実験番号：201803071（2 シフト）BL8S3

WAXS study of oriented polymer filled with GNP
Rodolfo Cruz-Silva,1 Roque Sanchez,1,2Seung Kang,3 Morinobu Endo,1 and Mauricio Terrones.4
1. Aqua Center of Innovation Shinshu University and Institute of Carbon Science, Faculty of Engineering,
Shinshu University, Nagano, Japan.
2. Instituto Potosino de Ciencia y Tecnologia, SLP, Mexico.
3. Korean Institute of convergence, KCTech,
4. Department of Materials Science, Pennsylvania State University.
Keywords: Nanocomposite, orientation, crystallinity, polyolefin.
1．Background and research purpose
In recent years, a lot of attention has been paid to new materials than can repair autonomeusly, extending its
service life without human intervation.1 Typical behavior involves the dissapearance of cracks and scratch aswell as the restoration of the original mechanical properties.2 This materials are known as self-healingmaterials and their microsctructure is key to explain how they reconstruct upon damaging. Polyethylene filledwith graphite nanoplatelets has long been known as a self healing material.3 Graphite nanoplatelets are a goodalternative to carbon nanotubes. In this work, we analyze several samples of graphite nanoplatelets filled
polyethylene as a promising material for self-healing applications.
2．Experiment contents
Polyethylene was melt-mixed with graphite nanoplatelets in different mass fractions. Then, samples wereprepared by compression molding under 10 T of force into a sheet of about 800 micron thick. Samples of about
1 mm of radius were cut from this material and analyzed by WAXS and SAXS at the Aichi Synchrothron
facility at the BL8S3 line in different orientations. The resulting patterns were analyzed using Fit2D software.4
3．Results and discussion
The Figure 1 shows the WAXS patterns obtained for the plain polyethylene material (Figure 1a) and thegraphene nanoplatelet filled polyethylene containing 8 wt% of the nanoplatelets (Figure 1b). Polyethylene
show the typical rings due to the (110) and (200) reflections. After adding the graphite nanoplatelets, weobserved a new ring in the composite due to the highly crystalline graphite material embedded in thecomposite. The 002 peak of graphitic carbon has a clear orientation indicating that the layers of graphite areparallel to the beam, which indicates an in-plane orientation during the hot-pressing process. However, theSAXS patterns (not shown) indicate a reduction of the spherulite size upon addition of the graphiticnanoplatelets. The WAXS patterns show a clear in-plane orientation due to the flow of polymer during thecompression molding. This orientation affect is markedly higher in the graphite nanoplatelets reinforced
sample shown in the Figure 1b. It is well known that compression molding induce biaxial orientation in thefilms due to the radial flow of the molten thermoplastics. The peak-to-peak ratio of the crystalline peaks to theamorphous phase area shows a large increase after adding the graphite nanoplatelets, suggesting a nucleating
effect. These samples will be examined by calorimetry in order to calculate the crystallinity degree andcompare with the values obtained by X-ray diffraction. These results shown that graphite nanoplatelets arewell dispersed and aligned within the polyethylene matrix and support a possible improvement on themechanical properties and the possibility to generate a self-healing behavior.

Figure 1. Radially integrated Wide-angle X-ray scattering patterns of a) polyethylene and b) polyethylene
filled with graphite nanoplatelets nanocomposite (8 wt % loading).

References
1. Wu, D. Y.; Meure, S.; Solomon, D. Self-healing polymeric materials: A review of recent developments.
Progress in Polymer Science 2008, 33, 479-522.
2. Chen, K. L.; Wu, Y.; Zhou, S. X.; Wu, L. M. Recent Development of Durable and Self-Healing Surfaces
with Special Wettability. Macromolecular Rapid Communications 2016, 37, 463-485.
3. Gu, J. W.; Li, N.; Tian, L. D.; Lv, Z. Y.; Zhang, Q. Y. High thermal conductivity graphite
nanoplatelet/UHMWPE nanocomposites. Rsc Advances 2015, 5, 36334-36339.
4. Hammersley, A. P., FIT2D: a multi-purpose data reduction, analysis and visualization program. Journal ofApplied Crystallography 2016, 49, 646-652.