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Journal ArticleDOI

Quantitative mapping of surface elastic moduli in silica-reinforced rubbers and rubber blends across the length scales by AFM

22 Jan 2011-Journal of Materials Science (Springer)-Vol. 46, Iss: 10, pp 3507-3516
TL;DR: In this article, the surface elastic moduli of silica-reinforced rubbers and rubber blends were investigated by atomic force microscopy (AFM)-based HarmoniX material mapping.
Abstract: The surface elastic moduli of silica-reinforced rubbers and rubber blends were investigated by atomic force microscopy (AFM)-based HarmoniX material mapping. Styrene–butadiene rubbers (SBR) and ethylene–propylene–diene rubbers (EPDM) and SBR/EPDM rubber blends with varying concentrations of silica nanoparticles (0, 5, 10, 20, 50 parts per hundred rubber, phr) were prepared to investigate the effect of different composition on the resulting morphology, filler distribution and elastic moduli of a specific rubber or rubber blend sample. For SBR, the elastic modulus values varied from 0.5 MPa for unfilled SBR to 5 MPa for 50 phr reinforced SBR with the increase in the concentration of filler. For EPDM, the corresponding values increased from 1.4 MPa for unfilled EPDM to 4.5 MPa for 50 phr reinforced EPDM. Local stiff and soft domains in silica-reinforced SBR and EPDM rubbers and rubber blends were identified by HarmoniX AFM imaging. While the stiff silica particles show modulus values as high as 2 GPa, the rubber matrix reveals modulus values in the range of ca. 30 MPa for the rubber blends to ca. 300 MPa for the unfilled rubbers. The lower value of elastic modulus of the EPDM phase in the blend, compared to the blank EPDM compound can be attributed to the presence of Sunpar oil in the compound which has a very good affinity with EPDM and decreases the rubber modulus. The elastic moduli maps revealed an increase of the areal fraction of silica particles showing an intrinsic surface modulus value with rising silica content in the compound preparation mixture. HarmoniX AFM measurements revealed the formation of larger silica aggregates in EPDM in contrast to SBR where isolated silica particles were observed. For silica-reinforced rubber blends a phase separation into a soft (ca. 40 MPa) and a significantly harder phase could be observed (ca. 500 MPa–1.5 GPa) indicating the incorporation of silica particles in the SBR phase. Using HarmoniX AFM imaging significantly higher surface elastic moduli were observed compared to those obtained by bulk tensile testing. Possible reasons for the observed differences between bulk modulus values and those measured by AFM are discussed in detail, including the aspect of different averaging procedures like inherent to surface probing by AFM versus bulk tensile testing, different filler distributions in SBR and EPDM and the AFM modulus calibration procedures.

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Citations
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Journal ArticleDOI
TL;DR: In this article, a comprehensive survey is presented to report the cluster-cluster aggregation model, and jamming, percolation and soft colloidal dynamics theories and their applications in NPFPs in relation to nanoparticle reinforcement of polymers beyond hydrodynamics.

180 citations

Journal ArticleDOI
TL;DR: Dynamic measurements demonstrate that rod-like particles induce stronger reinforcement of rubber, increasing with the AR, related to the self-alignment of the anisotropic silica particles in domains able to immobilize rubber.
Abstract: Silica–styrene butadiene rubber (SBR) nanocomposites were prepared by using shape-controlled spherical and rod-like silica nanoparticles (NPs) with different aspect ratios (AR = 1–5), obtained by a sol–gel route assisted by a structure directing agent. The nanocomposites were used as models to study the influence of the particle shape on the formation of nanoscale immobilized rubber at the silica-rubber interface and its effect on the dynamic-mechanical behavior. TEM and AFM tapping mode analyses of nanocomposites demonstrated that the silica particles are surrounded by a rubber layer immobilized at the particle surface. The spherical filler showed small contact zones between neighboring particles in contact with thin rubber layers, while anisotropic particles (AR > 2) formed domains of rods preferentially aligned along the main axis. A detailed analysis of the polymer chain mobility by different time domain nuclear magnetic resonance (TD-NMR) techniques evidenced a population of rigid rubber chains surrounding particles, whose amount increases with the particle anisotropy, even in the absence of significant differences in terms of chemical crosslinking. Dynamic measurements demonstrate that rod-like particles induce stronger reinforcement of rubber, increasing with the AR. This was related to the self-alignment of the anisotropic silica particles in domains able to immobilize rubber.

97 citations

Journal ArticleDOI
TL;DR: The state of the art of the main AFM-based methods for qualitative and quantitative single-point measurements and imaging of mechanical properties of polymeric thin films are described, illustrating their specific merits and limitations.
Abstract: Polymeric thin films have been awakening continuous and growing interest for application in nanotechnology. For such applications, the assessment of their (nano)mechanical properties is a key issue, since they may dramatically vary between the bulk and the thin film state, even for the same polymer. Therefore, techniques are required for the in situ characterization of mechanical properties of thin films that must be nondestructive or only minimally destructive. Also, they must also be able to probe nanometer-thick ultrathin films and layers and capable of imaging the mechanical properties of the sample with nanometer lateral resolution, since, for instance, at these scales blends or copolymers are not uniform, their phases being separated. Atomic force microscopy (AFM) has been proposed as a tool for the development of a number of techniques that match such requirements. In this review, we describe the state of the art of the main AFM-based methods for qualitative and quantitative single-point measurements and imaging of mechanical properties of polymeric thin films, illustrating their specific merits and limitations.

74 citations


Cites methods from "Quantitative mapping of surface ela..."

  • ...2 GPa....

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  • ...6 GPa for the PS matrix, according to the vendor....

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  • ...5 GPa [42]: although the result for LDPE is acceptable, that for PC appears to be inconsistent with the one obtained by TH-AFM....

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  • ...TH-AFM has been demonstrated to allow accurate quantitative elastic modulus measurements and mapping on several polymeric bulk samples, thin films, blends, and reinforced polymers with elastic modulus ranging between 1 MPa and 10 GPa [129, 134, 135]....

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  • ...5 GPa and MSBS060 MPa, which are definitely in the ranges of the values reported in literature, although in the comparison one should always remember that the properties of polymeric thin films may vary dramatically with the synthesis and deposition procedure [35, 37, 129–133]....

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Journal ArticleDOI
TL;DR: In this paper, the double-layer structure of the interphase between nanofillers and rubber matrix was quantitatively identified by using peak force quantitative nanomechanical mapping (PFQNM) mode of Atomic Force Microscope (AFM).

60 citations

Journal ArticleDOI
24 Jan 2013-Polymer
TL;DR: In this paper, the effect of altering the molecular weight (Mw) of PTMO, which is used as a soft segment (SS), on the microstructure was investigated by atomic force micros- copy (AFM) and compared with elastic modulus data measured from AFM-enabled indentation, dynamic nanoindentation (nanoDMA), and dynamic mechanical analysis (DMA).

53 citations

References
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Journal ArticleDOI
TL;DR: The atomic force microscope (AFM) is not only used to image the topography of solid surfaces at high resolution but also to measure force-versus-distance curves as discussed by the authors, which provide valuable information on local material properties such as elasticity, hardness, Hamaker constant, adhesion and surface charge densities.

3,281 citations

Journal ArticleDOI
TL;DR: In this paper, the authors review the fundamentals, applications and future tendencies of dynamic atomic force microscopy (AFM) methods and present a detailed quantitative comparison between theoretical simulations and experiment.

1,908 citations

Journal ArticleDOI
TL;DR: A specially designed cantilever tip is created that allows these interaction forces to be measured with good (sub-microsecond) temporal resolution and material properties to be determined and mapped in detail with nanoscale spatial resolution.
Abstract: Tapping-mode atomic force microscopy (AFM), in which the vibrating tip periodically approaches, interacts and retracts from the sample surface, is the most common AFM imaging method. The tip experiences attractive and repulsive forces that depend on the chemical and mechanical properties of the sample, yet conventional AFM tips are limited in their ability to resolve these time-varying forces. We have created a specially designed cantilever tip that allows these interaction forces to be measured with good (sub-microsecond) temporal resolution and material properties to be determined and mapped in detail with nanoscale spatial resolution. Mechanical measurements based on these force waveforms are provided at a rate of 4 kHz. The forces and contact areas encountered in these measurements are orders of magnitude smaller than conventional indentation and AFM-based indentation techniques that typically provide data rates around 1 Hz. We use this tool to quantify and map nanomechanical changes in a binary polymer blend in the vicinity of its glass transition. Phase changes and chemical compositional variations in materials on the nanoscale have been studied using various scanning force microscopy techniques. In these techniques, a force-sensing cantilever with a sharp tip is placed in continuous contact with the sample surface. Dynamical properties of the cantilever are adjusted depending on the material in contact with the tip. Examples of these techniques include ultrasonic force microscopy 1 , force modulation microscopy 2 , shear modulation force microscopy and lateral force microscopy 3,4 .T hese

469 citations

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01 Oct 1988

377 citations