- Rapid electroplating of photocatalytically highly active TiO sub 2 -Zn nanocomposite films on steel
Deguchi, T; Imai, K; Matsui, H; Iwasaki, M; Tada, H; Ito, S
Journal of Materials Science (USA), vol. 36, no. 19, pp. 4723-4729, 1 Oct. 2001
Nanocomposite films consisting of TiO sub 2 and Zn with thickness of 10-15 mu m (TiO sub 2 -Zn) have been electrodeposited on steel plates by rapid plating from a ZnSO sub 4 -based bath (I sub d > 10 A dm exp -2 ). Upon addition of NH sub 4 NO sub 3 to the bath (<0.3g L exp -1 ), the uptake of TiO sub 2 in the film significantly increased. Glow discharge optical emission spectrometry clarified that TiO sub 2 particles were incorporated throughout the film and the loaded amount increased near the surface. The first-order rate constant (k/h exp -1 ) for gas-phase CH sub 3 CHO oxidation was employed as an indicator of the photocatalytic activity. The k value for the TiO sub 2 -Zn film prepared at Id = 12 A dm exp -2 (0.20 h exp -1 ) was comparable to that for the sample from a ZnCl sub 2 -based bath at I sub d = 4 A dm exp -2 (0.27 h exp -1 ). X-ray diffraction measurements indicated that a TiO sub 2 -ZnO nanocomposite layer was generated on the surface by the heat treatment in air at 673 K for 6 h. Consequently, the photocatalytic activity was further improved (k = 0.29 h exp -1 ); this effect was explained in terms of the synergy of TiO sub 2 and ZnO in photocatalysis.
- Wear-resistant amorphous and nanocomposite steel coatings
Branagan, DJ; Swank, WD; Haggard, DC; Fincke, JR
Metallurgical and Materials Transactions A (USA), vol. 32A, no. 10, pp. 2615-2621A, Oct. 2001
In this article, amorphous and nanocomposite thermally deposited steel coatings have been formed by using both plasma and high-velocity oxy-fuel (HVOF) spraying techniques. This was accomplished by developing a specialized iron-based composition with a low critical cooling rate (approx =10 exp 4 K/s) for metallic glass formation, processing the alloy by inert gas atomization to form micron-sized amorphous spherical powders, and then spraying the classified powder to form coatings. A primarily amorphous structure was formed in the as-sprayed coatings, independent of coating thickness. After a heat treatment above the crystallization temperature (568 deg C), the structure of the coatings self-assembled (i.e., devitrified) into a multiphase nanocomposite microstructure with 75 to 125 nm grains containing a distribution of 20 nm second-phase grain-boundary precipitates. Vickers microhardness testing revealed that the amorphous coatings were very hard (10.2 to 10.7 GPa), with further increases in hardness after devitrification (11.4 to 12.8 GPa). The wear characteristics of the amorphous and nanocomposite coatings were determined using both two-body pin-on-disk and three-body rubber wheel wet-slurry sand tests. The results indicate that the amorphous and nanocomposite steel coatings are candidates for a wide variety of wear-resistant applications. (Stainless steel substrates.)
- Microstructures and the magnetic properties of Fe sub 3 B/(Nd, Dy) sub 2 Fe sub 14 B nanocomposite microalloyed with Cu and Zr
Kajiwara, K; Mono, K; Hirosawa, S
Materials Transactions (Japan), vol. 42, no. 9, pp. 1858-1861, Sept. 2001
The effect of Zr and Cu addition to a Nd sub 34 Dy sub 1 Fe sub 72.3 B sub 18.5 Cr sub 2.4 Co sub 2.4 alloy on the microstructure and the magnetic properties of Fe sub 3 B/Nd sub 2 Fe sub 14 B nanocomposite has been investigated by a three-dimensional atom probe (3DAP) and transmission electron microscopy (TEM). Addition of a small amount of Zr and/or Cu is effective in improving the hard magnetic properties of the base alloy. Cu atoms form clusters in the early stage of crystallization, and Zr atoms are segregated at the interfaces of Fe sub 3 B/Nd sub 2 Fe sub 14 B being rejected from the Fe sub 3 B soft magnetic phase on the optimal heat-treated condition. This causes refining the nanocomposite microstructure, resulting in improved hard magnetic properties compared to those of the base alloy.
- Hydrogen sorption properties of an Mg-Ti-V-Fe nanocomposite obtained by mechanical alloying
Khrussanova, M; Grigorova, E; Mitov, I; Radev, D; Peshev, P
Journal of Alloys and Compounds (Switzerland), vol. 327, no. 1-2, pp. 230-234, 30 Aug. 2001
The absorption-desorption characteristics with respect to hydrogen of a magnesium-based nanocomposite obtained by high-energy ball milling have been investigated. The composite contains 5 wt.% (approx3 at.%) Ti, 10 wt.% (approx5.5 at.%) V and 10 wt.% (approx5 at.%) Fe, of which the former two transition metals only form a binary hydride. It has been shown that at 623 K the composite may be hydrided up to a very high absorption capacity whose values remain appropriate for practical purposes even at much lower hydriding temperatures. Part of the iron present in the composite has been found to interact with magnesium and hydrogen under the hydriding conditions, the ternary hydride Mg sub 2 FeH sub 6 being formed. Its presence in the composite-hydrogen system has been assumed to be responsible for the reduced rate of hydrogen desorption from the particle surfaces and for some peculiarities of the composite behaviour during hydriding.
- Abrasion resistant low friction diamond-like multilayers
Dekempeneer, E; Acker, KV; Vercammen, K; Meneve, J; Neerinck, D; Eufinger, S; Pappaert, W; Sercu, M; Smeets, J
Elsevier Science SA, Surface and Coatings Technology (Switzerland), vol. 142-144, pp. 669-673, July 2001
Over the past few years, we have investigated plasma deposited amorphous hydrogenated carbon (DLC) films modified with B, N and Si dopants. Whereas, all three elements have the advantage to induce stress relief in the films (combined with hardness reduction), Si appeared to be the most interesting alloying element for tribological applications (friction and wear). Following this work, multilayer coatings consisting of a stack of DLC layers alternated with Si-doped DLC films and more recently, diamond-like nanocomposite (Dylyn, a-C:H/a-Si:O) films were developed. A major advantage of the multilayer structure is the stress relief enabling the deposition of thick layers (10 mu m) without any loss of good adhesion properties. These thick multilayers show improved abrasion resistance as well as extremely low friction properties (friction coefficient < 0.1 independent of the relative humidity). This paper discusses the mechanical and tribological properties of these multilayer coatings and presents a comparison to various other layer systems (TiN, CrN and hard Cr). Materials used as substrates: M2 steel.
- Characteristics of high energy milled W-Ni-Fe nanocomposite powders
Fan, J; Huang, B; Qu, X; Zhao, M
Xiyou Jinshu Cailiao yu Gongcheng (Rare Metal Materials and Engineering) (China), vol. 30, no. 3, pp. 208-211, June 2001
Systematic investigations were carried out on the structural change, surfacial characteristic and thermal stability of the 90W-7Ni-3Fe(mass%) high energy milled powders using a combination of X-ray powder diffraction, brunauer-emmett-teller (BET) nitrogen adsorption technique and differential thermal analysis assited by DTA. The experimental results show that ball-milling could produce an ultrafine composite powders in which large lattice distortion, supersolidus solution, amorphous phase and solubility extension of W in gamma phase were occurred due to the fast diffusion induced by high density of lattice defects and nanograin boundaries. BET results provide a further evidence that milling led the specific surface area of powders, surface of mesopore, pore size to decrease and micro pores to produce.
- Structure and properties of HVOF sprayed amorphous polymer matrix nanocomposite coatings
Knight, R; Fang, X; Twardowski, TE
ASM International, Thermal Spray 2001: New Surfaces for a New Millenium: Proceedings of the International Thermal Spray Conference (USA), pp. 361-368, Apr. 2001
The high velocity oxy-fuel [HVOF] combustion spray technique has previously been shown to be an excellent solution for depositing crystalline matrix nano-reinforced polymer coatings. Dense polymer coatings can be produced by controlling both the particle dwell time in the HVOF jet and through substrate thermal management. Use of an amorphous matrix material, polycarbonate, will enable the role of matrix crystallinity on the structure and properties of thermally sprayed polymer matrix nanocomposite coatings to be separated from effects resulting from the reinforcing phase. An amorphous, commercial polycarbonate powder with a broad particle size distribution and irregular particle morphology has been successfully deposited by HVOF spraying using hydrogen as fuel gas. Polycarbonate matrix coatings up to 18 mils thick with zero to 10 vol.% loadings of nano-sized hydrophobic and hydrophilic silica, and carbon-black have been sprayed onto Al substrates. Results from optical microscopy, X-ray diffraction, scratch, density, microhardness and dilute- solution viscometry measurements will be presented. These indicate that incorporation of the nanosized filers improved the scratch resistance and microhardness of the coatings by 50% and 23%, respectively, relative to sprayed pure polymer. Some degradation of the polymer matrix was also detected, with molecular weight being reduced from 17,000 in the feedstock to approx =5,000 in the sprayed deposits. The influence of variations in process parameters such as fuel: oxygen ratio, total gas flow, spray distance, nozzle length, total travel distance, and spray distance/nozzle length ratio on coating structure will also be addressed. The threshold loading of silica in the polycarbonate matrix for which dense coatings can be obtained has also been determined. Substrates: 6061 aluminum.
- Enhancement of corrosion protection effect in polyaniline via the formation of polyaniline-clay nanocomposite materials
Yeh, J-M; Liou, S-J; Lai, C-Y; Wu, P-C; Tsai, T-Y
Chemistry of Materials (USA), vol. 13, no. 3, pp. 1131-1136, Mar. 2001
A series of nanocomposite materials that consisted of emeraldine base of polyaniline and layered montmorillonite (MMT) clay were prepared by effectively dispersing the inorganic nanolayers of MMT clay in organic polyaniline matrix via in-situ polymerization. Organic aniline monomers were first intercalated into the interlayer regions of organophilic clay hosts and followed by an one-step oxidative polymerization. The as-synthesized polyaniline-clay lamellar nanocomposite materials were characterized by infrared spectroscopy, wide-angle powder X-ray diffraction, and transmission electron microscopy. Polyaniline-clay nanocomposites (PCN) in the form of coatings with low clay loading (e.g., 0.75 wt %) on cold-rolled steel (CRS) were found much superior in corrosion protection over those of conventional polyaniline based on a series of electrochemical measurements of corrosion potential, polarization resistance, and corrosion current in 5 wt % aqueous NaCl electrolyte. The molecular weights of polyaniline extracted from PCN materials and bulk polyaniline were determined by gel permeation chromatography (GPC). Effects of the material composition on the gas barrier property, thermal stability, and mechanical strength of polyaniline along with PCN materials, in the form of both fine powder and free-standing film, were also studied by gas permeability measurements, differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical analysis.
- Ultra high strength nanofilamentary conductors: the way to reach extreme properties
Thilly, L; Lecouturier, F; Coffe, G; Peyrade, JP; Askenazy, S
Physica B: Condensed Matter (Netherlands), vol. 294-295, pp. 648-652, Jan. 2001
To enhance the intensity of non-destructive magnetic fields with long pulse duration, reinforced conductors are needed with extremely high mechanical strength and good electrical conductivity. The ideal conductors for this application should have an action integral close to that of pure copper. An elaboration process based on cold drawing and restacking has been developed at LNCMP for this purpose. The best results have been obtained with Cu/Nb nanocomposite wires with a section of 3 x 10 exp -2 mm exp 2 composed of a copper matrix embedding 9 x 10 exp 6 continuous parallel niobium whiskers with a diameter of 40 nm. The ultimate tensile strength is 1950 MPa at 77 K. The fundamental properties linked to the effect of nanometer size have been investigated. Nevertheless, because of their small section these conductors cannot be practically used in the winding of our magnets. Therefore, we are elaborating a new generation of optimized Cu/Nb nanostructured wires exhibiting ultra high strength in a section of 2 mm exp 2 . The latest developments are presented. Concurrently, we are developing Cu/Ta multifilamentary conductors. Since the shear modulus of tantalum is greater than that of Nb ( mu sub Ta approx = 2 mu sub Nb ) the Cu/Ta UTS should be enhanced. However, drawing of Cu/Ta billets leads to the formation of a macroscopic roughness at the Cu/Ta interface and to the fracture of Ta. This phenomenon is interpreted in terms of stress-driven rearrangement (Grinfeld instabilities). We have investigated some solutions to prevent its formation.
- Nanocomposites: auto exteriors and beyond
Injection Molding (USA), vol. 9, no. 11, pp. 52, Nov. 2001
General Motors now has in production a van step-assist that is molded from a new TPO nanocomposite material and is found on the 2002 GMC Safari and Chevy Astro vans. Three years ago, GM and Basell Polyolefins began work on a new nanocomposite TPO material with a smectite clay filler. The nanocomposite step-assist replaces a talc-filled TPO version and saves up to 20% in weight. Nanocomposite materials are making headway in other applications as well, according to compounder RTP, which introduced a nanocomposite nylon 6 material (filled with nano-sized clay particles) more than two years ago. Contact: Michelle Talmo, Basell North America, Wilmington, Delaware, USA, tel 302/996-6000, website: www.basell.com; Steve Bowen, RTP Co, Winona, Minnesota, tel 507/454-6900, website: www.rtpcompany.com.
- Nanocomposites broaden roles in automotive, barrier packaging
Plastics Technology (USA), vol. 47, no. 10, pp. 64-69, Oct. 2001
Nanocomposites are gradually gaining acceptance in the mainstream of global plastics processing. These polymer compounds, containing relatively low loadings (<6 wt.%) of nanometer-sized mineral particles, are starting to show up in polypropylene and TPO-based automotive exterior claddings, barrier beer bottles, nylon packaging films, polyethylene pipe and wire/cable coatings, and more. An expanding supply base, a growing range of matrix resins, and new-generation reinforcements all point to broad market impact in the next few years.
- Nanocomposite debuts on GM vehicles
Automotive Engineering International (USA), vol. 109, no. 10, pp. 56, Oct. 2001
The 2002 Chevrolet Astro and GMC Safari midsize vans are the first vehicles to use an advanced thermoplastic olefin nanocomposite on an exterior application, reports General Motors Corp. The application is a step-assist, a running board designed to help people enter and exit a vehicle. GM and three supplier partners (Basell, Southern Clay Products, and Blackhawk Automotive Plastics, Inc) worked to bring the TPO-based nanocomposite to production. A technology breakthrough deals with how the very thin flakes of a clay filler are peeled apart.
- Polymer matrix nanocomposite cuts structure weight, cost
Advanced Materials & Processes (USA), vol. 159, no. 8, pp. 19-20, Aug. 2001
Polymer matrix nanocomposites based on the molecular-level dispersion of highly anisotropic, inorganic, nanoscale rods or plates have been developed by Triton Systems Inc, with the support of the Air Force Research Laboratory Materials and Manufacturing Directorate. Polymer nanocomposites exibit significant increases in thermal stability and over tenfold improvement as a barrier to oxygen and water vapor compared to conventional polymer resins. The nanoscale inorganic particles comprise <10% of the weight of the composites, compared with conventional polymer composites in which the reinforcement materials comprise >30% of the weight. Potential applications include replacement of filled and structural components in automobiles, high barrier food packaging, and upgrading of fiber composites. Contact: Air Force Research Laboratory, Materials and Manufacturing Directorate, Technology Information Center, Wright Patterson Air Force Base, Ohio 45433, USA; tel 937/255-6469, email: firstname.lastname@example.org; refer to item #00-002.
- University of Akron poised to advance nano-technology
Polymer News (USA), vol. 26, no. 2, pp. 60, Feb. 2001
Efforts by the University of Akron (Akron, Ohio, USA) to establish a national nanotechnology research center has received a substantial boost from Washington, DC. It includes a $1 million provision for the creation of the center in a federal spending bill. The nanotechnology center will serve public and private sector research agencies in the development of advanced materials and devices, including new lightweight polymer materials. The center will focus on nanocomposites. Leading the University of Akron in this research will be the institution's College of Polymer Science and Polymer Engineering.
- NIST/industry consortium to tackle complex polymer interphases
NIST Update (USA), pp. 3, 8 Jan. 2001
The interphase is vital to the durability and performance of nanocomposites, particle-filled materials, paints on plastics and metals, and fiber-reinforced polymer composites. In December 2000, the US National Institute of Standards and Technology (NIST) and industry partners established the Consortium on Characterization and Modeling of the Interface and Interphases of polymeric Materials and Systems (also known as the Polymers Interphase Consortium or PIC) to conduct a three-year investigation of the chemical, physical and morphological characteristics of the interface/interphase region. Contact: Tinh Nguyen, tel 301 /975-6718, email: email@example.com; or, Charles Han, tel 301 /975-6772, email: firstname.lastname@example.org.
- Nanocomposites: polymer technology for the next century, 1999
Plastics Engineering (USA), vol. 56, no. 4, pp. 136-137, Apr. 2000
Although the nanocomposite market is in "its embryonic stage of development," according to a new report from Principia Partners, developing nanocomposite technologies are poised for strong growth over the next ten years. Principia projects that demand in each major region will grow at comparable rates from 2004 through 2009, and the market will reach approx1.2 billion lb in 2009. The study makes a detailed investigation of the driving forces behind the development of and potential markets for these materials. Contact: Principia Partners, Exton, PA, USA; tel 610/458-3738; website: www.principiaconsulting.com.
- Polymer nanocomposites market expected to grow to $195 million by 2004
Business Communications Co., Inc. (USA), pp. 2, 2 Mar. 2000
Polymer nanocomposites have been making a large splash in the media and throughout several industries of late. Polymer nanocomposites are thermoplastics or thermosets combined with fillers having dimensions measured in nanometers. Given all the interest in these materials, it is perhaps surprising to find that actual applications are few and far between. According to a new study, the total US market, which is only in pilot amounts today, is expected to exceed 55 million lb in production by 2004. The value of the market is forecast to reach $195 million by then. The report, RP-234 Polymer Nanocomposites (published April 2000, price $3850), is available from Business Communications Company, Inc (tel 203/853-4266, fax 203/853-0348, website: http://buscom.com)
- A POLYAMIDE COMPOSITION COMPRISING A LAYERED CLAY MATERIAL MODIFIED WITH AN ALKOXYLATED ONIUM COMPOUND
Eastman Chemical Company. Inventors: Bagrodia, Shriram; Gilmer, John, Walker; Matayabas, James, Christopher, Jr.; Owens, Jeffrey, Todd; Bernard, Linda, Gale; Turner, Sam, Richard; Lan, Tie; Psihogios, Vasiliki. Patent Application Number: US0016483. Date: 14 Jun 2000
Patent Number WO0104197
This invention relates to a composite composition comprising one or more polyamide polymers or copolymers, one or more layered clay materials, and one or more alkoxylated ammonium cations. The invention also relates to a process for preparing a nanocomposite and articles produced from the nanocomposite, including bottles.
- POLYAMIDE NANOCOMPOSITES WITH OXYGEN SCAVENGING CAPABILITY
Eastman Chemical Company. Inventors: Bernard, Linda, Gail; Clauberg, Horst; Cyr, Michael, John; Gilmer, John, Walker; Matayabas, James, Christopher, Jr.; Owens, Jeffrey, Todd; Stewart, Mark, Edward; Turner, Sam, Richard; Bagrodia, Shriram. Patent Application Number: US0021629. Date: 8 Aug 2000
Patent Number WO0110945
The present invention relates to polymer-platelet particle composites comprising at least one polyamide resin, at least one oxygen scavenging system, and platelet particles derived from at least one layered silicate material.
- MULTIMODAL STRUCTURED HARDCOATINGS MADE FROM MICRO-NANOCOMPOSITE MATERIALS
Rutgers, The State University; Nanopowder Enterprises Inc. Inventors: Kear, Bernard, H; Skandan, Ganesh. Patent Application Number: US0022340. Date: 16 Aug 2000
Patent Number WO0112431
A thermal spray method for the fabrication of ceramic/metal and ceramic/ceramic hardcoatings for wear applications. The method makes use of feedstock powder, composed of micron-scale aggregates of hard phase material particles that are either mixed or coated with a readily fusible nano-scale binder phase material (12). Thus, during thermal spraying (14), the nanostructured material undergoes rapid melding while the aggregated material is heated but not necessarily melted. A dense coating is formed when the molten nano-material fills the available pore spaces between the heated and softened aggregates, providing a strong and tough matrix for the consolidated material. Optimal wear properties are achieved when the volume fraction of aggregated particles is high, typically in the range 0.5-0.9. Aggregated material may be composed of one, two or more particles of different sizes and/or compositions, with particle size distribution that gives high packing density for the hard phase.
- POLYMER COMPOSITE AND A METHOD FOR ITS PREPARATION
The Dow Chemical Company. Inventors: Polansky, Christine, A.; White, Jerry, E.; Garces, Juan, M.; Kuperman, Alex; Ridley, David, Z. Patent Application Number: EP99912796. Date: 6 Apr 1999
Patent Number EP1088024
A polymer composite comprising an epoxy vinyl ester resin or unsaturated polyester matrix having dispersed therein particles derived from a multilayered inorganic material which possesses organophilic properties. The dispersion of the multilayered inorganic material in the polymer matrix is such that an increase in the average interlayer spacing of the layered inorganic material occurs to a significant extent resulting in the formation of a nanocomposite.
- POLYMERIC NANOCOMPOSITE MATERIALS WITH A FUNCTIONAL MATRIX AND A METHOD OF READING AND WRITING THERETO
Inventors: Kumacheva, Eugenia; Kalinina, Olga. Patent Application Number: CA0001415. Date: 1 Dec 2000
Patent Number WO0140872
A nanocomposite material having a plurality of core particles formed of a core material. The core material has a first glass transition temperature. A shell encapsulates each core particle. The shell is formed of a shell material that has a second glass transition temperature less than the first glass transition temperature. When subjected to a temperature greater than the second glass transition temperature and less than the first glass transition temperature, the shells form a continuous matrix surrounding the core particles. The shell material includes a functional component that can be activated in response to an external excitation. This functional component can include either photosensitive, semiconductor, magnetic, piezoelectric or electro-active components just to mention a few. The different components may be chemically or physically bound to the shell or cores. These nanocomposite materials are used as storage media.
- Magnetically anisotropic rare earth-based nanocomposite permanent magnet
Shin-Etsu Chemical Co., Ltd. Inventors: Nomura, Tadao; Ohashi, Ken. Patent Application Number: 153893. Date: 16 Sep 1998
Patent Number US6261385
Disclosed is a novel magnetically anisotropic rare earth-based permanent magnet having a nanocomposite structure consisting of a hard magnetic phase such as Nd2Fe14B and a soft magnetic phase such as bcc-iron, Fe3B and Fe2B in a volume ratio of 10:90 to 90:10 uniformly dispersed each in the other in a fineness of a few tens nanometers, in which particles of the hard magnetic phase are aligned in a direction relative to the easy magnetization axes of the particles. Such an anisotropic permanent magnet can be prepared by the method comprising: preparing a starting amorphous alloy of a composition susceptible to dispersion precipitation of the hard magnetic phase, for example, by the melt-spun method; forming the amorphous alloy into a magnet block; heating the magnet block at 600 to 1000 C. to effect dispersion precipitation of the hard magnetic phase; and deforming the magnet block at the elevated temperature by compression unidirectionally so that the particles of the hard magnetic phase are aligned relative to the easy magnetization axes of the particles.
- Nanocomposite dense sintered alumina based ceramic cutting tool
Metalloceramica Vanzetti S.p.A.; H.C. Starck GmbH & Co. KG. Inventors: Ferrari, Alberto; Pedrazzi, Giorgio; Schwier, Gerd; Schmitz, Heinz Withold; Morrell, Roger; d'Errico, Giampaolo. Patent Application Number: EP00200076. Date: 11 Jan 2000
Patent Number EP1116703
The present invention concerns a nanocomposite dense sintered alumina and/or alumina/zirconia ceramic cutting tool, obtainable by cold pressing a spray-dried suspension of a nanosized powder of alumina and/or alumina/zirconia, containing of from 1 to 35% by weight of a hard particle phase, in presence of additives, by sintering the so obtained pressed product at a maximum temperature of 1600 C, for a time of from 30 to 90 minutes in an inert atmosphere under raised gas pressure, and by machining the so obtained densified material into standard indexable insert cutting tool.
- A COLORANT COMPOSITION, A POLYMER NANOCOMPOSITE COMPRISING THE COLORANT COMPOSITION AND ARTICLES PRODUCED THEREFROM
Eastman Chemical Company. Inventors: Barbee, Robert, Boyd; Weaver, Max, Allen; Matayabas, James, Christopher, Jr. Patent Application Number: EP99965942. Date: 30 Nov 1999
Patent Number EP1147147
This invention relates to a colorant composition comprising a layered clay material intercalated with at least one cationic colorant, optical brightener or a mixture thereof. This invention also relates to a polymer-clay nanocomposite comprising: (i) a melt-processible matrix polymer; and (ii) a layered clay material intercalated with at least one cationic colorant, optical brightener or a mixture thereof, wherein the clay-cation colorant /optical brightener intercalate is incorporated into the matrix polymer. The invention further relates to articles produced from the polymer nanocomposite.
- NANOCOMPOSITE SURGICAL MATERIALS AND METHOD OF PRODUCING THEM
The Brigham and Women's Hospital, Inc. Inventors: Bellare, Anuj; Fitz, Wolfgang; Gomoll, Andreas, H.; Scott, Richard, D.; Thornhill, Thomas, S. Patent Application Number: EP00918531. Date: 31 Mar 2000
Patent Number EP1163016
Nanocomposite surgical materials, such as cements, having very fine heterogenous structure are formed by incorporating into a polymeric matrix a well dispersed solid, liquid or gaseous filler having an average mass diameter ranging from about 750 nanometers to about 1 nanometer. The average ligament thickness of the surgical composite cements ranges from about 750 nanometers to about 1 nanometer. Methods and apparatus for avoiding air contact during the preparation and transfer of a cement to an in vivo side are described.
- DIAMOND-LIKE NANOCOMPOSITE THIN FILMS FOR AUTOMOTIVE POWERTRAIN COMPONENT COATINGS
Advanced Refractory Technologies, Inc. Inventors: Goel, Arvind; Bray, Donald, J. Patent Application Number: US9615367. Date: 25 Sep 1996
Patent Number WO9714555
A method for inhibiting wear and reducing friction of components in a powertrain assembly comprising applying to said component a coating made from a class of diamond-like solid state materials formed interpenetrating networks comprising a first network of diamond-like carbon stabilized by hydrogen, a silicon network stabilized by oxygen, and optionally at least one network made from dopant elements or dopant compounds containing elements from Groups 1-7b and 8 of the periodic table.
- Thermoplastic elastomer-asphalt nanocomposite composition
Exxon Research & Engineering Company. Inventors: Eidt, Jr, Clarence Martin; Gorbaty, Martin Leo; Elspass, Chester W; Peiffer, Dennis George. Patent Application Number: 556151. Date: 9 Nov 1995
Patent Number US5652284
A composite material is provided comprising an elastomer, from about 0.1 wt % to about 15 wt. % of a layered mineral based on the weight of the total composition and from about 0.1 wt. % to about 15 wt. % of asphalt based on the weight of the total composition.
- Organoclay-aerospace epoxy nanocomposites. I - Carbon fiber composites
Rice, Brian P; Chen, Chenggang; Cloos, Larry; Curliss, David
SAMPE Journal (0091-1062), vol. 37, no. 5, Oct. 2001, p. 7-9
The development of nanostructured materials opens a new paradigm where composite matrix resins can be tailored to optimize properties of interest just as fiber orientation is used to optimize current advanced composites. The type of nanoreinforcement selected for this research is a montmorillonite-based organoclay which is commercially available at a reasonable cost. We have demonstrated two approaches for fabricating continuous carbon fiber composites with an aerospace epoxy/organoclay matrix. Matrix-dominated mechanical properties were measured as well. (Author)
- Organoclay-aerospace epoxy nanocomposites. II - Resin matrix composites
Chen, Chenggang; Curliss, David
SAMPE Journal (0091-1062), vol. 37, no. 5, Oct. 2001, p. 11-18
A low-cost epoxy resin suitable for use as a composite matrix (Epon 862 and Curing Agent W) was modified with various modified clays (montmorillonite) and characterized. The organic treatment of clay was found to be compatible with aerospace epoxy resin and was used to prepare the nanocomposites. The characterization of the wide-angle XRD, small-angle X-ray scattering, and TEM demonstrates that exfoliated nanocomposites were formed. Dynamic mechanical analysis shows that the storage modulus of the nanocomposite is higher than that of the pristine polymer, which is ascribed to the high aspect ratio and high strength of the nanoclay. The solvent uptake, such as acetone for the nanocomposite, is significantly reduced compared with the pristine polymer, which is ascribed to the barrier effect of nanosheets of the nanoclay. Mechanical property measurement of nanocomposite materials includes fracture toughness, strength, and modulus. (Author)
- Ultrathin film actuators fabricated by layer-by-layer molecular self-assembly
Zeng, T; Claus, R; Zhang, F; Du, W; Cooper, K L
Smart Materials and Structures (0964-1726), vol. 10, no. 4, Aug. 2001, p. 780785
Polymer/metal cluster nanocomposite thin films as new types of electroactive polymer (EAP) material have been synthesized by the layer-by-layer (LBL) electrostatic self-assembly process. A self-assembled 11-bilayer poly-S- 119/Pt nanocluster film, with a thickness of approximately 30 nm and a Pt content of 0.49 at. percent, exhibited an actuation response similar to that of conventional ionic polymer-metal composite films for low applied voltage in air, but nonlinear bending behavior in response to a slightly higher applied voltage. The film has a uniform nanostructure with the Pt nanoclusters dispersed within the multiple molecular layers, as confirmed by atomic force microscopy. The self-assembled electroactive films may have different actuation mechanisms from those of traditional piezoelectric materials, and from other EAP materials, due to the quite different LBL laminated structure. Further studies concerning the principles governing the novel processing of the films and applications are under way. (Author)
- Design and properties of hybrid organic-inorganic nanocomposites for photonics
Sanchez, Clement ; Lebeau, Benedicte
MRS Bulletin (0883-7694), vol. 26, no. 5, May 2001, p. 377-387
Some of the latest advances in the area of photochromism, rare earth emission, electroluminescence, and optical sensors are discussed. The emphasis is on emergent photonic materials whose structure and function are organized hierarchically. (CSA)
- Mechanical behavior of polymer and ceramic matrix nanocomposites
Siegel, R W; Chang, S K; Ash, B J; Stone, J; Ajayan, P M; Doremus, R W; Schadler, L S
International Conference on Nanostructured Materials (NANO 2000), Sendai, Japan, Aug. 20-25, 2000, Proceedings, Scripta Materialia (1359-6462), vol. 44, nos. 8-9, 18 May 2001, p. 2061-2064
Recent studies on polymer matrix nanocomposites and nanocrystalline ceramics have shown that tremendous changes in properties can be achieved in these systems compared to analogous materials with micron-scale structures. This paper presents a brief report on the tensile behavior of spherical nanoparticle alumina-filled polymethylmethacrylate (PMMA) and the hardness and fracture toughness of nanotube-filled nanograined alumina. In each case dramatic enhancements were observed in specific mechanical properties at particular values of the volume fraction, dispersion, and/or surface chemistry of the nanoscale filler. (CSA)
- Preparation of polystyrene-graphite conducting nanocomposites via intercalation polymerization
Chen, G-H; Wu, D-J; Weng, W-G; He, B; Yan, W-L
Polymer International; 50 (9) Sep 2001, p.980-5
In situ polymerization of styrene was conducted in the presence of expanded graphite obtained by rapid heating of a graphite intercalation compound (GIC), to form a polystyrene-expanded graphite conducting composite. The composite showed excellent electrically conducting properties even though the graphite content was much lower than in normal composites. The transition of the composite from an electrical insulator to an electrical semiconductor occurred when the graphite content was 1.8 wt%, which is much lower than that of conventional conducting polymer composites. TEM, SEM and other studies suggest that the graphite was dispersed in the form of nanosheets in a polymer matrix with a thickness of 10-30 nm, without modification of the space between carbon layers and the structure of the graphite crystallites. The composite exhibited high electrical conductivity when the graphite content was 2.8-3.0 wt%. This great improvement of conductivity could be attributed to the high aspect ratio (width-to-thickness) of the graphite nanosheets. The rolling process strongly affected the conductivity and the mechanical properties of the composite. (Original abstract)
- Plastic deformation behaviour of thermoplastic/clay nanocomposites
Gloaguen, J M; Lefebvre, J M
Polymer; 42 (13) Jun 2001, p.5841-7
Polymer/clay nanocomposites are materials that display unique properties, even at low clay content, by comparison with conventional mineral-filled polymers. Two systems are considered in the present study: nylon 6/clay hybrids which in situ polymerization is aimed at obtaining a nylon matrix strongly bonded to the delaminated clay platelets; and materials prepared by melt dispersion of organophilic clay in polypropylene (PP), which should in principle result in a reduced degree of polymer-clay interaction. Dynamic viscoelastic analysis is indeed indicative of a noticeable difference when referring to the molecular dynamics glass transition. Plasticity results, in which volume strain is recorded by video-extensometry, show extensive cavitational behaviour retaining a fairly large strain at break, as long as deformation is performed above the glass transition temperature of the matrix. (Original abstract - amended)
- It's a small world
Chemistry and Industry; (6) 19 Mar 2001, p.174-7
Current developments in nanocomposite materials, in which ultramicroscopic crystals of clay or carbon are embedded in plastics, are reviewed. Most of the current applications are in the automotive and packaging fields. Focuses on the groundbreaking work of Toyota in developing unusually fire resistant materials based on nylon-6 and montmorillonite and the subsequent generation of nanocomposites based on the same combination. The particular suitability of nylon-6 for mixing with clays is noted, along with the way in which small quantities of inorganic materials can alter the properties of plastics. The added strength is attributed to the fact that plastics fail under stress due to the propagation of cracks and the filler particles block this stress propagation. The major plastics companies are set to exploit the potential for these materials for applications such as nanotube based composites.
- NANOCLAYS. OPPORTUNITIES IN POLYMER COMPOUNDS
Quarmley, J; Rossi, A
Ind.Miner. No.400, 2001, p.47-49, 52-53.
Nanoclays are a new generation of processed clays of interest in a wide range of high performance composites. A nanoclay is defined as a clay having nanometre-thick platelets that can be modified to make the clay complexes compatible with organic monomers and polymers. Natural smectite clays, particularly montmorillonite, have been the first choice for producing nanoclays, due to their availability, easy extraction, and relatively low cost. The heterogeneity of natural clay can be a problem, however. This can be overcome by using synthetic clays such as hydrotalcite and laponite. Montmorillonite clay suppliers are referred to. The two methods for treating clays, namely, onium ion substitution reaction and the dipole moment approach, are described. The manufacture of nanoclay composites, their market potential, market opportunities, threat to currently used materials, requirements for commercialisation, nanocomposite formulation and process development technology, and the marketing effort required are considered in turn. Significant growth in demand (35% p.a.) is expected over the period 2004-2009.
- LUSTRE POTTERY FROM THE THIRTEENTH CENTURY TO THE SIXTEENTH CENTURY: A NANOSTRUCTURED THIN METALLIC FILM
Perez-Arantegui, J; Molera, J; Larrea, A; Pradell, T; Vendrell-Saz, M; Borgia, I; Brunetti, BG; Cariati, F; Fermo, P; Mellini, M; Sgamellotti, A; Viti, C
J.Am.Ceram.Soc. Vol.84, No.2, 2001, p.442-446.
Lustre is a decorative metallic film that was applied on the surface of mediaeval glazed pottery. It can be obtained via the low-temperature (about 650 C), controlled reduction of copper and silver compounds. It is shown that lustre is a thin layered film (200-500 nm thick) that contains metallic spherical nanocrystals dispersed in a silicon-rich matrix and has a metal-free outermost glassy layer that is 10-20 nm thick. Silver nanocrystals seem to be separated from those of copper, forming aggregates 5-100 micron in diameter. This composite structure exhibits optical properties that are dependent on both the particle size and the matrix. Lustre was thus the first reproducible nanostructured thin metallic film to be made by man. 21 refs.
- SYNTHESIS OF A HYDROXYAPATITE/COLLAGEN/CHONDROITIN SULPHATE NANOCOMPOSITE BY A NOVEL PRECIPITATION METHOD
Rhee S-H; Tanaka, J
J.Am.Ceram.Soc. Vol.84, No.2, 2001, p.459-461.
The nanocomposite, partly mimicking the composition of cartilage, was synthesised using a calcium hydroxide suspension and phosphoric acid solutions that contained several mixing ratios of type II collagen (Col) and chondroitin sulphate (ChS). The precipitates were shaped and consolidated via filter pressing and subsequent cold isostatic pressing, respectively. A preferential alignment of the crystallographic c-axis of the hydroxyapatite nanocrystals along the longitudinal direction of the Col and ChS mixture was observed. The fracture strength and Vickers hardness of the nanocomposites were in the ranges of 35-50 and 119-219 MPa, respectively. This nanocomposite may be applicable for use as a bone substitute, because of its potential capability of bone remodelling through endochondral ossification. 15 refs.
- MECHANICAL AND MAGNETIC PROPERTIES OF Ni-Co DISPERSED Al2O3 NANOCOMPOSITES
Oh S-T; Sando, M; Niihara, K
J.Mat.Sci. Vol.36, No.7, 2001, p.1817-1821.
Effects of the fabrication processing on the microstructure and properties of composites were investigated. High-density Ni-Co dispersed-Al2O3 (Al2O3/Ni-Co) composites were obtained by hydrogen reduction and consolidated using hot pressing and pulse electric current sintering (PECS) of Al2O3, Ni(NO3)2.6H2O and Co(NO3)2.6H2O powder mixtures. Microstructural investigations of the hot-pressed composite fabricated using again wet/dry ball-milled powder mixture after calcination revealed that fine Ni-Co particles, about 145 nm in diameter, dispersed homogeneously at the matrix grain boundaries. In particular, fine microstructure of dispersion with the average size of 90 nm was realised for the specimen consolidated by PECS method. High strength of over 1 GPa and hardness of 19 GPa were measured for the nanocomposites prepared from the again ball-milled powder mixture. The ferromagnetism of nanosized Ni-Co contributes to the magnetic properties of the composites. A change in the coercive force with dispersion size was observed. Also, the extent of magnetic response by an applied stress was strongly influenced by the size of Ni-Co particles. The relationship between microstructure, mechanical and magnetic properties are discussed. 18 refs.
- SYNTHESIS, CHARACTERISATION AND PHOTOCATALYTIC ACTIVITY OF ZnFe2O4 /TiO2 NANOCOMPOSITE
Yuan, ZH; Zhang, LD
J.Mater.Chem. Vol.11, No.4, 2001, p.1265-1268.
A new nanocomposite material, ZnFe2O4/TiO2, was prepared by a colloid chemistry method and characterised by XRD and TEM. The corresponding photocatalytic activity in the mineralisation of phenol was evaluated and compared with pure ZnFe2O4 and TiO2 nanomaterials. From XRD measurements, it was found that, when annealed at relatively low temperature, ZnFe2O4 and TiO2 crystallite phases in the composite separate from each other, and, when annealed at high temperature, a solid reaction between ZnFe2O4 and TiO2 takes place. It was also found that the ZnFe2O4 nanoparticles seem to play a role in inhibiting the anatase-to-rutile phase transformation of TiO2. The phenol degradation showed that the ZnFe2O4/TiO2 nanocomposite is more effective as a photocatalyst than pure TiO2, showing that the nanocomposite approach could be an excellent choice to improve the photoactivity of TiO2. 47 refs.
- COMPOSITE ON BASE OF 2-D NANOTUBULAR LATTICE AS IDEAL HIGH-Tc SUPERCONDUCTOR
Physica C (Amsterdam) 351,No.1,2001,p.71-77
Combining Little's and Ginzburg's ideas with recent progress in nanotubes (NTs) research, a novel type of material is advanced as a perspective high-Tc superconductor on base of a 2-D lattice of quasi-1-D superconducting NTs. Superconducting coaxial multilayer NTs of the correlation length in diameter are an ideal and natural trap for pinning of Abriskosov vortex. Nanotube should be layered superconductor, such as LuNiBC, YBaCuO, etc. Mechanism of superconductivity was proposed and substantiated quantitatively on base of a whispering mode, which is responsible for a strong enhancement of electron-phonon interaction and for an increase of critical temperature. Nanocomposite built from such quasi-1-D NTs when coinciding with vortex lattice provides ideal conditions for the pinning, resonance, distortion, proximity induced, ordering and Little-Parks effects, the joint action of which is suggested to result in synergetic effect increasing the superconductivity. Such 2-D nanotubular crystal is proposed to be synthesized by template approach using zeolite-like membrane. 38 refs.
- IN SITU PROCESSING OF ELECTROCERAMIC FINE PARTICLES/POLYMER HYBRIDS
Hirano, S; Yogo, T; Sakamoto, W; Yamada, S; Nakamura, T; Yamamoto, T; Ukai, H
J.Eur.Ceram.Soc. Vol.21, No.10/11, 2001, p.1479-1483.
Electroceramic fine particles/polymer hybrids have been receiving great attention in emerging areas. The conventional blending of fine particles into polymer or oligomer causes particle agglomeration, leading to the degradation of properties. The newly developed method is based on the nucleation and growth control of crystalline oxide particles in an organic matrix through the reaction control of a metallorganic precursor with a combination of hydrolysis and polymerisation below 100 C. The selection of reaction conditions does influence the size and crystallinity of ceramic particles in the organic matrix. The nano-sized Fe2O3 magnetic particle/polymer hybrid exhibits the interesting features of superparamagnetics and the quantum size effect. The crystalline particles of BaTiO3/polymer and PbTiO3 /polymer hybrids are dielectric and show typical electro-rheological behaviour. 11 refs.
- Processing and characterization of aligned vapor grown carbon fiber reinforced polypropylene
Kuriger, RJ; Alam, MK; Anderson, DP; Jacobsen, RL
Composites Part A: Applied Science and Manufacturing (UK), vol. 33A, no. 1, pp. 53-62, 2002
This investigation describes a method for aligning vapor grown carbon nano-fibers suspended in a polymer flow during extrusion to produce an improved thermoplastic composite. A twin-screw extruder was used to shear mix and extrude fiber/polypropylene mixtures through a converging-annular die that generates fiber alignment along the flow direction. The degree of fiber alignment was quantified by using X-ray diffraction. It was shown that fiber alignment could be improved by increasing the residence time in the die channel. Tensile specimens were fabricated by molding the extruded strands and the strength properties of the aligned samples increased with fiber content. The tensile strength improved with greater fiber orientation, however, more fiber alignment had little affect on the modulus. The addition of vapor grown carbon nano-fiber also increased the thermal conductivity and decreased the electrical resistivity. (The two kinds of VGCF used were PR-21-PS and PR-19-HT, both consisting epoxy and poly(phenylene sulfide) matrices.)
- Polymer-layered silicate nanocomposites. 1. A study of poly(ethylene oxide)/Na exp + -montmorillonite nanocomposites as polyelectrolytes and polyethylene-block-poly(ethylene glycol) copolymer /Na exp + -montmorillonite nanocomposites as fillers for reinforcement of polyethylene
Liao, B; Song, M; Liang, H; Pang, Y
Polymer (Netherlands), vol. 42, no. 25, pp. 10007-10011, 1 Dec. 2001
Poly(ethylene oxide) PEO/Na exp + -montmorillonite and polyethylene--poly(ethylene glycol) (PE--PEG) diblock copolymer /Na exp + -montmorillonite nanocomposites have been prepared by melt intercalation method. The effect of thermal treatment on the amount of PEO and PE--PEG diblock copolymer intercalated into layers of Na exp + -montmorillonite and on ionic conductivity of PEO/Na exp + -MMT nanocomposites have been evaluated. It was found that PEO can be intercalated into the layers of Na exp + -MMT by simple mechanical blending and part of PE in PE--PEG diblock copolymers was also intercalated into the layers of Na exp + -MMT. The intercalated amount increases with thermal treatment time, which improves the ionic conductivity of the PEO/Na exp + -MMT nanocomposites. PE--PEG diblock copolymer/Na exp + -MMT hybrids can be considered as a new kind of fillers for the reinforcement of polyethylene. By only adding a small amount (1--15% by weight) of these fillers, tensile strength of polyethylene was improved significantly. This research provides valuable information for the development of new kinds of fillers for polymer reinforcement, and polyelectrolytes.
- Synthesis and characterization of polypropylene/clay nanocomposites
Ma, J; Qi, Z; Hu, Y
Journal of Applied Polymer Science (USA), vol. 82, no. 14, pp. 3611-3617, 27 Dec. 2001
Polypropylene/clay (PP/clay) nanocomposites were synthesized via intercalative polymerization. The nanostructure of the composites was investigated by wide-angle X-ray diffractometry (WAXD) and transmission electron microscopy (TEM). The WAXD patterns of the PP/clay nanocomposites indicated that the characteristic diffraction peak of the clay disappeared. The TEM image showed the clay was exfoliated into nanometer size and dispersed uniformly in thePP matrix. The composites exhibited much higher storage modulus compared to that of pure PP. At temperatures higher than T sub g , the storage modulus of the PP/clay nanocomposites with 8.1 wt % clay content increased three times that of the pure PP. Additionally, the thermal stability of the nanocomposites significantly increased. The maximum decomposition temperature was increased by 44 deg C with the introduction of about 10 wt % clay. The heat-distortion temperatures (HDTs) of the nanocomposites also increased.
- The friction and wear characteristics of nanometer ZnO filled polytetrafluoroethylene
Li, F; Hu, K-A; Li, J-L; Zhao, B-Y
Wear (Switzerland), vol. 249, no. 10-11, pp. 877-882, Nov. 2001
The friction and wear characteristics of nanometer ZnO filled polytetrafluoroethylene (PTFE) composite blocks with different filler proportions in sliding against stainless steel ring under dry friction condition were studied. The microstructures, worn surfaces and transfer films of PTFE and nanometer ZnO/PTFE composite were then examined with scanning electron microscope (SEM). Experimental results show that filling nanometer ZnO to PTFE could greatly reduce the wear of this polymer and the best anti-wear property was obtained with the composite containing 15 vol.% nanometer ZnO. In comparison with pure PTFE, the friction property of these composites was maintained. With the increase of load and sliding velocity, the coefficient of friction of nanometer ZnO/PTFE composites was reduced and the anti-wear ability of them was not very damaged. It was seen from the cross-section micrographs of PTFE and nanometer ZnO/PTFE composite that the fiber structures that existed in pure PTFE were disappeared by filling nanometer ZnO into PTFE. This indicated that this filler could prevent the destruction of PTFE banded structures during friction process. SEM pictures of the transfer films indicated that with the frictional couple of stainless steel ring/composite block filled with 15 vol.% nanometer ZnO, a uniform and tenacious transfer film was formed on the ring surface, which promised an excellent anti-wear property of this composite. SEM examination of 15 vol.% nanometer ZnO/PTFE composite also showed that some cracks on the worn surface of the composite appeared during sliding under 300 N. The creation and development of the cracks led to deterioration of the wear property of this composite under higher load.
- Advances in the science and technology of carbon nanotubes and their composites: a review
Thostenson, ET; Ren, Z; Chou, T-W
Composites Science and Technology (UK), vol. 61, no. 13, pp. 1899-1912, Oct. 2001
Since their first observation nearly a decade ago by Iijima (Iijima S. Helical microtubules of graphitic carbon Nature. 1991; 354: 56-8), carbon nanotubes have been the focus of considerable research. Numerous investigators have since reported remarkable physical and mechanical properties for this new form of carbon. From unique electronic properties and a thermal conductivity higher than diamond to mechanical properties where the stiffness, strength and resilience exceeds any current material, carbon nanotubes offer tremendous opportunities for the development of fundamentally new material systems. In particular, the exceptional mechanical properties of carbon nanotubes, combined with their low density, offer scope for the development of nanotube-reinforced composite materials. The potential for nanocomposites reinforced with carbon tubes having extraordinary specific stiffness and strength represent tremendous opportunity for application in the 21st century. This paper provides a concise review of recent advances in carbon nanotubes and their composites. We examine the research work reported in the literature on the structure and processing of carbon nanotubes, as well as characterization and property modeling of carbon nanotubes and their composites. (Sample composite materials: carbon nanotubes in a polystyrene matrix.)
- Photo-oxidation of polymeric-inorganic nanocomposites: chemical, thermal stability and fire retardancy investigations
Tidjani, A; Wilkie, CA
Polymer Degradation and Stability (UK), vol. 74, no. 1, pp. 33-37, Oct. 2001
Nanocomposites of polypropylene-graft-maleic anhydride/clay and polypropylene/clay were prepared by melt blending using two different approaches. X-ray diffraction results showed an intercalated structure. Samples of nanocomposites were exposed to UV light under atmospheric oxygen and their photo-oxidative stability was studied using FTIR and UV spectroscopy. The consequences of this photo-oxidation on the thermal stability and fire retardant performance of the nanocomposites were also addressed from thermogravimetry analysis and Cone calorimetry.
- Nano-scale mechanics of nanotubes, nanowires, and nanobelts
Wang, ZL; Goo, RP; Pan, ZW; Dai, ZR
Advanced Engineering Materials (Germany), vol. 3, no. 9, pp. 657-661, Sept. 2001
One-dimensional (ID) nanostructures have numerous potential applications in science and engineering. Nanocomposites made of nanowires, such as carbon nanotubes, are likely to decrease material's density and increase its strength, which are of critical importance to space technology. To investigate the uniqueness offered by these materials, new techniques must be developed to quantitatively measure the properties of individual wire-like structures whose structures are well characterized by electron microscopy techniques, because their properties may sensitively depend on their geometrical shape/configurations and crystal as well as surface structures. Within the framework of in-situ TEM we have recently developed a novel approach that relies on electric field induced mechanical resonance for measuring the properties of individual wire-like structures, such as Young's modulus, electron field emission, tip work function, and electrical quantum conductance. This is a new technique that provides the properties of a single nanowire with well characterized.
- Preparation and characterization of polyimide nanocomposites with different organo-montmorillonites
Chang, J-H; Park, KM; Cho, D; Yang, HS; Ihn, KJ
Polymer Engineering and Science (USA), vol. 41, no. 9, pp. 1514-1520, Sept. 2001
Poly (amic acid) nanocomposites were synthesized from a dimethylacetamide (DMAc) solution with two organophilic montmorillonites (organo-MMTs). It was then heated at various temperatures under vacuum, yielding 15-20 um thick films of polyimide/organo-MMT hybrid with different clay contents (1-8 wt%). Dodecy-lamine (C sub 12 -) and hexadecylamine (C sub 16 -) were used as aliphatic alkylamines in organo-MMT. The ultimate strength monotonically increased with increasing clay content in the polymer matrix. Maximum enhancement in the initial modulus was observed for the blends containing 2 wt% clay with two kinds of organo-clays, and values did not alter significantly with further increases in clay content. Additions of only 2 wt% C sub 12 - and C sub 16 -MMT to the polyimide were shown to cause 94%-95% reduction in oxygen gas permeability. This is caused by the barrier properties of the clay layers dispersed in the composite. In general, C sub 16 -MMT is more effective than C sub 12 -MMT in increasing both the tensile property and the gas barrier in a polyimide matrix. Intercalations of the polymer chains in clay were examined through wide-angle X-ray diffraction (XRD) and electron microscopies (SEM and TEM).
- Manufacture of nano-composites by compounding techniques
Plastics Age (Japan), vol. 47, no. 8, pp. 80-87, Aug. 2001
Article deals with use of compounding techniques to fabricate polymer series nano-composites comprising polymers as a matrix and nano ultra-fine particles (generally inorganic matter) as a dispersed phase. In the compounding processes, a stable nano-composite is prepared by melting and mulling polymers and nano particles. A fabrication process of layer desquamatory type composites is introduced. This process includes a insertion procedure, in which organics as a guest are sandwiched in between layered inorganics as a host, and desquamation procedure, in which the layered inorganics are dispersed to be a single layer in polymers by polymerization or blending. The properties of nano composites are explained as well as effects extruder and screw structures on composite formation. The recent progress of compounding techniques is reviewed.