Morphology and mechanical properties of a novel amorphous polyamide/nanoclay nanocomposite

A novel amorphous polyamide/montmorillonite nanocomposite based on poly(hexamethylene isophthalamide) was successfully prepared by melt intercalation. Wide angle X-ray diffraction and transmission electron microscopy showed that organoclay containing quaternary amine surfactants with phenyl and hydroxyl groups was delaminated in the polymer matrix resulting in well-exfoliated morphologies even at high montmorillonite content. Differential scanning calorimetry results indicated that clay platelets did not induce the formation of a crystalline phase in this amorphous polymer. Tensile tests demonstrated that the addition of nanoclay caused a dramatic increase in Young's modulus (almost twofold) and yield strength of the nanocomposites compared with the homopolymer. The nanocomposites exhibited ductile behavior up to 5 wt % of nanoclay. The improvement in Young's modulus is comparable with semicrystalline aliphatic nylon 6 nanocomposites. Both the main chain amide groups and the amorphous nature of the polyamide are responsible for enhancing the dispersion of the nanofillers, thereby, leading to improved properties of the nanocomposites. The structure-property relationship for these nanocomposites was also explored. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 2605–2617, 2008     

Polyimide-silver nanocomposite containing phosphine oxide moieties in the main chain: Synthesis and properties

<正>New flame-retardant polyimide-silver nanocomposite containing phosphine oxide moiety in the main chain was synthesized by a convenient ultraviolet irradiation technique.A precursor such as AgNO_3 was used as the source of the silver particles.Polyimide 6 as a source of polymer was synthesized by polycondensation reaction of bis(3-aminophenyl) phenyl phosphine oxide 4 with pyromellitic anhydride 5 in the presence of iso-quinoline as base and in m-cresol solution.The resulting composite film was characterized by FTIR spectroscopy,X-ray diffraction(XRD),transmission electron microscopy(TEM),thermogravimetry(TGA) and differential scanning calorimetry(DSC).The average size of the nanometer Ag particles is about 10 nm.The temperature of 5 and 10%weight loss and also the char yield at 600℃of polyimide-silver nanocomposite 6a were higher than the pure PI 6.     

Synthesis and properties of polyimide/silver nanocomposite containing dibenzalacetone moiety in the main chain

A new thermally stable polyimide–silver nanocomposite containing dibenzalacetone moiety in the main chain was synthesized by a convenient ultraviolet irradiation technique. A precursor such as AgNO₃ was used as the source of the silver nanoparticles. Polyimide 6 as a source of polymer was prepared by polycondensation reaction of 2,5-bis(4-aminobenzylidene) cyclopentanone 4 with pyromellitic anhydride 5 in m-cresol solution and in the presence of iso-quinoline as a base. The resulting nanocomposite film was characterized by FTIR spectroscopy, X-ray diffraction (XRD), Scanning electron microscopy (SEM), Thermal gravimetric analyses (TGA), differential gravimetric analyses (DTG) and differential scanning calorimetry (DSC). Scanning electron microscopy (SEM) confirmed the formation and dispersion of silver nanoparticles in polymer matrix having average size of ～20 nm. Incorporation of inorganic metal silver nanoparticles has improved the thermal behavior of the nanocomposite film as compared to pure polyimide film. Also 2,5-bis(4-aminobenzylidene) cyclopentanone 4 was synthesized by using a two-step reaction.     

Morphology and mechanical properties of binary triblock copolymer blends

The influence of the morphology on the mechanical properties of binary styrene–butadiene (SB) triblock copolymer blends of a thermoplastic block copolymer and a thermoplastic elastomer (TPE) with different molecular architectures was studied with bulk samples prepared from toluene. Both block copolymers contained SB random copolymer middle blocks, that is, the block sequence S–SB–S. The two miscible triblock copolymers were combined to create a TPE with increased tensile strength without a change in their elasticity. The changes in the equilibrium morphology of the miscible triblock copolymer blends as a function of the TPE content (lamellae, bicontinuous morphology, hexagonal cylinders, and worms) resulted in a novel morphology–property correlation: (1) the strain at break and Young's modulus of blends with about 20 wt % TPE were larger than those of the pure thermoplastic triblock copolymer; (2) at the transition from bicontinuous structures to hexagonal structures (～35 wt % TPE), a change in the mechanical properties from thermoplastic to elastomeric was observed; and (3) in the full range of wormlike and hexagonal morphology (60–100 wt % TPE), elastomeric properties were observed, the strength greatly increasing and high‐strength elastomers resulting. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 429–438, 2005     

The POSS side chain epoxy nanocomposite: Synthesis and thermal properties

The IPI‐POSS‐modified epoxy resin (IPEP) was prepared from isocyanato‐propyldinethylsilyl‐isobutyl‐POSS (IPI‐POSS) and diglycidyl ether of bisphenol A epoxy resin. The steric hindrance of the IPEP bulky POSS side chain improved the curing activation energies. The POSS particles sizes were about 2–3 nm and dispersed uniformly. At lower IPEP concentration (POSS < 12 wt %), the glass transition temperatures (T_gs) of the IPEP nanocomposites increased from 118 to 170 °C. The char yield increased from 15 to 20 wt %, and the LOI values increased from 22 to 28. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 643–652, 2010     

Morphology and physical properties of polyethylene/silicate nanocomposite prepared by melt intercalation

Maleated polyethylene (PEMA)/silicate nanocomposites with a different aspect ratio of silicate and maleated PEMA/SiO₂ composite were prepared by melt intercalation. The nanocomposites with a high aspect ratio silicate (montmorillonite) showed a faster decrease in the terminal slope of the storage modulus and a steeper increase in complex viscosity than those with a low aspect ratio silicate (laponite) and SiO₂. The addition of montmorillonite increases the crystallization and the melting temperature of PEMA but decreases above 3 vol % of the silicate content because of the increased viscosity. The nanocomposite with montmorillonite showed the highest yield strength and secant modulus among the composites because of the highest aspect ratio of the filler. It also revealed strong interfacial adhesion with the matrix and orientation during tensile deformation. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1454–1463, 2002     

Morphology of isotactic polypropylene-polyamide 66 blends and their mechanical properties

Compounds were prepared with isotactic polypropylene (iPP) matrix and recycled polyamide 66 fibres (PA66), which were obtained as soft waste in industrial production process. Blends with pristine PA66 pellets were prepared as comparison. The blends showed the presence of PA66 particles dispersed in the PP continuous phase. Considering the incompatibility of the two polymers the addition of isotactic polypropylene grafted with maleic anhydride (iPPgMA) as compatibilizer was investigated: the blends were characterized by thermal, mechanical, dynamic-mechanical and morphological analyses. The presence of the compatibilizer significantly influences the morphology of the blends, inducing a finer dispersion and promoting interfacial adhesion. The characterization of pristine and recycled PA66 did not show a meaningful difference in the value of molecular weight, on the other hand marked differences were presented in the flexural moduli of the two materials; analogous differences were exhibited by the blends: compounds prepared with recycled PA66 showed flexural moduli higher than compatibilized blends with pristine PA66.     

Preparation,characterization, mechanical and barrier properties investigation of chitosan-kaolinite nanocomposite

The purpose of this study was to prepare a novel Clay Bio-Polymer Nanocomposite (CBPN) films by mixing polymer (chitosan, C) with exfoliated nanoclay (kaolinite, k). DRX has shown that the mechano-chemical treatment of kaolinite allows its exfoliation and the significant reduction of its particles size. Physicochemical properties namely thickness, water solubility, color, light transmission and transparency of the films were studied. Fourier transform infrared analysis (FTIR) was to study the interaction between chitosan and kaolinite. Differential scanning calorimetry (DSC) scans showed that the transition temperature (Tg) of films depends on the film's composition. The surface morphology of the films was also studied by scanning electron microscopy (SEM). Results showed that water solubility (Ws) decrease with the increase of the amount of clay. In addition, the presence of clay in the said films increases the mechanical strength. All prepared films were tested for their antimicrobial activities against gram-positive and gram-negative bacteria (strain). It was found that all CBPN films showed good inhibitory activity against all the tested bacteria. The above analysis suggested that the CBPN films could be used as potential candidates for therapeutic application.     

Transparent h-BN/polyacrylamide nanocomposite hydrogels with enhanced mechanical properties

In this study, a facile way has been proposed to prepare transparent, tough and flexible polyacrylamide (PAM) hydrogels which is composed of a dually crosslinked single network by chemical crosslinking of N,N'-methylenebisacrylamide (BIS) and physical crosslinking of hydrophilic hexagonal boron nitride (hBN) nanosheets. The resulting h-BN/PAM nanocomposite hydrogels are highly transparent, and exhibit significantly enhanced mechanical properties compared to the dark (GO)/PAM nanocomposite hydrogels or chemical crosslinking PAM hydrogels. Thus it opens up new opportunities for developing nextgeneration transparent, tough and flexible hydrogels that hold great promise in such important applications as light responsive soft robot and liquid microlenses.     

Morphology and mechanical properties of poly(ether-imide)-modified polycyanurates

A high temperature thermosetting bisphenol A dicyanate (BADCy) was modified with a novel thermoplastic poly(ether-imide) (PEI) at various compositions. Fourier transform infrared spectroscopy was used to measure the conversion of BADCy. Curing kinetics of the BADCy/PEI blend were studied by the dynamic differential scanning calorimeter method. Morphologies of PEI-modified polycyanurates were investigated by scanning electron microscopy (SEM). It was found that the phase structures of the blends changed dramatically with the PEI content and molecular weight. The tensile results showed that the mechanical properties could be correlated with the morphologies. The blend with cocontinuous morphology had the highest tensile strength and elongation at break while the blend with ribbon-like morphology had the lowest one despite PEI molecular weight.     

Effect of ZnO nanoparticles on the thermal and mechanical properties of epoxy-based nanocomposite

Effect of ZnO nanoparticles particles on the mechanical properties and the curing behavior of an epoxy nanocomposite were studied. Nanocomposites were prepared using different loadings of pre-dispersed ZnO nanoparticles having an average size of 40 nm. The surface topography and morphology of the nanocomposites were studied using atomic force microscope (AFM). The mechanical properties of nanocomposites were studied using analytical techniques including dynamic mechanical thermal analysis and micro-Vickers hardness. Effects of ZnO nanoparticles on the curing behavior of these nanocomposites were investigated utilizing isothermal and non-isothermal differential scanning calorimeter techniques. In addition, chemical compositions of coatings containing different ZnO nanoparticles contents were studied using a Fourier transform inferred. It was found that, ZnO nanoparticles can effectively influence the mechanical properties of epoxy coating. In addition, lower curing degrees, and therefore crosslinking density of epoxy coating including higher ZnO nanoparticles were obtained. This effect was completely different at low and high loadings of the particles.     

Synthesis and characterization of fluorinated polyurethane containing carborane in the main chain: Thermal,mechanical and chemical resistance properties

In this study, two fluorinated polyurethanes(FPU) containing carborane groups in the main chains were firstly designed and synthesized via the reaction of hexamethylene diisocyanate trimer(HDI trimer) with fluorinated polyesters(CFPETs) having hydroxyl-terminated carborane groups at room temperature. The structures of carborane fluorinated polyesters(CFPETs) and polyurethanes(CFPUs) were characterized by gel permeation chromatography(GPC), Fourier transform infrared(FTIR) spectroscopy and nuclear magnetic resonance(NMR) measurements. The thermal stability, mechanical properties, Shore A hardness, solvent resistance and acid-alkali resistance of the carborane fluorinated polyurethane films were also studied. Thermogravimetric analysis(TGA) tests manifested that the introduction of carborane groups into the main chain of fluorinated polyurethane endowed the obtained fluorinated polyurethane with excellent thermal stability. The thermal decomposition temperature of carborane fluorinated polyurethane(CFPU) increased by 190 °C compared with that of the carborane-free fluorinated polyurethane(FPU). Even at 800 °C, CFPU showed the char yield of 66.5%, which was higher than that of FPU(34.3%). The carborane-containing fluorinated polyurethanes also showed excellent chemical resistance and prominent mechanical property even after the cured films being immersed into Jet aircraft oil or 37% HCl for 168 h or at high temperature(700 °C). It is found that the structural characteristics of carborane group and the compacted structure of CFPU effectively improve the thermal stability, mechanical property, solvent resistance and acid-alkali resistance of the carborane-free fluorinated polyurethane. These excellent properties make CFPU as the useful raw materials to prepare the high temperature resistant coatings or adhesives for automotive engines, engine or fuel tank of aircraft and other equipment working in high-temperature or high concentrations of acid-alkali environments.     

Preparation and characterization of a novel stimuli-responsive nanocomposite hydrogel with improved mechanical properties

A novel stimuli-responsive organic/inorganic nanocomposite hydrogel (NC hydrogel) with excellent mechanical properties was synthesized by in situ polymerization of 2-(2-methoxyethoxy) ethyl methacrylate (MEO(2)MA), oligo (ethylene glycol) methacrylate (OEGMA) and acrylic acid (AAc), as the polymeric matrix (PMOA), and fibrillar attpulgite (AT), as the reinforcer and cross-linker. The effect of the AT content on the mechanical properties for the swollen and dried NC hydrogels was determined by tensile testing and dynamic mechanical analysis (DMA), respectively. The tensile testing results showed that the incorporation of AT nanoparticles significantly enhanced the mechanical properties of NC hydrogels. As the content of AT increased, the tensile strength, tensile modulus and effective cross-linked chain density increased. The DMA results showed that the storage modulus of AT/PMOA NC hydrogels was increased and the glass transition temperatures shifted to higher temperature compared to the pure PMOA hydrogel, which further indicated that the enhancement of mechanical property depended upon the presence and content of AT. In addition, the faster swelling rates of the NC hydrogels were observed in comparison with the corresponding physically cross-linked PMOA hydrogel, except for 1% AT/PMOA sample. However, the deswelling kinetics of NC hydrogels was obviously retarded.     

Polyolefin-functionalized graphene oxide and its GO/HDPE nanocomposite with excellent mechanical properties

An effective strategy for the polyolefin-functionalized graphene oxide (fGO) using two-step methods has been reported for GO/HDPE nanocomposite with excellent mechanical properties.     

Dynamic mechanical properties of crosslinked polyurethanes containing sodium tetraphenylborate

Crosslinked polyurethane elastomers consisting of low-molecular-weight polyethylene oxide or polypropylene oxide segments crosslinked with an aromatic triisocyanate have been studied. Networks have been prepared containing different amounts of sodium tetraphenylborate. The effects of temperature and salt concentration on their viscoelastic properties have been investigated by modulus and loss-tangent measurements. Variations of the storage modulus with salt concentration or network chemical structure are directly correlated with variations in the glass transition temperature. In fact, superposition of the various modulus plots on a reduced temperature scale, T-T_g, suggests that there is no dependence on salt concentration or polyether chemical structure.     

Synthesis and properties of new biotin compounds containing hexyltriethylene glycol chain

The synthesis of a new halogenide containing hexyltriethylene glycol chain functionalized with biotin is reported. The general possibility of this linker to use as the building block for biotinylated compounds syntheses is demonstrated. Two biotinylated esters with different properties for useful surface modification and as fluorescence probes for proteins marking were synthesized. The properties of mentioned compounds were investigated by using surface plazmon resonance ellypsometry and fluorescence spectroscopy.     

Morphology, morphology development and mechanical properties of polystyrene/polybutadiene blends

Polystyrene/polybutadiene (PS/PB) blends with different plastic/rubber ratios were prepared by melt mixing. A detailed investigation on phase morphology development of 30/70 wt.% PS/PB blends as a function of processing conditions was quantitatively analyzed. Morphology is developed at the initial stages of mixing. Suitable blending conditions resulting in optimum phase morphology were obtained at 180 °C, 60 rpm and at 8 min mixing time. Phase morphologies of the blends were also studied as a function of composition. Mechanical properties of the blends were measured. Attempts were made to correlate the morphologies with the properties. Parallel-Voids model has been applied to characterize phase morphology of these blends.     

Bioactivity and mechanical properties of nickel‐incorporated hydrogenated carbon nanocomposite thin films

In this paper, the influence of nickel incorporation on the mechanical properties and the in vitro bioactivity of hydrogenated carbon thin films were investigated in detail. Amorphous hydrogenated carbon (a‐C:H) and nickel‐incorporated hydrogenated carbon (Ni/a‐C:H) thin films were deposited onto the Si substrates by using reactive biased target ion beam deposition technique. The films' chemical composition, surface roughness, microstructure and mechanical properties were investigated by using XPS, AFM, TEM, nanoindentation and nanoscratch test, respectively. XPS results have shown that the film surface is mainly composed of nickel, nickel oxide and nickel hydroxide, whereas at the core is nickel carbide (Ni₃C) only. The presence of Ni₃C has increased the sp² carbon content and as a result, the mechanical hardness of the film was decreased. However, Ni/a‐C:H films shows very low friction coefficient with higher scratch‐resistance behavior than that of pure a‐C:H film. In addition, in vitro bioactivity study has confirmed that it is possible to grow dense bone‐like apatite layer on Ni/a‐C:H films. Thus, the results have indicated the suitability of the films for bone‐related implant coating applications. Copyright © 2011 John Wiley & Sons, Ltd.