The mechanical properties and tribological behavior of epoxy resin composites modified by different shape nanofillers

Mechanical properties and tribological behavior of epoxy resin (EP) and EP nanocomposites containing different shape nanofillers, such as spherical silica (SiO₂), layered organo‐modified montmorillonite (oMMT) and oMMT‐SiO₂ composites, were investigated. The SiO₂‐oMMT composites were prepared by in situ deposition method and coupling agent modification, and transmission electron microscopy (TEM) analysis shows that spherical SiO₂ is self‐assembled on the surface of oMMT, which forms a novel layered‐spherical nanostructure. The mechanical properties test results show that oMMT obviously improves the strength of EP and SiO₂ enhances its toughness, but oMMT‐SiO₂ exhibits a synergistic effect on toughening and reinforcing EP simultaneously. A pin‐on‐disc rig was used to test friction and wear loss of pure EP and EP nanocomposites. The tribological test results prove that these nanofillers with different shapes play different roles for improving the wear resistance of EP nanocomposites. Morphologies of the worn surfaces were studied further by scanning electron microscopy (SEM) observations, and it was clarified that the EP and EP nanocomposites undergo similar wear mechanisms. Copyright © 2006 John Wiley & Sons, Ltd.     

Hierarchical MoS2/polyaniline binary hybrids with high performance for improving fire safety of epoxy resin

Here we report a facile strategy to fabricate phosphoric acid doped polyaniline/molybdenum disulfide (PANI/MoS₂) hybrids as high-performance nanofillers in epoxy (EP) resin for the first time. In situ growth of PANI on the surface of two-dimensional MoS₂ template resulted in the uniform dispersion and strong interfacial adhesion of PANI/MoS₂ hybrids within EP matrix, which can be confirmed by the obvious increase (13.5°C) in glass transition temperature (T_g) of EP composites. The MoS₂ nanosheets also acted as a critical component to generate synergistic effect with PANI on reducing the fire hazards of EP resin. It resulted in a remarkable removal of flammable decomposed products and a considerable reduction of toxic CO yield. The dramatical decreases in real-time smoke density and total smoke production, and high-graphitized char layer in condensed phase were obtained for EP composite with 5 wt% PANI/MoS₂ hybrids. The multiple synergistic effects (synergistic dispersion and synergistic char formation) are believed to be the primary source for these obvious enhancements of properties of EP composites. This facile strategy may achieve the potential application of functionalized MoS₂ in polymeric nanocomposites.     

Surface modification of PBO fibers with 2,2-Bis (3-amino-4-hydroxyphenyl) hexafluoropropane in supercritical carbon dioxide for enhancing interfacial strength

PBO fiber is one of the most promising reinforcements in resin matrix composite because of its excellent mechanical properties. However, the inert and smooth surfaces make it the poor interface adhesion with resin matrix, which seriously limits the application in composites. In this article, we report a method to modify the surface of PBO fibers with 2,2-Bis (3-amino-4-hydroxyphenyl) hexafluoropropane（BisAPAF）in supercritical CO₂ to enhance interfacial properties. Chemical structures, surface elemental composition and functional groups, and surface morphology were characterized by FT-IR spectrometer, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM), respectively. The mechanical properties of the samples were tested by a tensile tester. Static contact angle and microdebonding tests were used to characterize the wetting ability and interfacial shear strength (IFSS) of the fiber and epoxy resin. The results showed that the BisAPAF could be solved in scCO₂ and introduced more groups, –NH₂, –OH, and –CF₃ on the fiber surface, resulting in the mechanical properties and the wettability of PBO fiber slightly improved. Moreover, the fiber surface roughness was also increased obviously. The IFSS between the modified PBO fiber and epoxy resin increased from 8.18 MPa to 31.4 MPa when the treating pressure was 14 MPa. In general, the method to modify PBO fibers surface using BisAPAF in scCO₂ can effectively improve their interfacial properties.     

The influence of mesoporous silica modified with phosphorus and nitrogen‐containing hyperbranched molecules on thermal stability,combustion behavior,and toxic volatiles of epoxy resin

A hybrid material (HPPA‐SH‐mSiO₂) containing multiple flame‐retardant elements was synthesized and characterized using NMR, FTIR, and XPS techniques. This hybrid was synthesized by the “thiol–ene” click reaction of thiol‐functionalized mesoporous silica (SH‐mSiO₂) with ene‐terminated hyperbranched polyphosphate acrylate (HPPA).When 2 wt% HPPA‐SH‐mSiO₂ hybrid was added to an epoxy matrix, thermogravimetric analysis (TGA) showed that the incorporation of HPPA‐SH‐mSiO₂ increased the thermal stability of epoxy resin composites. Moreover, the combustion behavior of epoxy composites was investigated using a cone calorimeter, and the results show that the PHRR and THR of EP/HPPA‐SH‐mSiO₂ composites clearly decreased by 28.7% and 16%, respectively. Volatile toxic compounds such as aromatic compounds, CO, carbonyl compounds, and hydrocarbons were identified using TGA‐infrared spectroscopy coupling technique. The effect of HPPA‐SH‐mSiO₂ hybrids on the removal of toxic volatiles was also investigated. Functionalized mesoporous silica and polymer composites have potential applications.     

Activated carbon spheres (ACS)@SnO2@NiO with a 3D nanospherical structure and its synergistic effect with AHP on improving the flame retardancy of epoxy resin

A novel activated carbon spheres (ACS)@SnO₂@NiO hierarchical hybrid architecture was first synthesized and applied for enhancing the flame retardancy of epoxy (EP) resin via a cooperative effect. Herein, using activated carbon microspheres as the template, SnO₂ and NiO nanospheres were successively anchored to it by a sedimentation‐calcination strategy. The well‐designed ACS@SnO₂@NiO significantly enhanced the flame retardancy for consistency of EP composites, as demonstrated by thermogravimetric and cone calorimeter experiments. For instance, the incorporation of 2 wt% ACS@SnO2@NiO decreased by 15.5% maximum in the total smoke production, accompanying the higher graphitized char layer. In addition, the synergetic mechanism of flame retardancy between ACS@SnO₂@NiO and aluminum hypophosphite (AHP) was investigated. The obtained sample satisfied the UL‐94 V‐0 rating with a 5.0 wt% addition of AHP and ACS@SnO₂@NiO (the ratio of the mass fraction of AHP to ACS@SnO₂@NiO is 4.5:0.5). Notably, the incorporation of AHP and ACS@SnO₂@NiO resulted in a significant decrease in the fire hazard properties of EP resin; for instance, 4.5AHP‐0.5ACS@SnO₂@NiO/EP resulted in a maximum decrease of 32.4% in the total smoke production as compared with that of pure EP resin. It should be noted that the improved flame‐retardant performance for the EP composites is primarily attributed to the synergistic effect of ACS@SnO₂@NiO and AHP in promoting the formation of residual char in the condensed phase.     

Effects of noncovalently functionalized multiwalled carbon nanotube with hyperbranched polyesters on mechanical properties of epoxy composites

In order to improve the dispersibility and interface properties of multi-walled carbon nanotubes (MWCNTs) in epoxy resin (EP), aromatic hyperbranched polyesters with terminal carboxyl (HBP) and aromatic hyperbranched polyesters with terminal amino groups (HBPN) were used for noncovalent functionalization of MWCNTs. Epoxy composites reinforced by different types of MWCNT were prepared. The effects of noncovalent functionalization of MWCNTs on the dispersibility, wettability, interface properties and mechanical properties of epoxy composites were investigated. The results show that the dispersibility and wettability of MWCNTs are significantly improved after noncovalent functionalization. A large number of terminal primary amines (NH₂) on noncovalently functionalized MWCNT with HBPN (HBPN-MWCNT) form covalent bonds with EP matrix, and thus the interfacial adhesion is enhanced significantly, resulting in high load transfer efficiency and substantial increase in mechanical properties. The interface with covalent bonding formed between the flexible hyperbranched polyester layer on the surface of HBPN-MWCNT and the EP matrix promotes plastic deformation of the surrounding EP matrix. The toughening mechanisms of HBPN-MWCNT are MWCNT pull-out and a large amount of plastic deformation of the surrounding EP matrix.     

Synthesis of a novel phosphorus‐containing curing agent and its effects on the flame retardancy,thermal degradation and moisture resistance of epoxy resins

A novel phosphorus‐containing compound diphenyl‐(1, 2‐dicarboxylethyl)‐phosphine oxide defined as DPDCEPO was synthesized and used as a flame retardant curing agent for epoxy resins (EP). The chemical structure of the prepared DPDCEPO was well characterized by Fourier transform infrared spectroscopy, and ¹H, ¹³C and ³¹P nuclear magnetic resonance. The DPDCEPO was mixed with curing agent of phthalic anhydride (PA) with various weight ratios into epoxy resins to prepare flame retardant EP thermosets. The flame retardant properties, combustion behavior and thermal analysis of the EP thermosets were respectively investigated by limiting oxygen index (LOI), vertical burning tests (UL‐94), cone calorimeter measurement, dynamic mechanical thermal analysis and thermogravimetric analysis (TGA) tests. The surface morphologies and chemical compositions of the char residues for EP thermosets were respectively investigated by scanning electron microscopy and X‐ray photoelectron spectroscopy (XPS). The water resistant properties of the cured EP were evaluated by putting the samples into distilled water at 70°C for 168 hr. The results revealed that the EP/20 wt% DPDCEPO/80 wt% PA thermosets successfully passed UL‐94 V‐0 flammability rating and the LOI value was as high as 33.2%. The cone test results revealed that the incorporation of DPDCEPO effectively reduced the combustion parameters of the epoxy resin thermosets, such as heat release rate and total heat release. The dynamic mechanical thermal analysis test demonstrated that the glass transition temperature (Tg) decreased with the increase of DPDCEPO content. The TGA results indicated that the incorporation of DPDCEPO promoted the decomposition of epoxy resin matrix ahead of time and led to a higher char yield and thermal stability at high temperatures. The surface morphological structures and analysis of the XPS of the char residues of EP thermosets revealed that the introduction of DPDCEPO benefited the formation of a sufficient, compact and homogeneous char layer with rich flame retardant elements on the epoxy resin material surface during combustion. The mechanical properties and water resistance of the cured epoxy resins were also measured. After water resistance tests, the EP/20 wt% DPDCEPO/80 wt% PA thermosets retained excellent flame retardancy, and the moisture adsorption of the EP thermosets decreased with the increase of DPDCEPO content in EP thermosets because of the existence of the P–C bonds and the rigid aromatic hydrophobic structure in DPDCEPO. Copyright © 2015 John Wiley & Sons, Ltd.     

Synergistic flame‐retardant effect and mechanisms of boron/phosphorus compounds on epoxy resins

To explore the component synergistic effect of boron/phosphorus compounds in epoxy resin (EP), 3 typical boron compounds, zinc borate (ZB), boron phosphate (BPO₄), and boron oxide (B₂O₃), blended with phosphaphenanthrene compound TAD were incorporated into EP, respectively. All 3 boron/phosphorus compound systems inhibited heat release and increased residue yields and exerted smoke suppression effect. Among 3 boron/phosphorus compound systems, B₂O₃/TAD system brought best flame‐retardant effect to epoxy thermosets in improving the UL94 classification of EP composites and also reducing heat release most efficiently during combustion. B₂O₃ can interact with epoxy matrix and enhance the charring quantity and quality, resulting in obvious condensed‐phase flame‐retardant effect. The combination of condensed‐phase flame‐retardant effect from B₂O₃ and the gaseous‐phase flame‐retardant effect from TAD effectively optimized the action distribution between gaseous and condensed phases. Therefore, B₂O₃/TAD system generated component synergistic flame‐retardant effect in epoxy thermosets.     

Tailoring the surface chemistry of carbon fiber and E‐glass composites for improved adhesion

The main challenges in the manufacture of composite materials are low surface energy and the presence of silicon‐containing contaminants, both of which greatly reduce surface adhesive strength. In this study, carbon fiber (CF) and E‐glass epoxy resin composites were surface treated with the Accelerated Thermo‐molecular adhesion Process (ATmaP). ATmaP is a multiaction surface treatment process where tailored nitrogen and oxygen functionalities are generated on the surface of the sample through the vaporization and atomization of n‐methylpyrrolidone solution, injected via specially designed flame‐treatment equipment. The treated surfaces of the polymer composites were analyzed using XPS, time of flight secondary ion mass spectrometry (ToF‐SIMS), contact angle (CA) analysis and direct adhesion measurements. ATmaP treatment increased the surface concentration of polar functional groups while reducing surface contamination, resulting in increased adhesion strength. XPS and ToF‐SIMS showed a significant decrease in silicon‐containing species on the surface after ATmaP treatment. E‐glass composite showed higher adhesion strength than CF composite, correlating with higher surface energy, higher concentrations of nitrogen and C?O functional groups (from XPS) and higher concentrations of oxygen and nitrogen‐containing functional groups (particularly C₂H₃O⁺ and C₂H₅NO⁺ molecular ions, from ToF‐SIMS). Copyright © 2010 John Wiley & Sons, Ltd.     

Surface molecular characterisation of different epoxy resin composites subjected to UV accelerated degradation using XPS and ToF-SIMS

Epoxy resin composites reinforced with E-glass (E), 3D glass (3D) and carbon fibre (CF) were subjected to an intense UV and high temperature accelerated degradation environment. X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) were used to provide a molecular characterisation of the surface of the degraded composites. The response at the surface of the epoxy resin composites to oxidative degradation is influenced by the composite reinforcement type and characteristics. XPS results indicate that 3D resin composites exhibit more surface oxidation as a result of the accelerated degradation in comparison with E and CF composites. Principal components analysis (PCA) of the ToF-SIMS positive ion spectra showed that E and 3D resin composites suffered chain scission while CF composites suffered chain scission and cross-linking reactions as a result of the intense UV exposure. The extent of the surface oxidation, cross-linking/condensation reaction and loss of low molecular weight (lower than C₄H_x) aliphatic hydrocarbons may be indicated using PCA of both the ToF-SIMS positive and negative ion spectra. PCA also provides insight for proposing epoxy resin chain scission and oxidation reaction mechanisms.     

Friction and wear properties of combined surface modified carbon fabric reinforced phenolic composites

Carbon fabric (CF) was surface treated with silane-coupling agent modification, HNO₃ oxidation, combined surface treatment, respectively. The friction and wear properties of the carbon fabric reinforced phenolic composites (CFP), sliding against GCr15 steel rings, were investigated on an M-2000 model ring-on-block test rig. Experimental results revealed that combined surface treatment largely reduced the friction and wear of the CFP composites. Scanning electron microscope (SEM) investigation of the worn surfaces of the CFP composites showed that combined surface modified CFP composite had the strongest interfacial adhesion and the smoothest worn surface under given load and sliding rate. SEM and X-ray photoelectron spectroscopy (XPS) study of carbon fiber surface showed that the fiber surface became rougher and the oxygen concentration increased greatly after combined surface treatment, which improved the adhesion between the fiber and the phenolic resin matrix and hence to improve the friction-reduction and anti-wear properties of the CFP composite.     

The influence of mesoporous SiO2‐graphene hybrid improved the flame retardancy of epoxy resins

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.     

The dynamic mechanical behavior of random-in-plane short fiber-reinforced epoxy resin composites

In the present paper, the dynamic mechanical properties of random-in-plane short fiber-reinforced epoxy resin composites were studied by using a rheometrics solids analyzer. The three-point bend testing of the four composites (glass fiber/913 epoxy resin, glass fiber/924 epoxy resin, carbon fiber/913 epoxy resin and carbon fiber/924 epoxy resin) was carried out over temperatures from −100°C to 200°C at a frequency of 10 Hz and strain 0.05%. The composites based on 924 epoxy resin, which has been designed specially for high temperature applications, have less energy loss than the 913 epoxy resinbased composites. For the same resin, the carbon fiber-reinforced composites have less energy loss than the glass fiber-reinforced composites. All the composites have less energy loss than their corresponding matrices; the greater the fiber content, the lower the energy loss. The beta transition of 913 epoxy resin has been shifted to a higher temperature after being reinforced. It was shifted from −50°C to −30°C after being reinforced with glass fiber and made a diffuse shoulder-like peak commencing at −30°C after being reinforced with carbon fiber. The 924 epoxy resin has undergone the same change in beta transition as the 913 resin, though to a smaller extent. The phenomenon suggested that interactions between the macromolecules of the epoxy resins and the molecules along the fiber's surface.     

Viscoelastic properties and morphology of dicyanate ester/epoxy co-polymers modified with polysiloxane and butadiene–acrylonitrile rubbers

Dynamic mechanical analysis was conducted on specimens prepared from cyanate ester (CE) and epoxy (EP) resins cured together at various mass compositions. Increase of amount of epoxy resin in composition was shown to have a disadvantageous effect on glass transition temperature (T _g). It was shown that post-curing procedure was needed to produce a polymer matrix with a single glass transition relaxation, but increase in post-cure temperature up to 250 °C resulted in slight reduction in T _g for epoxy/cyanate copolymers. TG results proved that the presence of epoxy resin reduces thermal stability of the cyanate/epoxy materials. The neat CE and EP/CE systems containing 30 wt% of epoxy resin were modified using epoxy-terminated butadiene–acrylonitrile rubber (ETBN) and polysiloxane core–shell elastomer (PS). The scanning electron microscopy (SEM) results showed the existence of second phase of ETBN and PS modifiers. Only in the case of EP/CE composition modified with ETBN, well-dispersed second phase domains were observed. Analysis of SEM images for other CE- and EP/CE-modified systems revealed the formation of spherical aggregates.     

Pyrolysis and fire behaviour of epoxy resin composites based on a phosphorus-containing polyhedral oligomeric silsesquioxane (DOPO-POSS)

The pyrolysis and fire behaviour of epoxy resin (EP) composites based on a novel polyhedral oligomeric silsesquioxane containing 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO-POSS) and diglycidyl ether of bisphenol A (DGEBA) have been investigated. The pre-reaction between the hydroxyl groups of DOPO-POSS and the epoxy groups of DGEBA at 140 °C is confirmed by FTIR, which means that DOPO-POSS molecules of hydroxyl group could easily disperse into the epoxy resin at the molecular level. The EP composites with the DOPO-POSS were prepared through a curing agent, m-phenylenediamine (m-PDA). The morphologies of the EP composites observed by SEM indicate that DOPO-POSS disperses with nano-scale particles in the EP networks, which implies good compatibility between them. The thermal properties and pyrolysis of the EP composites were analyzed by DSC and TGA, TGA-FTIR, and TGA-MS. The analysis indicates that the DOPO-POSS change the decomposition pathways of the epoxy resin and increase its residue at high temperature; moreover, the release of phosphorous products in the gas phase and the existence of Si-O and P-O structures in the residue Is noted. The fire behaviour of the EP composites was evaluated by cone calorimeter (CONE). The CONE tests show that incorporation of DOPO-POSS into epoxy resin can significantly improve the flame retardancy of EP composites. SEM and XPS were used to explore micro-structures and chemical components of the char from CONE tests of the EP composites, they support the view that DOPO-POSS makes the char strong with the involvement of Si-O and P-O structures.     

Novel flame retardancy effects of DOPO-POSS on epoxy resins

A series of flame retarded epoxy resins (EP) was prepared with a novel polyhedral oligomeric silsesquioxane containing 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO-POSS). The flame retardancy of these EPs was tested by the LOI, UL-94, which indicates that DOPO-POSS has meaningful effects on the flame retardancy of EP composites. 2.5 wt.% DOPO-POSS incorporation into epoxy resin (EP-2.5), results in a LOI value 30.2 and UL-94 V-1 (t₁ = 8 s and t₂ = 3 s) rating. Moreover, self-extinguishing effect through the pyrolytic gases spurt is observed in UL-94 test for the EP-2.5. The pyrolytic gases and thermal stability of epoxy resins with and without DOPO-POSS were detected by TGA-FTIR under air atmosphere. Releases of gaseous species are found to be similar for the pure EP and EP-2.5. The details of fire behaviour, such as TTI, HRR, p-HRR, TSR, SEA, COPR, CO₂PR, and TML, were tested by cone calorimeter. It is notable that 2.5 wt.% DOPO-POSS could make COPR and CO₂PR reach a maximum, which could explain the blowing-out extinguishing effect.     

An experimental investigation of wear of glass fibre-epoxy resin and glass fibre-polyester resin composite materials

In this paper, the effects of resin content on the wear of woven roving glass fibre-epoxy resin and glass fibre-polyester resin composite materials have been examined. Furthermore, composite materials are experimentally investigated under different loads and speeds by using a block-on-shaft wear tester. The influences of two thermosetting resins epoxy and polyester on the wear of glass-woven roving reinforced composites under has been investigated dry conditions. The glass fibre-epoxy resin and the glass fibre-polyester resin composite materials specimens have been tested under different experiment conditions. Tests were conducted for 0.39 and 0.557 m/s speeds, at two different loads of 5 and 10 N. The weight losses were measured after measuring different sliding distances. Wear in the experiments was determined as weight loss. For each experiment, one specimen was used. The amount of wear was measured before the experiment and after the experiment with the apparatus of balance scales with the accuracy of 10⁻³ g. Glass fibre-epoxy resin composites generally showed higher strength and minimum wear when compared with glass fibre-polyester resin composites materials. In addition, Scanning electron microscopy (SEM) is used to study the worn surface to verify the results.     

A novel halogen‐free co‐curing agent with linear multi‐aromatic rigid structure as flame‐retardant modifier in epoxy resin

A novel halogen‐free 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO)‐containing co‐curing agent, 6,6′‐(1,4‐phenylenebis(((4‐(phenylamino)phenyl)amino)methylene))bis(dibenzo[c,e][1,2]oxaphosphinine 6‐oxide) (DPN) was synthesized via a simple 1‐pot or 2‐step procedure with yield of 86.2% and 70.8%, respectively. The molecular structures of 4,4′‐((1,4‐phenylenebis(methanylylidene))bis(azanylylidene))bis(N‐phenylaniline) (DPN intermediate) and DPN are characterized by FTIR, NMR, and MS. TGA tests show that the char yield of DPN/EP composites raises to 30.9% when the molar ratio of DPN to 4,4‐diaminodiphenyl methane(DDM) is 20:80. T_g values of DPN/EP composites tested by DSC and DMA are similar to neat epoxy resin (EP), which is due to the secondary amine in DPN that participates in the cross‐linking reaction of epoxy resin. The storage modulus in the rubber stage (E′‐190 °C) of flame‐retardant epoxy resin is close to that of neat EP, while their tanδ's are lower, which indicates the similarity of samples' cross‐linking density due to the participation of DPN in the cross‐linking reaction. The results show that when the molar ratio of DPN and DDM is 5:95, the epoxy has a higher T_g value and better mechanical properties than other samples. The introduction of DPN efficiently improves the flame‐retardant properties of epoxy resin with V‐0 rating of UL‐94 vertical burning test, non‐dripping, 41% of limit oxygen index (LOI) value, low peak heat release rate (PHRR), and total heat release (THR).     

Strong interfacial modified aramid fabric reinforced degradable thermosetting composites: reinforcing and tribological effects

In this work, dense molybdenum disulfide (MoS₂) nanosheets were grown onto polydopamine (PDA) functionalized aramid fabric (AF) surface via a simple hydrothermal method to improve the wettability between AF surface and polyhexahydrotriazine (PHT) resin, thus resulting in stronger AF/resin interfacial bonding. The PDA-assisted surface modification on AF generated a high active interface allowing the nucleation and subsequent growth of MoS₂. Moreover, this nanosheet-coated reinforcement fiber enabled the viscous liquid of resin precursor to spread over and form intimate contact with its surface, which eventually promoted the formation of strong interfacial bonding between AF-MoS₂ and cured resin matrix. In addition, the enhanced interfacial bonding between the reinforcement and matrix generated stable mechanical interlock within the resulting AF-MoS₂/PHT composites, and thus, contributed better thermal stability, higher tensile strength, and tribological properties. Compared with AF/PHT composites, the tensile strength and elongation at break of the AF-MoS₂/PHT composites increased by 32.5% and 50%, and the average friction coefficient and wear rate of AF-MoS₂/PHT composites decreased by 43.9% and 86.3%, respectively. Furthermore, the composites realized the non-destructive recovery of expensive AF at 25 °C. Overall, our study demonstrates a dependable strategy to construct the recyclable AF-MoS₂/PHT composites, which exhibit valuable applications in tribology.     

Influence of zinc stannate and graphene hybrids on reducing the toxic gases and fire hazards during epoxy resin combustion

Spinel zinc stannate (Zn₂SnO₄, ZS) was successfully synthesized by a simple hydrothermal route, and graphene(G) was used as the carrier to form graphene‐zinc stannate (G‐ZS) hybrids. The resulted G‐Zn₂SnO₄ (G‐ZS) was incorporated to epoxy resin for the purpose of reducing the toxicity hazards during combustion. Toxic gas analyzer results showed that the ZS hybrids possess high efficiency on reducing the generation of NOx, HCN, and CO. Cone calorimeter results of the G‐ZS/EP composites showed about 40% decrease on peak heat release rate compared with pristine EP which meant better fire performance. Also, TG‐IR technology was used to further investigate the gases release during the EP decomposition process. Particularly, the CO release had decreased about 80% than pure EP. This work constructs a new strategy to make a binary metal oxides system which would be efficient in reducing the toxic gases during polymer combustion. Besides, a proper bridge‐effect is proposed to illustrate the proper mechanism.