Showing papers on "Epoxy published in 2019"
385 citations
TL;DR: In this article, a few-layered Ti3C2Tx MXene was fabricated by ionic intercalation and sonication-assisted method, followed by thermal reduction at medium-low temperature.
Abstract: Few-layered Ti3C2Tx MXene was fabricated by ionic intercalation and sonication-assisted method, followed by thermal reduction at medium-low temperature. Then annealed Ti3C2Tx/epoxy electromagnetic interference (EMI) shielding nanocomposites were obtained by solution casting method. XRD, SEM, AFM and TEM indicated the successful preparation of few-layered Ti3C2Tx. FTIR, XPS and XRD showed that thermal reduction removed partial polar groups on the surface of Ti3C2Tx with no by-product. For a fixed Ti3C2Tx loading, compared with Ti3C2Tx/epoxy EMI shielding nanocomposites, the annealed Ti3C2Tx/epoxy EMI shielding nanocomposites exhibited relatively higher electrical conductivity and excellent EMI shielding effectiveness (SE). When the mass fraction of annealed Ti3C2Tx was 15 wt%, the annealed Ti3C2Tx/epoxy EMI shielding nanocomposites presented the optimal electrical conductivity of 105 S/m and EMI SE of 41 dB, 176% and 37% higher than that of 15 wt% Ti3C2Tx/epoxy EMI shielding nanocomposites. Furthermore, the 5 wt% annealed Ti3C2Tx/epoxy EMI shielding nanocomposites exhibited the optimal Young's modulus of 4.32 GPa and hardness of 0.29 GPa, respectively.
287 citations
TL;DR: In this paper, a Schiff base epoxy thermoset combining excellent recyclability and high performance was facilely prepared from a synthesized formyl group-containing vanillin-based monoepoxide and a diamine via in situ formation of the Schiff base structure and epoxy network.
266 citations
TL;DR: In this article, a simple and inexpensive approach to fabricating a robust super-hydrophobic coating by spraying a fluorine-free suspension composed of epoxy resin (EP), polydimethylsiloxane (PDMS), and modified SiO2 on various substrates was presented.
227 citations
TL;DR: In this paper, the Fe3O4/TAGA/epoxy nanocomposites presented the highest electromagnetic interference shielding effectiveness (EMI SE of 35 dB in the X-band).
214 citations
TL;DR: In this paper, a functionalized graphene oxide (GO) nanosheets with different contents was introduced into the carbon fiber (CF) interface by sizing process and the uniform distribution of GO sheets on CF surface and the enhancement of surface roughness were obtained.
Abstract: To improve the dispersion of graphene oxide (GO) nanosheets in sizing agent and to enhance the interfacial adhesion between GO and epoxy, GO nanosheets were chemically modified with cyanuric chloride (TCT) and diethylenetriamine (DETA). The functionalized GO (i.e. GO-TCT-DETA) with different contents was introduced into the carbon fiber (CF) interface by sizing process. The uniform distribution of GO sheets on CF surface and the enhancement of surface roughness were obtained. Moreover, significant enhancements (i.e., 104.2%, 100.2%, and 78.3%) of interfacial shear strength (IFSS), interlaminar shear strength (ILSS), and flexural properties were achieved in the composites with only 1.0 wt% GO-TCT-DETA sheets introduced in the fiber sizing. The GO-TCT-DETA in the interface region enhanced the stress being transferred effectively and the local stress concentrations being relieved. This study indicates that the utilization of functionalized GO is one of the alternative approaches for controlling the fiber-matrix interface and improving the mechanical properties of CF epoxy composites.
193 citations
TL;DR: In this paper, mechanical, thermal, and water uptake behavior of silane-treated sea-urchin spike filler and kenaf fibre mat-reinforced neem oil blended epoxy resin composite has been studied.
Abstract: In this research mechanical, thermal, and water uptake behaviour of silane-treated sea-urchin spike filler and kenaf fibre mat-reinforced neem oil blended epoxy resin composite has been studied. The principal aim of this research was fabrication of eco-friendly composite and explicit the importance of silane-treatment on reinforcement’s surface. Neem oil blended with epoxy resin to convert it as an eco-friendly one, whereas additions of kenaf fibre and sea urchin particles into neem-epoxy matrix made the composites tougher. Both filler and fibre was surface-treated by an amino silane (APTMS). The results revealed that, additions of surface-treated sea urchin particle and kenaf fibre increased the mechanical properties of composite. Similarly thermal results exposed that addition of sea urchin bio ceramic filler increased the thermal stability of neem-epoxy bio composite. SEM fractograph showed uniform dispersion of sea urchin filler and improved adhesion of kenaf fibre with epoxy matrix.
170 citations
TL;DR: In this paper, a new derivative aromatic heteroatom epoxy resin synthesized in a laboratory, namely, triglycidyl ether of triethoxy triazine (TGETET), was characterized by FT-IR spectroscopy.
161 citations
TL;DR: In this paper, the dimensional stability and dynamic mechanical properties of hybrid composites were analyzed by thermomechanical anlayzer (TMA) and DMA, respectively, and it was concluded that 50:50 weight ratio of bamboo and kenaf fibers is the optimum mixing ratio to enhance both dimensional and mechanical properties.
Abstract: The dimensional stability and dynamic mechanical properties on bamboo (non woven mat)/kenaf (woven mat) hybrid composites was carried out in this study. The hybridization effect of bamboo (B) and kenaf (K) fibers at different weight ratio were studied at B:K:70:30, and B:K:30:70 while maintaining total fiber loading of 40% by weight. The coefficient of thermal expansion (CTE) and dynamic mechanical properties of composites were analyzed by thermomechanical anlayzer (TMA), and dynamic mechanical analyzer (DMA), respectively. Positive hybridization effects were observed on B:K:50:50 hybrid composite with lowest CTE and highest dynamic mechanical properties among all composites. The dimensional stability were strongly influence by the fiber orientation where all composites shows prominent expansion in the transverse fibers direction but relatively low expansion in longitudinal fibers direction. Dynamic mechanical properties in term of complex modulus (E*), storage modulus (E′), loss modulus (E″), Tan delta and Cole-Cole plot were studied. DMA results reveal that B:K:50:50 hybrid composite possess the highest complex modulus due to the strong fiber/matrix interfacial bonding which supported by the coefficient of effectiveness and Cole-Cole plot. Hence, it is concluded that 50:50 weight ratio of bamboo and kenaf fibers is the optimum mixing ratio to enhance both dimensional and dynamic mechanical properties of hybrid composites, and it can be utilized for automotive or building materials applications which demand high dimensional stability and dynamic mechanical properties.
159 citations
TL;DR: In this article, composites were fabricated by functionalizing carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) using noncovalent functionalization to prevent agglomeration of nanofiller and produce direct C N bonds with the epoxy matrix.
Abstract: Low-dimension carbon nanomaterials, such as carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs), are effective mechanical reinforcements in polymer composites. Epoxy matrix composites were fabricated by functionalizing CNT and GNP nanofillers using melamine and nondestructive ball milling. This noncovalent functionalization prevents agglomeration of nanofiller and produces direct C N bonds with the epoxy matrix. Compared to pristine CNTs and GNPs/epoxy nanocomposites, melamine-functionalized CNT (M-CNT)/epoxy and melamine-functionalized GNP (M-GNP)/epoxy nanocomposites exhibited considerably higher tensile strengths and fracture toughness (single edge notch bending, SENB). At 2 wt%, both M-CNT/epoxy and M-GNP/epoxy nanocomposites exhibited enhanced Young's modulus values (M-CNT: 64% and M-GNP: 71%) and ultimate tensile strengths (M- CNT: 22% and M-GNP: 23%). Fracture toughness increased by 95% with the 2 wt% M-CNT/epoxy and by 124% with the 2 wt% M-GNP/epoxy nanocomposite. The reinforcing effects of the two-dimensional M-GNPs were greater than those of the one-dimensional M-CNTs due to differences in pull-out mechanisms and bridging effects. Crack propagation in the nanocomposites, as it relates to fracture toughness, was also investigated.
158 citations
TL;DR: In this article, a self-polymerized polydopamine (PDA) coating and subsequent amino GO grafting on the aramid fiber (AF) surface was attributed to the increase in its surface roughness and surface active groups.
TL;DR: Two diepoxides containing a two-benzene-ring-conjugated Schiff base when cured with an aromatic diamine result in high-performance thermosets combining excellent controlled degradability, stability and antibacterial properties as discussed by the authors.
Abstract: Two diepoxides containing a two-benzene-ring-conjugated Schiff base when cured with an aromatic diamine result in high-performance thermosets combining excellent controlled degradability, stability and antibacterial properties. Epoxy resins have been widely used in coatings, adhesives, composites, electronic packaging materials, etc., but they are arduous to recycle and have no antibacterial activity. In this paper, two-benzene-ring-conjugated Schiff base diepoxy monomers were synthesized and further cross-linked with 4,4-diaminodiphenylmethane. The chemical structures of the diepoxides as well as their thermosets were characterized in detail. The property investigation manifested that the thermosets possessed a far higher glass transition temperature of ∼206 °C, tensile strength of ∼122 MPa, and tensile modulus of ∼2646 MPa than a commonly used high-performance bisphenol A epoxy resin. Moreover, they possessed excellent acidity and temperature-controlled degradability, and superior stability in common solvents, thermal treatment and hygrothermal aging. Furthermore, they presented excellent coating properties (including hardness, adhesion, and solvent resistance) and antibacterial properties with a bactericidal capability of ∼91%.
TL;DR: In this article, a few-layered Ti3C2Tx MXene/C hybrid foam (MCF) was prepared by ionic intercalation and sonication-assisted method, and the MCF-5/epoxy EMI shielding nanocomposites were obtained via vacuum-assisted impregnation followed by curing process.
Abstract: Few-layered Ti3C2Tx MXene was prepared by ionic intercalation and sonication-assisted method. Porous three-dimensional (3D) Ti3C2Tx MXene/C hybrid foam (MCF) was fabricated by sol-gel followed by thermal reduction. The MCF/epoxy EMI shielding nanocomposites were obtained via vacuum-assisted impregnation followed by curing process. When the mass fraction of MCF was 4.25 wt% (MCF-5), the MCF-5/epoxy EMI shielding nanocomposites exhibited the optimal electrical conductivity of 184 S/m and the maximum EMI SE of 46 dB, 3.1 × 104 and 4.8 times higher than that of MCF-0/epoxy nanocomposites (without Ti3C2Tx MXene), respectively. Furthermore, the corresponding Young's modulus of 3.96 GPa and hardness of 0.31 GPa was increased by 13% and 11%, respectively. Conductive networks can realize the attenuation and dissipation of electromagnetic waves by multiple reflection & reabsorption, and absorption is main shielding mechanism. Unique 3D conductive networks of MCF would expand wider application of the Ti3C2Tx MXene/polymer-based nanocomposites in high-tech EMI shielding fields.
TL;DR: In this paper, the authors report the preparation of epoxy-based composites with enhanced dielectric properties and thermal conductivity, by employing intelligently designed core/shell Alumina/Polydopamine (indicated as AO*) and strawberry-like core-shell (AO*@Ag) particles as fillers.
Abstract: We report the preparation of epoxy-based composites with enhanced dielectric properties and thermal conductivity, by employing intelligently designed core/shell Alumina/Polydopamine (indicated as AO*) and strawberry-like core/shell structured Alumina/Polydopamine/Silver (indicated as AO*@Ag) particles as fillers. The introduction of the core-shell AO* and AO*@Ag particles into the epoxy matrix can distinctly enhance both the dielectric permittivity and dielectric breakdown strength of composites, as compared to that incorporating AO particles as fillers. For example, the dielectric breakdown strength of AO*@Ag/epoxy with 22.9 vol% filler loading is up to 65.5 kV/mm, representing an improvement of 24% compared with AO/epoxy composite at the same filler loading (52.8 kV/mm), while it has enhanced dielectric permittivity at room temperature at low frequency. Additionally, the strawberry-like core/shell particle-filled composites still take on a high thermal conductivity.
TL;DR: The flame-retardant mechanism was disclosed that DOP-ABZ produced phosphorus-containing acids so as to dehydrate and carbonize epoxy macromolecules leading to the formation of graphitized chars.
TL;DR: In this paper, a novel design of dielectric composites consisting of core-shell structured porous Ni@BaTiO3 scaffolds infiltrated with epoxy was developed, and it was demonstrated that the dielectrics of the composites could be as high as 6397@10 kHz, which is approximately 1777 times higher than pure epoxy matrix (er.
Abstract: Dielectric composites have drawn increasing attention owing to their wide applications in electrical systems. Herein, a novel design of dielectric composites consisting of core-shell structured porous Ni@BaTiO3 scaffolds infiltrated with epoxy was developed. It is demonstrated that the dielectric constants of the composites could be as high as 6397@10 kHz, which is approximately 1777 times higher than pure epoxy matrix (er ≈ 3.6@10 kHz). Meanwhile, the dielectric loss (tanδ ≈ 0.04@10 kHz) remains comparable to that of pure epoxy (tanδ ≈ 0.01@10 kHz). It is believed that the strong charge accumulation and interfacial polarizations on the huge interfaces, especially the Ni/BaTiO3 and Ni/epoxy interfaces, give arise to the substantially enhanced er. Besides, the sintered insulating BaTiO3 coating can block the transportation of charge carriers, resulting in the low loss. The ultrahigh dielectric constants and low loss make these composites promising candidates for microstrip antennas, field-effect transistors and dielectric capacitors.
TL;DR: In this article, a binary nanofiller strategy was used to obtain high tensile strength and high electrical conductivity in epoxy with trace nanopolystyrene grafted with epichlorohydrin (nano g-PS).
TL;DR: In this article, Epichlorohydrin (ECH) was successfully grafted onto the surface of GFs ( f-GFs), in favor of improving the mechanical properties of the f -GFs/epoxy laminated composites.
TL;DR: In this article, the authors have shown that fiber type was very effective on the mechanical properties of composites and that molded fiber production method had a very promising future for the development of natural fiber reinforced composites.
Abstract: The aim of this research is the production of epoxy resin composites reinforced by birch, palm, and eucalyptus fibers with resin transfer molding technique and molded fiber production technique combination. The tensile stress of birch, palm, and eucalyptus reinforced epoxy composites were determined as 29.53, 42.24, and 45.28 MPa, respectively. Bending stress of birch, palm and eucalyptus reinforced epoxy composites were found as 58.83, 68.58, and 79.92 MPa, respectively. The birch epoxy composite had 0.105 J impact energy while palm and eucalyptus epoxy composites were determined as 0.130 and 0.124 J, respectively. It is clearly observed that fiber type was very effective on the mechanical properties of composites. The results of studies showed that molded fiber production method had a very promising future for the development of natural fiber reinforced composites.
TL;DR: In this paper, a few-layer Ti3C2 nanosheets were successfully prepared by etching aluminum atoms layer of Ti3AlC2 precursor along with layering technique.
TL;DR: In this article, reduced graphene oxide with honeycomb structure (rGH) was successfully constructed and prepared by freeze-drying & thermal annealing using aluminium oxide (Al2O3) honeycomb as a template.
TL;DR: In this paper, the mechanical, hygral, and interfacial strength of continuous bamboo fiber reinforced epoxy composites were investigated, and the results showed that the tensile strength and Young's modulus of the composite increase with the decrease of the bamboo fiber diameter.
Abstract: This study is to investigate the mechanical, hygral, and interfacial strength of continuous bamboo fiber reinforced epoxy composites. The untreated and alkali-treated continuous bamboo fibers were prepared from cutting the nature bamboo culm. The basic characteristics of the bamboo fibers, such as density, equivalent diameter, and tensile properties were experimentally measured. The bamboo fiber reinforced epoxy (BF/EP) composites were fabricated by the resin transfer molding (RTM) process with the resulting fiber volume fraction about 42%. The strength of bamboo fiber was found to decrease with the alkaline treatment. However, alkali-treated bamboo fiber reinforced epoxy composites acquired better tensile strength than those with untreated bamboo fibers. The untreated bamboo fiber was believed to have weak interface with the epoxy resin, which was verified by the subsequent interface strength tests. The size effect of bamboo fibers on the tensile properties of the BF/EP composites were also studied. The results showed that the tensile strength and Young's modulus of the composite increase with the decrease of the bamboo fiber diameter. For the hygrothermal aging test, BF/EP composites are highly sensitive to moisture absorption, and the moisture has a detrimental effect on the mechanical properties of the BF/EP composite.
TL;DR: In this paper, a new idea imitating the process of growing grass was proposed to solve the low adhesion, weak wear resistance and poor corrosion resistance of the general superhydrophobic coatings.
TL;DR: In this article, a spiro diacetal structure was utilized to synthesize readily recyclable thermosetting materials with high performance, which can be used in composites, coatings, electronic packing materials, etc.
Abstract: Conventional thermosets, widely used in composites, coatings, electronic packing materials, etc., are typically made of non-sustainable fossil resources and cannot be recycled under mild conditions. Degradable thermosets are promising alternatives, while combining ready degradability and high performance is a challenge. In this paper, for the first time, a spiro diacetal structure was utilized to synthesize readily recyclable thermosetting materials with high performance. A renewable bioresource, lignin derived vanillin, was used to produce a rigid spiro diacetal trigger and further built into three thermosets. Among them, spiro diacetal epoxy resin was systematically investigated and was proved to be readily degradable under mild acidic conditions while maintaining stability under neutral or basic conditions and showing outstanding thermal stability. Meanwhile, its glass transition temperature, tensile strength, modulus, elongation at break are comparable to or even better than those of conventional bisphenol A epoxy resin. Moreover, facilely recyclable carbon fiber reinforced composites and convenient-removal coatings were achieved from this epoxy resin accompanied by excellent performances.
TL;DR: Results from electrochemical behaviors showed that the proper incorporation of POSS-GO could availably improve the anticorrosion ability of epoxy based coatings in simulate marine environment.
TL;DR: In this article, a facile and effective Layer-by-Layer self assembly method was proposed to deposit graphene oxide/silica (GO/SiO2) multilayers films onto CFs surface.
TL;DR: In this article, the authors used hand lay-up technique to evaluate the best loading of date palm fibres (DPF) at different loading (40, 50, and 60% by wt.) and evaluate the flexural, thermal stability and dynamic mechanical properties of epoxy composites.
Abstract: The aim of the present study is to improve the flexural, thermal stability and dynamic mechanical properties of epoxy composites by reinforcing date palm fibres (DPF) at different loading (40%, 50% and 60% by wt.) and to evaluate the best loading through hand lay-up technique. Three point bending dynamic properties in terms of storage modulus (E′), loss modulus (E″) damping factor, Cole–Cole plot and thermal properties were analyzed by dynamic mechanical and thermogravimetric analyser, respectively. Flexural test results show that loading of 50% DPF increases both the flexural strength and modulus of pure epoxy composites from 26.15 MPa to 32.64 MPa and 2.26 GPa to 3.28 GPa, respectively. TGA results revealed that reinforcement of DPF in epoxy composites also improves the thermal stability and residual content. The residual content of epoxy (9.58%), 40% DPF/epoxy (12.51%), 50% DPF/epoxy (19.8%) and for 60% DPF/epoxy composites (15.2%) was noted, revealing that 50% DPF/epoxy composites confers the best result. Incorporation of DPF into epoxy also improves the E′ and E″ but 50% DPF show more remarkable improvement compared to 40% and 60% DPF loading. Moreover, damping factor decreases considerably by the reinforcement of DPF and are found lowest for 50% DPF/epoxy composites among all composites. Drawn Cole–Cole plot also suggests the existence of certain heterogeneity in DPF/epoxy composites compared to homogenous nature of epoxy composites. We concluded that 50% DPF loading is the ideal loading to enhanced flexural, thermal stability and dynamic properties of epoxy composites.
TL;DR: In this paper, the effect of hybridization and chemical treatments on the mechanical properties of a novel intralaminar natural fibre hybrid composite was investigated, and it was found that the properties evaluated are significantly improved by addition of the natural fibres to pure jute based composites.
Abstract: The main objective of this work was to investigate the effect of hybridization and the effect of chemical treatments on the mechanical properties of a novel intralaminar natural fibre hybrid composite. Jute, sisal and curaua fibres were selected as natural fibre reinforcements for the epoxy matrix based composites which were produced by hand lay-up technique. The total volumetric fraction used in the fabrication of the hybrid composites was 30% of fibres and 70% of epoxy resin. Tensile, flexural and impact tests were carried out according to ASTM standards to characterize the novel hybrid composites. It was found that the mechanical properties evaluated are significantly improved by addition of the natural fibres to pure jute based composites. The fibre treatments had different effects on the mechanical properties of the hybrid composites. For sisal reinforced hybrid composites, the alkaline treatment had a positive impact on the composite properties (tensile, flexural and impact), while for the jute + curaua hybrid composites the alkali treatment had a negative effect on the tensile and impact properties. The mixed (alkalization + silanization) treatment had a positive effect on the jute + curaua flexural properties, while decreased the flexural properties for the jute + sisal composite. A scanning electron microscopy (SEM) was used to examine the fracture surface of the tested specimens.
TL;DR: In this paper, the performance of the single lap joint specimens with different nanocomposite adhesives was further investigated using 3D finite element analysis and it was shown that the failures in the adhesite adhesive layers occurred due to Mode II failure.
Abstract: Carbon nanomaterials secure promises of incorporating exceptional mechanical performance and multifunctional properties into polymers. However, questions concerning type of carbon nanofiller, fraction and corresponding change in relevant property are yet to be answered. In this study, graphene platelets (GnPs) and carbon nanotubes (CNTs) were added individually into epoxy adhesive and corresponding structure-property relations were investigated experimentally and numerically. The study shows that: at fractions 0.25 vol%. The mechanical performance of the single lap joint specimens with different nanocomposite adhesive were further investigated using 3D finite element analysis. The numerical analysis not only confirms the outcomes of the experiments but also shows that the failures in the nanocomposite adhesive layers occurred due to Mode II failure. Electrical conductivity measurements of epoxy nanocomposite adhesives showed lower percolation threshold (0.54 vol%) for epoxy/CNT nanocomposite adhesive compared to 0.63 vol% when GnPs were used. The contrast in the geometrical structure between GnP (plate-like structure) and CNT (tube-like structure) is crucially responsible for epoxy nanocomposite adhesives’ properties. This research pointed out that selecting a carbon filler for a polymer composite is key-factor to determine the end-product function.
TL;DR: In this article, the authors reviewed the research conducted in the last ten years pertaining to the fabrication, characterization and applications of Ga/CNTs-epoxy composites and highlighted the major challenges faced by the researchers in developing epoxy nanocomposites for high performance applications.