JP2009532531A - Carbon nanotube reinforced nanocomposite - Google Patents

Abstract

  The combination of MWNT (where MWNT has more than two layers) and DWNT significantly improves the mechanical properties of the polymer nanocomposites. Reinforcement with a small amount of DWNT (<1 wt%) significantly improves the bending strength of epoxy matrix nanocomposites. Reinforcement with the same or similar amount of MWNT significantly improves the flexural modulus (stiffness) of the epoxy matrix nanocomposite. Both the flexural strength and the flexural modulus of epoxy nanocomposites reinforced with MWNT and DWNT are much improved compared to epoxy nanocomposites reinforced with the same amount of DWNT or MWNT. In this epoxy / DWNT / MWNT nanocomposite system, SWMT can also function instead of DWNT. In addition to epoxies, other thermosetting polymers can also function.

Description

  This application claims priority to US Provisional Application No. 60/788234, filed March 31, 2006, and US Provisional Application No. 60 / 810,394, filed June 2, 2006.

Since being first discovered in 1991 by Iijima, carbon nanotubes (CNT, carbon nanotube) have been an important research subject (Non-Patent Document 1). Many researchers have reported the remarkable physical and mechanical properties of this new form of carbon. The diameter of the CNT is typically 0.5 to 1.5 nm for a single-walled CNT (SWNT, single wall CNT), 1 to 3 nm for a double-walled CNT (DWNT, double wall CNT), The thickness is 5 nm to 100 nm for multi-wall CNT (MWNT, multi-wall CNT). Starting with its inherent electronic properties and higher thermal conductivity than diamond, it leads to the mechanical properties that its stiffness, strength and elasticity are superior to any existing material, and CNTs are for the development of completely new material systems. Provides a huge opportunity. In particular, the exceptional mechanical properties of CNTs (E> 1.0 TPa, and 50 GPa tensile strength) combined with low density (1 to 2.0 g / cm ³ ) have allowed the development of CNT reinforced materials. It will be attractive (Non-Patent Document 2). CNT is the strongest of the known materials on the earth. Compared to MWNT, SWNT and DWNT are more potent as reinforcing materials due to their larger surface area and higher aspect ratio. Table 1 lists the surface area and aspect ratio of SWNT, DWNT and MWNT.

S. Iijima, “Helicic microtubules of graphic carbon”, Nature, 1991, 354, p. 56 Eric W. Wong, Paul E.W. Sheehan, Charles M .; Lieber, “Nanobeam Mechanics: Elasticity, Strength, and Toughness of Nanords and Nanotubes”, Science, 1997, 277, p. 1971

  The problem is that both SWNT and DWNT are more expensive than MWNT. While the price of purified MWNT is 1-10 dollars / g, the price of both purified SWNT and DWNT can be as high as $ 500 / g. Thus, MWNT reinforced nanocomposites are much cheaper than SWNT or DWNT reinforced nanocomposites.

  The combination of MWNT (where MWNT has more than two layers) and DWNT significantly improves the mechanical properties of the polymer nanocomposites. Reinforcement with a small amount of DWNT (<1 wt%) significantly improves the bending strength of epoxy matrix nanocomposites. Reinforcement with the same or similar amount of MWNT significantly improves the flexural modulus (stiffness) of the epoxy matrix nanocomposite. Both the flexural strength and the flexural modulus of epoxy nanocomposites reinforced with MWNT and DWNT are much improved compared to epoxy nanocomposites reinforced with the same amount of DWNT or MWNT. In this epoxy / DWNT / MWNT nanocomposite system, SWMT can also function instead of DWNT. In addition to epoxies, other thermosetting polymers can also function.

  For one embodiment of the present invention, a detailed example of this embodiment is given to better illustrate the present invention.

Epoxy resin (bisphenol A) was obtained from Arisawa, Japan. The company obtained a curing agent (dicyandiamide) used to cure epoxy nanocomposites. DWNT and MWNT were obtained from Nanocyl, Belgium. These CNTs were functionalized with amino (—NH ₂ ) functional groups. The amino functional group CNT helps to improve the bond between the CNT and the epoxy molecular chair and can further improve the mechanical properties of the nanocomposite. However, original CNTs or CNTs functionalized by other methods (carboxyl functional groups, etc.) can also function (for example, pellets manufactured by Arkema, Japan (product name: RILSAN BMV-P20 PA11). )). The clay was manufactured by Southern Clay, USA (product name: Cloisite® series 93A). This is a natural montmorillonite modified with a ternary ammonium salt. The elastomer was styrene / ethylene butylene / styrene (SEBS) purchased from Kraton, USA (product name: G1657).

  FIG. 1 shows a schematic diagram of a process flow for producing an epoxy / CNT nanocomposite. All ingredients were dried in a vacuum oven at 70 ° C. for at least 16 hours to completely remove moisture. CNTs were placed in acetone 101 and diffused by a micro-fluidic machine (available from Microfluidics) (step 102). Microfluidic machines use high-pressure flows that impinge at very high speeds in precisely defined micron-sized channels. The combined force of the shear and impact acts on the product to produce a uniform dispersion. CNT / acetone is gel 103, resulting in CNTs well dispersed in acetone solvent. However, other methods such as sonication processes may also work. A surfactant may be used to disperse the CNTs in the solution. Thereafter, in step 104, epoxy was added to the CNT / acetone gel to produce an epoxy / CNT / acetone solution 105. This was followed by a sonication process (step 106) for 1 hour at 70 ° C. in a bath to produce an epoxy / CNT / acetone suspension 107. In step 108, in step 108, the CNTs were further dispersed in the epoxy using a mixing process with a stirrer at a speed of 1400 revolutions per minute for 30 minutes at 70 ° C. Was generated. Thereafter, in step 110, the curing agent was added to the epoxy / CNT / acetone gel 109 at a ratio of 4.5 wt%, followed by stirring at 70 ° C. for 1 hour. In step 112, the resulting gel 111 was degassed in a vacuum oven at 70 ° C. for at least 48 hours. The material 113 was then poured into a Teflon mold and cured at 160 ° C. for 2 hours. The mechanical properties (bending strength and flexural modulus) of this sample were characterized after the polishing process 115.

  Table 2 shows the mechanical properties (bending strength and flexural modulus) of the epoxy produced using the process flow of FIG. 1 for producing an epoxy / CNT nanocomposite. As shown in FIG. 2, the bending strength of epoxy / DWNT is higher than the bending strength of epoxy / MWNT in the CNTs with the same loading capacity. On the other hand, as shown in FIG. 3, the bending elastic modulus of epoxy / DWNT is lower than the bending elastic modulus of epoxy / MWNT in the CNTs having the same loading capacity. The flexural strength and flexural modulus of epoxy / DWNT (0.5 wt%) / MWNT (0.5 wt%) are both higher than that of epoxy / DWNT (1 wt%).

The manufacturing method of an epoxy / CNT nanocomposite is illustrated. The graph which shows the bending strength of an epoxy nanocomposite is illustrated. The graph which shows the bending elastic modulus of an epoxy nanocomposite is illustrated.

Claims (13)

  A method for producing a composite material comprising a thermosetting resin, the composite material comprising double-walled carbon nanotubes (CNT) and multi-walled CNTs at a concentration that increases both the bending strength and the flexural modulus of the composite material.   The manufacturing method according to claim 1, wherein the concentration of double-walled CNTs and multi-walled CNTs is optimized to increase both the bending strength and the bending elastic modulus of the composite material.   The manufacturing method according to claim 2, wherein the composite material has a double-walled CNT content of 0.01 to 40 wt%.   The composite material. The manufacturing method of Claim 2 which has 0.01-20 wt% of bilayer CNT content.   A composite having a thermosetting resin content of 60 to 99.98 wt%, a MWNT content of 0.01 to 20 wt%, and a DWNT content of 0.01 to 20 wt%.   The composite of claim 5, wherein the thermosetting resin comprises an epoxy.   6. The composite of claim 5, wherein the MWNT and the DWNT are purified or unpurified and are a metal, a semiconductor or an insulator.   A method for producing a carbon nanotube composite, wherein the amount of carbon nanotubes added to the composite is varied as a function of the carbon nanotube diameter to produce a carbon nanotube composite with a particular set of properties.   The manufacturing method according to claim 8, wherein the carbon nanotube is a double-walled carbon nanotube.   The manufacturing method of Claim 8 whose said carbon nanotube is a multi-walled carbon nanotube.   The manufacturing method according to claim 8, wherein a ratio between the double-walled carbon nanotube and the multi-walled carbon nanotube in the composite is changed to obtain a specific set of properties.   The manufacturing method according to claim 11, wherein the composite further includes a thermosetting resin.   The manufacturing method according to claim 11, wherein the composite further includes an epoxy.

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