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Purpose: To assess satisfaction and preference among rugby union players for custom mouthguards with and without labial reinforcement, and to assess discomfort and perceived protection. Materials and Methods: This prospective RCT used a crossover design of four 1-week periods to compare conventional (Type A) and labial reinforced (Type B) customized mouthguards for rugby union players from February to May 2022. Type B mouthguards included a 0.75-mm insert of polyethylene terephthalate glycol (Duran) in the anterior labial region. We ensured intraoral occlusion accommodation for both mouthguards. Players wore each mouthguard type when training and in competitive matches for 2 weeks according to one of two randomized sequences. After each session, they rated the mouthguard on 10-point scales regarding discomfort, functional interference, protection, and general satisfaction. After 4 weeks, we asked participants to nominate their preferred mouthguard. Results: In total, 22 of the 24 invited players (16 men and 6 women) were included. We observed no significant differences in discomfort, functional interference, protection, or general satisfaction by mouthguard type (P > .05, Wilcoxon test). Ultimately, 12 players (55%) preferred the Type A mouthguard and 10 (45%) preferred the Type B mouthguard (P = .832; one-sample binomial test). No serious adverse events occurred. Conclusions: Labial reinforcement does not affect satisfaction, perceived comfort and protection, or mouthguard preference among rugby union players. [ABSTRACT FROM AUTHOR]

A composite of polyethylene terephthalate (PET) and hollow glass beads (HGB) with two different HGB sizes was prepared and investigated Theologically. When the HGB content reaches approximately 30 wt%, the PET/HGB composite changes from a Newtonian fluid to a pseudoplastic one within the measured frequency range. If the HGB content is below the critical value, the viscosity of the composite may be lower than that of the neat PET melt. This is because scrolling or sliding of the HGB in the PET melt increases the apparent shear rate and reduces the torque measured by the rheometer rotor. Meanwhile, the size of the HGB affects the viscosity of the composite. The 40 pm HGB has a more pronounced effect, resulting in higher viscosity than 50 pm HGB. Furthermore, the composite containing 40 [micro]m HGB has a lower density than the one containing 50 [micro]m HGB. This is because the 40 [micro]m HGB has a lower breaking rate and higher volume fraction compared to the 50 [micro]m HGB at the same mass fraction. The peak relaxation time of the PET/HGB composite increases with the HGB content, and higher temperatures correspond to shorter relaxation times. DSC analysis showed that the addition of HGB filler decreased the melting temperature and increased the crystallization temperature of the PET material. Since the PET/HGB composite has a longer relaxation time than pure PET, the corresponding aggregates made of PET chains and HGBs are expected to have larger characteristic sizes compared to PET and HGB. These sizes can be determined approximately using a grid drawing method. The coupling agent CS-101 enhances the bonding between PET and HGB. This is evidenced by comparing the viscosity curves of the composite with and without the coupling agent. Highlights * The polyethylene terephthalate (PET)/hollow glass beads (HGB) composites with low levels of HGB might exhibit unusual viscosity. * Abnormal viscosity in molten PET occurs due to the rolling or sliding of HGB. * The composites with high HGB levels may exhibit a solid-like modulus plateau. * The proposed aggregate consists of PET, HGB, and broken glass shards. KEYWORDS HGB, interface, PET, rheology, 1 | INTRODUCTION Polyethylene terephthalate (PET) is a type of engineering plastic with a wide range of applications, including packaging, electronic devices, automobile parts, and the wind power industry. This [...]

In this work, a low-profile optical transparent wideband metamaterial absorber based on radiation–absorption reciprocal theory is proposed. The top layer and bottom layer are composed of indium tin oxide–polyethylene terephthalate films, and the middle layer is a transparent substrate polymethyl methacrylate. The method of transparent wideband absorption using reciprocal theory is proposed to guide the design. Based on characteristic mode analysis and calculated equivalent aperture efficiency, the absorber consisting of composite resonators is analyzed and designed. The equivalent circuit model and surface current distributions are studied to verify the design. The numerical results show that high absorption of greater than 90% in the frequency range of 5.7–16.4 GHz is obtained. A wideband absorption rate of greater than 80% at a 60° incident angle under TM polarization and an absorption rate of greater than 65% at a 60° incident angle under TE polarization are obtained. The proposed design has the advantages of broadband absorption, polarization insensitivity, light transmittance of more than 70%, and compact structure, which can be applied to special scenes that require optical transparency, such as anechoic chamber glass and cockpit glass. [ABSTRACT FROM AUTHOR]

This research explores the Low-Velocity Impact behavior of thermoplastic composite sandwich panels with 100% recycled Polyethylene Terephthalate (PET) foam sourced from post-consumer plastic water bottles. Being recognized as a reliable technique, hybridization using stainless-steel mesh layers was employed to reinforce the panels' composite facesheets of sandwich panels accessible for modular housing, cold storage rooms and cargo trucks. Adequate impregnation of the reinforcement metallic mesh layer alongside proper skin-to-core adhesion was accomplished by optimizing a two-phase compression molding method. The effect of hybridization on impact response of sandwich panels with two different PET foam core thicknesses, and stacking sequence were evaluated. It was revealed that reinforcing the impacted surface of the composite sandwich panels significantly increased the perforation threshold. Moreover, analyzing the post-impact section view of the samples indicated that hybridization modified the damage propagation response of the PET foam core sandwich composites, through which the energy absorption capacity was improved. [ABSTRACT FROM AUTHOR]