Nano-Indentation Response of Ultrahigh Molecular Weight Polyethylene (UHMWPE): A Detailed Analysis

Abstract

Nano-indentation, a depth sensing technique, is a useful and exciting tool to investigate the surface mechanical properties of a wide range of materials, particularly polymers. Knowledge of the influence of experimental conditions employed during nano-indentation on the resultant nano-mechanical response is very important for the successful design of engineering components with appropriate surface properties. In this work, nano-indentation experiments were carried out by selecting various values of frequency, amplitude, contact depth, strain rate, holding time, and peak load. The results showed a significant effect of amplitude, frequency, and strain rate on the hardness and modulus of the considered polymer, ultrahigh molecular weight polyethylene (UHMWPE). Load-displacement curves showed a shift towards the lower indentation depths along with an increase in peak load by increasing the indentation amplitude or strain rate. The results also revealed the strong dependence of hardness and modulus on the holding time. The experimental data of creep depth as a function of holding time was successfully fitted with a logarithmic creep model (R2 ≥ 0.98). In order to remove the creeping effect and the nose problem, recommended holding times were proposed for the investigated polymer as a function of different applied loads.

Investigation of Soft Matter Nanomechanics by Atomic Force Microscopy and Optical Tweezers: A Comprehensive Review

“…Furthermore, the continuous necessity of measuring the elastic properties of specific local areas drove the progress of single-molecule techniques in the contribution to the physical models described in the next section. Indentation measurements have been used to study the mechanical properties of polyethylene [ 130 ] and chitosan [ 131 ] polymers, hydrogel coatings [ 132 ], acrylonitrile butadiene styrene and polycarbonate blends [ 133 ] or smart composites [ 134 ], liquid crystals [ 135 ] and bone tissues [ 136 ].…”

Intraspherulitic mechanical heterogeneities and microstructure of i-PP highlighted by nanoindentation and atomic force microscopy

“…Nanoindentation is most often used for the characterization of polymers considered homogeneous such as amorphous polymers like PMMA [22][23][24][25], PC [24,26], or PS [24]. For semi-crystalline polymers, nanoindentation was used on commercial samples prepared by conventional manufacturing processes, such as injection molding or extrusion, that usually induce a microstructure gradient between the skin and the core of the sample [27][28][29][30][31][32][33]. These studies aimed to evaluate the mechanical response in the different zones (skin-transition-core layers) of the prepared sample.…”

Sol-gel processing of a covalent organic framework for the generation of hierarchically porous monolithic adsorbents

“…These values are significantly higher than those previously obtained for COF aerogel pellets 26 and slightly above those known for high-molecular-weight polyethylene. 32 A full comparison of the mechanical properties of the COF monolith and those of other COF bodies reported in the literature is included in Table S6. These results suggest mechanical robustness and potential industrial suitability, possibly as a result of weak, non-crystalline-layer interfaces between COF crystallites, which serve to dissipate stress.…”