SINGLE WALL NANOHORNS AND HIGH DENSITY POLYETHYLENE COMPOSITE by morgossi7a6

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									        SINGLE WALL NANOHORNS AND HIGH DENSITY
               POLYETHYLENE COMPOSITE

                                  Michael J. Pepka
                                   NanoCraft, Inc
                                   P.O. Box 3429
                              Renton, Washington 98056

                                     ABSTRACT

Single Wall Nanohorns (SWNH) clusters have high surface area and adsorption
capability this suggests that they may be good filler materials for composites. Data to
characterize SWNH is presented including TEM, TGA, Raman, and X-Ray diffraction.
An application of SWNH in a composite is presented.
Single Walled Nanohorn (SWNH) / HDPE composites were fabricated using Toshiba
ISG 90 Injection Molding Machine with a 42 gram shot capacity and a 82 metric ton
clamp tonnage. The SWNH were precoated onto HDPE spheres in ratio of 0.5%, 1%,
2%, and 5%. Improvement in tensile properties began at 1% loading and tensile
properties improved with additional material up to 5% loading.

KEY WORDS: Nanomaterials, Polyethylene, Toughened Composites


                                  1. INTRODUCTION
Single wall nanotubes were predicted by Dr. Richard Smalley in his 1991 patent
application in which he wrote “Fullerenes are not necessarily spherical. They may take
the form of long tubular structures with hemispherical caps at each end of the tube” [1].
The majority of single wall nanotubes made today are contaminated with metallic
particles of iron, cobalt, nickel and other metals and combinations of metals. An
exception to this rule is Single Wall Carbon Nanohorns, SWNH that are made with out
a catalyst.

Nanohorns belong to the single wall nanotube family. Nanohorns form under certain
controlled conditions from a high temperature carbon plasma. Nanohorns are 2 to 3 nm
in diameter and 30 to 50 nm in length with a 19 degree closed end called a horn. They
form into clusters with a diameter of about 30 to 120 nm. SWNH can be produced in
high volume and nanohorns have the potential to be a low cost material. Nanohorns
can be produced with 95% purity indicated by TGA, X-ray diffraction and TEM analysis
and nanohorns can be purified further. Nanohorns can be treated with simple
processes to yield 1600 square meters of area per gram.

Nanohorns have a uniquely wide range of applications including absorption, filtration,
lubrication, super-capacitors, storage of methane [2], methanol fuel cells support [3],
biomedical, field emission [4], adhesives, composites, electrical and much more.
Peter Harris first discovered single Wall Nanohorns in 1994 in soot collected from arc-
evaporation process [5]. The results of this discovery were disclosed in print in 1994 in
the J. Chem. So. Faraday Trans, vol. 90, p2799 (1994) [5]. In 1999, a new way of
producing SWNH was discovered in Japan by team lead by Sumio Iijima using CO2
laser [6]. In 2003, the author of this paper discovered a new high volume plasma
process that is now patent pending. The materials studied in this paper were produced
with this new process.



                         2. MATERIAL CONSIDERATIONS
NanoCraft, Inc provided material used in this study. The TEM, Raman, X-Ray
Diffraction and TGA/DTG data included in this study were all based on material made
with the NanoCraft, Inc. process.

2.1 Electron Microscope Photo, TEM

NanoCraft, Inc.'s nanohorn material can be described as self assembled clusters of
single wall nanotubes that are held together with van der Waal forces. The clusters
range in size from 50 to 120 nm in diameter. The clusters are spherical rather then flat.
Figure 1: TEM of Single Wall Nanohorns
Thermal Gravimetric Analysis (TGA)

Thermal Gravimetric Analysis (TGA) is a simple analytical technique that measures the
weight loss (or weight gain) of a material as a function of temperature. The nanohorn
TGA conforms to the expectations for a burn pattern for single wall nanotubes that
begins at approximately 400 degree C and ends at about 650 degree C. The peak rate
of oxidation occurs at 628.81 degree C.

Note the gradual and small, less then 15%, weight loss below 500 degree C, which
demonstrates very little if any amorphous carbon impurity. This particular sample had
7.639 % residue at 900 degree C.

Controlled oxidation cycle allows the closed horns of nanohorns to removed selectively
[7]. Nanohorn tubes can be opened by oxidizing the ends while retaining most of the
single wall tubes.

Oxidizing can also induced controlled porosity [7] in oxygen at 673 degrees K for ten
minutes followed by eight hours in H2O2. Opened nanohorns can have up to six times
the surface area of closed nanohorns.




                        Figure 2: TGA of Single Wall Nanohorns
2.3 X-ray Diffraction of Single Wall Nanohorns

The SWNH material is further characterized by X-ray Diffraction as shown in Figure 3. This
pattern shows the result of an experiment with and without methane (1 atmosphere and at 595 psi
methane). The main peak at near 26 degrees two theta is typical for carbon signature.




                                 Figure 3: X-Ray Diffraction

2.4 RAMAN of Single Wall Nanohorns

   Single Wall Nanohorns have a distinctive RAMAN signature as shown in Figure 4.




                                      Figure 4: Raman
                                 3. EXPERIMENTAL


3.1 HDPE/SWNH Composite

3.1.1 Coupon Preparation An application of SWNH in a composite is presented.
The SWNH were precoated onto HDPE spheres in ratio of 0.5%, 1%, 2%, and 5%.
3.1.1 Single Walled Nanohorn (SWNH) / HDPE composites were fabricated using
      Toshiba ISG 90 Injection Molding Machine with a 42 gram shot capacity and a
      82 metric ton clamp tonnage.


3.1.2 Test Method Dog bone coupons with a cross section of 1.27 cm by 0.31 cm
were tested by Tensile Elastomer Test at an initial speed of 12.7 cm per minute and a
secondary speed of 5.0 cm per minute. Improvement in tensile properties began at 1%
loading and tensile properties improved with additional material up to 5% loading. 5
coupons for each test were tested for each variable. 100% HDPE were tested as
controls.

3.1.3 Test Data Table 1 – test data SWNH/HDPE

                 HDPE         0.5%        1.0%           2.0%       5.0%
                Control      SWNH        SWNH           SWNH       SWNH
     Mean       91.19 kg    92.41 kg    94.94 kg       95.38 kg   97.09 kg
     Peak
      load
    Peak Ld     6.00 kg      3.77 kg     1.57 kg       5.08 kg    3.08 kg
    Std Dev
     Mean        22.91       23.22        23.85         23.96      24.39
     Peak        MPa         MPa          MPa           MPa        MPa
       Str
    Peak Str   1.51 MPa     0.95 MPa    0.40 MPa    1.28 MPa      0.77 MPa
    Std Dev

                                  Table 1: Test Data

                               4.0 CONCLUSIONS
Single Wall Nanohorns (SWNH) clusters have high surface area and adsorption
capability this suggests that they may be good filler materials for composites. Data to
characterize SWNH is presented including TEM, TGA, Raman, and X-Ray diffraction.
An application of SWNH in a composite is presented.
Single Walled Nanohorn (SWNH) / HDPE composites were fabricated using Toshiba
ISG 90 Injection Molding Machine with a 42 gram shot capacity and a 82 metric ton
clamp tonnage. The SWNH were precoated onto HDPE spheres in ratio of 0.5%, 1%,
2%, and 5%. Improvement in tensile properties began at 1% loading and tensile
properties improved with additional material up to 5% loading.



                             5.0 ACKNOWLEDGEMENTS
The author wishes to thank Colin MacLean, a student of Dr. William G. Lamb, Winningstad
Chair in the Physical Sciences at the Oregon Episcopal School in Portland, Oregon who
suggested the nanotube/HDPE project and who coordinated the coupon fabrication and testing.
Coupon fabrication labor, material and equipment was donated by R&D Plastics of Portland,
Oregon thanks to Sal Gonzalez, VP Operations and the tensile testing was donated by Nike IHM
Polymer R&D Portland, Oregon.

The author also wishes to acknowledge the collaboration with Professor Stephen Guggenheim of
the University of Illinois at Chicago for X-Ray Diffraction and Rochester Institute of Technology
(RIT) for the TGA and Raman.

                                    6.0 REFERENCES

   1. U.S. Pat. 5,227,038 (July 13, 1993) Smalley, et al (William Marsh Rice
      University)
   2. P. Harris et al, J. Chem. Soc., 90, pp 2799 (1994)
   3. S. Iijima et al, Chemical Physics Letters, 309, 165 (1999).
   4. M. Yudasaka et al, J. Phys. Chem. B, 107, 4681 (2003)
   5. J. M. Bonard et al, J. Appl. Phys, 91, 10107 (2002)
   6. E. Bekyarova et al, J. Physical Chemistry B, 107, 4479 (2003)
   7. T. Yoshitake et al, J. Physica B, 323, 124 (2002)

								
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