Department of Biomedical Materials Science, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS, 39216-4505, USA.
Research and Development, Prismatik Dentalcraft Inc., 17644 Daimler St, Irvine, CA 92614, USA.
J Mech Behav Biomed Mater. 2024 Dec;160:106713. doi: 10.1016/j.jmbbm.2024.106713. Epub 2024 Sep 3.
Young's modulus of elasticity (or stiffness, E) is an important material property for many applications of polymers and polymer-matrix composites. The common methods of measuring E are by measuring the velocity of ultrasonic pulses through the material or by resistance to flexure, but it is difficult for ultrasound to penetrate polymers that contain filler particles, and flexural measurements require large specimens that may not mimic the clinical case. Thus, it may be difficult to determine E using conventional techniques. It would be useful to have a relatively rapid technique that could be applied to small specimens, highly filled materials, and even specimens cured in situ. We suggest using a microhardness indentation technique that was originally developed for ceramic materials. We tested two unfilled rigid polymers, four resin composites, and four unfilled polymers with lesser hardness for this study. The study found that greater Vickers hardness loads yielded more consistent results than lesser loads. We developed a modified equation for E based on Knoop microhardness indentations. We concluded that laboratories may use a microhardness indenter to estimate the elastic moduli of polymers and resin composites. The results support our initial hypotheses that the slope of the equation relating the indentation parameter and the hardness/elastic modulus ratio was different for polymers and resin composites than for ceramics; however, the intercept is the same irrespective of the material tested.
杨氏弹性模量（或刚度，E）是许多聚合物和聚合物基复合材料应用的重要材料特性。测量 E 的常用方法是通过测量材料中超声波脉冲的速度或通过弯曲阻力来测量，但对于含有填充颗粒的聚合物，超声波很难穿透，而弯曲测量需要可能无法模拟临床情况的大样本。因此，使用传统技术可能很难确定 E。如果有一种相对快速的技术，可以应用于小样本、高填充材料，甚至原位固化的样本，那就太好了。我们建议使用最初为陶瓷材料开发的微硬度压痕技术。我们为此研究测试了两种未填充的刚性聚合物、四种树脂复合材料和四种硬度较低的未填充聚合物。研究发现，较大的维氏硬度载荷比较小的载荷产生更一致的结果。我们基于努普微硬度压痕开发了一个改进的 E 方程。我们得出的结论是，实验室可以使用显微硬度压痕计来估计聚合物和树脂复合材料的弹性模量。结果支持我们最初的假设，即与压痕参数和硬度/弹性模量比相关的方程的斜率对于聚合物和树脂复合材料与陶瓷材料不同；然而，无论测试的材料如何，截距都是相同的。
