Effect of fiber content and fiber orientation on mechanical behavior of fused filament fabricated continuous-glass-fiber-reinforced nylon

Purpose Fused filament fabrication of continuous-fiber-reinforced polymers is a promising technique to achieve customized high-performance composites. However, the off-axis tensile strength (TS) and Mode I fracture toughness of fused filament fabricated (FFFed) continuous-glass-fiber-reinforced (CGFR) nylon are unknown. The purpose of this paper is to investigate the mechanical and fracture behavior of FFFed CGFR nylon with various fiber content and off-axis fiber alignment. Design/methodology/approach Tensile tests were performed on FFFed CGFR-nylon with 9.5, 18.9 and 28.4 fiber vol. %. TS was tested with fiber orientations between 0∘ and 90∘ at 15∘ intervals. Double cantilever beam tests were performed to reveal the Mode I fracture toughness of FFFed composites. Findings TS increased with increasing fiber vol. % from 122 MPa at 9.5 vol. % to 291 MPa at 28 vol. %. FFFed nylon with a triangular infill resulted in 37 vol. % porosity and a TS of 12 MPa. Composite samples had 11–12 vol. % porosity. TS decreased by 78% from 291 MPa to 64 MPa for a change in fiber angle θ from 0∘ (parallel to the tensile stress) to 15∘. TS was between 27 and 17 MPa for 300 < θ < 900. Mode I fracture toughness of all the composites were lower than ∼332 J/m2. Practical implications Practical applications of FFFed continuous-fiber-reinforced (CFR) nylon should be limited to designs where tensile stresses align within 15∘ of the fiber orientation. Interlayer fracture toughness of FFFed CFR composites should be confirmed for product designs that operate under Mode I loading. Originality/value To the best of the authors’ knowledge, this is the first study showing the effects of fiber orientation on the mechanical behavior and effects of the fiber content on the Mode I fracture toughness of FFFed CGFR nylon.

EVALUATION OF THE POSSIBILITY OF USING REFTINSKAYA GRES ASH IN THE PRODUCTION OF CONTINUOUS GLASS FIBER

The article presents the results of the evaluation of the study of the possibility of using ash and slag waste (ash) of Reftinskaya GRES as a component of the charge used in the production of continuous glass fiber of high-modulus (type E), dielectric resistant (type S) and high-strength, chemically stable basalt (type B) compositions. Since the chemical composition of ash is multicomponent and significantly differs from the compositions of raw materials traditionally used in the production of glass fiber, in order to establish the technological features of its use as a component of the charge, experimental compositions of glasses were designed to achieve their specified physical and mechanical properties, with the maximum possible content of ash in the composition of glass charges. A priori assessment showed that acceptable properties of glass for glass fiber compositions E, S and B can be obtained at the content of 36%, 68% and 64% ash in the charges, respectively, for the listed types of glass. The determination of the glass transition temperature intervals of the experimental charge compositions showed that an increase in the ash content in them increases the temperature that ensures the production of a high-quality melt. Studies of the tendency of experimental glass compositions to crystallization, which prevents the effective process of fiber formation, allowed us to determine that almost all compositions have a reduced tendency to crystallization, therefore, they can be used in the production of glass fibers of types S, E and B.

The Effect of Material Type and Location of an Orthodontic Retainer in Resisting Axial or Buccal Forces

The purpose of this study was to investigate the effect of retainer material and retainer position on a tooth to resist movement of the tooth in a simulation model. Bidirectional continuous glass fiber-reinforced composite (FRC) retainers and control retainers of steel wires were tested. The FRC retainers had a polymer matrix of bisphenol-A-glycidyldimethacrylate (bis-GMA) and poly(methylmethacrylate) (PMMA), and it was cured with a photoinitiator system. The retainers were adhered to a lower jaw Frasaco model in two different positions. Resistance against the movement of one tooth was measured from two directions. The average load values within the FRC retainer groups were higher than within the metal retainer groups. The load values for the groups loaded from the axial direction were higher than those loaded from the buccal direction. FRC retainers, which were located 1–2 mm from the incisal edge, showed higher load values than those located 4–5 mm from the incisal edge. There was a significant difference in load values between FRC retainers and metal retainers (p < 0.01). The wire position and the direction of force also had significant effects (p < 0.01). There were no significant differences between metal retainer groups. The results of this study suggest that metal retainers are more flexible, allowing for tooth movements of larger magnitude than with FRC retainers.