillage and industrial organic pollution in the future.

Recycling of waste melamine formaldehyde foam as flame-retardant filler for polyurethane foam

In the present research, the waste leftovers of a thermoset polymer foam with intrinsic flame resistance, melamine formaldehyde foam (MF), were pulverized to fine powder and added into polyurethane foam (PUF) as a flame-retardant filler. A series of characterizations were employed to investigate the obtained MF powder and the properties of the new flame retardant PUF. It was revealed that the pulverization process could produce fine MF powder. Moreover, it showed that the incorporation of MF powder could greatly decrease the heat release rate (HRR) and flammability of PUF without obvious impairment of mechanical property. Combined with a small amount of guanidine phosphate (GP), it could achieve quick self-extinguishment of the modified PUF. The process for recycling waste MF is easy and cheap, indicating an eco-friendly way for waste MF recycling, as well as a successful preparation of a low-cost and halogen-free flame retardant PUF.

Stretchable and compressible strain sensor based on carbon nanotube foam/polymer nanocomposites with three-dimensional networks

In this study, a flexible strain sensor based on nanocomposites filled with three-dimensional carbon nanotube (CNT) foam was developed. CNT sample was prepared by using melamine-formaldehyde foam as a template, and the prepared material showed hydrophobic properties and the ability to spontaneously adsorb uncured polymer (polydimethylsiloxane) with excellent structural stability, thus ultimately eliminating the problems associated with the dispersion and re-agglomeration of CNTs in a polymer matrix. The flexible nanocomposite sensor showed excellent piezoresistivity under both compression and tension strain with high sensitivity and could be sustained with outstanding stability under the cyclic runs. The principle verification results demonstrated that the developed sensor could monitor the motion of a finger and serve as an electronic skin to display the distribution of pressure, suggesting its great potential for applications in wearable and flexible electronics.