Thermal Stability Of Epoxy Resin Research Articles

Wear and thermal resistance properties of aluminium particulate microcomposites

Wear resistance and thermal stability are not fundamental properties of materials, but their effects are inevitable in applications involving two-body contact because of friction-induced wear and heat. Wear resistance and thermal stability of epoxy containing 10% by weight of 66.34 μm aluminium particles were examined using mass loss per sliding distance approach and glass transition temperature (Tg) was used as a parameter for thermal stability. The results obtained revealed a reduction in the wear rate due to addition of aluminium particles. About 62, 58 and 39% reductions at 9 N/0.65 m s−1; 9 N/1.3 m s−1 and 25 N/1.3 m s−1, respectively imply that both sliding speed (v) and the applied load (F) contribute to an increase in the wear rate. A lower coefficient of friction of epoxy aluminium composites signifies lower surface wear rate in comparison with that of the epoxy polymer upon contact with another body in applications. The linear model establishes that v with a P value of 0.0046 has a greater significant influence on the wear resistance of the composite than F with a higher P value (0.0103). By the model, the epoxy aluminium composite under 24.63 N is expected to experience a wear rate of 0.000537 g m−1 which is 1380% lower than that established by the results of the experiment. About 36% increase in Tg is observed and 2FI model affirms that there is a gradual increase in Tg with heat flow through the sample during the glass transition period. Hence, the 2FI model having adequate precision of 164 > 4 is appropriate to be used for navigating a design phase for thermal stability properties.

Flame-retardant behaviors of aluminum phosphates coated sepiolite in epoxy resin

Aluminum phosphates coated sepiolite nanocomposite was fabricated via a simple one-pot heterogeneous precipitation strategy, and the effects of aluminum phosphates on the morphology of aluminum phosphates coated sepiolite were investigated. Moreover, the effect of aluminum phosphates coated sepiolite on the flame-retardant behavior, mechanical properties, and thermal stability of epoxy resin have been discussed. The results indicated that the introduction of only 20 wt% aluminum phosphates coated sepiolite in epoxy resin increased the limited oxygen index from 21.8% to 30.1%, thus the material met the UL-94 V-0 rating. Thermogravimetric analyses revealed that char yield increased in the presence of aluminum phosphates coated sepiolite form thermally stable carbonaceous char. Aluminum phosphates–coated sepiolite could improve the mechanical performance, thermal stability of epoxy resin.

Synergistic toughen epoxy resin by incorporation of polyetherimide and amino groups grafted MWCNTs

In this work, low content of polyetherimide (PEI) and amino groups grafted MWCNTs (NH2-MWCNTs) were simultaneously employed in order to toughen epoxy resin without scarifying the thermal properties. The grafted NH2 groups on the surface of MWCNTs leads to outstanding dispersibility. The influence of PEI and NH2-MWCNTs on the epoxy resin including the curing behaviors, mechanical properties, phase structures, and thermal properties were investigated systematically. The NH2-MWCNTs/PEI/Epoxy ternary composites with 5 phr (parts per hundred of resin) PEI and 0.4 phr NH2-MWCNTs shows the maximum value of 73.1%improvement of the fracture toughness in term of KIC compared to that of neat epoxy. A prefer dispersion of NH2-MWCNTs with PEI microspheres was unambiguously detected from the detailed SEM phase structures, which is most likely associated with the dramatic improvement of the toughness. Thus, an interestingly synergistic toughening effect were obtained through coupling matrix crack bridging, deflection or plastic deformation of PEI microspheres and crack bridging or pulling out of carbon nanotubes. The glass transition temperature of ternary composite material with low content of PEI and NH2-MWCNTs was significantly increased, and the decomposition initial temperature of the ternary composite material did not sacrifice the thermal stability of the epoxy resin. In addition, the thermal stability of epoxy resin was also slightly improved by incorporation of low content of PEI and NH2-MWCNTs.

Thermal Stability of Epoxy Resin Modified with Developed Flame Retardant System Based on Renewable Raw Materials

A novel flame retardant system, embraced shell (S) and histidine diphosphate (H) as intumescent flame retardant developed in the Department of Chemical, Biological and Aerosol Hazards laboratory, was added to the epoxy resin and examined. The influence of flame retardant system on the thermal stability was assessed based on thermogravimetric analysis (TGA). Moreover, the flame retardant components were characterized by grain size distribution. It was found that the incorporation of the developed flame retardant system caused the formation of thermal stable char, which may inhibit the burning process.

Super‐crosslinked ionic liquid‐intercalated montmorillonite/epoxy nanocomposites: Cure kinetics, viscoelastic behavior and thermal degradation mechanism

AbstractSuper‐crosslinked epoxy nanocomposites containing N‐octadecyl‐N′‐octadecyl imidazolium iodide (IM)‐functionalized montmorillonite (MMT‐IM) nanoplatelets were developed and examined for cure kinetics, viscoelastic behavior and thermal degradation kinetics. The structure and morphology of MMT‐IM were characterized by FTIR, XRD, TEM, and TGA. Synthesized MMT‐IM revealed synergistic effects on the network formation, the glass transition temperature (Tg) and thermal stability of epoxy. Cure and viscoelastic behaviors of epoxy nanocomposites containing 0.1 wt% MMT and MMT‐IM were compared based on DSC and DMA, respectively. Activation energy profile as a function of the extent of cure was obtained. DMA results indicated a strong interface between imidazole groups of MMT‐IM and epoxy, which caused a significant improvement in storage modulus and the Tg of epoxy. Network degradation kinetics of epoxy containing 0.5, 2.0, and 5.0 wt% MMT and MMT‐IM were compared by using Friedman, Kissinger‐Akahira‐Sunose (KAS), Flynn‐Wall‐Ozawa (FWO) and the modified Coats‐Redfern methods. Although addition of MMT to epoxy was detrimental to the Tg value, as featured by a fall from 94.1°C to 89.7°C detected by DMA method, and from 103.3°C to 97.9°C by DSC method, respectively. By contrast, meaningful increase in such values were observed in the same order from 94.1°C to 94.7°C and from 103.3°C to 104.7°C for super‐crosslinked epoxy/MMT‐IM systems.

Investigation on dual functional epoxy resins containing photosensitive group in the main chain for photoresist applications

Dual functional photosensitive epoxy resins were synthesized by solution polycondensation of 1,3-bis(4-hydroxyphenyl)propenone (BHPP) and 3-(4-hydroxy-3-methoxyphenyl)-1-(4-hydroxyphenyl)propenone (HMPHPP) with epichlorohydrin. The characterization of synthesized epoxy resins comprised Fourier transform infrared (FTIR) spectroscopy, 1H-NMR, and 13C-NMR spectroscopic techniques. The thermal properties of the epoxy resins were studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) under a nitrogen atmosphere and found that the synthesized resins were stable up to 300 °C. The effect of curing agents diaminodiphenylsulfone (DDS) and diaminodiphenylmethane (DDM) on the thermal stability of epoxy resin was compared and found that DDS cured epoxy resin has higher thermal than DDM. The photocrosslinking properties of the epoxy resins were studied with UV-Visible spectroscopy, and we observed that the olefinic double bond undergoes 2π-2π cycloaddition and leads to cyclobutane ring. Also, the effect of solvents on the photocrosslinking of the epoxy resin was also studied. Solvents with higher polarity favored the 2π-2π cycloaddition. The dual functionality of the resins was confirmed by FTIR study. The storage stability of the synthesized epoxy resins remained over more than 60 days. The synthesized epoxy resins successfully applied as negative photoresists.

Synthesis of a Novel Phosphorus-Containing Curing Agent and Its Effects on the Flame Retardancy, and Thermal Stability of Epoxy Resins

A novel curing agent containing phosphorus and carboxyl group compound diphenyl(2,3-dicarboxylpropyl)phosphine oxide (DPDCPPO) was synthesized and used as a curing and flame retarding agent for epoxy resins (EP). Its chemical structure was well characterized by Fourier transform infrared (FTIR) spectroscopy, 1H, 13C and 31P NMR. The DPDCPPO was mixed with phthalic anhydride (PA) by different weight ratios into epoxy resins to prepare flame retardant EP thermosets. The flame retardant properties, combusting performances, and thermal degradation behaviors of the EP thermosets were investigated by limiting oxygen index (LOI), vertical burning tests (UL-94), cone calorimeter measurement, and thermogravimetric analysis (TGA) tests. The surface morphologies and chemical compositions of the char residues for EP thermosets were investigated by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. The water resistant properties were evaluated by placing the samples into distilled water at 70°C for 168 h. The results revealed that the flame retardant EP thermosets passed V-0 flammability rating and the LOI value reached 33.2% when the weight ratio of DPDCPPO and PA was 20 : 80. The cone test results revealed that the combustion parameters of the flame retardant EP thermosets including heat release rate (HRR) and total heat release (THR) significantly decreased compared with pure EP thermosets. The TGA results indicated that the incorporation of DPDCPPO promoted the decomposition of epoxy resins matrix ahead of time compared with that of pure EP, and led to a higher char yield and thermal stability at high temperature. The morphological structures and analysis of the XPS of the char residues revealed that DPDCPPO benefited the formation of a sufficient, compact and homogeneous char layer, with rich flame retardant elements on the epoxy resin material surface during combustion. After completing the water resistance tests, the EP/20 wt % DPDCPPO/80 wt % PA thermosets retained excellent flame retardancy, and the moisture absorption of the EP thermosets decreased with the increase of DPDCPPO content in the thermosets, due to the existence of the P–C bonds and the rigid aromatic hydrophobic structure.

Effect of functionalized graphene oxide with phosphaphenanthrene and isocyanurate on flammability, mechanical properties, and thermal stability of epoxy composites

ABSTRACTMaleic anhydride, 9, 10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide, and 1, 3, 5‐triglycidyl isocyanurate functionalized graphene oxide (GO) was prepared in this paper. The resultant phosphorus‐nitrogen functionalized GO called GOMT was homogeneously dispersed and incorporated into diglycidyl ether of bisphenol A to prepare composites. The char residue of GOMT/EP composites increased and its LOI value increased to 28.1% with UL‐94 V‐1 rating. T g of composite containing 1 phr GOMT increases to 165.6 °C, and the storage modulus of the sample with 3 phr GOMT was increased by 19% compared with pure EP. Furthermore, the elastic modulus and flexural strength of epoxy composite with 5 phr GOMT were increased by 17.9 and 26.7% at room temperature, respectively. Besides, the incorporation of GOMT into EP significantly reduces the PHRR and THR of the matrix. Therefore, the as‐designed GOMT not just obviously enhances the flame retardancy with low loading but raises the mechanical behavior and thermal stability of epoxy resins. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48761.

Biomass Chitosan-Induced Fe3O4 Functionalized Halloysite Nanotube Composites: Preparation, Characterization and Flame-Retardant Performance

An inorganic–organic nanohybrid flame retardant, HNT@CS@Fe3O4, is prepared by Halloysite nanotubes (HNT) as nanotemplate, chitosan (CS) as char-forming agent and ferroferric oxide (Fe3O[Formula: see text] playing in a catalytic role, aiming to endow enhanced flame-retardant performance of its nanohybrid. Results show that HNT@CS@Fe3O4 nanohybrids have a corn-like structure and can significantly improve the flame retardancy and thermal stability of epoxy resin (EP). Especially, the initial thermal degradation temperature of EP/HNT@CS@Fe3O4 is significantly improved by [Formula: see text]C relative to pure EP, and the residual carbon yield under air atmosphere is 8.8[Formula: see text]wt.%, which is significantly higher than other EP composites, indicating a higher thermal stability is offered by the as-prepared nanohybrid. The limiting oxygen index of EP/10HNT@CS@Fe3O4 is 31.3%, which is 10.2% higher than that of pure EP. Meanwhile, the HNT@CS@Fe3O4 nanofiller reduces the peak heat release rate, CO production and peak smoke production release of EP nanocomposite by 32.0%, 44.0% and 33.0% in a cone calorimeter test, respectively. This is because the HNT-based composite can form a three-dimensional network structure into the EP matrix to inhibit heat release and diffusion of flammable moieties upon burning of EP. In the meantime, the incorporated Fe3O4 nanoparticle can in situ catalyze the charring of CS and EP matrix on the surface of HNT during the combustion process, which also contributes to the significantly increased fire safety of EP.

High mechanical and thermal performance of Sasobit-modified epoxy resin, prepared via vacuum shock technique

In this study, thermal and mechanical properties of novel nanocomposite, epoxy resin reinforced with octadecylamine functionalized graphene oxide (GO-ODA) and Sasobit, prepared via creative vacuum shock technique, were investigated. By introducing 1, 3 and 5 wt% Sasobit to the neat epoxy resin, the tensile strength increased remarkably by 104%, 315% and 266%, respectively due to the unique stiff and crystalline structure of Sasobit. In addition, considerable enhancement of 125% in Young's modulus, 351% in toughness, 562% in impact resistance, ~19 °C in thermal stability and ~7 °C in glass transition temperature of epoxy resin with 3 wt% Sasobit loading was demonstrated. The composite containing 3 wt% Sasobit alone, were found to have even superior properties than GO-ODA/epoxy nanocomposite, as surprisingly 3, 2.9, 2.2 and 2 times more improvement, respectively in tensile strength, toughness, impact strength and thermal stability of epoxy resin compared to reinforcement with GO-ODA were obtained.

Optimization of thermo-mechanical and antibacterial properties of epoxy/polyethylene glycol/MWCNTs nano-composites using response surface methodology and investigation thermal cycling fatigue

Abstract This work aimed to develop mechanical/thermal properties of polymer-based nanocomposite in aerospace applications. Hence, herein nanocomposites were prepared through the direct blending of epoxy (EP) with Polyethylene glycol (PEG) and multiwalled carbon nanotubes (MWCNTs) as filler. Weight fraction of fillers was optimized by central composite design (CCD) to get maximum tensile strength and elongation. Interestingly, cross-section scanning electron microscopy (cross-section SEM) and thermal gravimetric analysis (TGA) observations revealed that MWCNTs were well dispersed on polymer matrix and thermal stability of EP was strengthened. The optimized EP/PEG/MWCNTs nanocomposites were tested under 150 thermal cycles and results were shown elongation 24.83% and tensile strength 17.96% were decreased after 150 cycles. Also, cross-section SEM images clearly showed that the fractures have increased slightly. In addition, MWCNTs-Ag nanostructures were synthesized and EP/PEG/MWCNTs-Ag nanocomposites were prepared for investigation antibacterial activity. Energy dispersive spectroscopy (EDS) mapping images of MWCNTs-Ag were confirmed the homogeneous and efficient anchoring of silver on the MWCNTs. Results indicate that, Ag nanoparticles can be enhanced the antibacterial activity of EP/PEG/MWCNTs.

Synthesis of DOPO‐based pyrazine derivative and its effect on flame retardancy and thermal stability of epoxy resin

A novel DOPO‐based pyrazine derivative 6‐((2‐hydroxyphenyl)(pyrazin‐2‐ylamino)methyl)dibenzo[c,e][1,2]oxaphosphinine 6‐oxide (DHBAP) was triumphantly synthesized by a two‐step addition reaction using 2‐aminopyrazine, 2‐hydroxybenzaldehyde and 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) as reactants, and characterized by Fourier‐transform infrared (FTIR),31P nuclear magnetic resonance (NMR) and1H NMR. Afterwards, the addition type flame retardant (DHBAP) was utilized to modify epoxy resin (EP) by blending method. When the content of DHBAP in neat EP was 8 wt%, it reached to the V‐0 rating and the limited oxygen index (LOI) value up to 34.0%. Furthermore, according to the cone calorimeter (CC) test results, the heat release rate (HRR), total heat release (THR), smoke produce rate (SPR) and total smoke production (TSP) of EP/8% DHBAP decreased by 26.3%, 21.3%, 37.0% and 60.9% when compared with neat EP, respectively, indicating that DHBAP had good inhibition on heat and smoke releases. Eventually, the flame‐retardant mechanism of DHBAP was further explored by X‐ray photoelectron spectroscopy (XPS), Raman spectroscopy, and pyrolysis‐gas chromatography/mass spectrometry (Py‐GC/MS). The results showed that DHBAP had good flame‐retardant activity in the gasous‐condensed two phases.

Mechanical and Thermal Stability of Epoxy – TEOS Hybrids Materi-als using Sol-Gel Method

Sol-gel method is the simplest method and has to preparation of nano particles, nano fibers, and nano flaks. The preparation of hybrid epoxy thermosets enables their improvement in characteristics such as mechanical properties (bending,and hardness), thermal properties. The effect of water absorption on bending and hardness test for tetraethylorthosilicate (TEOS) and epoxy hybrid have been investigated. TEOS with (0%,2%,4%,6%and 8%) volume per-centage mixed with epoxy to prepared sheets of hybrid, these sheets cut as samples for ASTM water absorption, bending and hardness tests.
 The results show that, adding TEOS to epoxy will increase absorbance of water. bending test shows that there are increase in values of bending stress with increasing TEOS but after im-mersion in water all the values for bending stress will reduce. Hardnessvalues at least for the samples immersion in water from dry samples, occur the diffusion of molecules water in the polymer and hybrids leads to space molecular chains for each other and decrease the hard-ness values. Thermal stability of hybrids increase with increasing TE

Novel H2Pc/Epoxy nanocomposites: Electrochemical and mechanical property investigation as anti-corrosive coating

In this study, H2Pc/Epoxy nanocomposite coating was fabricated for anti-corrosion applications. The electrochemical, cross-cut adhesion, impact resistance, bend test, contact angle, scanning electron microscopy (SEM) and thermogravimetric analysis (TGA) analysis were employed to evaluate the performance of new nanocomposites. Corrosion monitoring was achieved in saline solution (3.0 wt.% NaCl). The improvement of the corrosion performance of the epoxy coating containing H2Pc particles by comparison with neat epoxy resin was confirmed by the high coating resistance. Degradation of H2Pc/Epoxy nanocomposite coating was observed after 14 days. It was found that H2Pc particles improved the cross-cut adhesion, impact resistance and thermal stability of epoxy resin.

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.

Effect of a novel P/N/S-containing reactive flame retardant on curing behavior, thermal and flame-retardant properties of epoxy resin

A novel P/N/S-containing flame retardant DHBAZ was synthesized with 9, 10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, p-hydroxybenzaldehyde and 2-aminothiazole, and used as a co-curing agent for epoxy resin (EP). With the aid of DHBAZ, EP/7.5% DHBAZ passed UL-94 V-0 rating, and owned a LOI value of 31.4%. Besides, DHBAZ also played a positive role in inhibiting the release of heat and the production of smoke. Through non-isothermal DSC tests it revealed that in the presence of DHBAZ, epoxy resin was cured at a lower temperature and showed lower curing-reaction activity energy. DMA analyses indicated that EP/7.5% DHBAZ showed an increased storage modulus, and it had a close glass transition temperature with EP. While, DHBAZ presented a decreased effect on the thermal stability of epoxy resin acquired from TG analyses. Finally, the flame-retardant mechanism studied by TG-FTIR and py-GC/MS deduced that DHBAZ worked in the gaseous phase by producing P, PO and incombustible gases.

Low-flammability epoxy resins with improved mechanical properties using a Lewis base based on phosphaphenanthrene and 2-aminothiazole

As is known to all, the reduced flammability of modified epoxy resin is always accompanied with damaged mechanical properties. Surprisingly, in this work, we synthesized a novel Lewis base, namely D–AZ sourced from 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 2-aminothiazole to modify epoxy resin, and found that it could not only impart excellent flame retardance to epoxy resin, but also improve the strength of epoxy resin simultaneously. For instance, epoxy resin with 5% loading of D–AZ possessed limited oxygen index as high as 34.7%, and it passed V-0 rating. By comparison with neat epoxy resin, tensile strength of epoxy resin with 10% loading of D–AZ increased by 20%, flexural strength by 38%, and izod unnotched impact strength by 92%. Besides, D–AZ also played an important role in inhibiting the heat release of epoxy resin during combustion, thanks to its gaseous phase and condensed-phase flame-retardant mechanism. Imperfectly, it exhibited that the addition of D–AZ caused some decrease in the thermal stability of epoxy resin, especially in the initial decomposition temperature. Nevertheless, epoxy resin with 10% loading of D–AZ still displayed glass transition at 157 °C, and there was not much difference in the storage and loss modulus of epoxy resins in the low temperature. Briefly, epoxy resins containing D–AZ possessed excellent flame retardance and outstanding mechanical properties with comparison to neat epoxy resin, showing high promise for application.

Combined effects of ammonium polyphosphate and talc on the fire and mechanical properties of epoxy/glass fabric composites

The combined effects of ammonium polyphosphate and talc on the fire and mechanical behaviour of epoxy/glass fabric composite systems and neat epoxy resin were investigated. Recorded data from cone calorimeter and UL-94 vertical burning experiments reveal that the incorporation of additives can enhance the flame retardancy of both epoxy resin and glass fabric reinforced composites. TGA results demonstrate that the introduction of additives improve the thermal stability of epoxy resin at high temperatures. Moreover, the addition of flame retardants to epoxy resin increases the tensile and flexural moduli. However, due to the incompatibility of the additives with epoxy, the strengths are compromised. Then again, the epoxy/glass fabric composites with flame retardant additives have improved the fire properties without significantly affecting the mechanical performance.

다중벽 탄소나노튜브와 마이크로미터 크기 실리카 입자로 강화된 에폭시 복합재료의 열 안정성에 관한 연구

다중벽 탄소나노튜브와 마이크로미터 크기 실리카 입자로 강화된 에폭시 복합재료의 열 안정성에 관한 연구

Effect of graphene oxide sheet size on the curing kinetics and thermal stability of epoxy resins

This work revealed the influences of graphene oxide (GO) sheet size on the curing kinetics and thermal stability of epoxy resins. A series of GO/epoxy nanocomposites were prepared by the incorporation of three different sized GO sheets, namely GO-1, GO-2 and GO-3, the average size of which was 10.79 μm, 1.72 μm and 0.70 μm, respectively. The morphologies of the nanocomposites were observed by field emission gun scanning electron microscope. The dispersion quality of each sized GO was comparable in the epoxy matrix. The curing kinetics was investigated by means of differential scanning calorimetry and analyzed based on kinetics model. Addition of a small amount of GO (0.1 wt%) exhibited strong catalytic effect on the curing reaction of epoxy resin. The activation energy was reduced by 18.9%, 28.8% and 14.6% with addition of GO-1, GO-2 and GO-3, respectively. GO-2 with medium size (1.72 μm) showed the most effective catalysis on the cure. The thermal stability of the cured resins was evaluated based on thermogravimetric analysis. GO/epoxy nanocomposites showed improved thermal stability in the range of 420 °C–500 °C, compared with the pure resin. A ∼ 4% more residue was obtained in each of the incorporated system. The variations of GO sheet size did not influence the enhancement effect on the thermal stability.