Crystallization and hardening of poly(ethylene-co-vinyl acetate) mouthguards during routine use

• DOI: 10.1038/srep44672
• Publication Date: 2017-03-15T10:18:40Z
• Authors: Ryoko Kuwahara; Ryotaro Tomita; Natsumi Ogawa; Kazunori Nakajima; Tomotaka Takeda; Hiroki Uehara; Takeshi Yamanobe
• Keywords: Ethylene-vinyl acetate; Hardening (computing); Vinyl acetate; Poly ethylene

Mouthguards (MGs) made from poly(ethylene-co-vinyl acetate) (EVA) are widely used in contact sports to prevent injuries such as breaking teeth and lip lacerations reduce brain concussion. However, the changes morphology molecular mobility of EVA, which can affect its physical properties during practical usage, have not been precisely examined. Therefore, we attempted determine main factors lead MG performance after one season use by high school rugby players. Solid-state nuclear magnetic resonance (NMR) pulse NMR measurements showed hardening MGs, was associated with an increased crystallinity EVA resulting prolonged usage. Furthermore, our data indicated that increase relative amount crystalline phase may be primarily attributed temperature fluctuations repeated pressure, could cause eventually diminish protective ability MGs.