(207h) Multiscale Characterization of Wear-Resistance in Epoxy/Nanoparticle Composites

Development of transparent and wear-resistant composite materials is of great significance in maintaining mechanical durability of optical surfaces (e.g., lenses, photographic film, windshields, goggles, energy cell panels, and packaging) [1]. Unlike the modulus and hardness values frequently measured from linear elastic regions in material systems, wear resistance parameters are more related to interactions between surfaces - specifically the removal and deformation of material on a surface as a result of mechanical action of the opposite surface [2]. The definition, measurement, and evaluation, as well as mechanism explanation of wear-resistance have been challenging [3-6]. For instance, wearing has been described variously in terms of abrasion, adhesion, corrosion, and erosion, and evaluated by gloss reduction, topography change, deformation, roughness, and weight loss, just to name a few [7]. In addition, it is difficult to obtain acceptable accuracy, variability, and reproducibility at multi scales due to limitations in different instrument types [8] and difficulties in micro- and nano-structural controls. The degree of wearing in nanoparticle-filled composites depends on several factors, namely, (i) physical and chemical compositions of the materials, such as dispersion quality, interfacial interactions, particle volumes, and particle orientations [9]. The measurement of wear resistance can become very unreliable for polymer composites [10]. At nano-scale, crystalline and amorphous regions in semicrystalline polymers and nanoparticles may generate divergent resistance to wearing [8]. At micro- and macro-scale, multiple combinations between polymer chain conformations and nanoparticle configurations may produce dissimilar or opposite trends [8]; and (ii) test environmental parameters, including scratching tip geometry, contact conditions determined by the applied normal and friction force, temperature, wearing rate, and so on [11, 12]. Therefore, it is of paramount importance to control both the material structure and test conditions for wear resistance consistency [13].

In this research, we studied the multi-scale wear-resistance in epoxy/nanoparticle composites prepared by spray coating method. Nano-scale scratching, micro-scale sand falling, and macro-scale Taber Abrasion characterizations were used to measure wear resistance. The nanoindentation, stylus profilometery, atomic force microscopy (AFM), and scanning electron microcopy (SEM), UV-Vis were used for characterizations. The tribological observations in this study have brought to light the potential of aligning nanoparticles in composites to increase the wear resistance and to preserve the transmittance, which is practically applicable in optical systems.

References:

[1] Aliofkhazraei, M. (2011) Characterization of nanostructured coatings. In Nanocoatings, Springer Berlin Heidelberg, Berlin, pp. 77-110.

[2] Ebert, D., Bhushan, B. (2012) Transparent, superhydrophobic, and wear-resistant coatings on glass and polymer substrates using SiO2, ZnO, and its nanoparticles. Langmuir, 28, 11391-11399.

[3] Liu, J., Notbohm, J.K., Carpick, R.W., Turner, K.T. (2010) Method for characterizing nanoscale wear of atomic force microscope tips. ACS Nano, 4, 3763-3772.

[4] Aoike, T., Uehara, H., Yamanobe, T., Komoto, T. (2001) Comparison of macro-and nanotribological behavior with surface plastic deformation of polystyrene. Langmuir, 17, 2153-2159.

[5] Ren, S., Yang, S., Zhao, Y. (2003) Micro-and macro-tribological study on a self-assembled dual-layer film. Langmuir, 19, 2763-2767.

[6] Huovinen, E., Hirvi, J., Suvanto, M., Pakkanen, T.A. (2012) Microâ??micro hierarchy replacing microâ??nano hierarchy: A precisely controlled way to produce wear-resistant superhydrophobic polymer surfaces. Langmuir, 28, 14747-14755.

[7] Bhushan, B., Gupta, B.K. (1991) Handbook of tribology: Materials, coatings, and surface treatments. McGraw-Hill, New York, NY, Malabar, FL.

[8] Friedrich, K., Zhang, Z., Schlarb, A.K. (2005) Effects of various fillers on the sliding wear of polymer composites. Composites Science and Technology, 65, 2329-2343.

[9] Song, K., Zhang, Y., Meng, J., Green, E.C., Tajaddod, N., Li, H., Minus, M.L. (2013) Structural polymer-based carbon nanotube composite fibers: Understanding the processingâ??structureâ??performance relationship. Mater., 6, 2543-2577.

[10] Myshkin, N., Petrokovets, M., Kovalev, A. (2006) Tribology of polymers: Adhesion, friction, wear, and mass-transfer. Tribology International, 38, 910-921.

[11] Patnaik, A., Satapathy, A., Chand, N., Barkoula, N., Biswas, S. (2010) Solid particle erosion wear characteristics of fiber and particulate filled polymer composites: A review. Wear, 268, 249-263.

[12] Biswas, S., Vijayan, K. (1992) Friction and wear of PTFEâ??a review. Wear, 158, 193-211.

[13] Carpick, R.W., Salmeron, M. (1997) Scratching the surface: Fundamental investigations of tribology with atomic force microscopy. Chemical Reviews, 97, 1163-1194.