On the Planarization Mechanism and Pad Aging Effects of Soft Pad Polishing: A Perspective From the Micro-Mechanical Properties of Soft Pads

The local viscoelastic properties of soft polishing pads with different usage durations are measured by a micro-scale mechanical analysis testing platform. The testing reveals stimulus-adaptive local viscoelasticity of soft pads under the activation of asperity contact. This phenomenon suggests asperity-dependent local modulus. Such an increase of local modulus induced by higher asperity provides a further enhancement effect to the planarization of surface asperity. Furthermore, the measurement outcomes suggest that the reaction of local micro-scale viscoelastic properties of the soft pad surface to the workpiece asperity will decay with usage time. The current study provides a detailed understanding of the aging effects for the soft pad and explains the performance decay during soft pad polishing from a local micro-scale interfacial perspective.

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Mechanism of aging effects on viscoelasticity in ethylene-methacrylic acid ionomer studied by local thermal-mechanical analysis

Journal of Materials Research ◽

10.1557/jmr.2009.0083 ◽

2009 ◽

Vol 24 (3) ◽

pp. 1087-1092 ◽

Cited By ~ 12

Author(s):

Harsha P. Kulkarni ◽

Gregory Mogilevsky ◽

William M. Mullins ◽

Yue Wu

Keyword(s):

Aging Time ◽

Structural Relaxation ◽

Viscoelastic Properties ◽

Room Temperature ◽

Mechanical Analysis ◽

Easy Access ◽

Aging Effects ◽

Scanning Calorimetry ◽

Burger Model ◽

Thermal Mechanical Analysis

A unique atomic force microscope-based local thermal-mechanical analysis (LTA) technique was used to study the influence of room temperature aging on viscoelastic properties of ethylene-methacrylic (E/MAA) acid ionomers. This approach permits easy access to structural relaxation effects on viscoelasticity at a short aging time, for instance, before the occurrence of secondary crystallization differential scanning calorimetry (DSC) melting peak. A Burger model along with finite element method yields quantitative analysis of viscoelastic properties versus the aging time. Creep curves were obtained with LTA after various times of aging at room temperature upon cooling from the melt. Measurements were carried out at both 30 and 70 °C. The results reveal the effects of structural relaxation upon aging in the ion-rich amorphous region, the influence of secondary crystallites on the viscoelastic properties, and shed light on the processes associated with aging in E/MAA ionomers.

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Viscoelastic properties of woody hemp core

Holzforschung ◽

10.1515/hf.2010.111 ◽

2011 ◽

Vol 65 (2) ◽

Cited By ~ 14

Author(s):

Rahime Bag ◽

Johnny Beaugrand ◽

Patrice Dole ◽

Bernard Kurek

Keyword(s):

Cell Wall ◽

Viscoelastic Properties ◽

Specific Effect ◽

Mechanical Analysis ◽

Low Molecular Weight ◽

Dielectric Analysis ◽

Technological Transformation ◽

Chain Mobility ◽

Cell Wall Polymers

Abstract The aim of this study was to determine the effect of removing extractives from the woody core of hemp (chènevotte) on the chain mobility of hemicelluloses and lignins, which can react during technological transformation such as de-fibering and/or composite materials production. Extractives are molecules with low molecular weight, which are present in the cell wall matrix and can be readily removed by solvents. In the present paper, the nature and amounts of extractives, removed under different conditions and with solvents of different polarities, were determined. The mobility and structural relaxations of lignins and hemicelluloses were stu-died in situ by dynamic mechanical analysis and dielectric analysis under controlled moisture content. Extractions at low temperature led to rigidification of lignins and plasticizing of hemicelluloses, probably due to local changes by the selective removal of molecules interacting with the polymers. Probably, the accessibility of hemicelluloses to plasticizing water was increased at controlled humidity. In contrast, hot extractions including water induced rigidification of the hemi-celluloses and plasticizing of lignins. This could be related to a combination of molecule extractions and chemical modi-fications of both polymers. This interpretation is supported by the variation of activation energy for relaxation of hemi-celluloses. It can be concluded that each type of extraction has a clear specific effect on the relaxation properties of the amorphous cell wall polymers.

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Impact of material concentration and distribution on composite parts manufactured via multi-material jetting

Rapid Prototyping Journal ◽

10.1108/rpj-01-2017-0005 ◽

2018 ◽

Vol 24 (5) ◽

pp. 872-879 ◽

Cited By ~ 6

Author(s):

Nicholas Alexander Meisel ◽

David A. Dillard ◽

Christopher B. Williams

Keyword(s):

Material Properties ◽

Viscoelastic Properties ◽

Design Space ◽

Base Material ◽

Material Design ◽

Mechanical Analysis ◽

Material Composition ◽

Significant Shift ◽

Content Type ◽

Property Changes

Purpose Material jetting approximates composite material properties through deposition of base materials in a dithered pattern. This microscale, voxel-based patterning leads to macroscale property changes, which must be understood to appropriately design for this additive manufacturing (AM) process. This paper aims to identify impacts on these composites’ viscoelastic properties due to changes in base material composition and distribution caused by incomplete dithering in small features. Design/methodology/approach Dynamic mechanical analysis (DMA) is used to measure viscoelastic properties of two base PolyJet materials and seven “digital materials”. This establishes the material design space enabled by voxel-by-voxel control. Specimens of decreasing width are tested to explore effects of feature width on dithering’s ability to approximate macroscale material properties; observed changes are correlated to multi-material distribution via an analysis of ingoing layers. Findings DMA shows storage and loss moduli of preset composites trending toward the iso-strain boundary as composition changes. An added iso-stress boundary defines the property space achievable with voxel-by-voxel control. Digital materials exhibit statistically significant changes in material properties when specimen width is under 2 mm. A quantified change in same-material droplet groupings in each composite’s voxel pattern shows that dithering requires a certain geometric size to accurately approximate macroscale properties. Originality/value This paper offers the first quantification of viscoelastic properties for digital materials with respect to material composition and identification of the composite design space enabled through voxel-by-voxel control. Additionally, it identifies a significant shift in material properties with respect to feature width due to dithering pattern changes. This establishes critical design for AM guidelines for engineers designing with digital materials.

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Development of an Advanced Dynamic Microindentation System to Determine Local Viscoelastic Properties of Polymers

Polymers ◽

10.3390/polym11050833 ◽

2019 ◽

Vol 11 (5) ◽

pp. 833 ◽

Cited By ~ 2

Author(s):

Esther Ramakers-van Dorp ◽

Thomas Haenel ◽

Dominik Ciongwa ◽

Bernhard Möginger ◽

Berenika Hausnerova

Keyword(s):

High Density Polyethylene ◽

Viscoelastic Properties ◽

Thermoplastic Polyurethane ◽

Mechanical Analysis ◽

Polybutylene Terephthalate ◽

Tungsten Electrode ◽

Complex Moduli ◽

Spatially Resolved ◽

Material Information ◽

Adequate Method

This study presents a microindentation system which allows spatially resolved local as well as bulk viscoelastic material information to be obtained within one instrument. The microindentation method was merged with dynamic mechanical analysis (DMA) for a tungsten cone indenter. Three tungsten cone indenters were investigated: tungsten electrode, tungsten electrode + 2% lanthanum, and tungsten electrode + rare earth elements. Only the tungsten electrode + 2% lanthanum indenter showed the sinusoidal response, and its geometry remained unaffected by the repeated indentations. Complex moduli obtained from dynamic microindentation for high-density polyethylene, polybutylene terephthalate, polycarbonate, and thermoplastic polyurethane are in agreement with the literature. Additionally, by implementing a specially developed x-y-stage, this study showed that dynamic microindentation with a tungsten cone indenter was an adequate method to determine spatially resolved local viscoelastic surface properties.

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A methodology to assess the evolution of viscoelastic properties of hardened cement pastes through dynamic mechanical analysis

Construction and Building Materials ◽

10.1016/j.conbuildmat.2019.07.268 ◽

2019 ◽

Vol 226 ◽

pp. 849-858

Author(s):

Francisco Evangelista Junior ◽

Fabiano Campos Macedo ◽

Márcio Muniz Farias

Keyword(s):

Dynamic Mechanical Analysis ◽

Viscoelastic Properties ◽

Mechanical Analysis ◽

Hardened Cement ◽

Cement Pastes ◽

Dynamic Mechanical ◽

Hardened Cement Pastes

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EHL with Rough Surface Asperity Contact

Encyclopedia of Tribology ◽

10.1007/978-0-387-92897-5_100381 ◽

2013 ◽

pp. 852-852

Keyword(s):

Rough Surface ◽

Asperity Contact ◽

Surface Asperity

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Determination of viscoelastic properties of thin pressure sensitive adhesive using dynamic mechanical analysis

Mechanics of Time-Dependent Materials ◽

10.1007/s11043-019-09412-5 ◽

2019 ◽

Vol 24 (2) ◽

pp. 129-140

Author(s):

H. Jung ◽

H. Song ◽

M. Lee ◽

Y. Kim ◽

S. Youn ◽

...

Keyword(s):

Dynamic Mechanical Analysis ◽

Viscoelastic Properties ◽

Mechanical Analysis ◽

Pressure Sensitive Adhesive ◽

Dynamic Mechanical ◽

Pressure Sensitive

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Energy Dissipation Due to Surface Asperity: A Micro-scale Study

Proceedings of GeoShanghai 2018 International Conference: Fundamentals of Soil Behaviours ◽

10.1007/978-981-13-0125-4_108 ◽

2018 ◽

pp. 975-983

Author(s):

Can Wang ◽

An Deng ◽

Abbas Taheri

Keyword(s):

Energy Dissipation ◽

Surface Asperity ◽

Micro Scale

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Heat Built Up During Dynamic Mechanical Analysis (DMA) Testing of Rubber Specimens

Volume 9: Mechanics of Solids, Structures, and Fluids ◽

10.1115/imece2018-88627 ◽

2018 ◽

Cited By ~ 1

Author(s):

Roja Esmaeeli ◽

Ashkan Nazari ◽

Haniph Aliniagerdroudbari ◽

Seyed Reza Hashemi ◽

Muapper Alhadri ◽

...

Keyword(s):

Dynamic Mechanical Analysis ◽

Heat Generation ◽

Temperature Rise ◽

Viscoelastic Properties ◽

Mechanical Analysis ◽

Compression Tests ◽

Element Analysis ◽

Dynamic Mechanical ◽

Fea Model ◽

Static And Dynamic Moduli

The viscoelastic properties of rubbers play an important role in dynamic applications and are commonly measured and quantified by means of Dynamic Mechanical Analysis (DMA) tests. The rubber properties including the static and dynamic moduli are a function of temperature; and an increase in the temperature leads to a decrease in both moduli of the rubber. Due to the heat generation inside the rubber during the DMA test and the possible change of the rubber properties it is important to quantify the amount of temperature rise in the rubber specimen during the test. In this study, a Finite Element Analysis (FEA) model is used to predict the heat generation and temperature rise during the rubber DMA tests. This model is used to identify the best shape of the specimen to achieve the minimum increase in temperature during the test. The double sandwich shear test and the cyclic compression tests are considered in this study because these two tests are mostly used in industry to predict the rubber viscoelastic properties.

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