Synthesis of EP‐POSS mixture and the properties of EP‐POSS/epoxy,SiO2/epoxy,and SiO2/EP‐POSS/epoxy nanocomposite

The hybrid material of EP‐POSS mixture was synthesized by the hydrolysis and condensation of (γ‐glycidoxypropyl) trimethoxysilane. A series of binary systems of EP‐POSS/epoxy blends, epoxy resin modified by silica nanoparticles (SiO₂/epoxy), and ternary system of SiO₂/EP‐POSS/epoxy nanocomposite were prepared. The dispersion of SiO₂ in the matrices was evidenced by transmission electron micrograph, and the mechanical properties, that is, flexural strength, flexural modulus, and impact strength were examined for EP‐POSS/epoxy blends, SiO₂/epoxy, and SiO₂/EP‐POSS/epoxy, respectively. The fractured surface of the impact samples was observed by scanning electron micrograph. Thermogravimetry analysis were applied to investigate the different thermal stabilities of the binary system and ternary system by introducing EP‐POSS and SiO₂ to epoxy resin. The results showed that the impact strength, flexural strength, and modulus of the SiO₂/EP‐POSS/epoxy system increased around by 57.9, 14.1, and 44.0% compared with the pure epoxy resin, T_i, T_max and the residues of the ternary system were 387°C, 426°C, and 25.2%, increased remarkably by 20°C, 11°C and 101.6% in contrast to the pure epoxy resin, which was also higher than the binary systems. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 810‐819, 2013     

Studies on Preparation and Property Researches of EP/SiC Thermal Conductivity Composites

The epoxy resin/silicon carbide thermal conductivity composites were prepared via casting method. The content of SiC and coupling reagents effecting on the thermal conductivity, mechanical and thermal properties of composites were investigated. Results revealed that the thermal conductivity properties of the composites were improved with the increasing mass fraction of SiC, and the thermal conductivity coefficient λ was 0.7152 W/mk with 50% mass fraction of SiC, being over 3 times of that of native epoxy resin. The flexural strength and impact strength of the EP/SiC composites increased firstly, but decreased with excessive addition of SiC, and the properties of EP/SiC composites were maximum with 10 wt% SiC. DSC and TGA analysis showed that the glass transition temperature (Tg) of composites decreased, but the heat resistance increased with the addition of SiC. SEM observation of impact fracture revealed that the impact strength had the relationships of large or small fracturing ability and the fracturing extended ability and the resin elasticity deformation.     

The Preparation and Cure Kinetics Researches of Thermal Conductivity Epoxy/AlN Composites

The aluminum nitride (AlN) was employed to prepare epoxy/AlN composites by blending-casting moulding method, two different coupling agents were used to functionalize the surface of AlN. The thermal conductivity and mechanical properties of the composites were investigated. And the cure kinetics of the EP/AlN composites was studied by means of isothermal DSC. Results revealed that the thermal conductivity of EP improved remarkably with the addition of AlN, a higher thermal conductivity of 1.05 W/mK can be achieved with 42 vol% AlN, about 5 times higher than that of native epoxy resin. And the flexural and impact strength of the EP/AlN composites were optimal with 3.3 vol% AlN. The curing process of the EP/AlN composites contained autocatalytic mechanism, the whole process was according with the Kamal model. The presence of AlN did not change the cure reaction mechanism, and had little effecting on the activation energy, but decreased the rate constants k_l and k₂.     

Preparation of silica-decorated graphene oxide nanohybrid system as a highly efficient reinforcement for woven jute fabric reinforced epoxy composites

In the current work, silica-decorated graphene oxide (SiO₂@GONPs) nanohybrids were used to reinforce the jute fiber/epoxy (JF/EP) composite. Tetraethylorthosilicate (TEOS) was utilized to prepare the SiO₂@GONPs using a facial route. The results of Fourier-transform infrared spectroscopy (FTIR), atomic force microscopy, and elemental X-ray mapping confirmed the successful synthesis of SiO₂@GONPs nanohybrids. Herein, the effects of SiO₂@GONPs loading (0, 0.1, 0.3, and 0.5 wt%) on the mechanical behavior of the JF/EP composite were investigated with emphasis on the flexural and high-velocity impact properties. The results revealed that reinforcement of matrix with 0.3 wt% SiO₂@GONPs enhanced the flexural strength of the JF/EP composite by about 40%. The energy absorption capability and impact limit velocity of the 0.3 wt% SiO₂@GONPs-filled JF/EP composite were 61 and 28%, respectively, higher than those of the neat specimen. Compared to the untreated-GONPs, the SiO₂@GONPs nanohybrid demonstrated an evident superiority in improving the mechanical properties of the JF/EP composite at the same loading. Evaluation of the fracture surfaces of the multiscale composites revealed that the improved fiber-matrix interfacial bonding was the basic mechanism of fracture in these specimens.     

Tribological properties of polyimide fabric‐epoxy composites modified by hollow silica microspheres

The polyimide (PI) fabric/epoxy (EP) composites modified with different content of micro‐SiO₂ hollow spheres were prepared by dip‐coating and subsequently hot‐press process. For comparison, the pure EP and the unmodified PI fabric/EP composite were also fabricated. The differential scanning calorimetry was conducted to investigate the crosslinking reaction of composites. The results indicated that there exhibited a remarkable improvement in the mechanical and tribological properties of PI fabric/EP composites after incorporating the micro‐SiO₂. The best tribological properties were obtained when the content of micro‐SiO₂ was 2 wt%, whose wear rate was 71.9% lower than that of unmodified PI fabric/EP composite. The worn surfaces were observed by a scanning electron microscope to illustrate the friction mechanisms. Note that the skeleton network structure of fabric throughout the whole composites supported the matrix. At the same time, the microparticulates filled in the interstices of fabrics interwoven structure and the gaps between layers of fabrics, which propped up the skeleton network of fabric under the high frictional load and afford excellent interface between fabrics and EP. This ensures the outstanding tribological properties of PI fabric/EP composites. POLYM. COMPOS., 38:2283–2293, 2017. © 2015 Society of Plastics Engineers     

Synthesis,characterization, and properties of polystyrene/SiO2 hybrid materials via sol–gel process

Isocyanate‐functionalized polystyrene (P(St‐co‐TMI)) was successfully synthesized by solution free radical polymerization, which was then used to react with (3‐aminopropyl) triethoxysilane (APTES) to prepare a precursor of polystyrene/inorganic composites (PS/SiO₂). To obtain PS/SiO₂ composites with chemical bond, the precursor was mixed with triethoxysilane (TEOS) under the sol–gel reaction condition. The chemical bond between the PS and SiO₂ particles made the crosslink network more stable and avoided aggregation compared with the physical connection and barely mechanical mixing. The Fourier transform infrared (FT‐IR) results indicate that the isocyanate group ( NCO) was completely reacted with APTES. The field‐emission scanning electron microscopy results show that the morphology of composites and the distribution of the particles, which exhibit good compatibility between organic and inorganic phases, and the inorganic particles show good spatial uniformity. The differential scanning calorimetry shows that the glass transition temperature (T_g) of the PS/SiO₂ composites was shifted to high temperature when the amount of APTES increased. The thermal degradation temperature of the PS/SiO₂ composites increases with the increasing of APTES content. Master curves at 200°C are constructed for the storage and loss modulus as well as complex viscosity. POLYM. COMPOS. 36:482–488, 2015. © 2014 Society of Plastics Engineers     

Mechanical and thermal properties of epoxy-POSS reinforced-(biphenyl diol formaldehyde/epoxy hybrid resin) composites

To enhance the properties of epoxy composites, the biphenyl diol formaldehyde resin (BPFR) and glycidyloxypropyl polyhedral oligomeric silsesquioxane (G-POSS) were synthesized and used for modification of fiber-glass reinforced composites of epoxy resin (ER). The BPFR was employed to cure epoxy resin with different G-POSS contents and the laminates of fiber-glass reinforced hybrid composites prepared from BPFR, ER and G-POSS. The dynamic mechanical properties, thermal properties, mechanical and electrical properties of the hybrid composites were characterized by dynamic mechanical analyzer, thermogravimetric analyzer and electroproperty detector. The results showed that the T _g of the composites is increased with the addition of G-POSS. When the content of G-POSS is 5 wt%, the tensile and impact strength of the hybrid composites are 249.87 MPa and 63.83 kJ/m², respectively, which are all 30 % higher than those of non-added composites. At G-POSS content of 7 wt%, T _g of the material is 9.6 °C higher than pure BPFR/ER composite, and the initial decomposition temperature, T _id, is enhanced by about 29 °C. Dielectric constant, ε, and dielectric loss, tanδ, of the hybrid composites are between 0.53–0.7 and between 0.004–0.012, respectively.     

Morphologies and properties of epoxy resin/layered silicate–silica nanocomposites

A new nanofiller containing layered organo‐modified montmorillonite (oMMT) and spherical silica (SiO₂) was prepared by an in situ deposition method and coupling agent modification. Fourier transform infrared spectrometry, X‐ray diffraction and transmission electron microscopy show that there are interactions between oMMT and SiO₂, and the spherical SiO₂ particles are self‐assembled on the edge of oMMT layers, forming a novel layered–spherical nanostructure. An epoxy resin (EP)/oMMT–SiO₂ nanocomposite was obtained by adding oMMT–SiO₂ to EP matrix. Morphologies and mechanical and thermal properties of the new ternary nanocomposite were investigated. For purposes of comparison, the corresponding binary nanocomposites, i.e., EP modified with either oMMT or SiO₂, were also tested. The results for the mechanical properties show that oMMT obviously improves the strength of EP, and SiO₂ enhances the toughness of EP, but oMMT–SiO₂ exhibits a synergistic effect on toughening and reinforcing of EP. The toughening and reinforcing mechanism is explained by scanning electron microscopy. In addition, the thermal resistance of EP/oMMT–SiO₂ is better than that of EP/SiO₂, but it is worse than that of EP/oMMT. Copyright © 2006 Society of Chemical Industry     

Study on Preparation of SiO2/Epoxy Resin Hybrid Materials by Means of Sol-Gel

Silicon dioxide/epoxy resin hybrid material was prepared by means of Sol-Gel based on epoxy resin, tetraethyl orthosioate (TEOS), [H₂N(CH₂)₃Si(OC₂H₅)₃](KH-550), Methyltetrahydrophthalic anhydride (MeTHPA), dimethyl phthalate (DMP-30) and (HOCH₂CH₂)N. The contents of TEOS, KH-550 and reacting temperature influencing on the properties of hybrid materials were studied. The behaviors of the hybrid materials were characterized by differential scanning calorimentry (DSC), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and Fourier transform-infrared ray (FT-IR) spectroscopy. The results showed that the properties of the material was optimal at approximately 3% TEOS, 2% KH-550, reacting at 60°C, and the mechanical and thermal properties were significantly improved compared with the pure epoxy resin. The dimension of SiO₂ particles was about 20 nm, and distributed homogeneously in the system.     

Synthesis and characterization of fluorinated poly(etherimide)s toughening for carbon fiber‐reinforced epoxy composites

Novel‐fluorinated poly(etherimide)s (FPEIs) with controlled molecular weights were synthesized and characterized, which were used to toughen epoxy resins (EP/FPEI) and carbon fiber‐reinforced epoxy composites (CF/EP/FPEI). Experimental results indicated that the FPEIs possessed outstanding solubility, thermal, and mechanical properties. The thermally cured EP/FPEI resin showed obviously improved toughness with impact strength of 21.1 kJ/m² and elongation at break of 4.6%, respectively. The EP/FPEI resin also showed outstanding mechanical strength with tensile strength of 91.5 MPa and flexural strength of 141.5 MPa, respectively. The mechanical moduli and thermal property of epoxy resins were not affected by blending with FPEIs. Furthermore, CF/EP/FPEI composite exhibited significantly improved toughness with Mode I interlaminar fracture toughness (G_IC) of 899.4 J/m² and Mode II interlaminar fracture toughness (G_IIC) of 1017.8 J/m², respectively. Flexural properties and interlaminar shear strength of the composite were slightly increased after toughening. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

Mechanical,thermal, and burning properties of viscose fabric composites: Influence of epoxy resin modification

The influence of epoxy resin modification by 3‐aminopropyltriethoxysilane (APTES) on various properties of warp knitted viscose fabric is reported in this study. Dynamic mechanical, impact resistance, flexural, thermal properties, and burning behavior of the epoxy/viscose fabric composites are studied with respect to varying content of silane coupling agent. The results obtained for APTES‐modified epoxy resin based composites reinforced with unmodified viscose fabric composites are compared to unmodified epoxy resin based composites reinforced with APTES‐modified viscose fabric. The dynamic mechanical behavior of the APTES‐modified resin based composites indicates improved interfacial adhesion. The composites prepared from modified epoxy resin exhibited a twofold increase in impact resistance. The improved adhesion between the fiber and modified resin was also visible from the scanning electron microscope analysis of the impact fracture surface. There was less influence of resin modification on the flexural properties of the composites. The 5% APTES modification induced early degradation of composites compared to all other composites. The burning rate of all the composites under study is rated to be satisfactory for use in automotive interior applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46673.     

Synthesis of monolithic alumina-silica hollow microspheres and their heat-shielding performance for adiabatic materials

Al₂O₃ ceramic foams-based composites were firstly synthesized to be used as the thermal insulation material which has excellent mechanical properties of the substrate material and better thermal properties of hollow microspheres. In this research, by doping TEOS, the monolithic hollow microspheres were prepared via a novel and effective synthesis route using propylene oxide as the gelation initiator to induce the gelation of aluminum chloride hexahydrate solution. The influence of TEOS on the morphology and high-temperature stability of the monolithic hollow microspheres was clarified in detail. Based on the optimized additive amount of TEOS, Al₂O₃ ceramic foams were introduced as the substrate material of alumina-silica hollow microspheres to fabricate the final Al₂O₃ ceramic foams-based composites. Benefited from this special structure, the Al₂O₃ ceramic foams-based composites displayed excellent mechanical properties and thermal properties. The samples changed less in appearance and did not show significant shrinkage after heat-treatment at 1200 °C. The density, bending strength and thermal conductivity of the Al₂O₃ ceramic foams-based composite were 0.32 g/cm³, 1.8 MPa and 0.12 W/m K, respectively.     

Effect of vapor‐grown carbon nanofibers and in situ hydrolyzed silica on the mechanical and shape memory properties of water‐borne epoxy composites

Vapor‐grown carbon nanofiber (VGCNF)/water‐borne epoxy (WEP) and SiO₂/WEP composites were successfully synthesized via freeze drying and hot‐press molding. VGCNFs were mixed directly with a WEP emulsion, while SiO₂ was synthesized by in situ hydrolysis of TEOS solution (3‐triethoxysilylpropylamine (KH550): tetraethoxysilane (TEOS): absolute ethanol = 1:5:20, w/w/w) dispersed in the WEP emulsion. WEP composites were obtained from these mixtures by freeze drying and compressing under a pressure of 10 MPa at 120°C for 2 h. The morphology and mechanical properties of the WEP composites were investigated by transmission electron microscopy, scanning electron microscopy, dynamic mechanical analysis and tensile testing. The shape memory (SM) properties of the WEP composites were evaluated by fold‐deploy SM testing. The effects of filler content and recovery temperature on the SM properties were revealed through systematic variation. The results confirmed that VGCNF and in situ hydrolyzed SiO₂ were homogenously dispersed and incorporated into the WEP matrices. Thus, significant improvements in the mechanical and SM properties of the composites were achieved. POLYM. COMPOS., 36:1712–1720, 2015. © 2014 Society of Plastics Engineers     

Dispersion,Mechanical and Thermal Properties of Epoxy Resin Composites Filled with the Nanometer Carbon Black

The nanometer carbon black (CB) was employed to prepare epoxy resin/carbon black (EP/CB) composites by blending-casting method. The different modified methods of silicone coupling agent were used to improve the dispersion of CB in epoxy resin. The mechanical and thermal properties of EP/CB composites were investigated. Experimental results showed that the mechanical properties increased at first, but decreased with excessive addition of CB. When the mass fraction of CB was 2%, the mechanical properties were maximum. The use of modified CB significantly enhanced the mechanical properties of the composites. For given CB loading, the CB modified by pretreatment method displayed better dispersion in the epoxy resin than that of the direct mixing method. SEM observation revealed that the tensile fracture surface of the composite filled with 2 wt% modified CB held more microcracks than that of 5 wt% modified CB, and the formed microcracks could consume more energy of rupture, finally to have better tensile strength. DSC analysis showed that the glass transition temperature (Tg) of the composites increased with the increasing mass fraction of CB.     

Silica solid particles toughening,strengthening and anti-aging on epoxy resin

Solid particles used to toughen polymer can induce shear bands and crazing to release the internal stress of polymer. Herein, SiO₂ particles with different sizes were prepared by sol–gel method and modified by triethylenetetramine (TETA) in water. 1, 2, 3 and 4 wt% of SiO₂ and SiO₂-TETA particles are used to toughen epoxy resin (EP). They can form chemical bond with EP to heighten polymer^'s storage modulus and glass transition temperature. SiO₂-TETA containing active hydrogen atoms is a better cross-linking agent than SiO₂. Both SiO₂ and SiO₂-TETA particles possess obvious strengthening effects on EP. Their toughening effect depends on size. The 100 nm SiO₂ nanoparticles showed better toughening performance than 300 or 500 nm SiO₂ particles attributing to their higher specific surface area. The impact strength of EP/SiO₂-TETA composites with 3 wt% of 100 nm particles is 16.26 kJ/m², which is 27.67% and 8.00% higher than EP and EP/SiO₂ respectively. In addition, its tensile strength is 63.13 MPa, which is higher than the other is too. The barrier effect of solid particles can effectively improve the heat and ultraviolet resistant properties of EP matrix; as a result, their anti-aging property is improved significantly.     

Novel Al<Subscript>2</Subscript>O<Subscript>3</Subscript>–SiO<Subscript>2</Subscript> aerogel/porous zirconia composite with ultra-low thermal conductivity

Highly porous zirconia fibers networks with a quasi-layered microstructure were successfully fabricated using vacuum squeeze moulding. The effects of inorganic binder content on the microstructure, room-temperature thermal and mechanical properties of fibrous porous zirconia ceramics were systematically investigated. Al₂O₃–SiO₂ aerogel was impregnated into fibrous porous ceramics, and the microstructures, thermal and mechanical properties of Al₂O₃–SiO₂ aerogel/porous zirconia composites were also studied. Results show that the Al₂O₃–SiO₂ aerogel/porous zirconia composites exhibited higher compressive strength (i.e., 1.22 MPa in the z direction) and lower thermal conductivity [i.e., 0.049 W/(m/K)]. This method provides an efficient way to prepare high-temperature thermal insulation materials.     

Effect of poly(etherimide) chemical structures on the properties of epoxy/poly(etherimide) blends and their carbon fiber‐reinforced composites

Poly(etherimide)s (PEIs) with different chemical structures were synthesized and characterized, which were employed to toughen epoxy resins (EP/PEI) and carbon fiber‐reinforced epoxy composites (CF/EP/PEI). Experimental results revealed that the introduction of the fluorinated groups and meta linkages could help to improve the melt processability of EP/PEI resins. The EP/PEI resins showed obviously improved mechanical properties including tensile strength of 89.2 MPa, elongation at break of 4.7% and flexural strength of 144.2 MPa, and good thermal properties including glass transition temperature (T_g) of 211°C and initial decomposition temperature (T_d) of 366°C. Moreover, CF/EP/PEI‐1 and CF/EP/PEI‐4 composites showed significantly improved toughness with impact toughness of 13.8 and 15.5 J/cm², respectively. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Properties and microstructures of epoxy resin/TiO2 and SiO2 hybrids

Epoxy resin/TiO₂ and epoxy resin/SiO₂ hybrids were prepared by different procedures, and their mechanical properties were correlated to their microstructures, as indicated by small‐angle X‐ray scattering (SAXS) measurements. Epoxy resin/TiO₂ hybrids were prepared by mixing the epoxy resin (EP828) with N‐(2‐aminoethyl)‐3‐aminopropyltrimethoxysilane (S320) in acetone, and then titanium‐n‐butoxide (TnBU) was added. In addition, epoxy/SiO₂ hybrids were prepared by mixing EP828 with a curing agent, a diamino heterocyclic compound (B002) in acetone, and an organo silica sol (silica nanoparticles dispersed in methylethylketone) was added. In the EP828/S320/TiO₂ hybrid systems, the TiO₂ component was attached to both of the chain ends of the epoxy matrix, hence leading to the formation of inorganic domains via the covalent bonds. SAXS profiles of these hybrids showed peaks at q = 2.3 nm^?1, caused by interference between the domains. The storage modulus increased with increasing TiO₂ content above the T_g, owing to the strong interactions between TiO₂ and the epoxy matrix. The tanδ peak position did not change, although the intensity decreased with increasing TiO₂ content. The SAXS profiles of the EP828/B002/SiO₂ hybrids were very different to those of the corresponding EP828/S320/TiO₂ hybrids, and indicated that SiO₂ particles with rough surfaces were randomly dispersed in the epoxy matrix. The storage moduli of the EP828/B002/SiO₂ hybrid systems increased only slightly with SiO₂ content, because of the weak interactions. These mechanical properties are well explained by the microstructures derived from the SAXS profiles. Copyright © 2004 Society of Chemical Industry     

一步法制备纳米SiO_2/环氧树脂杂化材料的研究

以正硅酸乙酯(TEOS)为无机前驱体、三乙烯四胺(TETA)为固化剂和γ-氨丙基三乙氧基硅烷(KH-550)为硅烷偶联剂,采用溶胶-凝胶一步法制备SiO2/EP(环氧树脂)杂化材料。研究了TEOS和丙酮含量对杂化材料的力学性能、热性能等影响,并对杂化材料的微观相态结构和性能进行了表征和分析。结果表明:当w(TEOS)=3%(相对于改性EP质量而言)时,不加丙酮的杂化材料具有相对最好的综合性能,其断面形貌呈韧性断裂,热变形温度和玻璃化转变温度均高于纯EP体系,生成的SiO2粒径为20 nm左右且分布较均匀;加入丙酮后的杂化材料透明性变好,但其力学强度和热性能均随丙酮含量增加而降低。     

Enhanced thermal and mechanical properties of epoxy composites by addition of hyperbranched polyglycerol grown on cellulose fibers

We reported a novel approach for epoxy composites by incorporation of hyperbranched polyglycerol (HPG) grafted sisal cellulose fibers (SCF). In this work, we have synthesized SCF wrapped HPG shell (SCF-g-HPG) by a “grafting from” strategy for the strong interfacial interaction between fillers and matrix. It was found that the thermal and mechanical properties of epoxy composites were greatly improved by incorporating SCF-g-HPG. For example, the impact strength, flexural strength, tensile strength, Young’s modulus and toughness of the composites with 3.0 wt% SCF-g-HPG loading were 38.35 KJ/m², 123.40 MPa, 86.62 MPa, 151.7 MPa, and 417.84 MJ/m³, significantly increased by 119.1 %, 55.2 %, 45.6 %, 43.1 %, and 166.1 % respectively, as compared with neat epoxy. In addition, thermal stability of SCF-g-HPG/epoxy composites also showed an obvious enhancement compared with neat epoxy.