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     

Effect of polyarylene ether nitriles on processing and mechanical behaviors of phthalonitrile‐epoxy copolymers and glass fiber laminated composites

A series of copolymers and glass fiber composites were successfully prepared from 2,2‐bis [4‐(3,4‐dicyanophenoxy) phenyl] propane (BAPh), epoxy resins E‐44 (EP), and polyarylene ether nitriles (PEN) with 4,4′‐diaminodiphenyl sulfone as curing additive. The gelation time was shortened from 25 min to 4 min when PEN content was 0 wt % and 15 wt %, respectively. PEN could accelerate the crosslinking reaction between the phthalonitrile and epoxy. The initial decomposition temperatures (T_i) of BAPh/EP copolymers and glass fiber composites were all more than 350°C in nitrogen. The T_g of 15 wt % PEN glass fiber composites increased by 21.2°C compared with that of in comparison with BAPh/EP glass fiber composite. The flexural strength of the copolymers and glass fiber composites reached 119.8 MPa and 698.5 MPa which increased by 16.6 MPa and 127.3 MPa in comparison with BAPh/EP composite, respectively. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Toward poly(furfuryl alcohol) applications diversification: Novel self‐healing network and toughening epoxy–novolac resin

Poly(furfuryl alcohol) bioresin (PFA) was synthesized and utilized through two distinct alloying strategies. It was crosslinked by a bismaleimide (BMI) via a Diels–Alder (DA) reaction. The novel PFA–BMI polyadduct network was spectrally, thermally, and thermo‐mechanically characterized and its thermally repeatable self‐healing behavior was visually established. The network showed a high pyrolytic thermostability (char yield ∼51% at 600 °C). PFA was also used for modification of epoxy–novolac resin (EP). EP hybrid resins containing 5, 10, and 15 wt % of PFA were cured by a polyamine hardener. Despite of different curing mechanisms of the two resins, PFA had no effect on EP curing behavior as revealed by differential scanning calorimetry, which proved homogeneous formation of the thermosets. PFA at the composition of 15 wt % improved tensile properties and toughness of EP, so that it almost doubled tensile modulus and elongation at break. However, PFA slightly deteriorated flexural properties of EP. PFA also decreased T_g of EP, with a maximum decrease of 22 °C. Besides, PFA disfavored initial thermostability of EP, but improved its pyrolytic char yield. In conclusion, PFA can be beneficial from smart materials to toughen hybrid epoxy thermosets with potential applications in composites, adhesives, and surface coatings. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45921.     

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     

High‐performance thermosetting films based on an amino‐functionalized poly(ether sulfone)

We have developed a sequence‐dependent synthesis of the amino‐functionalized poly(ether sulfone) P2 . The amino groups of P2 act as reactive sites toward epoxy resins. After curing P2 with diglycidyl ether of bisphenol A (DGEBA) and cresol novolac epoxy (CNE), we obtained the flexible, light‐yellow, transparent, epoxy thermosetting films P2 /DGEBA, and P2 /CNE, respectively, having glass transition temperatures (T_g) of 258 and 274°C, respectively. In addition, we also prepared a flexible film after condensation of the amino groups of P2 with the anhydride groups of 4,4′‐oxydiphthalic anhydride (ODPA); after imidization at 300°C for 1 h, the resulting P2 /ODPA thermosetting film possessed a value of T_g of 340°C. These three thermosetting films also exhibited flame retardancy with a UL‐94 VTM‐0 grade. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40980.     

High-performance poly(methylsilane arylether arylacetylene) resins with low curing temperatures and weak secondary relaxations

A series of poly(methylsilane arylether arylacetylene) (PSEA-H) resins were synthesized from methyldichlorosilane and isomeric arylether arylacetylenes, and characterized by ¹H-NMR and FT-IR spectroscopies. The effect of reactive Si-H groups and the linking positions of benzene rings in the arylether arylacetylene units on the properties of the resins were investigated. The results show that PSEA-H resins possess good processability with processing windows of over 80°C. The introduction of Si-H groups reduces the curing temperatures for PSEA-H resins and weakens the secondary relaxation for the cured PSEA-H resins. The cured resins and T300 carbon fiber (T300CF) reinforced composites display high mechanical properties. The flexural strengths of a cured PSEA-H resin and its T300CF composite at room temperature reach 64.2 and 426.5 MPa, respectively. The flexural properties depend on the linking positions of benzene rings. The cured PSEA-H resins show excellent heat resistance with a temperature of 5% weight loss (T_d5) above 500°C.     

Compatibilized the thermosetting blend of epoxy and redistributed low molecular weight poly(phenylene oxide) with triallylisocyanurate

Vinyl‐containing low molecular weight PPO (R‐PPO) was prepared by redistribution reaction between commercially available PPO and maleic anhydride (MAH) and used to modify epoxy resin (EP). TAIC was furthermore used as the compatibilizer of EP/R‐PPO system in this study. The curing reaction kinetics, compatibility of the components, morphology, dielectric properties and impact toughness of EP/R‐PPO/TAIC systems were investigated. The experimental results showed that the cured EP/R‐PPO (80/20) system had two phase morphology, the R‐PPO particles of about 1 µm were evenly dispersed in continuous epoxy phase. After addition of TAIC, the EP/R‐PPO/TAIC systems were transferred to single phase. The glass transition temperature of cured EP/R‐PPO/TAIC (80/20/10) system was 150.2 °C. With the increase of TAIC content, the dielectric constant (D_k) and dissipation factor (D_f) of cured EP/R‐PPO/TAIC systems were both reduced. The dielectric constant and dissipation factor at 1MHz of cured EP/R‐PPO/TAIC (80/20/10) system was 2.72 and 0.006, respectively. Compared with those of cured EP/R‐PPO (80/20) system (D_k = 2.82 and D_f = 0.0078 at 1MHz), they decreased by 3.6% and 23.1%, respectively. With the increase of TAIC content, the impact strength of cured EP/R‐PPO (80/20) system increased and reached to a maximum value (2.41 kJ/m²) when TAIC content was 10 phr, which was improved by 23% compared with that of cured EP/R‐PPO (80/20) system (1.96 kJ/m²). © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43293.     

Synthesis and characterization of bis(4‐cyanato‐3,5‐dimethylphenyl)anisylmethane/epoxy/glass fiber composites

Bis(4‐cyanato‐3,5‐dimethylphenyl)anisylmethane was prepared by treating CNBr with bis(4‐hydroxy‐3,5‐dimethylphenyl)anisylmethane and blended with commercial epoxy resin in different ratios and cured at 120°C for 2 h, 180°C for 1 h, and postcured at 220°C for 1 h using diamino diphenyl methane as curing agent. Castings of neat resin and blends were prepared and characterized. The composite laminates were also fabricated with glass fiber using the same composition. The tensile strength of the composites increased with increase in cyanate content (3, 6, and 9%) from 322 to 355 MPa. The fracture toughness values also increased from 0.7671 kJ/m², for neat epoxy resin, to 0.8615 kJ/m², for 9% cyanate ester‐modified epoxy system. The 10% weight loss temperature of pure epoxy (358°C) was increased to 390°C by the incorporation of cyanate ester resin. The incorporation of cyanate ester up to 9% in the epoxy resin increases the T_g from 143 to 147°C. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation and properties of bio‐based epoxy montomorillonite nanocomposites derived from polyglycerol polyglycidyl ether and ε‐polylysine

Glycerol polyglycidyl ether (GPE) and polyglycerol polyglycidyl ether (PGPE) were cured with ε‐poly(L ‐lysine) (PL) using epoxy/amine ratios of 1 : 1 and 2 : 1 to create bio‐based epoxy cross‐linked resins. When PGPE was used as an epoxy resin and the epoxy/amine ratio was 1 : 1, the cured neat resin showed the greatest glass transition temperature (T_g), as measured by differential scanning calorimetry. Next, the mixture of PGPE, PL, and montomorillonite (MMT) at an epoxy/amine ratio of 1 : 1 in water was dried and cured finally at 110°C to create PGPE‐PL/MMT composites. The X‐ray diffraction and transmission electron microscopy measurements revealed that the composites with MMT content 7–15 wt % were exfoliated nanocomposites and the composite with MMT content 20 wt % was an intercalated nanocomposite. The T_g and storage modulus at 50–100°C for the PGPE‐PL/MMT composites measured by DMA increased with increasing MMT content until 15 wt % and decreased at 20 wt %. The tensile strength and modulus of the PGPE‐PL/MMT composites (MMT content 15 wt %: 42 and 5300 MPa) were much greater than those of the cured PGPE‐PL resin (4 and 6 MPa). Aerobic biodegradability of the PGPE‐PL in an aqueous medium was ～ 4% after 90 days, and the PGPE‐PL/MMT nanocomposites with MMT content 7–15 wt % showed lower biodegradability. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Phase separation of poly(ether sulfone imide) modified epoxy resin

Poly(ether sulfone imide)s (PEI) with molecular weight M_n ∼ 10⁴ were synthesized from 3,3′,4,4′-benzophenone tetracarboxylic dianhydride and amine terminated poly(ether sulfone) having molecular weights ranging from M_n ∼ 400 to M_n ∼ 4000. Thus, the PEIs had the same molecular weight but various imide and ether sulfone contents. The PEIs were mixed with a stoichiometric mixture of diglycidyl ether bis-phenol-A (DGEBA)/diamino diphenyl sulfone (DDS). The effect of PEI on the curing reaction of DGEBA/DDS and the morphology of the polymer blend were studied by differential scanning calorimetry (DSC) and optical microscopy. In the DGEBA/DDS/PEI blend with a fixed PEI molecular weight and PEI concentration but with various imide content, the experimental data revealed the PEI with a higher content of ether sulfone had a lower T_g and a better compatibility with solvents and epoxy resins; the curing reaction rate of DGEBA/DDS/PEI was faster for PEI with a higher imide content; the DSC data of cured DGEBA/DDS/PEI showed two T_gs, indicating phase separation between PEI and cured epoxy resins; and the data of optical microscopy showed that the compatibility of PEI with epoxy resins increased with the content of ether sulfone in PEI. © 1996 John Wiley & Sons, Inc.     

Curing behavior,thermal, and mechanical properties of epoxy resins cured with a novel liquid crystalline dicarboxylic acid curing agent

A novel di‐carboxylic acid curing agent (DACA) was successfully synthesized and cured with three different epoxy resins: glycidyl end‐capped poly(bisphenol‐A‐co‐epichlorohydrin) (pDGEBA, M_n = 377), N,N‐diglycidyl‐4‐glycidyloxyaniline (TGAP), and 4,4′‐methylenebis(N,N‐diglycidylaniline) (TGDDM). The cured epoxy exhibited excellent thermal stability, which was indicated by high initial degradation temperature (T_id) and char yield. The T_id values of cured epoxy were in the range of 327–338°C, and the char yields increased with increasing epoxy functionality. The char yields of cured DACA/pDGEPA, DACA/TGAP, and DACA/TGDDM samples were 21.1, 60.4, and 66.9%, respectively. In addition, the cured epoxy samples also showed low coefficients of thermal expansion and high storage moduli (E′), which were around 60 ppm/°C and 2800 MPa, respectively. The failure surfaces were ductile and rough, so the cured epoxy samples are expected to have high fracture toughness and impact strength. POLYM. ENG. SCI., 54:695–703, 2014. © 2013 Society of Plastics Engineers     

Mechanical and thermal properties of biphenyldiol formaldehyde resin/gallic acid epoxy composites enhanced by graphene oxide

In this study, the gallic acid‐based epoxy resin (GA‐ER) and alkali‐catalysed biphenyl‐4,4′‐diol formaldehyde resin (BPFR) are synthesized. Glass fibre‐reinforced GA‐ER/BPFR composites are prepared. Graphene oxide (GO) is used to improve the mechanical and thermal properties of GA‐ER/BPFR composites. Dynamic mechanical properties and thermal, mechanical, and electrical properties of the composites with different GO content are characterized. The results demonstrate that GO can enhance the mechanical and thermal properties of the composites. The glass transition temperature, T_g, of the BPFR/GA‐ER/GO composites is 20.7°C higher than the pure resin system, and the 5% weight loss temperature, T_d5, is enhanced approximately 56.6°C. When the BPFR: GA‐ER mass ratio is at 4 : 6 and GO content is 1.0–1.2 wt %, the tensile and impact strengths of composites are 60.97 MPa and 32.08 kJ/m² higher than the pure resin composites, respectively. BPFR/GA‐ER composites have better mechanical properties, and can replace common BPA epoxy resins in the fabrication of composites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42637.     

Structure,thermal, and mechanical properties of DDM‐hardened epoxy/benzoxazine hybrids: Effects of epoxy resin functionality and ETBN toughening

Bifunctional, trifunctional, and tetrafunctional epoxy (EP) resins were hardened with stoichiometric amount of 4,4′‐diaminodiphenyl methane in presence and absence of benzoxazine (BOX). The EP/BOX ratio of the hybrid systems was constant, viz. 50/50 wt %. For the bifunctional EP, the EP/BOX range covered the ratios 75/25 and 25/75 wt %, as well. Epoxy‐terminated liquid nitrile rubber (ETBN) was incorporated in 10 wt % in the systems with trifunctional and tetrafunctional EP, and in 10, 15, and 20 wt % in the EP/BOX with bifunctional EP to improve their toughness. Information on the structure and morphology of the hybrid systems was received from differential scanning calorimetric, dynamic‐mechanical thermal analysis, atomic force microscopic, and scanning electron microscopic studies. The flexural, fracture mechanical properties, thermal degradation, and fire resistance of the EP/BOX and EP/BOX/ETBN hybrids were determined. It was found that some homopolymerized BOX was built in the EP/BOX conetwork in form of nanoscale inclusions, whereas ETBN formed micron scaled droplets of sea‐island structure. Incorporation of BOX improved the charring and fire resistance, enhanced the flexural modulus and strength, reduced the glass transition (T_g), the fracture toughness, and energy. Additional modification with ETBN decreased the charring, fire resistance, flexural modulus and strength, as well as T_g, however, improved the fracture toughness and especially the fracture energy. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Bis[4‐(4‐maleimidephen‐oxy)phenyl]propane/N,N‐4,4′‐bismaleimidodiphenylmethyene blend modified with diallyl bisphenol A

In this article, 2,2′‐bis[4‐(4‐maleimidephen‐oxy)phenyl)]propane (BMPP) resin and N,N‐4,4′‐bismaleimidodiphenylmethyene (BDM) resin blends were modified by diallyl bisphenol A (DABPA). The effects of the mole concentration of BMPP on mechanical properties, fracture toughness, and heat resistance of the modified resins were investigated. Scanning electron microscopy was used to study the microstructure of the fractured modified resins. The introduction of BMPP resin improves the fracture toughness and impact strength of the cured resins, whose thermal stabilities are hardly affected. Dynamic mechanical analysis shows that the modified resins can maintain good mechanical properties at 270.0°C, and their glass transition temperatures (T_g) are above 280.0°C. When the mole ratio of BDM : BMPP is 2 : 1(Code 3), the cured resin performs excellent thermal stability and mechanical property. Its T_g is 298°C, and the Charpy impact strength is 20.46 KJ/m². The plane strain critical stress intensity factor (K_IC) is 1.21 MPa·m^0.5 and the plane strain critical strain energy release rate (G_IC) is 295.64 J/m². Compared with that of BDM/DABPA system, the K_IC and G_IC values of Code 3 are improved by 34.07% and 68.10%, respectively, which show that the modified resin presented good fracture toughness. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40395.     

Comparison of thermoset soy protein resin toughening by natural rubber and epoxidized natural rubber

Fully bio‐based soy protein isolate (SPI) resins were toughened using natural rubber (NR) and epoxidized natural rubber (ENR). Resin compositions containing up to 30 wt % NR or ENR were prepared and characterized for their physical, chemical and mechanical properties. Crosslinking between SPI and ENR was confirmed using ¹H‐NMR and ATR‐FTIR. All SPI/NR resins exhibited two distinctive drops in their modulus at glass transition temperature (T_g ) and degradation temperature (T_d ) at around ?50 and 215 °C, corresponding to major segmental motions of NR and SPI, respectively. SPI/ENR resins showed similar T_g and T_d transitions at slightly higher temperatures. For SPI/ENR specimens the increase in ENR content from 0 to 30 wt % showed major increase in T_g from ?23 to 13 °C as a result of crosslinking between SPI and ENR. The increase in ENR content from 0 to 30 wt % increased the fracture toughness from 0.13 to 1.02 MPa with minimum loss of tensile properties. The results indicated that ENR was not only more effective in toughening SPI than NR but the tensile properties of SPI/ENR were also significantly higher than the corresponding compositions of SPI/NR. SPI/ENR green resin with higher toughness could be used as fully biodegradable thermoset resin in many applications including green composites. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44665.     

Tribological properties of micro‐ and nanoparticles‐filled poly(etherimide) composites

It has been found that nano‐ or microsized inorganic particles in general enhance the tribological properties of polymer materials. In the present study, 5 vol % nano‐TiO₂ or micro‐CaSiO₃ was introduced into a polyetherimide (PEI) matrix composite, which was filled additionally with short carbon fibers (SCF) and graphite flakes. The influence of these inorganic particles on the sliding behavior was investigated with a pin‐on‐disc testing rig at room temperature and 150°C. Experimental results showed that both particles could reduce the wear rate and the frictional coefficient (μ) of the PEI composites under the applied testing conditions. At room temperature, the microparticles‐filled composites exhibited a lower wear rate and μ, while the nano‐TiO₂‐filled composites possessed the lowest wear rate and μ at elevated temperature. Enhancement in tribological properties with the addition of the nano‐particles was attributed to the formation of transfer layers on both sliding surfaces together with the reinforcing effect. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1678–1686, 2006     

Synthesis,characterization, and properties of a polyhedral oligomeric octadiphenylsulfonylsilsesquioxane

A novel polyhedral oligomeric octadiphenylsulfonylsilsesquioxane (ODPSS) was synthesized from octaphenylsilsesquioxane and benzenesulfonyl chloride via a Friedel–Crafts reaction with a high yield. ODPSS was identified by Fourier transform infrared spectroscopy, ¹H‐NMR, ¹³C‐NMR, ²⁹Si‐NMR, matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI–TOF MS), wide‐angle X‐ray diffraction, and elemental analysis to be a kind of polyhedral oligomeric silsesquioxane of a T₈R₈ structure. ODPSS exhibited superior thermal stability according to thermogravimetric analysis. Its initial thermal decomposition temperature (T_onset) was at 491°C in air and 515°C in nitrogen. Thermal and mechanical properties of epoxy resin (EP) composites with ODPSS added were studied by differential scanning calorimetry and tensile testing. The results show that the incorporation of ODPSS at a low loading content not only improved the glass‐transition temperature of the EP composites but also enhanced their tensile strength. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40892.     

Epoxy resins toughened by poly(propylene carbonate)

Poly(propylene carbonate) (PPC) was used as a toughening agent for improving the brittleness of cured epoxy resins (EP). Methyl tetrahydrophthatic anhydride (MTHPA) was used as a curing agent. The activation energies for the reactions of PPC/MTHPA and EP/MTHPA measured by FTIR were 115.8 and 66.5 kJ/mol, respectively, while for the composite system of PPC/EP/MTHPA, the activation energy obtained from DSC was 52.9 kJ/mol. Gel contents, DMA, and DSC displayed that the cured resins of PPC/EP/MTHPA were phase-separation crosslinking systems and most of PPC could react with MTHPA or the epoxy group. The toughness of cured resins was reinforced by the addition of PPC. The optimum mechanical properties and toughness for cured resins of PPC/EP/MTHPA corresponded to the system containing 20 phr PPC, which achieved a 33% increase in tensile strength and a 45% increase in the fracture toughness at no expense of the elongation of cured resins. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 2457–2465, 1997     

Mechanical,thermomechanical, and creep performance of CNT embedded epoxy at elevated temperatures: An emphasis on the role of carboxyl functionalization

In contrast to polymeric composites, the role of interface/interphase has been widely acknowledged to govern their overall properties and performance. Environmental temperature has substantial effects on the interfacial durability of polymer nanocomposites. In this regard, present investigation has been carried out to study the mechanical performance of pristine (UCNT) and carboxylic functionalized CNT (FCNT) embedded epoxy nanocomposites under different elevated temperatures. Higher flexural strength and modulus of FCNT‐EP nanocomposite were recorded over UCNT‐EP and neat epoxy at room temperature environment. Flexural testing at elevated temperatures revealed a higher rate of strength degradation in polymer nanocomposites over neat epoxy. Postfailure analysis of specimens has been conducted to understand the alteration in failure micro‐mechanisms upon UCNTs and FCNTs addition in epoxy. Variation in viscoelastic properties with temperature has been studied from dynamic mechanical thermal analysis and significant reduction in glass transition temperature (T_g) is observed for nanocomposites. In the studied temperature and stress combinations, FCNT‐EP nanocomposites exhibited better creep resistance over UCNT‐EP and neat epoxy. Room temperature strengthening, elevated temperature strength degradations, improved creep resistance and reduction in T_g in nanocomposites over neat polymer have been discussed in terms of dynamic nature and gradient structure of CNT/epoxy interphase. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44851.     

Nano‐AlN functionalization by silane modification for the preparation of covalent‐integrated epoxy/poly(ether imide) nanocomposites

Aluminum nitride nanoparticle (nano‐AlN) organically modified with the silane‐containing epoxide groups (3‐glycidoxypropyltrimethoxy silane, GPTMS) was incorporated into a mixture of poly(ether imide) (PEI), and methyl hexahydrophthalic anhydride‐cured bisphenol A diglycidyl ether grafted by GPTMS was prepared for nanocomposite. Scanning electron microscopy, transmission electron microscopy, and atomic force microscopy were used to investigate the microscopic structures of nanocomposites. According to experimental results, it was shown that addition of nano‐AlN and PEI into the modified epoxy could lead to the improvement of the impact and bend strengths. When the concentrations of nano‐AlN and PEI were 20 and 10 pbw, respectively, the toughness/stiffness balance could be achieved. Dynamic mechanical analysis (DMA) results displayed that two glass transition temperatures (T_g) found in the nanocomposites were assigned to the modified epoxy phase and PEI phase, respectively. As nano‐AlN concentration increased, T_g value of epoxy phase had gradually increased, and the storage modulus of the nanocomposite at the ambient temperature displayed an increasing tendency. Additionally, thermal stability of the nanocomposite was apparently improved. The macroscopic properties of nanocomposites were found to be strongly dependent on their components, concentrations, dispersion, and resulted morphological structures. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010