Search

To address the issue of pavement cracking due to brittle concrete in road and bridge engineering, this study explores the use of high-ductility magnesium phosphate cementitious concrete (HD-MPCC) for rapid repairs. The deformation and frost properties of HD-MPCC are analyzed to assess its suitability for this application. Deformation properties were tested for HD-MPCC specimens cured in both air and water. Subsequent tests focused on the frost performance and mechanical properties after freeze-thaw cycles. A mercury penetration technique was utilized to examine the pore structure. The findings reveal that the expansion deformation of HD-MPCC increases with curing age in both air and water conditions, and the quantitative relationship between the expansion deformation and curing age of HD-MPCC was analyzed. Additionally, the freeze-thaw cycles led to a decrease in mass loss, the relative dynamic elastic modulus, the ultimate tensile strength, the ultimate tensile strain, the flexural strength, and the peak deflection. The volume fraction of harmless and less harmful pores gradually decreased as the freeze-thaw cycle increased, while the volume fraction of more harmful pores increased, resulting in a decrease in the strength, ultimate tensile strain, and peak deflection.

Glass ionomer cement (GIC) releases fluorides and has good biocompatibility, carbonated drinks, sometimes known as fizzy drinks, are carbonated liquids that contain dissolved carbon dioxide, sweeteners, and natural or artificial flavoring. The aim of our study is to determine the flexural strength of GIC after immersing in carbonated beverages. Twelve samples of GIC filling material were used among which six samples prepared were from the Dtech brand and six were prepared from the Shofu brand for the in vitro study. Bar-shaped specimens were prepared from each group with the dimension of 2 mm × 2 mm × 25 mm. They were immersed in Sprite, fizz drinks, and in distilled water as a control group. The immersion period was 7 days. Then, the determination of maximum force and displacement was done using INSTRON E3000 (ElectroPuls) universal testing machine, then the collected data were used to determine flexural strength. The mean flexural strength of Dtech GIC was 24.84 ± 6.523 Mpa. The mean flexural strength of Dtech GIC was 18.57 ± 11.60 Mpa. The independent sample t -test showed that P = 0.247 (>0.05) which was statistically not significant. The flexural strength of GIC material decreased after being immersed in Sprite and fizz drinks., Competing Interests: There are no conflicts of interest., (Copyright: © 2022 Journal of Advanced Pharmaceutical Technology & Research.)

Wood-plastic composite (WPC) is a kind of composite material that is made of plastic and wood fiber or wood powder. Because it is mothproof, is resistant to corrosion, and has plasticity, among other advantages, it has been researched and used increasingly in building materials. The flexural property of WPC is an important subject in evaluating its mechanical properties. In this paper, wood-plastic raw materials and processing technology are introduced; the internal and external factors of WPC which affect the flexural properties are analyzed; the different ways of enhancing the bending capacity, including the surface pretreatment, addition of different modifiers (compatibility agent and coupling agent) etc. are summarized; and the methods of operation and strengthening effect are analyzed. This work provides a reference for further research in related fields.

The long cycle of manufacturing continuous carbon fiber-reinforced composite has significantly limited its application in mass vehicle production. High-pressure resin transfer molding (HP-RTM) is the process with the ability to manufacture composites in a relatively short forming cycle (<5 min) using fast reactive resin. The present study aims to investigate the influence of HP-RTM process variables including fiber volume fraction and resin injection flow rate on void characteristics, and flexural properties of manufactured CFRP components based on experiments and numerical simulations. An ultrasonic scanning system and optical microscope were selected to analyze defects, especially void characteristics. Quasi-static bending experiments were implemented for the CFRP specimens with different void contents to find their correlation with material’s flexural properties. The results showed that there was also a close correlation between void content and the flexural strength of manufactured laminates, as the flexural strength decreased by around 8% when the void content increased by ~0.5%. In most cases, the void size was smaller than 50 μm. The number of voids substantially increased with the increase in resin injection flow rate, while the potential effect of resin injection flow rate was far greater than the effect of fiber volume fraction on void contents. To form complicated CFRP components with better mechanical performance, resin injection flow rate should be carefully decided through simulations or preliminary experiments., Competing Interests: The authors declare no conflict of interest.

In response to the high demand for light automotive, manufacturers are showing a vital interest in replacing heavy metallic components with composite materials that exhibit unparalleled strength-to-weight ratios and excellent properties. Unidirectional carbon/epoxy prepreg was suitable for automotive applications such as the front part of the vehicle (hood) due to its excellent crash performance. In this study, UD carbon/epoxy prepreg with 70% and 30% volume fraction of reinforcement and resin, respectively, was used to fabricate the composite laminates. The responses of different three stacking sequences of automotive composite laminates to low-velocity impact damage and flexural and crash performance properties were investigated. Three-point bending and drop-weight impact tests were carried out to determine the flexural modulus, strength, and impact damage behavior of selected materials. Optical microscopy analysis was used to identify the failure modes in the composites. Scanning electron microscopy (SEM) and C-scan non-destructive methods were utilized to explore the fractures in the composites after impact tests. Moreover, the performance index and absorbed energy of the tested structures were studied. The results showed that the flexural strength and modulus of automotive composite laminates strongly depended on the stacking sequence. The highest crash resistance was noticed in the laminate with a stacking sequence of [[0, 90, 45, -45] 2 , 0, 90] S . Therefore, the fabrication of a composite laminate structure enhanced by selected stacking sequences is an excellent way to improve the crash performance properties of automotive composite structures.

The standardized acrylonitrile-butadiene-styrene (ABS) or polycarbonate (PC) resin disk with added flame retardants (FRs) has a potential to be a suitable tool for predictions of both aging of the plastic materials and release rate of a flame retardants exposed under different outdoor and indoor conditions. The experiments examined the dynamics and kinetics of the release of dechlorane plus, tetrabromobisphenol A, triphenyl phosphate and antimony trioxide as FRs from a standardized plastic disk before and after exposure to artificial sunlight. Assessments were carried out independently to measure changes in the content of flame retardants and monitor the flame retardancy and flexural properties after exposure (60 W/m 2 ) over a period of 200 h and 500 h, which are reasonable to predict a short-time tendency and to receive any advice for a safe re-use. The releases of three organic flame retardants and four elements (Cl, Br, P and Sb) from weathered ABS and PC disks were very limited, except for surface delamination and resin microparticles. Triphenyl phosphate was stable without hydrolysis, while the degradation of tetrabromobisphenol A was observed (approximately 20% decrease for ABS disk and approximately 50% decrease for PC disk). During the study, no significant differences in the flame retardancy and flexural properties of the disks could be detected. In practice, the results obtained from disks of acrylonitrile-butadiene-styrene or polycarbonate resin with selected flame retardants used in specific conditions may provide technical expertise regarding weathering processes.

The purpose of this study was to investigate the influence of cellulose nanofibers (CNF) solution on the mechanical and biological properties of denture base resins (DBR). Two types of CNFs obtained from bamboo (BB) and needle-leaved (NB) trees were used in this study. We prepared 18 different CNF solutions based on their fibrillation (A-low, B-middle, and C-high) and concentration (0.05, 0.10, and 0.20 wt%). A heat-polymerized acrylic resin was used as DBR. The contact angles for each specimen were measured after immersion. The flexural properties of the immersed specimens, and the biological properties of the CNF solutions were examined. Specimens immersed in CNF-NB-C-0.05 wt% solution presented with the lowest contact angles. Specimens in CNF-NB-C and CNF-BB-A groups showed higher flexural modulus values. No cytotoxic or antimicrobial effects were observed for the CNF solutions. This study suggest that CNF solution may improve the surface wettability of the DBR without affecting its flexural property.

Fused deposition modeling possesses great advantages in fabricating high performance composites with controllable structural designs. As such, it has attracted attention from medical, automatic, and aerospace fields. In this paper, the influence of short carbon fibers (SCFs) and the orthogonal building orientation on the flexural properties of printed polyether ether ketone (PEEK) composites are systematically studied. The results show that the addition of SCFs raises the uniform nucleation process of PEEK during 3D printing, decreases the layer-to-layer bonding strength, and greatly changes the fracture mode. The flexural strength of vertically printed PEEK and its CF-reinforced composites show strengths that are as high as molded composites. X-ray micro-computed tomography reveals the microstructure of the printed composites and the transformation of pores during bending tests, which provides evidence for the good mechanical properties of the vertically printed composites. The effect of multi-scale factors on the mechanical properties of the composites, such as crystallization in different positions, layer-by-layer bonding, and porosity, provide a successful interpretation of their fracture modes. This work provides a promising and cost-effective method to fabricate 3D printed composites with tailored, orientation-dependent properties., Competing Interests: The authors declare no conflict of interest.

Tendon or ligament reconstructions often use autologous or allogenic tendons from either extrasynovial or intrasynovial sources. Allograft tendons must be lyophilized for preservation before transplantation, a process which can impact mechanical properties of the graft. Reconstituted graft properties that are similar to native tendon are desirable. Although tensile and compressive properties of tendons have been investigated, there is a paucity of information describing flexural properties of tendon, which can impact the gliding resistance. This study aims to design a testing method to quantify tendon flexural modulus, and investigate the effects of lyophilization/rehydration procedures on tendon flexibility. A total of 20 peroneus longus tendons (extrasynovial) and 20 flexor digitorum profundus tendons (intrasynovial) were collected. Ten of each tendon were processed with 5 freeze-thaw cycles followed by lyophilization and rehydration with saline solution (0.9%). Bend testing was conducted on tendons to quantify the flexural modulus with and without processing. As canine FDP tendons contain fibrous and fibrocartilaginous tissue regions, the flexural moduli were measured in both regions. Flexural modulus of rehydrated, lyophilized extrasynovial PL tendon was significantly lower than that of similarly processed intrasynovial FDP tendon (p < 0.001). Flexural moduli of both the fibrocartilaginous and non-fibrocartilaginous regions of intrasynovial tendon significantly increased after lyophilization (p < 0.001). The flexural modulus of the fibrocartilaginous region was significantly higher than that of the non-fibrocartilaginous region in intrasynovial tendon (p < 0.001). Lyophilization significantly increases the flexural modulus of extrasynovial and intrasynovial tendons, and flexural modulus differs significantly between these two tendon types. Increases in stiffness caused by lyophilization may impact the mechanical performance of the allograft in vivo., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Fused-deposition modeling (FDM), one of the additive manufacturing (AM) technologies, is an advanced digital manufacturing technique that produces parts by heating, extruding and depositing filaments of thermoplastic polymers. The properties of FDM-produced parts apparently depend on the processing parameters. These processing parameters have conflicting advantages that need to be investigated. This article focuses on an investigation into the effect of these parameters on the flexural properties of FDM-produced parts. The investigation is carried out on high-performance ULTEM 9085 material, as this material is relatively new and has potential application in the aerospace, military and automotive industries. Five parameters: air gap, raster width, raster angle, contour number, and contour width, with a full factorial design of the experiment, are considered for the investigation. From the investigation, it is revealed that raster angle and raster width have the greatest effect on the flexural properties of the material. The optimal levels of the process parameters achieved are: air gap of 0.000 mm, raster width of 0.7814 mm, raster angle of 0°, contour number of 5, and contour width of 0.7814 mm, leading to a flexural strength of 127 MPa, a flexural modulus of 2400 MPa, and 0.081 flexural strain., Competing Interests: The authors declare no conflict of interest.

The present study evaluated the flexural properties of a new temporary splint material, G-Fix, for use in dental trauma splints in comparison with other resin materials. Four types of resin materials were considered in the present study: MI Flow II, light-cured composite resin (MI); G-Fix, light-cured resin for splinting teeth (GF); Super-Bond C&B, adhesive resin cement (SB); and Unifast III, self-cured methyl-methacrylate resin (UF). The flexural properties of these four materials were tested according to ISO 4049. The flexural strength significantly increased in the order of UF (64.9 MPa) < SB (76.5 MPa) < GF (94.3 MPa) < MI (161.2 MPa). The elastic modulus significantly increased in the order of UF (2.11 GPa) ≒ SB (2.23 GPa) < GF (2.62 GPa) < MI (7.39 GPa). A splint made of GF may be more flexible than a composite splint, which is categorized as a rigid splint.

This study investigated the influence of porosity on the flexural property of a nanoporous alumina film. When the porosity of the alumina film increased, both bending strength and modulus declined. The results from the bending test revealed that the setting of the film during the bending test had significant influence on the flexural property. Fracture only occurred when the porous side of the alumina film suffered tensile stress. The ability to resist fracture in the barrier layer was higher than in the porous side; the magnitude of the bending strength was amplified when the barrier layer sustained tensile stress. When the porous layer suffered a tensile stress, the bending strength decreased from 182.4 MPa to 47.7 Mpa as the porosity increased from 22.7% to 51.7%; meanwhile, the modulus reduced from 82.7 GPa to 17.9 GPa. In this study, the most important finding from fractographic analysis suggested that there were a localized plastic deformations and layered ruptures at the porous side of the alumina film when a load was applied. The fracture behavior of the nanoporous alumina film observed in the present work was notably different from general ceramic materials and might be related to its asymmetric nanostructure., Competing Interests: The authors declare no conflict of interest.

Objective: High flexural properties are needed for fixed partial denture or implant prosthesis to resist susceptibility to failures caused by occlusal overload. The aim of this investigation was to clarify the effects of four different kinds of fibers on the flexural properties of fiber-reinforced composites., Materials and Methods: Polyethylene fiber, glass fiber and two types of carbon fibers were used for reinforcement. Seven groups of specimens, 2 × 2 × 25 mm, were prepared (n = 10 per group). Four groups of resin composite specimens were reinforced with polyethylene, glass or one type of carbon fiber. The remaining three groups served as controls, with each group comprising one brand of resin composite without any fiber. After 24-h water storage in 37°C distilled water, the flexural properties of each specimen were examined with static three-point flexural test at a crosshead speed of 0.5 mm/min., Results: Compared to the control without any fiber, glass and carbon fibers significantly increased the flexural strength (p < 0.05). On the contrary, the polyethylene fiber decreased the flexural strength (p < 0.05). Among the fibers, carbon fiber exhibited higher flexural strength than glass fiber (p < 0.05). Similar trends were observed for flexural modulus and fracture energy. However, there was no significant difference in fracture energy between carbon and glass fibers (p > 0.05)., Conclusion: Fibers could, therefore, improve the flexural properties of resin composite and carbon fibers in longitudinal form yielded the better effects for reinforcement.

Objectives: The aim of this research was to investigate the effects of heat treatment of polymethyl methacrylate powder on mechanical properties of denture base resin., Methods: PMMA powder was applied after heat treatment at 100°C for 2h (code: HT100) or 130°C for 2h (code: HT130). The test specimens were fabricated from autopolymerizing resin to investigate the flexural properties of denture base resin cross-linked with methacrylated dendrimer, the surface microhardness of PMMA beads, and the thickness of the swollen layer of PMMA beads. The specimens were autopolymerized, and all specimens were stored in 37°C water for 24h. Half of the specimens were immersed in 37°C water for an additional 6 months (water storage period: 24h and 6 months). The flexural strength and flexural modulus (n=10/group) were measured with a three point bending test. Statistical analysis was performed using ANOVA and the Newman-Keuls test at a significance level of 0.05., Results: Heat treatment and the water storage period had a significant effect on flexural strength. The flexural strength of HT130 showed significantly higher values than in other groups. The surface microhardness of PMMA beads of HT130 showed a significantly greater microhardness than other groups. The thickness of a swollen layer of PMMA beads of HT100 and HT130 was significantly decreased., Conclusions: The flexural strength and the surface microhardness were increased after heat treatment at 130°C. The thickness of a swollen layer of PMMA beads was decreased after heat treatment., (Copyright © 2014 Elsevier Ltd. All rights reserved.)