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Fuel cells are gaining increasing importance as a promising alternative to traditional energy sources, primarily due to their exceptional efficiency and environmental advantages. The electrical performance of proton exchange membrane fuel cells (PEMFCs) largely depends on the effectiveness of proton and electron transport within the cell components. A critical factor impacting this efficiency is the electrical conductivity of polymer‐based bipolar plates (BPPs), which play a fundamental role as current collectors. BPPs in PEMFCs can be made from various materials including coated metallic materials, graphitic materials, and polymer composites. This review exclusively concentrates on polymer composite BPPs. Enhancing the overall cell performance is achievable through the integration of electrically conductive additives into the polymer matrix of these plates. Graphite (GR), carbon black (CB), carbon fibers (CF), carbon nanotubes (CNT), and graphene (Gr) all emerge as highly promising functional materials capable of substantially elevating BPPs performance. This study, among its various objectives, delves into the synergistic effects of these electrically conductive additives and their capacity to enhance the electrical conductivity within polymeric matrices. Furthermore, this review article thoroughly explores the influence of the polymeric matrix, encompassing co‐continuous morphology and processing conditions. In essence, it focuses on the improvement of BPPs electrical conductivity through innovative designs of their polymer‐based composites and nanocomposites and the particular selection of the electrically conductive fillers. The insights derived from this study significantly contribute to a more profound understanding of how to effectively harness the potential of this vital PEMFC component. [ABSTRACT FROM AUTHOR]

In the past few years, epoxy resins utilization has gained much significant recognition from researchers worldwide as a result of its advantages in different sectors such as automotive, aerospace, electronic systems, constructions, and other related fields because of its outstanding mechanical performance, corrosion protection, and dielectric properties. The nanomaterials incorporation into the matrix has been duly examined to be the most productive route to enhance polymer composite's mechanical properties. Despite that, the inherent brittleness, relatively low fracture toughness, cross‐linking ability, poor electrical, and thermal properties of epoxy render it weak to growth and initiation of cracks, limiting its utilization in state‐of‐the‐art structural applications. Especially, epoxy is flammable while releasing a considerable amount of gases and smoke, thus, extending a potential risk to lives. Consequently, several nanofiller materials like graphene (Gr), transition metal dichalcogenides, MXene, and hexagonal boron nitride (h‐BN) produce extensive chances to equip multi‐functional characteristics and then reinforce the epoxy resins for the state‐of‐the‐art application. With this current review, the present literature investigation of epoxy filled with nano‐sized material has been examined thoroughly. Current advances in the approach of integrating nanosized materials in the epoxy matrices have been also introduced. Most significantly, anti‐corrosion, mechanical, and flame‐retardant properties of nanomaterials reinforced epoxy nanocomposites have also been reviewed in particular. Ultimately, the present statuses of the field in addition to the future approach have been considered concerning the usefulness of numerous nanofillers toward reinforcement of epoxy in construction and building materials. The expectation in this extensive review could produce a valuable reference, ingenuity, and guidance for researchers in this area of study. [ABSTRACT FROM AUTHOR]

In this work, a series of multi‐component intumescent PBS formulations were elaborated by the combination of intumescent flame retardant (IFR) system (consisting of ethylenediamine phosphate and melamine poly(aluminum phosphate), 7:3, wt:wt) and synergists. Three boron/zinc‐containing compounds (i.e., melamine borate, zinc oxide, zinc carbonate) were examined as potential synergists to improve the fire behavior and fire retardancy of PBS. The MLC results showed that the incorporation of all of these compounds enhanced the fire retardancy of PBS to some extent. Among them, zinc oxide exhibited the best fire retardant performances in terms of reduction of the peak heat release rate (pHRR, −61%), fire growth rate index (FIGRA, −19%), maximum average rate of heat emission (MARHE, −55%), and increase of the time to pHRR (+370 s) and to flameout (+650 s) as compared to PBS/IFR10%. Furthermore, the effect of zinc oxide loading on the fire retardancy of PBS was also investigated, the results showed that 2 wt.% loading exhibited the best performances. Solid‐state NMR characterization indicated that the presence of ZnO resulted in the formation of a crack‐free and dense intumescent char layer reinforced by complex aluminum‐zinc‐phosphates glassy species. The intumescent char layer provided a protective physical barrier with improved flexibility and cohesion, which effectively limits the heat and mass transfer between condensed and gas phases and hence, improving the fire retardancy of PBS. [ABSTRACT FROM AUTHOR]

Benzoxazines have been widely used in many fields, such as the aerospace, electronics, and automotive industries; however, these resins exhibit nonrecyclable nature and limited strength (for their brittleness). Introducing reversible covalent bonds in benzoxazines is expected to address these issues. Herein, two‐benzene‐ring‐conjugated Schiff‐base benzoxazine was successfully synthesized using a designed strategy. Using this strategy, possible side reactions, such as the transimination of the Schiff‐base, were prevented when preparing the target product via the traditional Mannich reaction. The cured benzoxazine could chemically degrade under acidic conditions and it undergoes controllable degradation when the temperature, acidity, and solvent are changed. The synthesized benzoxazine forms noticeable liquid crystals when heated to its melting point. Its glass transition temperature also reaches 265°C and the char yield at 800°C is 60.8%, considerably higher than that of traditional bisphenol A‐aniline based benzoxazine (BA‐a). Upon blending with epoxy (EP), the mechanical properties of the copolymers are significantly improved. With increasing benzoxazine content, the tensile strength of the copolymers increases from 63.6 to 95.2 MPa, an increase of ~50%. The rigid Schiff‐base structure is uniformly incorporated into the crosslinked network of EP and the EP curing agent via a transimination reaction during curing, thereby significantly improving the tensile modulus and strength of the composite material. [ABSTRACT FROM AUTHOR]

In this work, electro‐responsive shape‐memory actuators were developed by incorporating a conductive heater in a dual‐curing thiol‐acrylate‐epoxy shape‐memory polymer (SMP). A conductive heater, consisting of an electrically conductive silver‐ink track printed on Kapton® substrate, was assembled to the SMP, taking advantage of the dual‐curing processing. The shape‐memory effect (SME) was activated by the heat dissipated by the Joule effect in the conductive track. Boron nitride agglomerates were dispersed in the thiol‐acrylate‐epoxy layers to increase thermal conductivity and achieve faster shape‐recovery. A thermoelectric control unit was developed to control the shape recovery of the electro‐responsive actuators and provide different activation strategies. The electrically activated SME was investigated and compared to a traditional SME based on an external heating source given by the dynamic mechanical analyzer (DMA) apparatus. Electro‐responsive actuators were found extremely faster than the conventional SMPs based on external heating. The fastest recovery was obtained by the 15% boron nitride actuator, which recovered the 100% of the original shape in only 8 s. The thermoelectric controlling device provided an optimal control of the shape recovery speed based on the pulse width modulation of the heating current under the application of a low voltage (5 V). [ABSTRACT FROM AUTHOR]

In this study, a phosphorous‐containing benzoxazine was synthesized using a bio‐based primary amine, vanillin diamine true sample 2 (VDTS2, IUPAC name: 4‐(([3‐aminopropyl] imino) methyl)‐2‐methoxyphenyl(4‐(([3‐aminopropyl] imino) methyl)‐2‐methoxyphenyl) phenylphosphonate), paraformaldehyde and vanillin and tested for its use as a flame‐retardant. The molecular structure of the synthesized benzoxazines was characterized by FTIR spectroscopy and 1H NMR spectroscopy. Polybenzoxazine was obtained through the ring‐opening polymerization of the benzoxazine monomer, and the formation of the same was confirmed through FTIR spectroscopy. The polymerization mechanism of the benzoxazine was investigated using thermogravimetric analysis (TGA). The thermal properties of the benzoxazine were studied using differential scanning calorimetry and TGA. The flame‐retardant properties of the polybenzoxazine films obtained were investigated by the LOI. Due to the highly brittle nature of the polybenzoxazine, the synthesized polybenzoxazine was further crushed and incorporated into an epoxy system to investigate its use as a flame‐retardant additive. The thermal property and flame‐retardant property of the epoxy films were then studied. The flame‐retardant and thermal stability test results of the epoxy‐pbz films showed that the epoxy‐pbz films showed improved thermal stability and achieved a UL‐94 V‐0 rating and an LOI of 28% at 15% by weight of the polybenzoxazine concentration. SEM analysis was also conducted to study the surface morphology of the polybenzoxazine and epoxy‐pbz films pre and post the flame test. FTIR analysis was carried out to study the flame retardant mechanism of the polybenzoxazine and the epoxy‐pbz film. The respective films' mechanical properties were also investigated to study the film‐forming capability of the films. [ABSTRACT FROM AUTHOR]

Recycled polymeric materials recovered from E‐waste, have gained importance in the recent years, due to the value addition of properties in the recycled materials. In the current work, a polymeric blends formulated from keyboard waste plastics was value added using a flame retardant (FR), and these plastics are not incorporated with FR during its processing. This work was carried out to enhance the FR property of polymers recovered from keyboard waste, and to study the effects of these additives on the mechanical properties of the polymeric blends. The FR tri phenyl phosphate (TPP), and a hybrid FR combining TPP with sepiolite, was added in different proportions to the blend. The FR blends were analyzed with UL‐94 and LOI and it was observed that the blends with hybrid FR showed higher FR properties, as the results of UL‐94 and LOI showed V‐1 and 29%, respectively. The cone calorimetry results showed that the peak heat release rate of the blends was improved from 704 to 533 KJ/m2. The gas and condensed phase reaction has been explained with an illustration. FTIR and TGA with and without the FR were performed. The mechanical properties of the blends drastically reduced after the addition of FRs, hence an impact modifier was added in order to regain the lost mechanical properties, and a morphological analysis was carried out to compare the influence of impact modifier in the polymeric blend. [ABSTRACT FROM AUTHOR]

With the aim to improve the compatibility of polycarbonate (PC)/polypropylene (PP) blends, a novel aromatic polycarbonate diol (PCDL) was synthesized by the transesterification reaction, then a series of polycarbonate‐based thermoplastic polyurethane elastomers compatibilizers (TPU‐Gx) with octadecyl side chains were successfully prepared by introducing different content of PCDL and glyceryl monostearate (2,3‐Dihydroxypropyl octadecenoate; GMS). The structures of synthesized products were confirmed by Fourier transform infrared spectroscopy and Nuclear magnetic resonance hydrogen spectroscopy. Thermogravimetry results showed that all TPU‐Gx had good thermal stability. The effects of TPU‐Gx on the compatibilization of PC/PP blends were investigated in the aspect of morphology, mechanical, thermal, and rheological properties. The results showed that all TPU‐Gx could enhance the interfacial adhesion between PC/PP and improve the mechanical properties of PC/PP blends. Among them, the addition of TPU‐G1.5 containing 6.0 wt% PCDL and 1.5 wt% GMS made PC/PP/TPU‐G1.5 blends show the highest impact strength, which increased by 54.1% when compared with that of pure PC/PP blends. [ABSTRACT FROM AUTHOR]

A new series of high thermal boron nitride (BN) composites are prepared and characterized by several techniques. They are formed by an epoxy‐anhydride matrix and different BN contents, ranging from 30 to 80 wt%, of 120 μm agglomerates. For high BN ratio (≥60 wt%), epoxy mixtures were compressed (75 MPa) during 1 minute before curing, eliminating voids due to the high increase of viscosity, improving the compactness of the material and enhancing the thermal conductivity (TC). The curing process evolution was studied by calorimetric measurements to see if there was an influence of the filler on the curing rate. Rheological tests were performed to obtain the percolation threshold. It was observed that BN filler did not affect negatively the thermomechanical properties of the materials and allowed to enhance the TC from 0.17 W/m K in the case of the neat epoxy, to 3.06 W/m K when 80 wt% of BN agglomerates were added, which represents an improvement of 1700%. [ABSTRACT FROM AUTHOR]

The global concern over the environmental protection and bio‐sustainability of plastic waste materials has prompted a vibrant search for renewable and biodegradable polymers in the academia and industrial sectors. Amidst other biopolymers, poly(lactic acid) (PLA) is identified as the most promising thermoplastic aliphatic polyester. PLA is derived from agricultural products with unique physical and mechanical properties that are comparable with the conventional petroleum‐derived polymers. Yet, some of the properties are insufficient for advanced materials applications. Rigid nanoparticles are incorporated in the PLA matrix to alleviate its properties for specific high‐performance applications. Here, we report various approaches of preparing functional PLA nanocomposites with emphasis on the strengths and weaknesses of each of the methods, as well as the achieved properties enhancement for a targeted application. Designing high‐performance PLA nanocomposite involves careful selection of the most appropriate nanofillers or combinations of nanofillers, preparation technique and processing parameters. Besides multi‐walled carbon nanotubes (CNT) and montmorillonite (MMT) that are prominent as nucleating agents to achieve high thermal and mechanical properties, other nanofillers like silver nanoparticles (AgNP) play critical roles in improving antibacterial and high‐performance properties of PLA. [ABSTRACT FROM AUTHOR]

The quantitative analysis of zinc phosphate (ZnP) on the flame resistance of intumescent flame retardant coatings (IFRCs) is presented including cone calorimeter (CC) and pyrolysis kinetics, using aliphatic waterborne polyurethane (AWP) as the coating binder. The CC results show that an appropriate dosage (2 wt%) of ZnP in the AWP‐based coating constitutes an improved flame resistance, evidenced by the fire performance index increased from 0.41 to 0.71 seconds m2 kW−1, as well as the reduced fire growth index. The characterization analysis determines the dehydrated ZnP facilitates the formed amorphous char‐residue with a heat‐sink effect, leading to an increase in heat absorption, which climbs from the 253.00to 351.30 J·g−1. Besides, the pyrolysis kinetics verifies that the 3D Jander model (n = 2) mainly governs the whole pyrolysis process of pure coatings by the modified Coats‐Redfern integral method. The ZnP‐containing coating exerts an improved Eα corresponding to 95–200°C, which climbs from 24.96 to 35.80 kJ mol−1, leading to the formation of a continuous and compact char layer. It explores an effective quantitative analysis of the flame resistance of organic–inorganic hybrid IFRCs, deepening the flame‐retarding mechanism. [ABSTRACT FROM AUTHOR]

This study addresses the processing of nonwoven fibrous materials obtained by centrifugal spinning method, namely Forcespinning; a high yield and low production cost technique little explored in this field. Poly(D, L‐lactic acid) (PDLLA) and poly(3‐hydroxybutyrate) (PHB) were used as matrices and reinforced with zinc oxide nanoparticles (n‐ZnO). The morphology, mechanical, and thermal performance of the developed composites were analyzed as well as the antibacterial effect of n‐ZnO. Fibrous materials with n‐ZnO concentrations of 1, 3, and 5 wt. % for PDLLA and 1 and 3 wt. % for PHB were evaluated. The results showed that the incorporation of n‐ZnO produces an increase in the viscosity of the precursor solutions for both polymeric systems, which caused an increase in the average fiber diameter, though the morphology was not affected, obtaining mostly long, continuous, and homogenous fibers. In addition, a decrease in thermal stability was observed to a greater extent in PDLLA systems. Regarding the mechanical performance, optimal properties were obtained at a concentration of 3 and 1 wt. % of n‐ZnO for PDLLA and PHB, respectively. Antibacterial studies showed that PHB with 1 and 3 wt. % of n‐ZnO effectively combat strains of E. coli and S. aureus, presenting 100% of strain growth inhibition. In the case of PDLLA, a higher n‐ZnO concentration (5 wt. %) was required to reach a strain growth inhibition above 97%. Finally, cell viability tests demonstrated that the designed fibrous mats support cell proliferation, indicating their potential for use as scaffolds in bone tissue regeneration. [ABSTRACT FROM AUTHOR]

To achive excellent fire resistance, new microcapsule flame retardants (DMCAD and DMPPD) were prepared using 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide combined with melamine cyanurate or melamine polyphosphate as the shell material and diatomite as the core material. The successful assembly of DMCAD and DMPPD was detailed characterized by Fourier transform infrared (FT‐IR) spectra, X‐ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). Meanwhile, the flame retardancy and thermal stability of the unsaturated polyester resin (UPR)/DMCAD and UPR/DMPPD composites were also studied. The addition of DMCAD and DMPPD effectively improves the flame retardance properties of UPR, and the effect of DMPPD was better. The limiting oxygen index (LOI) of UPR/DMPPD‐3 increased by 11.6% when compared with that of UPR, and the sample achieved V‐0 rating. Moreover, the peak heat release rate (pHRR) and the total heat release (THR) rate of UPR/DMPPD‐3 were reduced by 67% and 26%, respectively. Under nitrogen condition and air condition, UPR/DMPPD showed better thermal stability and char‐forming ability from the thermogravimetric (TG) results. Residual char of the UPR composites was systematically analyzed with SEM and XPS. Finally, the flame retardant mechanism of DMPPD was proposed. [ABSTRACT FROM AUTHOR]

The natural basalt fiber (BF) was incorporated into EVA composites with environmental‐friendly nickel alginate‐brucite based flame retardant (NiFR), to further improve the flame‐retardant effect and mechanical properties. The flame retardancy of EVA composites were characterized by LOI, UL 94, and cone test. With 55 wt% loading, 3BF/52NiFR had the highest LOI value of 31.9 vol.% in all fiber reinforced composites and pass UL 94V‐0 ratting. And comparing to 55B composite with untreated brucite, 3BF/52NiFR decreased peak of heat release rate by 47.8%, total heat release by 21.9%, and total smoke production by 35.5% and kept more residue 54.0% during cone test. Moreover, 3BF/52NiFR also enhanced the mechanical properties of composites by better compatibility with EVA matrix. BF/NiFR exert synergistic flame‐retardant effect major in promoting charring effect in condensed phase during combustion. The fire‐resisted and rigid BF into the char layer reinforced the intensity of protective barrier which prolonged the residence time of pyrolysis carbonaceous groups degraded from EVA matrix, resulting in less heat and smoke release. [ABSTRACT FROM AUTHOR]

A type of trialkoxysilane‐containing naphtholoxazine compound (Naph‐boz) was successfully synthesized and combined with ammonium polyphosphate/melamine (APP/ME) as an intumescent flame retardant (IFR) to improve the flame‐retardant efficiency of polyoxymethylene (POM). The Underwriters Laboratories 94 (UL94) vertical burning test, limiting oxygen index (LOI), cone calorimeter, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and Raman spectral analysis were used to study the flame‐retardant properties and related mechanism. The results showed that the formulation with 20 wt.% of APP, 6 wt.% of ME, and 4 wt.% of Naph‐boz passed UL94 V‐1 rating, and the LOI value was improved to 40.3%. Compared with pure POM, the IFR with Naph‐boz had greater reduction in peak heat release rate (lower 74.9%) and total heat release (lower 40.2%). SEM images showed that compact and reinforcing charred layer was formed during the POM/IFR/4Naph‐boz samples combustion, which was beneficial at reducing and maintaining low combustion parameters throughout the cone calorimeter test. The synergistic flame‐retardant effect between Naph‐boz and APP/ME was considered as the reason for the improvement in flame retardancy POM. Furthermore, because of the Naph‐boz was conducive to the compatibility between the flame retardants and matrix, the notched Izod impact strength of POM/IFR/4Naph‐boz composite was higher than that of POM/IFR system. [ABSTRACT FROM AUTHOR]

A new phosphorus‐based organic additive (PDA) was designed and successfully synthesized using a three‐component reaction for improvement of the thermal and combustion resistance of polylactic acid (PLA). For compensate for mechanical properties of PLA, hydroxyapatite nanoparticles was modified via in situ surface modification with PDA and was used for preparation of PLA nanocomposites. The structure and morphology as well as thermal, combustion, and mechanical properties of the all PLA systems were investigated. The X‐ray diffraction (XRD) and field‐emission scanning electron microscopy (FE‐SEM) results indicated that the presence of PDA as surface modifier has been necessary for a desirable dispersion of hydroxyapatite (HA) nanoparticles in the PLA matrix. The thermal, combustion, and mechanical properties of the PLA system films were investigated using thermogravimetric analysis (TGA), microscale combustion calorimeter (MCC), and tensile test, respectively. The initial decomposition temperature and char residue of PLA containing 6 mass% of PDA along with 2 mass% HA nanoparticles were increased 20°C and 12% respectively, compared with that of the neat PLA. The peak of heat release rate was decreased from 566 W/g for the neat PLA to 412 W/g for PLA containing 2 mass% of PDA along with 6 mass% HA nanoparticles. By incorporation of only 2 mass% HA nanoparticles and 6 mass% of PDA, the tensile strength was obtained 51 MPa higher than that of the neat PLA. [ABSTRACT FROM AUTHOR]

Poly (lactic acid) (PLA) has become an important biopolymer with excellent properties but has limited engineering applications where fire safety is ultimate. An efficient flame retardant (FR) for PLA biocomposites based on azo‐boron coupled with 4,4′‐sulfonyldiphenol‐(((1E,1′E)‐(sulfonylbis(6‐hydroxy‐3,1‐phenylene))bis (diazene‐2,1‐diyl))bis(3,1‐phenylene))diboronic acid (SBDA) was synthesized and characterized by FTIR, 1H and 13C NMR spectra. SBDA was combined with calcium lignosulfonate (Calig) and compounded with PLA, and the FR, crystallization, and mechanical properties were investigated. The addition of 15 wt% FR (10 wt% Calig and 5 wt% SBDA) into PLA led to important reductions in peak heat release rate (PHRR) approximately 54%, total heat release (THR) approximately 28.6%, and the average effective heat of combustion (AEHC) approximately 29.4%. The fire performance index and fire growth index improved by approximately 56.4% and 33.1%, respectively. A V‐0 rating (vertical burning test) and a limiting oxygen index value of 28.8% were achieved for the FR PLA biocomposites. The combinatory SBDA/Calig reduced the segmental mobility of PLA in the organic‐inorganic interface with insignificant changes in the elongation at break and the Young Modulus. TG‐IR study showed significant reductions in pyrolysis gaseous products for the composites compared with PLA. This research work will expand the frontiers of knowledge on use of boron and calcium functionalized polyaromatic polyols for reducing the flammability of PLA. [ABSTRACT FROM AUTHOR]

Aliphatic polyketone (POK) is a new engineering plastic owning outstanding mechanics, chemical resistance, and gas/liquid barrier properties. However, analogous to other polymers, the nature of combustion severely restricts the widespread application of POK. Herein, the diethyl zinc phosphinate (ZnPi) was compounded with three grades of POKs, which were different among each other in viscosity as low (L), medium (M), and high (H) levels, by melt mixing. It is intriguing to suggest that increasing the viscosity of POK could remarkably improve the dispersion homogeneity of ZnPi, which was beneficial to superior flame retardancy, simultaneously with comprehensive mechanical properties. For the H‐POK matrix, only 10% well‐dispersed ZnPi resulted in a V0 ranking with a good maintenance of its notched impact strength, whereas the load of ZnPi for reaching V0 rank increased to 14% in L‐POKs and M‐POKs and the mechanical performances decreased mildly. By a combination of scanning electron microscopy (SEM), Fourier‐transform infrared (FTIR), thermogravimetric analysis (TGA), and cone calorimetry, it is well revealed that the flame retardancy induced by adding ZnPi could mainly ascribe to the formation of various zinc phosphate species. This work exploits a facile and feasible method for fabrication of antiflame engineering plastics, which will be promising for large‐scale applicability of high‐performance POK materials. [ABSTRACT FROM AUTHOR]

Three different polyhedral oligomeric silsesquioxanes (POSS), trisilanolphenyl polyhedral oligomeric silsesquioxane (T‐POSS), octaaminophenyl polyhedral oligomeric silsesquioxanes (OAPS), and octaphenyl polyhedral oligomeric silsesquioxanes (OPS) were incorporated into phenolic resin (PR), respectively; PR/POSS composites were successfully prepared, and the properties of PR/POSS composites were studied. The limiting oxygen index (LOI), cone calorimeter, and thermal gravimetric analysis (TGA) were used for the estimation of flame retardancy and thermal stability. Oxyacetylene flame test and flexural strength test were used to study the ablative and mechanical properties of the PR/POSS composites. The results indicated that T‐POSS was more effective in improving the flame retardancy of PR than OAPS or OPS. Meanwhile, compared with pure PR, the second line ablation rates of PR/4% T‐POSS, PR/4% OAPS, and PR/4% OPS were significantly reduced by 53.3%, 61.9%, and 40.0%, respectively. In addition, the thermal stability and flexural strength of PR/4% T‐POSS were significantly higher than that of all other PR composites. [ABSTRACT FROM AUTHOR]

This work visualizes the complementary actions of organic and mineral additives in model thermoplastic polymer composites in terms of Flame Retardancy Index (FRI). Thermal and flame retardancy behaviors of ethylene‐vinyl acetate copolymer (EVA) composites containing calcium carbonate (CC) mineral and ammonium polyphosphate (APP) organic additives were studied varying composition of additives in the 80/20 EVA/(xCC + (20 − x)APP) composites with x denoting 0, 5, 10, 15, and 20 wt%. Thermogravimetric analysis (TGA) revealed that the onset temperature of composites and the remaining residue were increased by combination of APP and CC, while cone calorimetry results were indicative of a promising flame retardancy performance at a given composition of APP and CC. Based on FRI values, we made distinguished samples from flame retardancy performance viewpoint, where the best flame retardancy was obtained by combination of 15 wt% APP and 5 wt% CC, as reflected in FRI value of 3.08. By contrast, samples containing only APP or CC revealed low resistance against flame, as signaled by FRI values of 0.99 and 0.89, respectively. X‐ray diffraction (XRD) analysis was made on remaining residue collected at the end of cone calorimetry measurements. Moreover, Raman analysis confirmed barrier effect of flame retardancy for EVA/(5APP + 15CC) sample, featured by a higher graphitization level as well as a thicker yet more homogenous char layer. Mechanical behavior analysis of composites revealed an acceptable level of properties, particularly high elongation at break, which was almost independent of formulation. However, a minor loss in yield stress was observed, especially for EVA(10CC + 10APP) sample. [ABSTRACT FROM AUTHOR]

In this work, a novel sulfur‐based flame retardant (SA‐M) was synthesized by the self‐assembly of melamine and sulfamic acid. The chemical structure of SA‐M was fully characterized. SA‐M, in company with Al2O3, was then introduced into polyamide 11 (PA 11) by melt compounding in order to improve the fire resistance of the polymer substrate. The observation by scanning electron microscopy (SEM) and electron probe microanalysis (EPMA) indicated the well dispersion of SA‐M in PA 11 matrix. The fire performance of PA 11 composites was evaluated by limiting oxygen index (LOI), vertical burning (UL‐94), and cone calorimeter tests, respectively. The results showed that the presence of 17.5% SA‐M and 2.5% Al2O3 increased the LOI value from 22.4% to 30.9%, upgraded the UL‐94 rating from no rating to V‐0, significantly eliminated the melt dripping, and decreased the peak heat release rate from 1024 to 603 kW/m2. The thermal behaviors were investigated by thermogravimeric analysis (TGA) and TGA‐Fourier transform infrared spectroscopy (FTIR). It was suggested that SA‐M took effects mainly in gas phase by diluting the combustible fuel, leading to the improvement of the fire resistance of PA 11. [ABSTRACT FROM AUTHOR]

Low‐flammability freeze‐dried cellulose nanofibril (CNF)/sodium montmorillonite (MMT) aerogels with improved mechanical properties were fabricated via a facile cross‐linking of boric acid (BA) and melamine‐formaldehyde (MF) resins. Scanning electron microscopy analysis showed that BA cross‐linking reduced the interspacing of layered CNF/MMT aerogels whereas introduction of MF formed polymeric fibrils that connected the layers. These changes on microstructures resulted in the improvement on compressive mechanical properties of the cross‐linked aerogels. Moreover, the boron (B)/nitrogen (N) containing flame retardant cross‐linkers greatly increased the limiting oxygen index values that could reach 85% and leveled the UL‐94 rating from no rating to V‐0. Cone calorimetric results suggested that BA and MF induced a synergistic effect on the flame retardant properties of the CNF/MMT aerogels. However, the thermal conductivity was little affected because pore structure and size was not substantially modified. This simple approach fabricated highly flame‐resistant and mechanically strong CNF‐based aerogels that could be used in various engineering fields. [ABSTRACT FROM AUTHOR]

The main purpose of this study was to investigate the effect of zinc oxide (ZnO) nanoparticles on the morphological, mechanical, thermal, and rheological properties of PLA/PP blend. In this regard, nanocomposites containing 1, 3, and 5 wt% of ZnO nanoparticles were prepared by melt mixing. In addition, three different mixing procedures were adopted to study their effects on the microstructure of nanocomposites. The rheological behaviors demonstrated a higher elasticity and less compatibility for two phases in the case of nanocomposites containing nanoparticles in harmony with the morphological observations. Accordingly, it was correlated to the elasticity originating from the interphase, anticipated coalescence of dispersed particles as a result of degradation of PLA chains triggered by ZnO nanoparticles (ZnO‐NPs) and also agglomeration of ZnO‐NPs depending on the content of nanoparticles and chosen mixing procedure. It was also found that mixing method puts a remarkable influence on the microstructure and rheological behavior of nanocomposites. Results of mechanical characterizations and thermogravimetric analysis (TGA) also confirmed the degradation induced by ZnO nanoparticles. [ABSTRACT FROM AUTHOR]

In the present work, a facile and environmental method was developed to fabricate the novel functionalized MoS2 hybrid. Firstly, MoS2 nanosheets were coated with polydopamine (PDA) through the self‐polymerization of dopamine (MoS2‐PDA) in a buffer solution. Then the decoration of Ni(OH)2 on the MoS2‐PDA was synthesized because of the strong affinity of Ni2+ with hydroxyl groups in PDA. Finally, the as‐synthesized MoS2‐PDA@Ni(OH)2 was introduced into poly(lactic acid) (PLA) matrix to explore flame retardancy, thermal stability, and crystalline property of the composites. As confirmed by X‐ray diffraction (XRD), Fourier‐transform infrared spectrometer (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA), the MoS2 nanosheets were dually modified with PDA and Ni(OH)2 without destroying the original structures. The thermal degradation of PLA with MoS2‐PDA@Ni(OH)2 generated a notably higher yield of char. Moreover, the crystallization rate of composites is higher than neat PLA. The cone calorimeter test revealed that the introduction of 3% MoS2‐PDA@Ni(OH)2 resulted in lower Peak Heat Release Rate (PHRR) (decreased by 21.7%). Thus, the research provided an innovative functionalization method for manufacturing PLA composites with high performances. [ABSTRACT FROM AUTHOR]

Nanocomposites consisting of semi‐aromatic polyamide (PA) and pristine or alkali activated halloysite nanotubes (HNT or mHNT, respectively) were synthesized by the in‐situ interfacial polymerization method. The condensation reactions were carried out between isophthaloyl dichloride in hexane and triethylenetetramine in water containing different amounts of HNT or mHNT. The interactions and crystallinity of the nanocomposites were studied by Fourier transform infrared (FTIR) spectroscopy and X‐ray diffraction (XRD) analysis, respectively. Development of hydrogen bonds between the functional groups of PA and hydroxyl groups of nanotubes was indicated by FTIR spectroscopy. According to the XRD analysis, the addition of HNT and mHNT nanotubes increased the crystallinity of the PA. This was ascribed to the role of nanotubes as nucleating agents in the PA matrix. Thermal resistance and char residue of PA, as revealed by thermogravimetric analysis, were enhanced by incorporating both HNT and mHNT and the latter was more effective in this regard. Furthermore, while the addition of pristine HNTs decreased the glass transition temperature (Tg) of the PA, the Tg could be increased by about 5°C, in the presence of 5 wt% of mHNTs. Finally, the facilely activated mHNT nanotubes were found to be highly efficient in improving the thermal and structural properties of semi‐aromatic PAs. [ABSTRACT FROM AUTHOR]

A novel mesoporous SiO2‐graphene nanohybrid was successfully synthesized by a 1‐pot hydrothermal synthesis method using tetraethylortho silicate and graphene oxide as initial materials to improve the dispersion of graphene in epoxy matrix. Subsequently, the SiO2‐graphene nanohybrids were added into epoxy resin to investigate their fire behaviors. It was found that the incorporation of the as‐prepared SiO2‐graphene nanohybrids into epoxy resin obviously increased the flame retardancy, compared with those of neat epoxy. This attractive feature of SiO2‐graphene epoxy nanocomposites was attributed to the barrier effect as well as the labyrinth effect contributed by SiO2‐graphene in EP resin. [ABSTRACT FROM AUTHOR]