Characterization of particle distribution in a black carbon-filled elastomer via nanoindentation

A new method to characterize the distribution of hard particles dispersed into a soft elastomer matrix is developed using nanoindentation. It is based on the measurement of the contact stiffness from the continuous stiffness measurement module (CSM). Theoretically, for a homogeneous material, the contact stiffness is directly proportional to the contact depth. However, when indenting a carbon black-filled fluoroelastomer (FKM) this relation is no longer valid and abnormal contact stiffness evolutions are measured (jumps). The tip-particle model developed in this work is simply based on the hypothesis that all the deformation is supported by the elastomer matrix and that black carbon aggregates play the role of hard extensions of the diamond tip, when touching it (grey particles 1,2 & 3, Fig. 1a). As a result, each abnormal variation of contact stiffness is related to a new aggregate in contact with the tip. By knowing the stiffness amplitude of a jump and the relative stiffness where it appeared , the equivalent projected area of a particle can be calculated (Fig. 1d). From this calculation, one can extract the distribution of particles surface density from nanoindentation measurements only. Ten experimental indentation tests have been performed and the results are displayed in Fig. 1e. The distribution of particles surface density extracted from experiments is compared to measurements performed by image analysis of a 100 nm thick slide of the material observed by Transmission Electron Microscopy (TEM) (black squares). Furthermore, the tip-particle model is simulated numerically on the same image analysis (down pointing triangles). The results obtained from this model are in excellent agreement with the TEM observation which is really promising. Indeed, this model is an alternative to microscopy characterization which can be complicated to implement. Please click Additional Files below to see the full abstract

Some cautions when applying nanoindentation tests on a fluoroelastomer: Experimental researches and application

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Study of the Fatigue of an Elastomer by Using Instrumented Indentation

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Extraction des proprietes mecaniques locales d'un elastomere par nanoindentation : developpement des des protocoles et application

National audienceThe local mechanical response of a fluoroelastomer is presented through nanoindentation results. It is well known that elastomers properties aretime-dependent and thus are influenced by the experimental protocol parameters such as the maximum applied load or loading rates. One should consider with great care this time-dependence in the case of nanoindentation tests as it can be in the case of global characterizations. The aim of this study is to determine the influence of the time-dependence during nanoindentation characterization of elastomers. In fine, these investigations should lead to a robust methodology, capable of giving quantitative measurements of the local mechanical properties of industrial products made of elastomers. Thus, this paper draws up a description of the nanoindentation technique applied on elastomers materials and discusses the results which are clearly dependent on the way they are driven. Finally, information provided by this study allowed the technique to be applied on a multilayered composite rubber/polymer, which proved the relevance of the technique by detecting properties gradients within the composite.La réponse mécanique locale d’un fluoroélastomère est présentée au travers de résultats denanoindentation. Les propriétés des élastomères présentent notamment une dépendance à la vitesse desollicitation et sont ainsi impactées par les variables du protocole expérimental choisies, telles que laforce maximale appliquée ou les vitesses de chargement. Cette caractéristique, intrinsèque à ce type de matériaux, est considérée avec soin dans le cadre d’essais à échelle globale et doit, au même titre, faire l’objet d’une attention particulière lors d’essais de nanoindentation. L’objectif de cette étude est d’appréhender l’impact de la dépendance au temps des élastomères lors de leur caractérisation en nanoindentation. Infine, les investigations doivent pouvoir mener à une méthodologie robuste capable de donner des mesures quantitatives des propriétés mécaniques locales d’élastomères de pièces réelles industrielles. Ce papier dresse donc une description de la technique de nanoindentation appliquée aux élastomères et discute les résultats qui apparaissent clairement dépendants de la manière dont les essais sont conduits. Enfin, les éléments apportés par cette prospection ont été appliqués à la caractérisation d’un composite multicouche caoutchouc/polymère. Cette étude applicative a prouvé l’aptitude de la nanoindentation à détecter desgradients de propriétés au sein du composite

Impact des paramètres expérimentaux de nanoindentation sur les mesures du module d’un élastomère

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IDENTIFICATION AND CONTROL OF SOME FACTORS AFFECTING NANOINDENTATION MEASUREMENTS ON ELASTOMERS

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Contributions on instrumented indentation of elastomers : practical case : Influence of thermal aging on local properties

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Instrumented indentation of an elastomeric material, protocol and application to vulcanization gradient

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Fatigue behavior evaluation using instrumented indentation

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Study of the Fatigue of an Elastomer by Using Instrumented Indentation

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