Dental Thermoplastic

Carbon fiber-reinforced thermoplastics (CFRTPs) have attracted attention in aerospace because of their superior specific strength and stiffness. It can be assembled by adhesive bonding; however, the existing evaluation of bonding strength is inadequate. For example, in a single-lap shear test, the weld zone fails in a combined stress state because of the bending moment. Therefore, the strength obtained experimentally is only the apparent strength. The true bonding strength was obtained via numerical analysis by outputting the local stress state at the initiation point of failure...

Thermoplastic composites are continuously replacing thermosetting composites in lightweight structures. However, the accomplished work on the fatigue behavior of thermoplastics is quite limited. In the present work, we propose a numerical modeling approach for simulating fatigue delamination growth and predicting the residual tensile strength of quasi-isotropic TC 1225 LM PAEK thermoplastic coupons. The approach was supported and validated by tension and fatigue (non-interrupted and interrupted) tests. Fatigue delamination growth was simulated using a mixed-mode fatigue crack growth model, which was based on the cohesive zone modeling method...

Polymer-metal hybrid structures combine the merits of polymer and metal materials, making them widely applicable in fields such as aerospace and automotive industries. However, the main challenge lies in achieving efficient and strong connections between the metal and polymer components. This paper uses the jet electrochemical machining (Jet-ECM) method to customize the surface morphologies on 6061 aluminum alloy (AA6061) sheets. The connection between AA6061 and carbon fiber-reinforced PA66 (CF/PA66) is then achieved through hot pressure welding (HPW)...

Benefitting from lightweight, high strength, long life, and green recyclability, continuous fiber reinforced thermoplastic composite (CFTPC) pipes have attracted extensive interest, especially in the on-orbit additive manufacturing of structural components. However, the preparation of CFTPC pipes remains challenging due to the on-orbit limited space and high processing temperature of thermoplastic resin. Here, we report an effective approach for high performance carbon fiber/polyether-ether-ketone (CF/PEEK) thin-walled pipes via bidirectional reinforcement using the pultrusion-winding technique...

Thermoplastic polyurethane (TPU) composites with eutectic gallium (Ga) and indium (In) (eGaIn) fillings of 0 wt%-75 wt% were prepared using the electrostatic spinning method. Field emission scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared (FTIR) spectroscopy were used to characterize the eGaIn NDs/TPU composites. To evaluate their X-ray shielding properties, Phy-X/PSD and WinXCom were employed to calculate the mass attenuation coefficients, linear attenuation coefficients, half-value layers, tenth value layers, mean free paths, and adequate atomic numbers of the eGaIn NDs/TPU composites...

BACKGROUND/AIM: Thermoplastic mouthguards have been a reliable means of protection against impacts and shocks for a century. Although orofacial injuries are prevalent among basketball players, many athletes still avoid using mouthguards due to concerns regarding impaired breathing, speech interference, and nausea. This study aims to compare basketball players' subjective assessments of two different thicknesses of custom-made mouthguards (MGs) with boil-and-bite MGs (B&B MG). MATERIAL AND METHODS: A total of 60 systematically healthy male professional basketball players, without active orthodontic treatment, were enrolled and randomly assigned to three groups: Group 1 (received B&B MGs; n = 20), Group 2 (received custom-made MGs with a 3 mm thickness [ethyl vinyl asetat]; n = 20), and Group 3 (received custom-made MGs with a 5 mm thickness; n = 20)...

The latest generation of high-temperature 3D printers enables the production of complex structural components from aerospace-grade thermoplastics such as PEEK (polyether ether ketone). However, adding long or continuous fibres is currently limited, and thermal stresses introduced during the process restrict the maximum part dimensions. Combining 3D-printed components with continuous fibre-reinforced components into one hybrid structure has the potential to overcome such limitations. This work aims to determine whether in situ bonding between PEEK laminates and PEEK 3D printing during overprinting is feasible and which process parameters are significantly responsible for the bonding quality...

Given the mechanical hazards occurring in the workplace, cut resistance is a particularly important protective parameter. 3D printing is an innovative technology that has recently garnered great interest. It enables the creation of functional polymeric materials with metal reinforcement for use in cut-resistant gloves. The present study characterized and tested 3D-printed polymeric materials intended for such applications. The materials were made from commercially available 3D printing polymer filaments. Metallic reinforcement (stainless steel wire with a diameter of 0...

This paper presents the characterisation of selective-laser-sintered (SLS) samples of polyamide 12 (PA12) under shear loading. PA12 is a semi-crystalline thermoplastic and is used in various industries. Its behaviour under shear stress, which is particularly important for product reliability, has not yet been sufficiently investigated. This research focuses on understanding the material and damage behaviour of PA12 under shear-induced stress conditions. The study included quasi-static experiments and numerical simulations...

This paper deals with the numerical modelling of non-destructive testing of composite parts using active thermography. This method has emerged as a new approach for performing non-destructive testing (NDT) on continuous carbon fibre reinforced thermoplastic polymer (CCFRTP) components, particularly in view of detecting porosity or delamination. In this context, our numerical model has been developed around references containing internal defects of various shapes and sizes. The first novelty lies in the fact that the heat source used in the experimental setup is modelled exhaustively to accurately model the radiation emitted by the lamp, as well as the convection and conduction around the bulb...

The fused deposition modeling (FDM) process, an extrusion-based 3D printing technology, enables the manufacture of complex geometrical elements. This technology employs diverse materials, including thermoplastic polymers and composites as well as recycled resins to encourage sustainable growth. FDM is used in a variety of industrial fields, including automotive, biomedical, and textiles, as a rapid prototyping method to reduce costs and shorten production time, or to develop items with detailed designs and high precision...

Sports equipment crafted from flexible mechanical metamaterials offers advantages due to its lightweight, comfort, and energy absorption, enhancing athletes' well-being and optimizing their competitive performance. The utilization of metamaterials in sports gear like insoles, protective equipment, and helmets has garnered increasing attention. In comparison to traditional truss and honeycomb metamaterials, the triply periodic minimal surface lattice structure stands out due to its parametric design capabilities, enabling controllable performance...

Fused filament fabrication (FFF) is an extrusion-based additive manufacturing (AM) technology mostly used to produce thermoplastic parts. However, producing metallic or ceramic parts by FFF is also a sintered-based AM process. FFF for metallic parts can be divided into five steps: (1) raw material selection and feedstock mixture (including palletization), (2) filament production (extrusion), (3) production of AM components using the filament extrusion process, (4) debinding, and (5) sintering. These steps are interrelated, where the parameters interact with the others and have a key role in the integrity and quality of the final metallic parts...

The mechanism behind the resilience of polymeric materials, typically attributed to the well-established entropy elasticity, often ignores the contribution of enthalpy variation (ΔH), because it based on the assumption of an ideal chain. However, this model does not fully account for the reduced resilience of thermoplastic polyurethane (TPU) during long-range deformation, which is mainly caused by the dynamics of physical crosslink networks. Such reduction is undesirable for long-range stretchable TPU considering its wide application range...

The expansion and low cost of additive manufacturing technologies have led to a revolution in the development of materials used by these technologies. There are several varieties of materials that can be used in additive manufacturing by fused deposition modeling (FDM). However, some of the properties of these materials are unknown or confusing. This article addresses the need to know the thermal conductivity in different filaments that this FDM technology uses, because there are multiple applications for these additive manufacturing products in the field of thermal insulation...

In this study, a high- Tg aerospace-grade epoxy composite plate was co-curing welded using a unidirectional PEEK thermoplastic carbon fibre tape to develop advanced composite joints. To account for the surface roughness and the weldability of carbon-epoxy/carbon-PEEK composites, plasma treatments were performed. The co-curing was conducted by the following steps: each treated thermoplastic tape was first placed in the mould, and followed by nine layers of dry-woven carbon fabrics. The mould was sealed using a vacuum bag, and a bi-component thermoset (RTM6) impregnated the preform...

BACKGROUND: Flexible denture base polymers have gained popularity in modern dentistry however, their biofilm formation tendency, adversely affecting the oral tissue heath, remains a concern. Consequently, this study aimed to evaluate surface roughness and biofilm formation tendency of two types of denture base resins manufactured with two techniques before and after surface coating with chlorohexidine (CHX) NPs. MATERIALS AND METHODS: Acetal (AC) and Polymethyl-methacrylate (PMMA) resins manufactured by conventional and CAD/CAM methods were shaped into disk (10 X 10 X 1 mm)...

BACKGROUND: The treatments with clear aligners (CA) showed an exponential higher percentage in the last years being almost invisible with major patient acceptability and a resulting improvement in quality of life. CA are composed of thermoplastic polyurethane not inert but subjected to changes due to heating and humidity, chewing forces, and prolonged exposure to enzymes in saliva in the oral cavity and external factors. Cigarette smoke (CS) and the aerosol produced by tobacco products with reduced health risks may be considered among the external factors affecting CA...

Additive manufacturing (AM) of aerogels increases the achievable geometric complexity, and affords fabrication of hierarchically porous structures. In this work, a custom heated material extrusion (MEX) device prints aerogels of poly(phenylene sulfide) (PPS), an engineering thermoplastic, via in situ thermally induced phase separation (TIPS). First, pre-prepared solid gel inks are dissolved at high temperatures in the heated extruder barrel to form a homogeneous polymer solution. Solutions are then extruded onto a room-temperature substrate, where printed roads maintain their bead shape and rapidly solidify via TIPS, thus enabling layer-wise MEX AM...

In this work, a comprehensive shrinkage and tensile strength characterization of unsaturated polyester (UPE-8340) and vinyl ester (VE-922) epoxy matrices and composites reinforced with multiwall carbon nanotubes (MWCNTs) was conducted. The aspect ratio of UPE and VE with methyl ethyl ketone peroxide (MEKP) was kept at 1:16.6; however, the weight of the MWCNTs was varied from 0.03 to 0.3 gm for the doping of the reinforced nanocomposites. Using a dumbbell-shaped mold, samples of the epoxy matrix without MWCNTs and with reinforced UPE/MWCNT and VE/MWCNT nanocomposites were made...