Watanabe Satoru, Ishida Yoshiki, Miura Daisuke, Miyasaka Taira, Shinya Akikazu
Department of Dental Materials Science, School of Life Dentistry at Tokyo, The Nippon Dental University, 1-9-20 Fujimi, Chiyoda-ku, Tokyo 102-8159, Japan.
Department of Life Science Dentistry, School of Life Dentistry at Tokyo, The Nippon Dental University, 1-9-20 Fujimi, Chiyoda-ku, Tokyo 102-8159, Japan.
Polymers (Basel). 2020 Nov 26;12(12):2803. doi: 10.3390/polym12122803.
For evaluating the impact strength of dental materials, the Izod test or Charpy test has been used, but specimen preparation for these tests is difficult due to the adjustment of a notch on them. By contrast, a weight-drop impact test does not require notched specimens. Therefore, it might be possible to measure the impact strength more accurately than conventional methods. This study aimed to establish appropriate conditions for applying the weight-drop impact test on small specimens of acrylic resin. To determine the most reliable impact fracture energy of acrylic resins, different diameters and thicknesses of PMMA resin specimens, diameters and weights of the striker, and diameters of the supporting jig were compared. For all specimen thicknesses, when the striker diameter was 6-10 mm, the impact fracture energy was constant when the inner diameter of the specimen-supporting jig was 8-10 mm. In addition, the measured E value was mostly equal to the median value of the impact fracture energy. Thus, for the weight-drop impact test, this method was effective for material testing of small specimens, by clearly specifying the test conditions, such as the thickness of disc-shaped specimens, the diameter of the striker, and the inner diameter of the specimen-supporting jig.
为了评估牙科材料的冲击强度，已采用艾氏冲击试验或夏比冲击试验，但由于需要在材料上加工缺口，这些试验的试样制备较为困难。相比之下，落锤冲击试验不需要有缺口的试样。因此，与传统方法相比，有可能更准确地测量冲击强度。本研究旨在确定对丙烯酸树脂小试样进行落锤冲击试验的合适条件。为了确定丙烯酸树脂最可靠的冲击断裂能，比较了聚甲基丙烯酸甲酯（PMMA）树脂试样的不同直径和厚度、冲击体的直径和重量以及支撑夹具的直径。对于所有试样厚度，当冲击体直径为6 - 10毫米时，若试样支撑夹具的内径为8 - 10毫米，则冲击断裂能恒定。此外，测得的E值大多等于冲击断裂能的中值。因此，对于落锤冲击试验，通过明确规定试验条件，如圆盘形试样的厚度、冲击体的直径和试样支撑夹具的内径，该方法对小试样的材料测试有效。
