Local mechanical spectroscopy with nanometer-scale lateral resolution

A new technique has been developed to probe the viscoelastic and anelastic properties of submicron phases of inhomogeneous materials. The measurement gives information related to the internal friction and to the variations of the dynamic modulus of nanometer-sized volumes. It is then the nanoscale equivalent to mechanical spectroscopy, a well-known macroscopic technique for materials studies, also sometimes called dynamic mechanical (thermal) analysis. The technique is based on a scanning force microscope, using the principle of scanning local-acceleration microscopy (SLAM), and allows the sample temperature to be changed. It is called variable-temperature SLAM, abbreviated T-SLAM. According to a recent proposition to systematize names of scanning probe microscope based methods, this technique should be included in the family of “mechanothermal analysis with scanning microscopy.” It is suited for studying defect dynamics in nanomaterials and composites by locating the dissipative mechanisms in submicron phases. The primary and secondary relaxations, as well as the viscoplasticity, were observed in bulk PVC. The wide range of phenomena demonstrate the versatility of the technique. A still unexplained increase of the stiffness with increasing temperature was observed just below the glass transition. All of these observations, although their interpretation in terms of physical events is still tentative, are in agreement with global studies. This technique also permits one to image the variations of the local elasticity or of the local damping at a fixed temperature. This enables the study of, for instance, the homogeneity of phase transitions in multiphased materials, or of the interface morphologies and properties. As an illustration, the homogeneity of the glass transition temperature of PVC in a 50/50 wt % PVC/PB polymer blend has been demonstrated. Due to the small size of the probed volume, T-SLAM gives information on the mechanical properties of the near-surface, which may differ from bulk properties.

[1]  Bernard Cretin,et al.  Scanning Microdeformation Microscopy , 1993 .

[2]  B. S. Berry,et al.  Anelastic Relaxation in Crystalline Solids , 1972 .

[3]  Ute Rabe,et al.  Acoustic microscopy by atomic force microscopy , 1994 .

[4]  Pascal Gallo,et al.  Scanning local‐acceleration microscopy , 1996 .

[5]  Oleg Kolosov,et al.  Nonlinear Detection of Ultrasonic Vibrations in an Atomic Force Microscope , 1993 .

[6]  S. Goto,et al.  Role of interfaces in creep of fibre-reinforced metal-matrix composites—I. Continuous fibres , 1991 .

[7]  A. Takahara,et al.  Imaging of Dynamic Viscoelastic Properties of a Phase-Separated Polymer Surface by Forced Oscillation Atomic Force Microscopy , 1994 .

[8]  Pierre-Emmanuel Mazeran,et al.  Force modulation with a scanning force microscope: an analysis , 1997 .

[9]  B. Nysten,et al.  Atomic-force Microscopy Imaging of Viscoelastic Properties in Toughened Polypropylene Resins , 1995 .

[10]  A. Kulik,et al.  Optimal sample shape for internal friction measurements using a dual cantilevered beam , 1985 .

[11]  H. Pollock,et al.  LOCALIZED THERMAL ANALYSIS USING A MINIATURIZED RESISTIVE PROBE , 1996 .

[12]  J. Ferry.  Viscoelastic properties of polymers , 1961 .

[13]  P. Hansma,et al.  A nondestructive method for determining the spring constant of cantilevers for scanning force microscopy , 1993 .

[14]  H. Pollock,et al.  Scanning thermal microscopy: Subsurface imaging, thermal mapping of polymer blends, and localized calorimetry , 1996 .

[15]  P. Hansma,et al.  Using force modulation to image surface elasticities with the atomic force microscope , 1991 .

[16]  C. G'sell,et al.  Plastic deformation of amorphous and semi-crystalline materials , 1982 .

[17]  M. Troyon,et al.  Force modulation microscopy for the study of stiff materials , 1997 .

[18]  Pascal Gallo,et al.  Materials" properties measurements: Choosing the optimal scanning probe microscope configuration , 1996 .

[19]  Hertz.  On the Contact of Elastic Solids , 1882 .

[20]  G. Gremaud.  THE HYSTERETIC DAMPING MECHANISMS RELATED TO DISLOCATION MOTION , 1987 .