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Wu H, Dave F, Mokhtari M, Ali MM, Sherlock R, McIlhagger A, Tormey D, McFadden S. On the Application of Vickers Micro Hardness Testing to Isotactic Polypropylene. Polymers (Basel) 2022; 14:polym14091804. [PMID: 35566972 PMCID: PMC9102282 DOI: 10.3390/polym14091804] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 04/11/2022] [Accepted: 04/25/2022] [Indexed: 01/27/2023] Open
Abstract
Hardness is a useful measure of a material’s resistance to permanent indentation; but for viscoelastic polymers, hardness data are highly dependent on the test type and the parameter set chosen. Vickers microhardness testing is used to leave small indents (<150 µm) and is shown to be applicable to polymers. A detailed investigation of the required steps for microhardness testing in isotactic polypropylene (iPP) is provided. Samples should be mounted in epoxy resin in order to maintain curing temperatures at room temperature. Mounted samples can be ground and polished in a semi-automatic polisher using graduated SiC paper (wet grinding) but progressing onto alumina suspension for polishing. Final polishing should be performed with 0.05-µm alumina suspension. The hardness measured was shown to be dependent on load and dwell time with a much greater dependency on dwell time. Strain recovery was shown to be completed after a time period equal to the dwell time. This study shows that indents can be measured thereafter, and it is recommended that they be measured within a 24 h period after the indent was created. After data fitting, the equation for hardness was shown to follow a power law with load and dwell time as the main variables. Fitting parameters were compared to those found in the literature, and it was found that parameters were significantly different to those reported elsewhere. Therefore, this study highlights the importance of calibrating on a case-by-case basis. Finally, to show the usefulness of the Vickers micro-hardness testing method, the calibrated test method was applied on iPP with additions of carbon black up to 3 wt.%. Comparisons were made with data from the literature, but the hardness data generated in our work were found to be at least twice that reported in the literature. The testing parameters were not cited in the literature: specifically, the dwell time was not provided, and this generated doubt on the usefulness of the cited data. Hence, this work is intended to serve as an exemplar of how to prepare and proceed with hardness testing of polymers.
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Affiliation(s)
- Hao Wu
- School of Computing, Engineering and Intelligent Systems, Ulster University, Londonderry BT48 7JL, UK
- Correspondence: (H.W.); (S.M.)
| | - Foram Dave
- Department of Mechanical and Manufacturing Engineering, Centre for Precision Engineering, Materials and Manufacturing Research, Institute of Technology Sligo, F91 YW50 Sligo, Ireland; (F.D.); (M.M.A.); (D.T.)
| | - Mozaffar Mokhtari
- National Graphene Institute and Department of Materials, School of Natural Sciences, The University of Manchester, Manchester M13 9PL, UK;
- School of Engineering, Ulster University, Newtownabbey BT37 0QB, UK;
| | - Muhammad Mahmood Ali
- Department of Mechanical and Manufacturing Engineering, Centre for Precision Engineering, Materials and Manufacturing Research, Institute of Technology Sligo, F91 YW50 Sligo, Ireland; (F.D.); (M.M.A.); (D.T.)
| | - Richard Sherlock
- Department of Life Science, Institute of Technology Sligo, F91 YW50 Sligo, Ireland;
| | | | - David Tormey
- Department of Mechanical and Manufacturing Engineering, Centre for Precision Engineering, Materials and Manufacturing Research, Institute of Technology Sligo, F91 YW50 Sligo, Ireland; (F.D.); (M.M.A.); (D.T.)
| | - Shaun McFadden
- School of Computing, Engineering and Intelligent Systems, Ulster University, Londonderry BT48 7JL, UK
- Correspondence: (H.W.); (S.M.)
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Amer I, van Reenen A, Mokrani T. Molecular weight and tacticity effect on morphological and mechanical properties of Ziegler–Natta catalyzed isotactic polypropylenes. POLIMEROS 2015. [DOI: 10.1590/0104-1428.2158] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
- Ismael Amer
- University of Stellenbosch, South Africa; University of South Africa, South Africa
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Benavente R, Caveda S, Pérez E, Blazquez E, Peña B, Grieken RV, Suárez I. Influence of β-nucleation on polymorphism and properties in random copolymers and terpolymers of propylene. POLYM ENG SCI 2012. [DOI: 10.1002/pen.23322] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Polymerisation and structure–property relationships of Ziegler–Natta catalysed isotactic polypropylenes. Eur Polym J 2011. [DOI: 10.1016/j.eurpolymj.2010.10.019] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Chvátalová L, Navrátilová J, Čermák R, Raab M, Obadal M. Joint Effects of Molecular Structure and Processing History on Specific Nucleation of Isotactic Polypropylene. Macromolecules 2009. [DOI: 10.1021/ma9005878] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Lenka Chvátalová
- Faculty of Technology, Department of Polymer Engineering, Tomas Bata University in Zlín, nám. T. G. Masaryka 275, 762 72 Zlín, Czech Republic
| | - Jana Navrátilová
- Faculty of Technology, Department of Polymer Engineering, Tomas Bata University in Zlín, nám. T. G. Masaryka 275, 762 72 Zlín, Czech Republic
| | - Roman Čermák
- Faculty of Technology, Department of Polymer Engineering, Tomas Bata University in Zlín, nám. T. G. Masaryka 275, 762 72 Zlín, Czech Republic
| | - Miroslav Raab
- Institute of Macromolecular Chemistry, AS CR, v. v. i., Heyrovského nám. 2, 162 06 Prague, Czech Republic
| | - Martin Obadal
- Borealis Polyolefine GmbH, St.-Peter-Strasse 25, 4021 Linz, Austria
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Flores A, Pieruccini M, Stribeck N, Funari S, Bosch E, Baltá-Calleja F. Structure formation in poly(ethylene terephthalate) upon annealing as revealed by microindentation hardness and X-ray scattering. POLYMER 2005. [DOI: 10.1016/j.polymer.2005.07.033] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Kotek J, Kelnar I, Baldrian J, Raab M. Structural transformations of isotactic polypropylene induced by heating and UV light. Eur Polym J 2004. [DOI: 10.1016/j.eurpolymj.2004.07.017] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Baltá Calleja FJ, Flores A, Michler GH. Microindentation studies at the near surface of glassy polymers: Influence of molecular weight. J Appl Polym Sci 2004. [DOI: 10.1002/app.20665] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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