Polyethylene Terephthalate Glycol Research Articles

Bonding positional accuracy of attachments and marginal adaptation of in-house aligners - A quality improvement laboratory study.

To evaluate the 3D accuracy of attachment positioning and the adaptation of aligners to attachments using in-house templates made with either polyethylene terephthalate glycol (PETG) or ethylene-vinyl acetate (EVA) and either pressure or vacuum thermoforming machines. Overall, 140 test specimens were resin-printed. Templates for the attachment bonding were made with 1-mm EVA or 0.5-mm PETG laminates. Orthodontic aligners were manufactured with 0.75-mm PETG. The thermoplastification process was carried out using either vacuum or pressure machines. The positional differences between the virtual and bonded attachments were assessed in the X, Y and Z coordinates. The marginal adaptation between the aligners and the attachments was measured. Minor inaccuracies in the positioning of the attachments were observed in all combinations of thermoforming machines and plastic laminates used to fabricate the templates, mainly in the superior-inferior (Z) dimension. PETG performed better than EVA in the anterior region (p < .05). No association was found between thermoplastification machines and the accuracy of the positioning of the attachments (p > .05). While small misadaptations between the aligners and the attachments were observed, the EVA templates performed better than the PETG templates. The inaccuracy of the attachment positioning and the misadaptation of the aligners to the attachments were slight. The vacuum and pressure thermoplastification machines showed no difference in attachment positioning accuracy. The PETG template was better than the EVA template in the anterior region, but the EVA attachments presented a better adaptation to the aligners than the PETG attachments.

4D printing thermo-magneto-responsive PETG-Fe3O4 nanocomposites with enhanced shape memory effects

In this groundbreaking study, Polyethylene Terephthalate Glycol (PETG)-Fe3O4 nanocomposites were developed for 4D printing, incorporating iron oxide (Fe3O4) nanoparticles into PETG matrix. The research contribution lies in its innovative approach to enhancing the shape memory effect (SME) through thermo-magnetic responsiveness, positioning PETG-Fe3O4 as a revolutionary material in smart additive manufacturing. The composites were synthesized using a melt mixing method, followed by 3D printing into specimens for comprehensive evaluation through dynamic mechanical thermal analysis (DMTA), scanning electron microscopy (SEM), and uniaxial tensile tests. The findings revealed that the incorporation of Fe3O4 nanoparticles significantly boosts the composites’ storage modulus and glass transition temperature, indicative of improved stiffness and thermal properties. Notably, the 15 % Fe3O4 composite emerged as the optimal blend, exhibiting the highest tensile strength and a favourable balance between mechanical integrity and flexibility. A key result was the enhanced SME under both thermal and magnetic stimuli, with recovery efficiency and speed escalating with nanoparticle concentration. This advancement underscores the potential of PETG-Fe3O4 nanocomposites in fabricating smart structures capable of environmental adaptability, paving the way for impacts in biomedical, aerospace, and robotic devices. Through this work, a new paradigm in material functionality for 4D printing has been established, demonstrating the viability of magnetic nanoparticle integration for added smart capabilities.

Additive Manufacturing Technology in the Furniture Industry: Future Outlook for Developing Countries

For the past few years, the adoption of 3D printing technology has benefited various manufacturing industries, including the furniture making industry. However, this adoption has been greatly seen in industrialized countries and lacking in developing countries. Therefore, to understand fully the capability of 3D printing and its benefits, this paper review discusses recent applications of 3D printing in the furniture industry and assesses the potential it can bring for developing countries’ furniture making industry, specifically in the Philippines and other developing countries in Asia. In addition, the drawbacks it brought to the industry, and the challenges that needed to be addressed are also discussed in the paper. The paper covers various 3D printing technologies such as material extrusion, sheet lamination, powder bed fusion, and vat photopolymerization, along with different materials currently used in the furniture industry. Numerous notable examples of applications of 3D-printed furniture are also presented. Based on the review paper, it was found that the most common 3D printing technologies used in the furniture industry are Material Extrusion (MEX) and Powder Bed Fusion (PBF) specifically Fused Deposition Modelling (FDM) and Selective Laser Sintering (SLS), respectively. The most common 3D printing materials used are Polyamide (PA), Polylactic acid (PLA), and recycled Polyethylene terephthalate glycol (PETG). The paper also discusses the possible adoption of 3D printing in developing countries and explores its potential to innovate traditional furniture manufacturing processes.

Design and evaluation of mechanical strength of multi-material polymeric implants for mandibular reconstruction.

Reconstruction of mandible implants to address segmental abnormalities is still a challenging task, both in vitro and in vivo. The mechanical strength of the materials used is a critical factor that determines how well bone is regenerated. The reconstruction technique of mandibular abnormalities widely uses polymeric implants. It is critical to evaluate the mechanical resilience under different load cases, including axial, combined, and flexural loading conditions. This study developed implants for mandibular defects using a combination of four materials: polylactic acid (PLA), polyethylene terephthalate glycol (PETG), thermoplastic polyurethane (TPU), and polycaprolactone (PCL), with the aim of mimicking the inherent characteristics of cortical and cancellous bone structures and evaluating their mechanical properties to support bone Osseo integration. The eleven of these combinations of structures result below the micro strain threshold level of <3000 µε, and the five combinations of the structures result in micro strain above the threshold value. The intact bone study results show that the stress under axial, combined, and flexural loading conditions is 27.6, 38.9, and 64.9 MPa, respectively. This study's stress results are lower than those from the intact bone study. The study found that the combinations of PLA and TPU material were most preferred for the cortical and cancellous bone regions of polymeric implants. These materials are also compatible with 3D printing. The results of this study can be used to find multi-material combinations that are strong and flexible.

Polydimethylsiloxane enabled triple-action water-resistant coating with desirable relaxation rate in clear aligner

Clear aligners undergo rapid stress relaxation in warm, moist oral environments, compromising therapeutic effectiveness and longevity of treatment. To develop an innovative multilayer composite material with improved stability and reduced stress release, we have engineered an innovative coating characterized by the surface aggregation of polydimethylsiloxane (PDMS), which imparts a pronounced hydrophobic effect. In addition, the chemically and physically cross-linked structure of the coating reduces the free volume created by molecular chain rearrangement owing to the presence of water molecules, thereby minimizing water penetration into the coating. Concurrently, the coating’s internal structure is enriched with numerous polar functional groups to capture water molecules that penetrate into the inside of the coating. Through combination of these mechanisms, water molecules are effectively sequestered, thereby impeding their penetration into the polyethylene terephthalate glycol (PETG) substrate. The impact of the polydimethylsiloxane content on the triple-action water-resistance mechanisms was thoroughly examined using attenuated total reflection (ATR)-Fourier transform infrared (FTIR), water absorption rate, water swelling rate, and X-ray photoelectron spectroscopy. The low surface energy cross-linked polyurethane coating is applied to the polyethylene terephthalate glycol (PETG) substrate to create a novel composite material with specific mechanical properties and reduced stress relaxation. The composite material remains stable in simulated oral environment with linear swelling rate of 0.58 % upon water absorption. Additionally, the stress release rate of the composite material within 336 h is notably lower (23.64 %) than that of PETG (62.29 %).

Optimization of adherend thickness and overlap length on failure load of bonded 3D printed PETG parts using response surface method

Purpose Adhesive bonding is critical to the effectiveness and structural integrity of 3D printed components. The purpose of this study is to investigate the effect of joint configuration on failure loads to improve the design and performance of single lap joints (SLJs) in 3D printed parts. Design/methodology/approach In this study, adherends were fabricated using material extrusion 3D printing technology with polyethylene terephthalate glycol (PETG). A toughened methacrylate adhesive was chosen to bond the SLJs after adherend printing. In this study, response surface methodology (RSM) was used to examine the effect of the independent variables of failure load, manufacturing time and mass on the dependent variable of joint configuration; adherend thickness (3.2, 4.0, 4.8, 5.6, 6.4, and 7.2 mm) and overlap lengths (12.7, 25.4, 38.1, and 50.8 mm) of 3D printed PETG SLJs. Findings The strength of the joints improved significantly with the increase in overlap length and adherend thickness, although the relationship was not linear. The maximum failure load occurred with a thickness of 7.2 mm and an overlap of 50.8 mm, whilst the minimum failure load was determined with a thickness of 3.2 mm and an overlap of 12.7 mm. The RSM findings show that the optimum failure load was achieved with an adherend thickness of 3.6 mm and an overlap length of 37.9 mm for SLJ. Originality/value This study provides insight into the optimum failure load for 3D printed SLJs, reducing SLJ production time and mass, producing lightweight structures due to the nature of 3D printing, and increasing the use of these parts in load-bearing applications.

Characterization of 3D printable Polyethylene Terephthalate Glycol composite filament reinforced with agricultural waste derived from pineapple plant

Characterization of 3D printable Polyethylene Terephthalate Glycol composite filament reinforced with agricultural waste derived from pineapple plant

Optimization of Flexural Performance of PETG Samples Produced by Fused Filament Fabrication with Response Surface Method.

Additive manufacturing (AM), particularly fused filament fabrication (FFF), has gained significant attention for its design flexibility and cost-effectiveness. This study focuses on optimizing FFF parameters that employ response surface methodology (RSM) to enhance the flexural performance of polyethylene terephthalate glycol (PETG) parts. Three essential parameters-layer height, print speed, and nozzle temperature-were varied, and their effects on flexural strength, flexural modulus, flexural toughness for ultimate strength, flexural toughness at 5% strain, and strain at ultimate strength were evaluated. Based on a Box-Behnken design, the experiments revealed significant effects of these parameters on the mechanical responses. The analysis of variance (ANOVA) indicates that layer height predominantly affects flexural modulus and toughness, while nozzle temperature significantly impacts flexural strength. The RSM models exhibited high accuracy, with R2 values exceeding 99%. Optimal parameter combinations yield remarkable improvements: flexural strength reached 39.55 MPa, flexural modulus peaked at 1344.60 MPa, flexural toughness for ultimate strength reached 218.22 J/mm3, flexural toughness at 5% strain reached 381.47 J/mm3, and strain at ultimate strength reached 3.50%. Validation experiments confirm the effectiveness of the optimization, with errors below 3.17%.

Variations in the Thermomechanical and Structural Properties during the Cooling of Shape-Memory R-PETG.

One of the useful features of 3D-printed specimens of recycled polyethylene terephthalate glycol (R-PETG) is the ability to repetitively develop free recovery as well as the work-generating, shape-memory effect. This behavior is enabled by the R-PETG's capacity to stiffen during cooling, thus allowing for a new temporary shape to be induced. Aiming to devise an explanation for the polymer's stiffening, in this study, the variation in some of the R-PETG's parameters during cooling are emphasized and discussed. The evolution of an R-PETG filament's shape was monitored during room-temperature-bending heating-cooling cycles. Straight-shape recovery and the complete loss of stiffness were observed at the start and the end of heating, respectively, followed by the forced straightening of the filament, performed by the operator, around 40 °C, during cooling. The tests performed by dynamic mechanical analysis disclosed the rise of the storage modulus (E') after 100 °C heating followed by either liquid-nitrogen- or air-cooling to room temperature, in such a way that E' was always larger after cooling than initially. Static tests emphasized a peculiar stress variation during a heating-cooling cycle applied in air, within the heating chamber of the tensile testing machine. Tensile-failure tests were performed at -10 °C at a rate of 100 mm/min, with specimens printed at various deposition directions between 10 and 40° to the transversal direction. The specimens printed at 40°, which had the largest ultimate strains, were broken with tensile rates between 100 and 500 mm/min. Deformation rate increase favored the shift from crazing to delamination failure modes. The correlation between the structural changes, the sharp E' increase on heating, and the stiffening induced by cooling represents a novel approach that enables the use of 3D-printed R-PETG for the fabrication of the active parts of low-priced lightweight resettable actuators.

Thermomechanical Material Characterization of Polyethylene Terephthalate Glycol with 30% Carbon Fiber for Large-Format Additive Manufacturing of Polymer Structures.

Large-format additive manufacturing (LFAM) is used to print large-scale polymer structures. Understanding the thermal and mechanical properties of polymers suitable for large-scale extrusion is needed for design and production capabilities. An in-house-built LFAM printer was used to print polyethylene terephthalate glycol with 30% carbon fiber (PETG CF30%) samples for thermomechanical characterization. Thermogravimetric analysis (TGA) shows that the samples were 30% carbon fiber by weight. X-ray microscopy (XRM) and porosity studies find 25% voids/volume for undried material and 1.63% voids/volume for dry material. Differential scanning calorimetry (DSC) shows a glass transition temperature (Tg) of 66 °C, while dynamic mechanical analysis (DMA) found Tg as 82 °C. The rheology indicated that PETG CF30% is a good printing material at 220-250 °C. Bending experiments show an average of 48.5 MPa for flexure strength, while tensile experiments found an average tensile strength of 25.0 MPa at room temperature. Comparison with 3D-printed PLA and PETG from the literature demonstrated that LFAM-printed PETG CF30% had a comparative high Young's modulus and had similar tensile strength. For design purposes, prints from LFAM should consider both material choice and print parameters, especially when considering large layer heights.

Kinetic and thermodynamic behavior of co-pyrolysis of olive pomace and thermoplastic waste via thermogravimetric analysis

This work represents the first attempt to analyze kinetics, thermodynamics and reaction mechanism of olive pomace (OP) and waste plastic materials (PM) co-pyrolysis. Among PM, polypropylene (PP), polystyrene (PS), high density polypropylene (HDPE), polyvinyl chloride (PVC) and poly (ethylene terephthalate) glycol (PETG) were selected. Non-isothermal TG experiments were carried out under inert conditions at four heating rates, namely 5, 10, 20 and 40 °C/min. The kinetic triplet for raw materials and their blends was determined using Starink, Kissinger-Akahira-Sunose and Ozawa-Flynn-Wall iso-conversional models. Pyrolysis mechanism reactions were explained by diverse models, depending on thermal degradation progress. Results shown that co-pyrolysis followed a complex multi-step reaction mechanism. A synergistic effect was detected during co-pyrolysis of OP/PM mixtures. The addition of 50 % (w/w) OP biomass to PM waste decreased the energy of activation (Ea) from 50 to 25 % for all blends, except for PVC/OP. Thermodynamic analysis reveals that adding OP generally reduces the energy barrier (ΔH), except for PS-OP, and improves energy efficiency (ΔG) by facilitating radical formation and molecular chain cleavage.As a conclusion, this study may open up new avenues for waste valorization and resource recovery. Thus, it may contribute to the transition towards a circular and sustainable economy, through zero waste goal.

Preparation and properties of UV curing varnish suited for various substrates

UV-curing varnish has gained widespread application in the field of surface treatment due to its advantages such as low-temperature curing, easy fading, and environmental friendliness. The aim of this study is to develop a high-performance UV-curing varnish compatible with various substrates. Five prepolymers, Polymethyl Methacrylate (PMMA), Poly (methyl methacrylate-random-acrylic acid) P(MMA-r-AA), Poly (methyl methacrylate-random-glycidyl methacrylate-random-styrene) (P(MMA-r-GMA-r-St)), Poly (methyl methacrylate-random-butyl acrylate-random-glycidyl methacrylate) (P(MMA-r-BA-r-GMA)) and Poly (butyl acrylate-random acrylic acid-random glycidyl methacrylate-random styrene)(P(BA-r-AA-r-GMA-r-St)), were synthesized by free radical polymerization. The film-forming effect of prepolymer on 13 substrates such as glass, coated paper, polyethylene, polyethylene glycol terephthalate and low density polyethylene was investigated. Based on the results, the two prepolymers with the best film-forming properties were selected and combined with five distinct diluents and two types of photoinitiators to produce multiple UV-curing varnish formulations. The effects of the types of prepolymer, the types and contents of photoinitiator, the types of diluent and the ratios of prepolymer to diluent on the photocuring rate of UV curing varnish were investigated. The structures of prepolymer were characterized by Fourier infrared spectrometer. The experimental results show that PMMA and P(MMA-r-GMA-r-St) have better film-forming effects on 13 substrates. When the prepolymer is P(MMA-r-GMA-r-St), the photoinitiator is ITX, the photoinitiator content is 75 mg/mL, diethylenetriamine:GMA = 1:3 (diluent), and the ratio of prepolymer to diluent is 1:4, the photocuring rate of UV curing varnish is the fastest.

Surface Topography of Thermoplastic Appliance Materials Related to Sorption and Solubility in Artificial Saliva.

(1) Background: PETG (polyethylene terephthalate glycol) is a transparent, inexpensive, and versatile thermoplastic biomaterial, and it is increasingly being used for a variety of medical applications in dentistry, orthopedics, tissue engineering, and surgery. It is known to have remarkable properties such as tensile strength, high ductility, and resistance to chemical insults and heat, but it can be affected by various environmental conditions. The aim of the present study was to evaluate the topographical characteristics of four thermoplastic dental appliance materials in relation to water sorption in simulated oral environments (artificial saliva samples with different pH values). (2) Methods: The following four types of PETG clear thermoplastic materials were selected for the present study: Leone (L), Crystal (C), Erkodur (E), and Duran (D). In relation to the desiccation and water-uptake stages, their water sorption (Wsp) and solubility (Wsl) were calculated, and the surface topographies were analyzed on two length scales. The surface roughness was determined using a contact profilometer, and nanoroughness measurements were generated by three-dimensional profiles using an atomic force microscope (AFM). Statistical analyses (one-way ANOVA and unpaired and paired Student t-tests) were performed. (3) Results: After saliva immersion, the weights of all samples increased, and the highest sorption was recorded in a basic environment. Among the materials, the water uptake for the L samples was the highest, and for E, it was the lowest. In relation to water solubility, significant values were registered for both the L and C samples' materials. After immersion and desiccation, a decreasing trend in microroughness was observed. The AFM high-resolution images reflected more irregular surfaces related to saliva immersion. (4) Conclusions: The sorption rates recorded in water-based artificial saliva were higher for basic pH levels, with significant differences between the samples. There were also significant differences related to the behaviors of the materials included in the study. In relation to roughness, on a microscale, the surfaces tended to be smoother after the saliva immersions, and on a nanoscale, they became more irregular.

Conductive recycled PETg additive manufacturing filament for sterilisable electroanalytical healthcare sensors

Current reports of healthcare sensors within literature that use additive manufacturing electrochemistry all utilise conductive PLA, which is unsuitable for widespread use within the industry. Poly(ethylene terephthalate glycol (PETg) is a polymeric material with proven attributes for additive manufacturing due to its thermal and mechanical properties. Likewise, its excellent chemical stability transforms PETg into a desirable alternative for developing healthcare sensing devices. In this work, we report the production, physicochemical and electrochemical characterisations, as well as the electroanalytical performance of an enhanced electrically conductive additive manufacturing filament made with recycled poly(ethylene terephthalate glycol (rPETg) and a combination of carbon black, multi-walled carbon nanotubes and graphene nanoplatelets as conductive fillers. The post-print activation of additive manufactured electrodes from this material is optimised and shown to produce enhanced electrochemical performance compared to non-activated electrodes, with a k0 of 1.03×10−3 cm s−1. The sterilisation for the real application of sensors in the biomedical field is a critical point, the electrodes were submitted to standard UV light treatment showing to be reliable compared to PLA in the determination of uric acid (30–500 µM) and sodium nitrite (0.1–5 mM) within synthetic urine using differential pulse voltammetry and chronoamperometry techniques. A sensitivity and LOD for uric acid of 25.7 µA µM−1 and 0.27 µM, and 52.6 µA mM−1 and 2.69 µM for nitrite were obtained within synthetic urine, respectively. The re-useability of the electrodes was also tested for the detection of uric acid, showing that the electrode could be used up to 10 times before a significant decrease in the results was observed. We demonstrate that a new conductive rPETg with superior electrochemical performance has a prominent place within the development of additive manufactured-printed healthcare sensors due to its ability to be sterilised and re-used, low solution ingress, and its potential to tackle rising costs and plastic waste problems within the healthcare sector.

Engineered 3D-printed poly(vinyl alcohol) vascular grafts: Impact of thermal treatment and functionalization

Cardiovascular diseases, a leading cause of global mortality, are driving increased demand for artificial blood vessels for surgical repair. This study discloses the fabrication of three-dimensional (3D)-printed small blood vessels as tissue-engineered grafts. Large-diameter artery and vein grafts are readily available in the market, but small-diameter blood vessels face issues due to the lack of suitable materials. Lysine-biofunctionalized and unmodified poly(vinyl alcohol) grafts (PVA grafts) (2 mm inner diameter and 3 mm outer diameter) suitable for veins and venules were designed using Fusion 360 software, Autodesk Fusion. The PVA channels were fabricated from the 3D virtual model through fused deposition modeling using a PVA filament. These channels underwent thermal treatment to adjust their crystallinity, chemical crosslinking, and functionalization to optimize their mechanical properties and biocompatibility. Crosslinking and biofunctionalization were assessed using Fourier-transform infrared spectroscopy with attenuated total reflectance, while X-ray diffraction and differential scanning calorimetry were utilized for structural analysis. PVA grafts were biologically tested using three specific types of cell cultures: bEnd.3 brain endothelial cells, L929 fibroblast cells, and U937 monocyte-like cells. The hemocompatibility of the optimized vascular grafts was evaluated using horse blood, following the guidelines outlined in ASTM F756-13 Standard Practice for Assessment of Hemolytic Properties of Materials. The direct method for hemoglobin determination was specifically employed. Additionally, we developed an external polyethylene terephthalate glycol (PETG) 3D-printed platform to house the PVA grafts in parallel. The assembled platform (PETG and PVA graft) was connected to both an inlet and an outlet to facilitate the passage of an aqueous flow through the internal section of the PVA grafts during a flow test conducted under simulated body conditions (vacuum and blood pressure: 40 mbar). The flow was induced by a vacuum pump connected to the outlet of the platform, while the inlet was connected to a feeding glass. In summation, we have established a suitable protocol for producing small vascular grafts and demonstrated that the optimization process could significantly affect graft properties.

Construction of Zwitterionic Coatings with Lubricating and Anti-Adhesive Properties for Invisible Aligner Applications.

Invisible aligners have been widely used in orthodontic treatment but still present issues with plaque formation and oral mucosa abrasion, which can lead to complicated oral diseases. To address these issues, hydrophilic poly(sulfobetaine methacrylate) (polySBMA) coatings with lubricating, antifouling, and anti-adhesive properties have been developed on the aligner materials (i.e., polyethylene terephthalate glycol, PETG) via a simple and feasible glycidyl methacrylate (GMA)-assisted coating strategy. Poly(GMA-co-SBMA) was grafted onto the aminated PETG surface via the ring-opening reaction of GMA (i.e., "grafting to" approach to obtain G-co-S coating), or a polySBMA layer was formed on the GMA-grafted PETG surface via free radical polymerization (i.e., "grafting from" approach to obtain G-g-S coating). The G-co-S and G-g-S coatings significantly reduced the friction coefficient of PETG surface. Protein adsorption, bacterial adhesion, and biofilm formation on the G-co-S- and G-g-S-coated surfaces were significantly inhibited. The performance of the coatings remained stable after storage in air or artificial saliva for 2 weeks. Both coatings demonstrated good biocompatibility in vitro and did not cause irritation to the oral mucosa of rats in vivo over 2 weeks. This study proposed a promising strategy for the development of invisible aligners with improved performance, which is beneficial for oral health treatment. This article is protected by copyright. All rights reserved.

Aligners: review of their chemical components, recycling, mechanical properties and therapeutic needs - Part 1

The aligner is a thermoformed plastic device composed of various chemical components: polyurethane, polyethylene terephthalate glycol, polypropylene…All these plastics must be sufficiently resistant to abrasion and translucent for aesthetic purposes, but their solubility to salivary enzymes, insertion-disinsertion fatigue and recyclability vary according to material. From an orthodontic point of view, they must facilitate tooth movement. However, their behavior differs from that of orthodontic archwires: their Young's modulus, resilience and unloading curve are distinct, resulting in mechanical properties that fall significantly below the orthodontic requirements of multi-bracket systems. The aim of this article was to review the chemical composition, recycling and mechanical properties of aligners, and to put them into perspective with therapeutic indications. Literature data were approximated to orthodontic needs. Neither plastic nor direct printing can match the mechanical properties of our archwires or the procedures of a reliable vestibular multi-attachment appliance. Aligners remain an interesting tool in targeted indications.

3D composite printing: study of carbon fiber incorporation to different construction thermoplastic matrices in regard to dilatation characteristics

PurposeThe purpose of this paper is to clarify the relationship between the use of different polymer matrices for the preparation of composite materials, namely, polyethylene terephthalate-glycol (PET-G) and polyamide (PA), using Composite Fiber Co-Extrusion technology with the application of two types of carbon fibers, short and continuous. The aim of the study is also to extend the knowledge of the production of composite materials with a defined structure from the point of view of their influence on the microstructure and their physical-mechanical properties.Design/methodology/approachAs part of the experiment, four types of samples were prepared, namely, two types of samples with PA polymer matrix and two types with PET-G polymer matrix. All types contained short carbon fibers and always one set from each polymer matrix in addition to continuous carbon fibers. All types were prepared using the same 3D printing parameters to avoid any further influence. The samples were then tested for microstructure using microCT, mechanical properties using a tensile test and dilatation characteristics from the point of view of aerospace applications. Finally, the raw materials themselves were tested.FindingsThe paper provides insight into the influence of polymer matrix types on the physico-mechanical properties of 3D printed composites. The analysis confirmed that the physico-mechanical results varied with respect to the interface between the polymer matrix and the carbon fiber. The implications of the conclusions can be extended to the development of products in the aerospace and automotive sectors.Originality/valueThis study provides information for composite applications in the aerospace industry, focusing on evaluating dilatation characteristics within very low temperatures (−60 °C) when using carbon fibers (continuous carbon fibers, short carbon fibers and a combination of both) in two types of thermoplastic matrices. This perspective on materials characterisation for aerospace applications is a very important and unpublished approach within the 3D printing of composites. These characteristics are important parameters in the design of prototypes and functional samples with regard to the resulting behaviour in real conditions.

Applying a heat transfer mathematical model for the cryopreservation of rainbow trout (Oncorhynchus mykiss) sperm: How straw location over liquid nitrogen level affects freezing rate and fertilization yield

Cryopreservation of rainbow trout semen under field conditions was analyzed. Straw location over liquid nitrogen level is a crucial variable that affects freezing rate and fertilization yield due to changes in nitrogen vapor external temperature. The objectives were: to analyze cryopreservation protocols by experimentally measuring the cooling rates and fertilization yield of 0.5 ml plastic straws located in nitrogen vapor at different heights corresponding to different external temperatures; to numerically simulate the freezing process, by solving the heat transfer partial differential equations with the corresponding thermo-physical properties of the biological system and the plastic straw; to evaluate and analyze the surface heat transfer coefficient (h) during the freezing process of the straws; to introduce a new variable, the characteristic freezing time (tc), that enables comparison between protocols; this variable was defined as the elapsed period between the initial freezing temperature and a final reference temperature of −40 °C (temperature in which more than 80 % of the water is in a frozen state). The mathematical model predicted the temperature distribution inside the straw, showing a low effect of straw plastic materials (polyethylene-terephthalate glycol, polyvinyl-chloride, and polypropylene) on freezing rates. The average h value obtained from numerical simulations was 25.5 W/m2 K, close to that obtained from the analytical Nusselt correlation for natural convection. An improvement on fertilization trials was observed when the average external nitrogen temperature was −129.6 °C (temperature range: −94 to −171 °C) with an average tc of 56.8 s (ranging between 47 and 72 s). These results corresponded to a height above the level of liquid nitrogen of 2 cm. Comparison with literature reported data showed satisfactory results. Applying mathematical models in the cryobiology field achieved results that are relevant for cryopreservation activities.

Experimental testing and numerical simulations of 3D-printed PETG pins used for vehicle pedals

Abstract In this study, experimental analyses and numerical simulations of polyethylene terephthalate glycol (PETG) pedal pins with optimum production parameters are performed concerning mechanical properties. The aim of this study is twofold: first, the effect of the three-dimensional (3D) manufacturing process, which has a significant impact on the mechanical properties of the 3D-printed part, is realized experimentally. Second, the mechanical behavior of the 3D-printed clutch pedal pin is evaluated using both numerical simulation and experimental tests, which is an important application for lightweight vehicles. It is observed that the determined production parameters can significantly improve the mechanical behavior of the materials and the pin of the vehicle pedal mechanism can be replaced with a lighter structure. Thus, the results obtained in this paper are of the utmost importance for the manufacturer to choose the optimum manufacturing parameters of three-dimensional printed materials and their application to vehicle pedals and other possible parts.