Unraveling the Mechanism of Nanoscale Mechanical Reinforcement in Glassy Polymer Nanocomposites

Cheng, Shiwang; Bocharova, Vera; Belianinov, Alex; Xiong, Shaomin; Kisliuk, Alexander; Somnath, Suhas; Holt, Adam P.; Ovchinnikova, Olga S.; Jesse, Stephen; Martin, Halie J.; Etampawala, Thusitha N.; Dadmun, Mark D.; Sokolov, Alexei P.

doi:10.1021/acs.nanolett.6b00766

Unraveling the Mechanism of Nanoscale Mechanical Reinforcement in Glassy Polymer Nanocomposites

Journal Article · Fri May 20 00:00:00 EDT 2016 · Nano Letters

DOI:https://doi.org/10.1021/acs.nanolett.6b00766· OSTI ID:1271894

Cheng, Shiwang ^[1]; Bocharova, Vera ^[1]; Belianinov, Alex ^[1]; Xiong, Shaomin ^[2]; Kisliuk, Alexander ^[1]; Somnath, Suhas ^[1]; Holt, Adam P. ^[3]; Ovchinnikova, Olga S. ^[1]; Jesse, Stephen ^[1]; Martin, Halie J. ^[3]; Etampawala, Thusitha N. ^[3]; Dadmun, Mark D. ^[3]; Sokolov, Alexei P. ^[4]

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Univ. of California, Berkeley, CA (United States)
Univ. of Tennessee, Knoxville, TN (United States)
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)

The mechanical reinforcement of polymer nanocomposites (PNCs) above the glass transition temperature, T_g, has been extensively researched. However, not much is known about the origin of this effect below T_g. In this paper, we unravel the mechanism of PNC reinforcement within the glassy state by directly probing nanoscale mechanical properties with atomic force microscopy and macroscopic properties with Brillouin light scattering. Our results unambiguously show that the "glassy" Young's modulus in the interfacial polymer layer of PNCs is two-times higher than in the bulk polymer, which results in significant reinforcement below T_g. We ascribe this phenomenon to a high stretching of the chains within the interfacial layer. Since the interfacial chain packing is essentially temperature independent, these findings provide a new insight into the mechanical reinforcement of PNCs also above T_g.

View Accepted Manuscript (DOE)

Research Organization:: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)

Sponsoring Organization:: USDOE Office of Science (SC)

Grant/Contract Number:: AC05-00OR22725

OSTI ID:: 1271894

Journal Information:: Nano Letters, Journal Name: Nano Letters Journal Issue: 6 Vol. 16; ISSN 1530-6984

Publisher:: American Chemical SocietyCopyright Statement

Country of Publication:: United States

Language:: English

References (61)

Modeling and Prediction of Polymer Nanocomposite Properties Mittal, Vikas https://doi.org/10.1002/9783527644346	book	January 2013
Characterization Techniques for Polymer Nanocomposites Mittal, Vikas Wiley‐VCH Verlag GmbH & Co https://doi.org/10.1002/9783527654505	book	July 2012
Multifrequency Imaging in the Intermittent Contact Mode of Atomic Force Microscopy: Beyond Phase Imaging Guo, Senli; Solares, Santiago D.; Mochalin, Vadym Small, Vol. 8, Issue 8 https://doi.org/10.1002/smll.201101648	journal	February 2012
On the rheology of concentrated dispersions van der Poel, C. Rheologica Acta, Vol. 1, Issue 2-3 https://doi.org/10.1007/BF01968867	journal	August 1958
Polymers at an interface; a simplified view de Gennes, P. G. Advances in Colloid and Interface Science, Vol. 27, Issue 3-4 https://doi.org/10.1016/0001-8686(87)85003-0	journal	July 1987
Thermoelastic properties of particulate composites with imperfect interface Hashin, Zvi Journal of the Mechanics and Physics of Solids, Vol. 39, Issue 6 https://doi.org/10.1016/0022-5096(91)90023-H	journal	January 1991
Rheological behavior of multiwalled carbon nanotube/polycarbonate composites Pötschke, Petra; Fornes, T. D.; Paul, D. R. Polymer, Vol. 43, Issue 11 https://doi.org/10.1016/S0032-3861(02)00151-9	journal	May 2002
Filled elastomers: A theory of filler reinforcement based on hydrodynamic and interphasial effects Goudarzi, Taha; Spring, Daniel W.; Paulino, Glaucio H. Journal of the Mechanics and Physics of Solids, Vol. 80 https://doi.org/10.1016/j.jmps.2015.04.012	journal	July 2015
Polymer nanotechnology: Nanocomposites Paul, D. R.; Robeson, L. M. Polymer, Vol. 49, Issue 15 https://doi.org/10.1016/j.polymer.2008.04.017	journal	July 2008
Current issues in research on structure–property relationships in polymer nanocomposites Jancar, J.; Douglas, J. F.; Starr, F. W. Polymer, Vol. 51, Issue 15 https://doi.org/10.1016/j.polymer.2010.04.074	journal	July 2010
Polymer/layered silicate nanocomposites: a review from preparation to processing Sinha Ray, Suprakas; Okamoto, Masami Progress in Polymer Science, Vol. 28, Issue 11 https://doi.org/10.1016/j.progpolymsci.2003.08.002	journal	November 2003
Theories and simulations of polymer-based nanocomposites: From chain statistics to reinforcement Allegra, Giuseppe; Raos, Guido; Vacatello, Michele Progress in Polymer Science, Vol. 33, Issue 7 https://doi.org/10.1016/j.progpolymsci.2008.02.003	journal	July 2008
Untangling the Effects of Chain Rigidity on the Structure and Dynamics of Strongly Adsorbed Polymer Melts Carrillo, Jan-Michael Y.; Cheng, Shiwang; Kumar, Rajeev Macromolecules, Vol. 48, Issue 12 https://doi.org/10.1021/acs.macromol.5b00624	journal	June 2015
Mechanical Reinforcement of Polymer Nanocomposites from Percolation of a Nanoparticle Network Chen, Quan; Gong, Shushan; Moll, Joseph ACS Macro Letters, Vol. 4, Issue 4 https://doi.org/10.1021/acsmacrolett.5b00002	journal	March 2015
Statistical theory of the adsorption of interacting chain molecules. 2. Train, loop, and tail size distribution Scheutjens, J. M. H. M.; Fleer, G. J. The Journal of Physical Chemistry, Vol. 84, Issue 2 https://doi.org/10.1021/j100439a011	journal	January 1980
AFM Probing of Polymer/Nanofiller Interfacial Adhesion and Its Correlation with Bulk Mechanical Properties in a Poly(ethylene terephthalate) Nanocomposite Aoyama, Shigeru; Park, Yong Tae; Macosko, Christopher W. Langmuir, Vol. 30, Issue 43 https://doi.org/10.1021/la502553q	journal	October 2014
Atomic Force Microscopy of Polymer Brushes: Colloidal versus Sharp Tips Halperin, A.; Zhulina, E. B. Langmuir, Vol. 26, Issue 11 https://doi.org/10.1021/la9047374	journal	May 2010
Surface modes and deformation energy of a molten polymer brush Fredrickson, Glenn H.; Ajdari, Armand; Leibler, Ludwik Macromolecules, Vol. 25, Issue 11 https://doi.org/10.1021/ma00037a015	journal	May 1992
Moduli of polymer brushes, contact mechanics, and atomic force microscope experiments Williams, D. R. M. Macromolecules, Vol. 26, Issue 19 https://doi.org/10.1021/ma00071a018	journal	September 1993
Evidence for the Shift of the Glass Transition near the Particles in Silica-Filled Elastomers Berriot, Julien; Montes, Hélène; Lequeux, François Macromolecules, Vol. 35, Issue 26 https://doi.org/10.1021/ma0212700	journal	December 2002
Origins of Linear Viscoelastic Behavior of Polymer−Nanoparticle Composites Pryamitsyn, Victor; Ganesan, Venkat Macromolecules, Vol. 39, Issue 2 https://doi.org/10.1021/ma051841z	journal	January 2006
Shear Modulus of a Polymer Brush Fujii, Yoshihisa; Yang, Zhaohui; Clough, Andrew Macromolecules, Vol. 43, Issue 9 https://doi.org/10.1021/ma100045m	journal	April 2010
Vibrational Eigenfrequencies and Mechanical Properties of Mesoscopic Copolymer Latex Particles Still, Tim; Retsch, Markus; Jonas, Ulrich Macromolecules, Vol. 43, Issue 7 https://doi.org/10.1021/ma1001589	journal	March 2010
Macromolecular Diffusion in a Crowded Polymer Nanocomposite Gam, Sangah; Meth, Jeffrey S.; Zane, Steve G. Macromolecules, Vol. 44, Issue 9 https://doi.org/10.1021/ma102463q	journal	May 2011
How Melt-Stretching Affects Mechanical Behavior of Polymer Glasses Zartman, Gregory D.; Cheng, Shiwang; Li, Xin Macromolecules, Vol. 45, Issue 16 https://doi.org/10.1021/ma300955h	journal	July 2012
Effect of Particle Size, Temperature, and Deformation Rate on the Plastic Flow and Strain Hardening Response of PMMA Composites Jancar, Josef; Hoy, Robert S.; Lesser, Alan J. Macromolecules, Vol. 46, Issue 23 https://doi.org/10.1021/ma400965c	journal	November 2013
Dynamics at the Polymer/Nanoparticle Interface in Poly(2-vinylpyridine)/Silica Nanocomposites Holt, Adam P.; Griffin, Philip J.; Bocharova, Vera Macromolecules, Vol. 47, Issue 5 https://doi.org/10.1021/ma5000317	journal	February 2014
Does Graphene Change T _g of Nanocomposites? Liao, Ken-Hsuan; Aoyama, Shigeru; Abdala, Ahmed A. Macromolecules, Vol. 47, Issue 23 https://doi.org/10.1021/ma501799z	journal	November 2014
Effect of Silica Nanoparticles on the Local Segmental Dynamics in Poly(vinyl acetate) Bogoslovov, R. B.; Roland, C. M.; Ellis, A. R. Macromolecules, Vol. 41, Issue 4 https://doi.org/10.1021/ma702372a	journal	February 2008
Immobilized Polymer Layers on Spherical Nanoparticles Harton, Shane E.; Kumar, Sanat K.; Yang, Hoichang Macromolecules, Vol. 43, Issue 7 https://doi.org/10.1021/ma902484d	journal	April 2010
Adsorption of Polymer Solutions onto a Flat Surface Semenov, A. N.; Bonet-Avalos, J.; Johner, A. Macromolecules, Vol. 29, Issue 6 https://doi.org/10.1021/ma950712n	journal	January 1996
Dispersing Grafted Nanoparticle Assemblies into Polymer Melts through Flow Fields Moll, Joseph; Kumar, Sanat K.; Snijkers, Frank ACS Macro Letters, Vol. 2, Issue 12 https://doi.org/10.1021/mz400447k	journal	November 2013
Detection of Surface-Immobilized Components and Their Role in Viscoelastic Reinforcement of Rubber–Silica Nanocomposites Mujtaba, A.; Keller, M.; Ilisch, S. ACS Macro Letters, Vol. 3, Issue 5 https://doi.org/10.1021/mz500192r	journal	April 2014
Segmental Dynamics of Polymer Melts with Spherical Nanoparticles Gong, Shushan; Chen, Quan; Moll, Joseph F. ACS Macro Letters, Vol. 3, Issue 8 https://doi.org/10.1021/mz500252f	journal	July 2014
Role of Polymer Graft Architecture on the Acoustic Eigenmode Formation in Densely Polymer-Tethered Colloidal Particles Schneider, Dirk; Schmitt, Michael; Hui, Chin Ming ACS Macro Letters, Vol. 3, Issue 10 https://doi.org/10.1021/mz500433h	journal	October 2014
Poly(vinyl alcohol)/SWNT Composite Film Zhang, Xiefei; Liu, Tao; Sreekumar, T. V. Nano Letters, Vol. 3, Issue 9 https://doi.org/10.1021/nl034336t	journal	August 2003
Mechanical Properties of Thin Glassy Polymer Films Filled with Spherical Polymer-Grafted Nanoparticles Maillard, Damien; Kumar, Sanat K.; Fragneaud, Benjamin Nano Letters, Vol. 12, Issue 8 https://doi.org/10.1021/nl301792g	journal	July 2012
Controlling the Thermomechanical Behavior of Nanoparticle/Polymer Films Zhao, Dan; Schneider, Dirk; Fytas, George ACS Nano, Vol. 8, Issue 8 https://doi.org/10.1021/nn503486e	journal	July 2014
Phase stability and dynamics of entangled polymer–nanoparticle composites Mangal, Rahul; Srivastava, Samanvaya; Archer, Lynden A. Nature Communications, Vol. 6, Issue 1 https://doi.org/10.1038/ncomms8198	journal	June 2015
Anisotropic self-assembly of spherical polymer-grafted nanoparticles Akcora, Pinar; Liu, Hongjun; Kumar, Sanat K. Nature Materials, Vol. 8, Issue 4 https://doi.org/10.1038/nmat2404	journal	March 2009
Nanoscale visualization and multiscale mechanical implications of bound rubber interphases in rubber–carbon black nanocomposites Qu, Meng; Deng, Fei; Kalkhoran, Salmon M. Soft Matter, Vol. 7, Issue 3 https://doi.org/10.1039/C0SM00645A	journal	January 2011
Applications of hybrid organic–inorganic nanocomposites Sanchez, Clément; Julián, Beatriz; Belleville, Philippe Journal of Materials Chemistry, Vol. 15, Issue 35-36 https://doi.org/10.1039/b509097k	journal	January 2005
Solid particles in an elastomer matrix: impact of colloid dispersion and polymer mobility modification on the mechanical properties Papon, Aurélie; Montes, Hélène; Lequeux, François Soft Matter, Vol. 8, Issue 15 https://doi.org/10.1039/c2sm06885k	journal	January 2012
Scaling theory of polymer adsorption De Gennes, P. G. Journal de Physique, Vol. 37, Issue 12 https://doi.org/10.1051/jphys:0197600370120144500	journal	January 1976
Theory of glassy dynamics in conformationally anisotropic polymer systems Oyerokun, Folusho T.; Schweizer, Kenneth S. The Journal of Chemical Physics, Vol. 123, Issue 22 https://doi.org/10.1063/1.2135776	journal	December 2005
A phenomenological molecular model for yielding and brittle-ductile transition of polymer glasses Wang, Shi-Qing; Cheng, Shiwang; Lin, Panpan The Journal of Chemical Physics, Vol. 141, Issue 9 https://doi.org/10.1063/1.4893765	journal	September 2014
Probing Soft Matter with the Atomic Force Microscopies: Imaging and Force Spectroscopy McConney, Michael E.; Singamaneni, Srikanth; Tsukruk, Vladimir V. Polymer Reviews, Vol. 50, Issue 3 https://doi.org/10.1080/15583724.2010.493255	journal	July 2010
The band excitation method in scanning probe microscopy for rapid mapping of energy dissipation on the nanoscale Jesse, Stephen; Kalinin, Sergei V.; Proksch, Roger Nanotechnology, Vol. 18, Issue 43 https://doi.org/10.1088/0957-4484/18/43/435503	journal	September 2007
Probing the temperature dependence of the mechanical properties of polymers at the nanoscale with band excitation thermal scanning probe microscopy Nikiforov, M. P.; Jesse, S.; Morozovska, A. N. Nanotechnology, Vol. 20, Issue 39 https://doi.org/10.1088/0957-4484/20/39/395709	journal	September 2009
Pressure and density dependence of the boson peak in polymers Hong, L.; Begen, B.; Kisliuk, A. Physical Review B, Vol. 78, Issue 13 https://doi.org/10.1103/PhysRevB.78.134201	journal	October 2008
Local mechanical properties of polymeric nanocomposites Papakonstantopoulos, George J.; Yoshimoto, Kenji; Doxastakis, Manolis Physical Review E, Vol. 72, Issue 3 https://doi.org/10.1103/PhysRevE.72.031801	journal	September 2005
Glass-Transition Temperature Gradient in Nanocomposites: Evidence from Nuclear Magnetic Resonance and Differential Scanning Calorimetry Papon, Aurélie; Montes, Hélène; Hanafi, Mohamed Physical Review Letters, Vol. 108, Issue 6 https://doi.org/10.1103/PhysRevLett.108.065702	journal	February 2012
Unexpected Molecular Weight Effect in Polymer Nanocomposites Cheng, Shiwang; Holt, Adam P.; Wang, Huiqun Physical Review Letters, Vol. 116, Issue 3 https://doi.org/10.1103/PhysRevLett.116.038302	journal	January 2016
Nanocomposites: Structure, Phase Behavior, and Properties Kumar, Sanat K.; Krishnamoorti, Ramanan Annual Review of Chemical and Biomolecular Engineering, Vol. 1, Issue 1 https://doi.org/10.1146/annurev-chembioeng-073009-100856	journal	June 2010
Band Excitation in Scanning Probe Microscopy: Recognition and Functional Imaging Jesse, S.; Vasudevan, R. K.; Collins, L. Annual Review of Physical Chemistry, Vol. 65, Issue 1 https://doi.org/10.1146/annurev-physchem-040513-103609	journal	April 2014
Irreversible Adsorption of a Concentrated Polymer Solution Guiselin, O. Europhysics Letters (EPL), Vol. 17, Issue 3 https://doi.org/10.1209/0295-5075/17/3/007	journal	January 1992
Gradient of glass transition temperature in filled elastomers Berriot, J.; Montes, H.; Lequeux, F. Europhysics Letters (EPL), Vol. 64, Issue 1 https://doi.org/10.1209/epl/i2003-00124-7	journal	October 2003
An improved technique for determining hardness and elastic modulus using load and displacement sensing indentation experiments Oliver, W. C.; Pharr, G. M. Journal of Materials Research, Vol. 7, Issue 06, p. 1564-1583 https://doi.org/10.1557/JMR.1992.1564	journal	June 1992
Polymer Nanocomposites: Status and Opportunities Vaia, Richard A.; Giannelis, Emmanuel P. MRS Bulletin, Vol. 26, Issue 5 https://doi.org/10.1557/mrs2001.93	journal	May 2001
Designed Interfaces in Polymer Nanocomposites: A Fundamental Viewpoint Schadler, Linda S.; Kumar, Sanat K.; Benicewicz, Brian C. MRS Bulletin, Vol. 32, Issue 4 https://doi.org/10.1557/mrs2007.232	journal	April 2007
Correction and extension of van der Poel's method for calculating the shear modulus of a particulate composite Smith, Jack C. Journal of Research of the National Bureau of Standards Section A: Physics and Chemistry, Vol. 78A, Issue 3 https://doi.org/10.6028/jres.078A.019	journal	May 1974

Cited By (16)

A Comparison of the Elastic Properties of Graphene- and Fullerene-Reinforced Polymer Composites: The Role of Filler Morphology and Size Lu, Chang-Tsan; Weerasinghe, Asanka; Maroudas, Dimitrios Scientific Reports, Vol. 6, Issue 1 https://doi.org/10.1038/srep31735	journal	August 2016
Viscoelasticity and Dynamics of Intercalated Polymer/Bentonite Nanocomposites Romo-Uribe, Angel Macromolecular Chemistry and Physics, Vol. 219, Issue 12 https://doi.org/10.1002/macp.201800077	journal	May 2018
Role of adsorbed chain rigidity in reinforcement of polymer nanocomposites Yang, Siyang; Hassan, Mohammed; Akcora, Pinar Journal of Polymer Science Part B: Polymer Physics, Vol. 57, Issue 1 https://doi.org/10.1002/polb.24751	journal	October 2018
Unexpected Molecular Weight Dependence to the Physical Aging of Thin Polystyrene Films Present at Ultra‐High Molecular Weights Thees, Michael F.; Roth, Connie B. Journal of Polymer Science Part B: Polymer Physics, Vol. 57, Issue 18 https://doi.org/10.1002/polb.24797	journal	February 2019
Significant improvement in static and dynamic mechanical properties of graphene oxide–carbon nanotube acrylonitrile butadiene styrene hybrid composites Jyoti, Jeevan; Babal, Arun Singh; Sharma, Sushant Journal of Materials Science, Vol. 53, Issue 4 https://doi.org/10.1007/s10853-017-1592-6	journal	November 2017
Microscopic mechanisms of deformation transfer in high dynamic range branched nanoparticle deformation sensors Raja, Shilpa N.; Ye, Xingchen; Jones, Matthew R. Nature Communications, Vol. 9, Issue 1 https://doi.org/10.1038/s41467-018-03396-5	journal	March 2018
Chemical heterogeneity in interfacial layers of polymer nanocomposites Yang, Siyang; Liu, Siqi; Narayanan, Suresh Soft Matter, Vol. 14, Issue 23 https://doi.org/10.1039/c8sm00663f	journal	January 2018
Temperature effects on the nanoindentation characterization of stiffness gradients in confined polymers Song, Jake; Kahraman, Rıdvan; Collinson, David W. Soft Matter, Vol. 15, Issue 3 https://doi.org/10.1039/c8sm01539b	journal	January 2019
Nanoparticle–polymer interfacial layer properties tune fragility and dynamic heterogeneity of athermal polymer nanocomposite films Begam, Nafisa; Das A., Nimmi; Chandran, Sivasurender Soft Matter, Vol. 14, Issue 43 https://doi.org/10.1039/c8sm01729h	journal	January 2018
Isostructural softening of the filler network in SBR/silica nanocomposites Trinh, Giang Hoang; Desloir, Marlène; Dutertre, Fabien Soft Matter, Vol. 15, Issue 15 https://doi.org/10.1039/c8sm02592d	journal	January 2019
Natural rubber–SiO ₂ nanohybrids: interface structures and dynamics Sattar, Md. Abdul; Nair, A. Sreekumaran; Xavier, P. J. Soft Matter, Vol. 15, Issue 13 https://doi.org/10.1039/c9sm00254e	journal	January 2019
Focus: Structure and dynamics of the interfacial layer in polymer nanocomposites with attractive interactions Cheng, Shiwang; Carroll, Bobby; Bocharova, Vera The Journal of Chemical Physics, Vol. 146, Issue 20 https://doi.org/10.1063/1.4978504	journal	May 2017
The interfacial zone in thin polymer films and around nanoparticles in polymer nanocomposites Zhang, Wengang; Emamy, Hamed; Pazmiño Betancourt, Beatriz A. The Journal of Chemical Physics, Vol. 151, Issue 12 https://doi.org/10.1063/1.5119269	journal	September 2019
Well-defined metal-polymer nanocomposites: The interplay of structure, thermoplasmonics, and elastic mechanical properties Reig, David Saleta; Hummel, Patrick; Wang, Zuyuan Physical Review Materials, Vol. 2, Issue 12 https://doi.org/10.1103/physrevmaterials.2.123605	journal	December 2018
Nanoparticle–polymer interfacial layer properties tune fragility and dynamic heterogeneity of athermal polymer nanocomposite films Begam, Nafisa; Das A., Nimmi; Chandran, Sivasurender Deutsches Elektronen-Synchrotron, DESY, Hamburg https://doi.org/10.3204/pubdb-2018-05897	text	January 2018
Electrostatic force microscopy for the accurate characterization of interphases in nanocomposites El Khoury, Diana; Arinero, Richard; Laurentie, Jean-Charles Beilstein Journal of Nanotechnology, Vol. 9 https://doi.org/10.3762/bjnano.9.279	journal	January 2018

Similar Records

Interplay between local dynamics and mechanical reinforcement in glassy polymer nanocomposites

Journal Article · Thu Nov 16 23:00:00 EST 2017 · Physical Review Materials · OSTI ID:1410906

Enhancing the Mechanical Properties of Glassy Nanocomposites by Tuning Polymer Molecular Weight

Journal Article · Tue Sep 11 00:00:00 EDT 2018 · ACS Applied Materials and Interfaces · OSTI ID:1476416

Addition of Short Polymer Chains Mechanically Reinforces Glassy Poly(2-vinylpyridine)–Silica Nanoparticle Nanocomposites

Journal Article · Mon Mar 23 00:00:00 EDT 2020 · ACS Applied Nano Materials · OSTI ID:1608195

Related Subjects

36 MATERIALS SCIENCE
77 NANOSCIENCE AND NANOTECHNOLOGY
Brillouin light scattering
Polymer nanocomposites
band excited atomic force microscopy
interfacial layer
mechanical reinforcement

Unraveling the Mechanism of Nanoscale Mechanical Reinforcement in Glassy Polymer Nanocomposites

Citation Formats

References (61)

Cited By (16)

Similar Records

Related Subjects