Analysis and modeling for time-dependent behavior of polymers exhibited in nanoindentation tests

Wei, Pal Jen; Shen, Wei; Lin, Jen Fin

doi:10.1016/j.jnoncrysol.2008.05.016

Cited by 12 publications

(8 citation statements)

References 12 publications

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“…(a) Dependence of contact resonance frequency on temperature and Young’s modulus was modeled according to the Hertzian + creep model described in the text. Initial slow increase in the contact radius is due to creep of polymer (after ref ); sharp increase at temperature higher than 180 °C is due to decrease in Young’s modulus (Hertzian model). (b) Mechanical model used for description of polymer creep.…”

Section: Resultsmentioning

confidence: 99%

Morphology Mapping of Phase-Separated Polymer Films Using Nanothermal Analysis

et al. 2010

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Polymers films are attractive, in part, because their physical properties can be tuned by blending polymer with complementary characteristics. However, blending is typically challenging because most polymers will undergo phase separation, resulting in unpredictable behavior. Here, we introduce band excitation nanothermal analysis (BE-NanoTA) as a nondestructive AFM-based technique for mapping the near surface, thermal properties of polymeric coatings. BE-NanoTA was used to investigate phase separation and domain growth in poly(styrene-ran-acrylonitrile):poly(methyl methacrylate) SAN: PMMA films. The size and shape of PMMA-rich domains are consistent with prior measurements on the same system using a destructive method, namely UV-ozone etching of PMMA followed by topography mapping using standard AFM. Moreover, new insights into the mechanism of phase separation were uncovered including the observation of SAN-and PMMA-rich channels near the surface at early times as well as small SAN-rich domains trapped within large PMMA domains during intermediate times. Because it is nondestructive, BE-NanoTA can be used to explore in situ phase evolution in soft matter systems (e.g., polymer nanocomposites) which do not lend themselves to the UV-ozone etching method.

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Section: Resultsmentioning

confidence: 99%

Morphology Mapping of Phase-Separated Polymer Films Using Nanothermal Analysis

et al. 2010

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“…According to the literature we analyzed, [9][10][11] this procedure, combined with creep tests, is used successfully on polymer materials. The indenters were mostly Vickers-or Berkovich-type indenters.…”

Section: Figure 1 Sinking-in and Pilling-up [2]mentioning

confidence: 99%

“…The literature [9][10][11] shows that although this method is spreading, tests are performed almost exclusively at room temperature. However, polymer objects can behave differently at other temperatures and humidity; therefore we decided that tests should be performed in a wide range of temperatures.…”

Section: Figure 1 Sinking-in and Pilling-up [2]mentioning

confidence: 99%

Pinpoint Loading Examinations of Poly(lactic acid) Biopolymers

Kotrocz

Bakonyi

2018

Acta Tech Jaur

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We have made a new mounting unit for Dynamic Mechanical Analysis (DMA) equipment, suitable for measuring microhardness and indentation, and examined its usability on thermoplastic poly(lactic acid) (PLA) material. We used a Vickers-type microhardness indenter, and examined the dimensions of the indented area and the loading force. This novel unit is suitable for measuring the short and long-term behavior of the material using pinpoint load not only at room temperature (20-23 °C) – like common hardness tests – but at a wide range of temperatures.

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“…The load conditions P p ͑t͒ produce the specimen's viscoplastic deformation as a function of time only during the loading process. 24 In a multilayer specimen, the indentation load ͑P͒-depth ͑h͒ relationship obtained at various loads is not constant; the exponent value of the indentation depth varies with the indentation depth. From a comparison of finite element analyses and numerical results, 21 it was found that the exponent values of h sl ͑l =1,2,3, ... ,m͒ and indenter's depth h i are equal.…”

Section: A Theoretical Model Developed For the Contact Of An Indentementioning

confidence: 99%

“…Previously proposed methods for determining the mechanical properties of hardness ͑plasticity͒ and modulus ͑elasticity͒ produce error because of the weak connection between elastic-plastic indentation and viscous-elastic-plastic indentation. [21][22][23][24][25] In addition, a constitutive model of plasticity and elasticity seems too simple to describe the deformation behavior exhibited in viscous-elastic-plasticity indentation. The time-delay behavior between indentation load and depth induced by the viscoplastic and viscoelastic deformations cannot be neglected in the metallic materials 22 and even in hard materials, 23 especially for indentations at a high loading rate.…”

Section: A Theoretical Model Developed For the Contact Of An Indentementioning

confidence: 99%

Determination of the strain energy release rate for C/a-Si composite film produced in nanoindentation tests

Han

Huang

et al. 2009

Journal of Applied Physics

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A general mechanical model that describes the contact behavior and deformations arising at all layers (including the substrate) is developed in the present study for multilayer specimens to evaluate the theoretical contact parameters. The governing differential equations for the depth solutions of the indenter tip formed at all layers of the specimen under their contact force and depth are developed individually. These two contact parameters allow the evaluation of the internal stress and strain using the membrane theory. The strain energy release rate can thus be determined if the internal stress is available. The mean value of these pop-in depths is almost constant when operating at various loading rates. The present model is precisely if it has good agreement with experiments. The pop-in internal stress was found to be strongly dependent on the C-film thickness (thus the material properties) but independent of the applied indentation system (thus indentation conditions). The pop-in internal stress and strain energy release rate can be significantly lowered by increasing the C-film thickness. Furthermore, pop-in always formed at a depth near the interface of the C/a-Si composite film and Si substrate.

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Analysis and modeling for time-dependent behavior of polymers exhibited in nanoindentation tests

Cited by 12 publications

References 12 publications

Morphology Mapping of Phase-Separated Polymer Films Using Nanothermal Analysis

Morphology Mapping of Phase-Separated Polymer Films Using Nanothermal Analysis

Pinpoint Loading Examinations of Poly(lactic acid) Biopolymers

Determination of the strain energy release rate for C/a-Si composite film produced in nanoindentation tests

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