Modified Epoxy Resin Research Articles

Effect of Acrylic Resin on the Protection Performance of Epoxy Coating for Magnesium Alloy

The low toughness of epoxy resin can influence its shielding performance against a corrosive medium and strength of adhesion to metal surfaces. Extensive efforts have been made to modify epoxy resin. In this research, acrylic resin was synthesized by the solution method, and 1 wt.%, 2.5 wt.%, and 5 wt.% were added to epoxy resin (E44 brand) to prepare coatings on the surface of AZ31B magnesium alloy. The effects of acrylic resin on the mechanical and protective properties of epoxy coatings were investigated via experiments measuring impact resistance, flexibility, and adhesion as well as the electrochemical impedance technique. Compared with the pure epoxy coating, the adhesion between the coating and the substrate increases by 1.37 MPa after the addition of 2.5 wt.% acrylic resin. Meanwhile, the pencil hardness has a slight change from 5B to 6B, and the flexibility significantly improves. Therefore, the epoxy coating exhibits enhanced anticorrosive properties after the addition of 2.5 wt.% acrylic resin.

Research on the synergistic flame retardation of epoxy resin through surface-modified aluminum diethylphosphinate in conjunction with DOPO and CFA

Surface modification of aluminum diethylphosphinate (ADP) was successfully achieved through the utilization of silane coupling agent KH-560. Simultaneously, the modified aluminum diethylphosphinate (K-ADP) served as the primary flame retardant, with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) as the phosphorus-based flame retardant and charring‐forming agent (CFA) as the nitrogen-based synergistic flame retardant. This approach was employed to investigate the flame-retardant modification of epoxy resin. The optimal dosage of the surface modifier was investigated through moisture absorption test and viscosity measurements. Synergistic flame-retardant interactions among K-ADP, DOPO, and CFA were examined using techniques such as cone calorimetry test, thermogravimetric analysis, and residual char infrared analysis. The results indicated that the optimal dosage of KH-560 is 5%, resulting in a significant reduction in moisture absorption to 0.195%. At 80 °C, the addition of K-ADP leaded to only a 22.7% increase in system viscosity, demonstrating a notable viscosity reduction effect. When the addition of K-ADP is 14%, the Limiting Oxygen Index (LOI) value reached 30.5%, achieving a V-0 rating. Moreover, by maintaining the total addition at 14% and introducing DOPO and CFA, it is evident that most of samples meet UL-94 V-0 rating, with the LOI elevated to 32.2%. CCT results indicated a significant decrease in both average heat release rate and total smoke production, reduced by 24.1% and 7.0%, respectively. This notably enhanced the flame-retardant and smoke-suppressant properties of the EP composite material. The addition of K-ADP, DOPO, and CFA improved the mechanical performance of the EP composite material, surpassing the effectiveness of adding ADP individually.

Synthesis of a silicon‐containing cyclotriphosphazene derivative for flame‐retardant modification of epoxy resin

AbstractAlthough epoxy resin (EP) has been widely used in many fields, it is still urgent to effectively improve its flame retardancy by halogen‐free strategies. Herein, a silicon‐containing cyclotriphosphazene derivative (HEP‐Si) was synthesized by nucleophilic substitution and silicon–hydrogen addition reaction using eugenol, hexachlorophosphazene and triethylsilane as raw materials. Then it served as a halogen‐free flame retardant for an EP/4,4′‐diaminodiphenylmethane system, and its performance was compared with that of commercial flame retardant hexaphenoxycyclotriphosphazene (HPP). The results showed that although the initial thermal decomposition temperature (T5%) of the cured products of EP/HEP‐Si was slightly lower than that of pure EP, T5% did not decrease further as the amount of HEP‐Si increased, indicating that good thermal stability was maintained. In addition, the char yield of the cured products of EP/HEP‐Si was significantly increased (more than 20 wt%) compared to that of pure EP. The cured EP with the addition of HPP and HEP‐Si both achieved a V‐0 rating in UL‐94 vertical burning test at 0.5 wt% phosphorus content, while the limiting oxygen index of the EP/HEP‐Si system was higher, reaching 33.2%. From cone calorimetric test results, the peak heat release rate, total heat release and total smoke production of the cured products of EP/HEP‐Si decreased by 61.5%, 37.1% and 26.2%, respectively, compared with that of pure EP. The cured EP/HEP‐Si materials also exhibited good thermomechanical and mechanical properties. Therefore, HEP‐Si is suggested to be a promising P/N/Si‐containing halogen‐free flame retardant for EP. © 2024 Society of Industrial Chemistry.

Novel resveratrol-based hyperbranched epoxy resin suitable for comprehensive modification of epoxy resins

Hyperbranched epoxy resins are efficient modifiers for epoxy resins but still require simultaneous improvements in terms of thermomechanical/mechanical properties and thermal stability. Herein, a novel resveratrol-based hyperbranched polyether epoxy resin (HBPEER) was designed for all-purpose epoxy resin modification. To this end, hyperbranched polyether with terminal phenolic hydroxyl groups was first synthesized from commercially available 1,6-dibromohexane (A2-type monomer) and resveratrol (B'B2-type monomer). Surface modification with epichlorohydrin was afterward implemented to produce hyperbranched polyether with terminal epoxy groups (HBPEER). Next, various HBPEER-modified epoxy thermosets were prepared and characterized. The results suggested that compared to the neat diglycidyl ether of bisphenol A (DGEBA) thermoset, the 6 wt% HBPEER-modified epoxy thermoset showed an increase in impact strength, elongation at break, critical stress intensity factor (KIC), critical crack propagation energy release rate (GIC), flexural strength, tensile strength, storage modulus, glass transition temperature (Tg), and initial thermal decomposition temperature (Td5%) by 69.6 %, 87.0 %, 32.0 %, 68.2 %, 29.3 %, 37.0 %, 8.1 %, 3.5 %, and 1.6 % respectively. Moreover, the dielectric constant and loss of 6 wt% HBPEER-modified epoxy thermoset decreased by 16.2 % and 16.5 %, respectively. Such comprehensive performance modifications were caused by the combined effects of crosslink density improvement, efficient intramolecular cavity, rigid stilbene units, and flexible aliphatic backbone of HBPEER.

Alginic acid derivatives/DOPO modified epoxy resins: Excellent flame retardancy, mechanical properties, chemical resistance

An alginic acid derivative AA@MEL with flame retardant effect in both gas and condensed phases was synthesized by the neutralization reaction of alginic acid (AA) and melamine (MEL). Modified EP obtained the UL-94 V-0 rating and limiting oxygen index (LOI) of 33.8 % when the total addition of AA@MEL and 9,10-dihydro-9-oxa-10-phosphophenanthrene-10-oxide (DOPO) in the epoxy resin was only 4 wt% and the phosphorus content was only 0.29 %. Compared with pure EP, the total heat release (THR) and total smoke production (TSP) of flame-retardant EP were reduced by 42 % and 60 %, respectively, and the quality of the char residue was improved by forming higher graphitization layer. The flame retardancy mechanism was proposed through the pyrolysis products analyses and the characterization of the condensed phase. Meanwhile, the appropriate amount of AA@MEL/DOPO can enhance the tensile property, flexural property and impact strength of EP materials. It was closely related to the -COOH/-OH in AA@MEL and the P-H bond and rigid structure of DOPO. In addition, the modified EP has good chemical resistance, which ensures long-lasting flame retardant and mechanical properties. The AA@MEL/DOPO system exhibits low cost, low loading, high flame-retardant efficiency and environmental friendliness for industrial needs, which is promising for industrial applications.

Thermophysical and adhesive properties of functional polymer materials based on epoxy resin and silicon-containing component

The work was aimed at developing an adhesive formulation with increased adhesive strength for metals. It contains an epoxy resin of the bisphenol type СHS-TROXY 520 (an analogue of ED-20), an amine hardener triethanolamine (TEA) and a silicon-containing component (3-isocyanatopropyl)triethoxysilane, designated as NCO-Si, with an optimal ratio of components. The content of NCO-Si in the formulations was 0.5, 1.0, 3.0 and 5.0 wt. %, respectively. The gradual transformation of the epoxy system into a three-dimensional network with the formation of ester and urethane groups was shown by IR spectroscopy method. Tensile and shear strength were determined using the tearing machine R-50 in accordance with current standards. It was found that the maximum values of physical and mechanical parameters were obtained when the amount of NCO-Si was 3 wt. %. The maximum values of adhesion strength to steel substrates δst. = 58.5 MPa significantly exceed those for neat epoxy formulations. The shear strength values for steel plates τst. = 21 MPa increase by 60 %, for aluminium plates they are δAl =14.5 MPa and increase by 48 %. The morphology of the samples has been studied by means of optical microscopy. It is shown that the modified NCO-Si samples are characterised by a phase-separated structure. At a minimum amount of NCO-Si (0.5 wt. %), structurally disordered spherical domains with a size of ~1÷3 μm are observed, an increase in the content of the organosilicon component leads to the formation of interconnected regular structures, which are less pronounced at 1.0 wt. % of NCO-Si and clear at 3.0 and 5.0 wt. % of NCO-Si. Thermogravimetric analysis (TGA) was performed as well. It is shown that the modification of epoxy resin by a silicon-containing component with NCO-Si groups leads to an improvement in thermophysical parameters, a decrease in internal stresses and the formation of a material with a structure close to equilibrium.

Metal–Organic Frameworks-Derived FeCo/C–CNT Nanocomposites Modified Epoxy Resin for Electromagnetic Protection Coatings for Buildings

Exploring an efficient electromagnetic protection strategy for buildings is of great significance to solve the problems caused by increasing electromagnetic pollution, as the rapid progress of technology continues. In this work, FeCo alloy/carbon–carbon nanotube (FeCo/C–CNT) nanocomposites, with significant microwave absorption performance, were successfully synthesized using a simple pyrolysis method involving FeCo–ZIF MOFs precursors and added to epoxy resin to prepare a novel electromagnetic wave absorption (EWA) coating. The minimum reflection loss (RLmin) of the coating applied on the surface of the ceramic tiles was −23.89 dB at 11.37 GHz and the effective absorption bandwidth (EAB) reached 8.85 GHz. Through microscopic characterization and analysis of the electromagnetic parameters of the FeCo/C–CNT nanocomposites, it was found that the EWA coating has an ultrabroad band wave absorption effect, mainly due to the comprehensive advantages of the polarization loss from CNTs, impedance matching, the dual loss synergy effect, and multiple reflection between the FeCo alloys, the carbon layer, and the CNTs. This study has successfully developed high-performance EWA materials and demonstrated the feasibility of an EWA coating applied to building surfaces, contributing to the improvement of electromagnetic protection functions of buildings.

Enhanced Electric Photoconductivity of Modified Epoxy Resin

The basic idea of this study is based on the hypothesis that it is possible to obtain nanostructures by stimulating local chemical reactions. Starting with this hypothesis we assumed that it is possible to disperse some inorganic agent into the epoxy resin and stimulating the mixtures we could get some nano-structures what are changing the basic electric behaviour of the polymer matrix. We dissolved some metallic chlorides in DMF (dimethylformamide) and we mixed together the solution with the epoxy resin (the main component). Applying various external stimuli we get materials showing various properties, different from the epoxy resin properties. The electric photoconductivity is increased (in some cases) but the mechanical properties are damaged due the solvent presence into the polymer matrix.

Study of the effect of combined reinforcement and modification of epoxy resin with rubbers on the impact strength of carbon fiber-reinforced plastic

Study of the effect of combined reinforcement and modification of epoxy resin with rubbers on the impact strength of carbon fiber-reinforced plastic

Influence of the Second-Phase Resin Structure on the Interfacial Shear Strength of Carbon Fiber/Epoxy Resin.

The toughening modification of epoxy resin has received widespread attention. The addition of the second-phase resin has a good toughening effect on epoxy resin. In order to investigate the effect of the second-phase resin on the interphase of composites, in this work the interfacial properties of carbon fiber (CF)/epoxy resin with the second-phase resin structure were investigated. Methodologies including surface structure observation, chemical characteristics, surface energy of the CF, and micro-phase structure characterization of resin were tested, followed by the micro-interfacial performance of CF/epoxy composites before and after hygrothermal treatment. The results revealed that the sizing process has the positive effect of increasing the interfacial bonding properties of CF/epoxy. From the interfacial shear strength (IFSS) test, the introduction of the second phase in the resin reduced the interfacial bonding performance between the CF and epoxy. After the hygrothermal treatment, water molecules diffused along the interfacial paths between the two resins, which in turn created defects and consequently brought about a reduction in the IFSS.

Development of high performance microwave absorption modified epoxy coatings based on nano-ferrites

With the rapid spread of wireless technologies and increasing electromagnetic energy, electromagnetic waves (EMW) have become a severe threat to human health. Therefore, minimizing the harmful effects of electromagnetic wave radiation is possible through the development of high-efficiency EMW absorption coatings. The aim of this work was to generate microwave absorbance coatings containing synthesized nano-CuFe2O4 and nano-CaFe2O4. Firstly, nano-CuFe2O4 and nano-CaFe2O4 were synthesized using the sol–gel method. Then, their structure, electrical, dielectric, and magnetic properties were investigated to find out the possibility of using these materials in high-frequency applications (e.g., microwave absorbance coatings). After that, two dosages (2.5 wt% and 5 wt%) of nano-CuFe2O4 and nano-CaFe2O4 were incorporated into epoxy resin to prepare modified epoxy resin as microwave coatings. The dielectric studies show that the AC conductivity of the prepared samples is high at high frequencies. Additionally, the magnetic properties reveal a low coercivity value, making these samples suitable for high-frequency devices. The microwave results illustrate that adding nano-ferrites with high content enhances the absorption characteristics of the tested films. The results showed that the two films have two absorption bands with RL < –10 dB ranging from 10.61 to 10.97 GHz and from 10.25 to 11.2 GHz. The minimum return loss achieved for the two cases is −13 and −16 dB, respectively. Indicating that the film coated with CuFe has a better absorption value than the one coated with CaFe.

A novel fiber-reinforced polymer rope: Concept design and experimental evaluation

The present study proposes using a twisted rope with flexible fiber-reinforced polymers (FRPs) instead of wire rope and synthetic rope in environments requiring high load-bearing capacity and corrosion resistance. Resin toughening modification was conducted to manufacture flexible FRPs, and experimental evaluations were performed to assess the tensile and flexural properties of the impregnated fiber bundles (IFBs), as well as the tensile behaviors of the seven-IFB strands and the seven-strand ropes. The results demonstrated that the modified epoxy resin exhibited a decrease in both strength and elastic modulus, while its ductility was enhanced. Tensile and bending experiments confirmed that incorporating an additional 10% of Qishi toughener (QS-VA-3) was the optimal choice for producing low-modulus and high-toughness resins. Although the tensile properties of resin modified IFBs may show a slight reduction, their repeated bending behavior can be significantly improved. The tensile load-displacement curves of the FRP strand and rope displayed a linear increasing trend and experienced intermediate fracture failure, resembling that observed in IFBs. Furthermore, it was found that the tensile strength and elastic modulus of the strand decreased with an increase in lay length. The secondary twisting can enhance the tensile behavior of ropes compared to strands with equivalent lay lengths.

Study on thermal conductivity of micron BN-nano SiO2 combined modified epoxy resin composites

Epoxy resin has attracted widespread attention in the field of power electronic packaging due to its favorable processing technology, high adhesion, and excellent dielectric properties. The enhancement of thermal conductivity in epoxy resin through the incorporation of diverse particles is a prominent area of interest in the realm of modified insulation materials. In this study, hexagonal boron nitride (h-BN) and silicon dioxide (SiO2) with good thermal conductivity were used as doped fillers to modify epoxy resin (EP). The analysis of experimental results indicated that the thermal conductivity of materials with a total doping amount of 20 wt% and a mass ratio of BN to SiO2 of 70:30 to 60:40 could increase the thermal conductivity by 118.1~126.0%. In contrast to pure EP, the thermal conductivity of composite epoxy resin materials has been significantly enhanced.

Rigid and crosslinkable polyimide curing epoxy resin with enhanced comprehensive performances

The flammability and hydrophilicity of epoxy resins hinder their applications in the high-tech fields of aerospace and electronics. To break these limitations, a highly rigid and hydrophobic polyimide structure has been designed as the harder for epoxy resins. This diamine monomer polyimide (PI–OH) featured a new spiral fluorene-xanthene core doubly grafted phenolic hydroxyl units, to match the commercial bi-trifluoromethyl dianhydride monomer. The curing performance of the polyimide PI-OH was studied in a concentration gradient fashion with the epoxy resin N, N, N′, N′-tetraglycidyl-4, 4′-diaminodiphenylmethane (TGDDM), and compared to the benchmark curer 4, 4′-diaminodiphenyl sulfone (DDS). Due to the unique structural rigidity of spiral crosslinks and the compatibility of the polyimide, the cured PI-OH/TGDDM exhibited Young's modulus of 6.18 GPa and a hardness of 480 MPa, 27.7% and 42.3% higher than that of DDS/TGDDM, demonstrating excellent comprehensive performance. The introduction of PI-OH also reduced the curing temperature with higher curing activity. Resin with 40% loading of the polyimide reached a residual carbon rate of 49.0% at 700 °C (under nitrogen), presenting flame retardancy superior to DDS/TGDDM. Furthermore, the involvement of trifluoromethyl groups reduced the surface free energy and hydrophilicity, lowering the water absorption rate for the modified epoxy resin. This study opens an avenue for comprehensively improving the performance of epoxy resins at lower curing temperatures, which has broad application prospects in aerospace and motor vehicle fields.

The effects of temperature on mechanical properties of neat and montmorillonite reinforced epoxy compounds

ABSTRACT The aim of the article was to determine the effect of temperature on the tensile strength of two types of the epoxy compounds: the neat and the montmorillonite reinforced epoxy compounds. These epoxy compounds were made in four variants, which included two epoxy resins based on bisphenol A (unmodified base epoxy resin and modified with polyester resin epoxy resin) as well as two curing agents: triethylenetetramine and polyamide curing agent. The samples were exposed in two types of environment: (i) at 80°C for 1 and 2 months in a thermal chamber and also (ii) in the temperature range from −40°C to 80°C for 1 and 2 months in a thermal shock chamber. The reference samples of epoxy compounds were also compared. After the aging time, the dog-bone samples of epoxy compounds were subjected to the tensile strength tests in accordance with PN-EN ISO 527–2. The compressive strength of reference samples is higher for epoxy compounds containing the triethylenetetramine curing agent (both for epoxy compounds comprising Epidian 5 and Epidian 57 epoxy resin), The values of tensile strength, elongation at break are affected by the ambient and curing temperature, the curing period and the presence of a filler (montmorillonite). The tensile strength of the reference epoxy compounds containing Epidian 5 epoxy resin and the triethylenetetramine curing agent is lower than that of epoxy compounds containing unmodified epoxy resin (Epidian 5) and the polyaminoamide curing agent, while the tensile strength of the epoxy compounds containing modified epoxy resin (Epidian 57) and the triethylenetetramine curing agent is higher than that of the epoxy compounds containing Epidian 57 epoxy resin and the polyaminoamide curing agent. Aging of the epoxy compounds both in the climatic chamber and in the thermal shock chamber in most cases it contributed to an increase in the tensile strength.

Preparation and physical properties of CeO2 doped and modified epoxy resin composites

AbstractEpoxy resin is a widely used polymer material, while its low mechanical properties and thermal stability limit its use in extreme environments such as high temperature and high pressure. In order to improve the performance of EP, this study assessed the enhancement of mechanical properties and thermal stability of EP by stearic acid‐modified n‐CeO2 and its mechanism. Laser particle size analyzers, transmission electron microscopes, and other instruments were used to characterize n‐CeO2. Universal testing machines, thermogravimetric analyzers, and other instruments were used to test n‐CeO2/EP nanocomposites. The results show that fatty acids effectively coated the surface of n‐CeO2, reducing its central particle size from 0.248 μm to 0.193 μm and improving its dispersion and compatibility. The tensile, flexural, impact strength, maximum decomposition temperature, and glass transition temperature (Tg) increased by 382%, 554%, 698%, 5%, and 10%, respectively with 2 wt% filler content. The scanning electron microscopy (SEM) images showed that the addition of n‐CeO2 induced plastic deformation and crack formation in the EP matrix, which enhanced the toughness of the composite material. This study provided the effective methods and basis for the preparation of high‐performance n‐CeO2/EP nanocomposites.Highlights Nano cerium dioxide was modified to improve its dispersion by using stearic acid. High‐performance nanocomposites were prepared by using modified nanoparticles. The stiffness and toughness of the epoxy resin were enhanced by adding n‐CeO2. Thermal stability and heat resistance of the epoxy resin were improved by doping n‐CeO2. SEM images of the impact section showed that n‐CeO2 can prevent crack propagation.

Compatibility evaluation between waterborne epoxy resin and SBR latex modified asphalt emulsion

Good compatibility between waterborne epoxy resin (WER) modifier and styrene-butadiene rubber (SBR) latex modified asphalt emulsion (SBRE) is an essential premise for good pavement performance of WER and SBR latex compositely modified asphalt emulsion (WSAE). This study aims to explore the compatibility between WER modifier and SBRE. To achieve the goal, several WER modifiers produced by two methods were first selected to modify SBRE, thus the WSAEs were prepared. Next, storage stability and workability of the WSAEs themselves, and high-temperature performance, rheological behavior and temperature sensitivity of their evaporated residues were compared and evaluated via performing a series of experiments, respectively, thus the WER modifier possessing an optimal modification effect was recommended. Results show that the storage stability of WSAEs is sensitive to the amount of WERs. The incorporation of 1% WERs by the mass of SBRE improves the storage stability of SBRE, while WERs that exceed 1% weaken its storage stability. When the WERs reach 3% and 4%, the 5 d storage stability of prepared WSAEs will be beyond the limitation of specification. Incorporating WERs into SBRE negatively affects the workability of SBRE, and the workability of WSAEs is adversely influenced by the WERs content and the storage time. To ensure the construction, the WSAEs with 3% and 4% WERs should not be stored for more than 36 h and 48 h, respectively. The WERs effectively improve the high-temperature performance of SBRE residue, especially the 3% WERs. Besides, the WERs notably enhance the rheological property and thermal stability of SBRE residue. In contrast, the WER modifier produced by chemically modified method has a smaller adverse impact on the storage stability and workability of WSAE, and a larger enhancement on the high-temperature performance, rheological property and thermal stability of SBRE residue, which is thus recommended to modify SBRE.

Synthesis of a novel dimethylglyoxime-bridged phosphinate and its application in flame-retardant epoxy resins

Considering the need for flame retardancy in epoxy resin (EP), a novel dimethylglyoxime-bridged phosphinate (DMG-DC) has been suggested and applied for the purpose of flame-retardant modification of epoxy resin. As a result of the substitution reaction between dimethylglyoxime (DMG) and diphenylphosphoryl chloride (DPPC), DMG-DC was successfully characterized chemically. The research has demonstrated a notable enhancement in the flame-retardant characteristics of EP/DMG-DC. Especially, with the addition of 15 wt.% DMG-DC, the EP composite passed the UL-94 test with a V-0 rating and achieved a limiting oxygen index (LOI) value of 28.4 %. In addition, cone calorimetry test (CCT) results showed that the peak heat release rate (PHRR), total heat release rate (THR), and carbon dioxide production (CO2P) of EP/DMG-DC-15 were reduced by 54.1 %, 35.2 %, and 64.4 %, respectively, compared to EP. Not merely, the activities of DMG-DC in the gas and condensed phases also enhanced the flame retardancy of EP. That was the decomposition of DMG-DC not only released phosphorus-containing radicals to trap reactive radicals and nitrogen-containing inert gases to dilute flammable materials but also promoted the epoxy matrix to form more char residues. Generally, this work develops a novel dimethylglyoxime-bridged phosphinate with the potential in the application of flame-retardant polymers.

POSS-polyurethane prepolymer strengthened and toughened CF/epoxy resin composites for room and simulated Arctic ambient temperature

As an important material candidate for automotive, aviation, and aerospace, the wide application of carbon fiber-reinforced epoxy resin composites (CFRPs) was important. However, restricted by the low toughness. Herein, octaaminopropyl cage polysilsesquioxane-polyurethane prepolymer (POSS-PU) was synthesized by in-situ polymerization of PU on the POSS, and then employed as the modifier for epoxy resin (EP). Compared to pristine EP, the toughness of the 7.5 wt% POSS0.5-PU/EP was increased by 115.3 % without compromising the tensile strength and Tg. The unnotched impact strength, interlaminar shear strength (ILSS), and flexural strength of the CFRPs prepared from the modified EP were increased by 73.5 %, 7.5 %, and 42.4 %, compared to CF/EP. Additionally, the mechanical properties of CFRPs maintained a substantial improvement under low-temperature, and the CF/7.5 wt% POSS0.5-PU/EP was increased by 72.9 % (impact strength) and 21.7 % (ILSS), compared to those of CF/EP. Compared to the improvement in the toughness of CFRPs at room temperature, the retention rate of toughness enhancement at low temperature was approximately 100 %. CFRPs prepared by POSSx-PU/EP offered outstanding mechanical properties and hence showed great potential for future industrial applications.

Insight into the mechanical properties and thermal expansion behavior of epoxy nanocomposites reinforced with multi‐walled carbon nanotube solvent‐free nanofluids

AbstractEpoxy resin (EP) is a promising material that exhibits great potential in the fields of packaging and adhesion. However, reducing its brittleness and coefficient of thermal expansion (CTE) at low filler content is still a challenge. To address this problem, three types of MWCNTs nanofluids (MWCNTs NFs) with different shell structures were designed to modify epoxy resin. With the addition of 1 wt% MWCNTs‐M1, the compression, impact, and lap shear strength of the composites increased to 88.97 MPa, 81.39 kJ/m2, 12.69 MPa, respectively, which are 21.7%, 66.1%, and 58.0% higher than pure epoxy. Meanwhile, incorporating MWCNTs NFs also improved the CTE and thermal conductivity, with a 19.7% decrease in CTE and a 40% improvement in thermal conductivity at 2 wt% NFs content. Particularly, the effect of MWCNTs NFs structure on the composite properties was explored, which can be an available reference for designing specific NFs epoxy composites.Highlights Three types of MWCNTs nanofluids with different structures were designed. The MWCNTs NFs were used in packaging materials for the first time. The impact performance of composite has been improved by 66%. The CTE of composite is 19.7% lower than pure EP. The thermal conductivity of the composite increased by 40%.