Plastic Components Research Articles

A deep learning-based crystal plasticity finite element model

This study presents an innovative deep learning-based surrogate model for the Crystal Plasticity Finite Element (CPFE) method, fundamentally transforming the generation of mechanical properties such as stress-strain curves in the study of crystal plasticity. Stress-strain curves are pivotal in understanding material deformation, elucidating the intricate relationship between a material's structure and its properties. Traditional CPFE methods, though thorough in their analysis, face significant computational challenges, largely due to the complexity of the crystal plasticity framework. The proposed model circumvents this bottleneck by utilizing an autoencoder architecture to learn intermediate data representations, which are then used to predict the plastic component of deformation. This predicted plastic component serves as a foundation for computing stress-strain curves, effectively bypassing the most time-intensive aspect of traditional CPFE methods, the plasticity self-consistency procedure (achieving a 29.3x speed increase without compromising accuracy).

Numerical analysis of the mechanics of foreign particle entry on automotive turbocharger compressor blades

Automotive turbochargers, essential for enhancing intake air pressure and boosting torque in internal combustion engines, operate at exceptionally high rotational speeds of approximately 100,000 to 300,000 rpm. Despite the implementation of dual or triple air filtration systems to filter contaminants, neglected maintenance can lead to clogged filters, resulting in the ingestion of metallic filter mesh, and other small-sized objects from filter indicators, washers, and plastic components into the turbocharger assembly. The current study explores the impact of foreign particles on the mechanics of turbocompressor impeller blades in automotive turbochargers through a computational approach. A finite element model of the turbocompressor wheel was developed with suitable boundary conditions for the turbocompressor and the foreign particle. A Design of Experiments (DoE) approach was employed using a Taguchi L12 orthogonal array to optimize the multiple parameters during the foreign particle impact. The study considered two geometric shapes of the foreign particle (conical with unit aspect ratio and hemispherical), two sizes, and two rotational speeds ranging from 150,000 to 250,000 rpm. ANSYS Explicit Dynamics® software was utilized for the numerical simulations to simulate the mechanics of foreign particle entry and the resulting damage on compressor blades.

Mechanical testing of colloidal solids with millipascal stress and single-particle strain resolution.

We introduce a technique, traction rheoscopy, to carry out mechanical testing of colloidal solids. A confocal microscope is used to directly measure stress and strain during externally applied deformation. The stress is measured, with single-mPa resolution, by determining the strain in a compliant polymer gel in mechanical contact with the colloidal solid. Simultaneously, the confocal microscope is used to measure structural change in the colloidal solid with single particle resolution during the deformation. To demonstrate the utility and sensitivity of this technique, we deform a hard-sphere colloidal glass in simple shear, and from the macroscopic shear strain and measured stress determine the stress-strain curve. Using the stress-strain curve and measured shear modulus, we decompose the macroscopic shear strain into an elastic and a plastic component. We also determine a local strain tensor for each particle using the changes in its nearest-neighbor distances. These local strains are spatially heterogeneous throughout the sample, but, when averaged, match the macroscopic strain. A microscopic yield criterion is used to split the local strains into subyield and yielded partitions; averages over these partitions complement the macroscopic elastic-plastic decomposition obtained from the stress-strain curve. By combining mechanical testing with single-particle structural measurements, traction rheoscopy is a unique tool for the study of deformation mechanisms in a diverse range of soft materials.

Insights into hydro thermal gasification process of microplastic polyethylene via reactive molecular dynamics simulations

Microplastics have become a pressing environmental issue due to their widespread presence in our ecosystems. Among various plastic components, polyethylene (PE) is a prevalent and persistent contaminant. Hydrothermal gasification (HTG), a promising technology for converting PE into syngas, holds great promise for mitigating the microplastic problem. In this study, we employ ReaxFF molecular dynamics simulations to investigate the HTG process of PE, shedding light on the intricate relationships between temperature, water content, carbon conversion efficiency, and product distributions. The results reveal that hydrothermal gasification of PE is a complex process involving multiple reaction pathways. Consistently with experimental findings, the calculations indicate that the gas phase exhibits a substantial hydrogen fraction, reaching up to 70%. Interestingly, our simulations reveal a dual role of water content in the HTG process. On one hand, water enhances hydrogen production by promoting the gas formation. On the other hand, it elevates the activation energy required for PE decomposition. Depending on the water content, the calculated activation energies range from 176 to 268 kJ/mol, which are significantly lower than those reported for thermal gasification (TG). This suggests that HTG may be a more efficient route for PE conversion. Furthermore, this study highlights the importance of optimizing both temperature and water content in HTG systems to achieve high yields of hydrogen-rich syngas. The results obtained from our ReaxFF MD simulations demonstrate the robustness of this computational methodology in elucidating complex chemical reactions under extreme conditions. Our findings offer critical insights into the design of advanced waste management strategies for microplastics and contribute to the development of sustainable practices for resource recovery. This work underscores the potential of HTG as a key technology for addressing the global challenge of plastic pollution.

Effects of Glycine on epigenetic modification and early embryonic development in porcine oocytes exposed to monobutyl phthalate

Monobutyl phthalate (MBP) is the primary active metabolite of dibutyl phthalate (DBP), the key plasticizer component. A substantial body of evidence from studies conducted on both animals and humans indicates that MBP exposure could result in harmful impacts on toxicity pathways. In addition, it can seriously affect human and animal reproductive health. In our present study, we showed that exposure to MBP causes abnormal epigenetic modifications in porcine oocytes and failure of early embryonic development. However, glycine (Gly) can protect oocytes and early embryos from damage caused by MBP. Our study indicated a significant decrease in the percentage of porcine oocytes that reached the metaphase II (MII) phase when exposed to MBP. SET-domain-containing 2(SETD2)-mediated H3K36me3 histone methylation was detected, and the results showed that MBP significantly decreased the protein expression of H3K36me3 and SETD2. Moreover, the expression of the DNA break markers γH2AX and the mRNA expression of Asf1a, and Asf1b increased in the MBP group. The detection of DNA methylation marker proteins showed that MBP significantly increased the fluorescence intensity of 5-methylcytosine (5mC). The results from our RT-qPCR analysis demonstrated a significant decrease in the mRNA expression of the DNA methylation-related genes Dnmt1 and Dnmt3a, as well as the embryonic developmental potential-related genes Oct4 and Nanog, in porcine oocytes following exposure to MBP. Additionally, the mRNA expression of p53 significantly increased. Subsequently, the effects of MBP on early embryonic development were examined via parthenogenesis activation (PA) and in vitro fertilization (IVF). Exposure to MBP significantly impacted the development of embryos in both PA and IVF processes. The TUNEL staining data showed that MBP significantly increased embryonic apoptosis. However, Gly can ameliorate MBP-induced defects in oocyte epigenetic modifications and early embryonic development.

Assessment by finite element analysis modelling of tissue strains associated with the use of two different nasogastric tube securement devices.

Nasogastric tube use can lead to pressure injury. Some nasogastric tube securement devices (NG-SD) include hard plastic components. In the current study, we assessed the differences in strain profiles for two NG-SD, one with hard segments and one without hard segments, using finite element analysis (FEA) to measure strain and deformation occurring at the nasogastric tube-tissue interface. FEA in silico models of devices were based on device mechanical test data and clinically relevant placements. Peak strain values were determined by modelling different scenarios using Abaqus software whereby the tubing is moved during wear. The modelling showed peak strains ranging from 52% to 434% for the two NG-SD depending on the tubing placement and device type. Peak strain was always higher for the hard plastic device. Tissue strain energy was a minimum of 133.8 mJ for the NG-SD with no hard parts and a maximum of 311.6 mJ for the NG-SD with hard parts. This study provided evidence through in silico modelling that NG-SD without hard components may impart less strain and stress to tissues which may provide an option for tube securement that is less likely to cause medical device-related pressure injury.

Analysis of waste generation characteristics as a reference for TPS 3R planning in community-based waste management efforts in Pandansari Lor Village, Malang Regency

Background: Waste management is a critical issue in Indonesia, particularly in rural areas like Pandansari Lor Village in Malang Regency. Improper waste disposal practices, such as open burning and dumping in rivers, pose environmental and health hazards. This study aims to analyze the waste generation characteristics in Pandansari Lor Village as a baseline for planning a community-based Reduce, Reuse, Recycle (3R) waste processing site (TPS 3R). Method: A waste sampling method was conducted following the SNI 19-3964-1994 guidelines to measure the waste generation rate, density, and composition. Findings: The results showed that the average waste generation rate in Pandansari Lor Village was 0.16 kg/person/day or 778.72 kg/day for the total population, with a waste density of 74.02 kg/m³. The waste composition was dominated by organic waste (62.26%), followed by plastic (26.74%), paper (5.89%), and other components. These findings suggest the need for a 3R-based waste management system that involves community participation. Conclusion: The TPS 3R facility should be designed to handle the projected waste generation for the next 10 years, with a capacity of 15,438 L/day. Proper waste segregation, composting of organic waste, and recycling of plastic and other recyclable materials are recommended. This study provides valuable insights for developing a sustainable and effective waste management strategy in rural areas, considering the specific waste characteristics and community involvement. Novelty/Originality of this article: This study proposes a 3R TPS model adapted to rural waste, focusing on organic waste composting and plastic recycling. This model is designed to increase community participation in waste management through community-based education and empowerment.

Deformation Estimation of Textureless Objects from a Single Image.

Deformations introduced during the production of plastic components degrade the accuracy of their 3D geometric information, a critical aspect of object inspection processes. This phenomenon is prevalent among primary plastic products from manufacturers. This work proposes a solution for the deformation estimation of textureless plastic objects using only a single RGB image. This solution encompasses a unique image dataset of five deformed parts, a novel method for generating mesh labels, sequential deformation, and a training model based on graph convolution. The proposed sequential deformation method outperforms the prevalent chamfer distance algorithm in generating precise mesh labels. The training model projects object vertices into features extracted from the input image, and then, predicts vertex location offsets based on the projected features. The predicted meshes using these offsets achieve a sub-millimeter accuracy on synthetic images and approximately 2.0 mm on real images.

Experimental analysis of the effects of feedstock composition on the plastic and biomass Co-gasification process

Co-gasification is a feasible approach to manage fast-growing plastic and biomass waste issues. The current work examines air gasification of plastic waste blending with biomass. The influence of plastic-type and biomass characteristics on product distribution under the same operating condition was studied. Ethylene-vinyl acetate, high-density polyethylene, and polypropylene were the investigated plastics while the biomass materials considered were pine sawdust (PS), used ground coffee (UGC), and wheat straw (WS) are compared. Additionally, co-gasification and thermogravimetric analyses (TGA) of plastic and individual biomass components, namely, cellulose, hemicellulose, and lignin, were conducted to identify the nature of the synergy arising from plastic and biomass integration. Similarities in the chemical structure and composition of the investigated plastics resulted in the type of plastic marginally influencing product distribution. The gas composition included 4.6 vol% CH4, 37.5 % CO2, 5.3 % CnHm, 42 % CO, and 10.8 % H2, with yields of 5.9 wt% char, 39.5 wt% gas, and 54.8 wt% tar. Conversely, the type of biomass had a substantial effect on both gas composition and product yields. WS and UGC, characterized by higher hemicellulose and lignin content, generated more hydrogen with 14.4 and 13.3 vol%, respectively, and exhibited lower tar content (45.7 and 47.8 wt%) compared to PS, which has a higher cellulose content and yielded 54.8 wt% tar. During EVA/cellulose co-gasification, the predominant gases produced are CO and CO2, with H2 concentration of 7.2 vol%. In contrast, co-gasification of EVA/xylan and EVA/lignin yields 13.5 and 19.9 vol% hydrogen, respectively. Interactions and synergism between the plastic and biomass were found to be more intensified when the biomass contained greater proportions of cellulose and lignin. Co-gasification and TGA analyses indicated that plastic/cellulose and plastic/lignin interactions in the gas and solid phases (volatile-volatile and volatile-char interactions) and plastic/xylan interactions in the gas phase (volatile-volatile interactions) were significant. Modeling the predictability of the output data revealed that if interactions between the plastic and biomass components are accounted for, the co-gasification results are predictable with a credible accuracy for all biomass types. The predictability model offers a practical approach for selecting an appropriate co-gasification feedstock combination to give a targeted process performance.

Whole Process Analysis and Fate Behavior of Microplastics in Urban Wastewater Treatment Plants, Including their Occurrence Forms, Components, and Removal Efficiency

Microplastics are among the most difficult new pollutants to remove in wastewater treatment plants. In order to explore the occurrence form, size distribution, composition, removal efficiency, migration law, and fate behavior characteristics of microplastic particles in sewage plants, taking a sewage treatment plant in Hohhot as an example, a total of 17 sampling sites were set up. The LAS X software counted the shape, abundance, and size of microplastics and conducted a full-process analysis. The results showed that： fibrous microplastics had the highest abundance and widest distribution and were the main form of existence, accounting for 61.8% of the total abundance； the size of microplastics ranged mainly between 0 and 1.00 mm, and among the four sizes, the abundance of microplastics 0.25 to 0.50 mm in China was the highest, accounting for 32.9%. Among the eight types of plastic components detected, polyester substances （PET, PBT）, cellulose, and polypropylene （PP） were the main components, accounting for 25%, 21%, and 17%, respectively. The influent abundance of the sewage plant was （73 ±5） n·L-1, the effluent abundance was （14 ±2） n·L-1, and the overall removal rate was （80.8 ±12.1）%. Among the three treatment stages of the sewage plant, only the primary treatment played a role in removal, and the abundance of microplastics surged in the secondary treatment. Different structures playing a major role in the removal of microplastics were fine grids （49.2 ±7.4）% and secondary sedimentation tanks （92.4 ±13.9）%. Microplastics mainly existed in the form of fibers, fragments, and films. The proportion of fibers was approximately 70%, and the size of fragments was mainly concentrated between 0.50 and 5.00 mm. Most fragments were in the range of 5.00 mm, accounting for 50%, making them the main form apart from fibrous. The film-like size was mostly concentrated in the range of less than 0.50 mm, accounting for more than 10%. Therefore, improving the removal of small-sized fibrous and film-like microplastics and large-sized fragmented microplastic particles can effectively reduce the pollution risk of microplastics in the environment caused by sewage plant drainage.

An assessment of workability, mechanical and durability properties of high-strength concrete incorporating nano-silica and recycled E-waste materials

BackgroundPresently, the proper disposal of E-waste is a major challenge for all nations. Portland cement and aggregates continue to play a major role in the construction industry's operations. Meanwhile, natural resources like gravel (aggregates) are becoming scarce. Thus, E-waste is now offering the building industry a chance to replace traditional aggregates. The main goal of the current study is to determine the highest amount of E-waste that may be replaced with 10-mm coarse aggregates with a nano-silica associated ternary blend in M-60 grade high-strength concrete while still maintaining the designed concrete's mechanical, durability, microstructural and workability characteristics.ResultsWhen compared to normal concrete, concrete with 15% E-waste replacement maintained the design-required compressive, flexural and tensile strength properties. When the E-waste plastic component percentage is considerably high (15–30%), there is a significant decremental performance regarding the mechanical properties and the decremental rate is found to be in the range of 13–23%. Even the microstructure characteristics of concrete validate the mechanical performance of concrete. Nevertheless, the durability characteristics of E-waste incorporated concrete were found to be promising.ConclusionsThe overall outcome of the study recommends 15% as the optimal replacement percentage of E-waste for conventional concrete, and it is recommended to adopt for real-time practices.

Effects of gamma, electron beam, and X-ray irradiation on the plastic components of a universal bone cement mixer medical device

Due to market and regulatory pressures, many healthcare manufacturers are considering alternatives to cobalt-60 gamma radiation, including accelerator-based electron beam (E-beam) and X-ray radiation for product sterilization. In this work, the effects of irradiation on a representative medical product, comprised of eight distinct polymer materials, were directly compared for three radiation technologies – cobalt-60 gamma, E-beam, and X-ray – at four dose levels (15, 25, 50, and 70 kGy). The objective was to determine how radiation effects (deleterious or beneficial) are influenced by source and dose level, with the specific goal of determining whether E-beam radiation and/or X-ray radiation could be viable alternatives to gamma radiation for device sterilization. The specific product considered is a single-use medical device for orthopedic surgery, the Stryker Instruments MixeVac III bone cement mixer, which is currently sterilized using gamma radiation from cobalt-60 sources. Following ASTM International standards and input from the manufacturer, we characterized the effects of the three radiation sources on product functionality as well as on the mechanical and optical properties of the constituent polymers. Results indicate that although measurable differences in properties between the standard gamma irradiated materials and the alternative E-beam and X-ray irradiated materials were observed, those differences were small. Statistically significant differences were noted in the case of yellowness index for polyvinyl chloride, high-density polyethylene, and polycarbonate, and in the case of tensile elongation at break for high impact polystyrene and polyvinyl chloride. In general, the results of this study support the viability of E-beam and X-ray radiation as alternative options to cobalt-60 gamma radiation for sterilization of Stryker single-use universal bone cement mixer medical devices.

Challenges in the Recycling of Battery Casing Materials

AbstractCurrent recycling methods for the very popular lithium‐ion batteries (LIBs) focus mainly on recovering valuable metals such as cobalt and nickel for economic reasons. The cell casing components, which are mainly made of aluminum, can make a significant contribution to achieving political recycling targets. Mechanical processes are used to separate the casing components from the overall LIB material stream. The aluminum, copper, steel, and plastic components are then further concentrated into various potential products by, e.g., magnetic separation, eddy current separation, and air classification. Considering the benefits of additional stress to compact the metal parts, the knowledge gained from the individual sorting steps can be combined to form a process flow chart.

SISTEM INFORMASI PERMINTAAN PEMBELIAN BAHAN BAKU DAN ATK PADA PT MADA WIKRI TUNGGAL MENGGUNAKAN LARAVEL 9

PT Mada Wikri Tunggal is an automotive industrial company in the field of metal and plastic components that produces goods in the form of spare parts for two-wheeled (2) and four-wheeled (4) vehicles. The purchasing department at PT Mada Wikri Tunggal is responsible for the availability of goods needed by other departments according to the time required. Before carrying out the process of purchasing raw materials and stationery, the purchasing department must have a purchase request form for raw materials or stationery originating from the department concerned. In the process of purchasing raw materials and stationery, several problems were found, such as purchasing the same goods in one purchase request, and also the loss of the purchase request form which could hamper the process of purchasing raw materials or stationery. Therefore, it is necessary to design an information system application for purchasing requests for raw materials and stationery by depicting it using UML diagrams, ERD, and interface design as well as web-based integrated development using the Laravel framework and applying the waterfall method. The existence of an information system for purchasing requests for raw materials and stationery can minimize errors in purchasing raw materials and stationery in the purchasing department at PT Mada Wikri Tunggal so that there will be no duplication of the same purchase in one purchase request and it will not take a long time to send purchase orders. to suppliers.

From Control to Chaos: Visual-Cognitive Progression During Recovery from ACL Reconstruction.

BACKGROUND: Anterior cruciate ligament tear is a serious knee injury with implications for central nervous system (CNS) plasticity. To perform simple knee movements, people with a history of ACL reconstruction (ACL-R) engage cross-modal brain regions and when challenged with cognitive-motor dual-tasks, physical performance deteriorates. Therefore, people with ACL-R may increase visual-cognitive neural processes for motor control. CLINICAL QUESTION: What components of CNS plasticity should the rehabilitation practitioner target with interventions, and how can practitioners augment rehabilitation exercises to target injury associated plasticity? KEY RESULTS: This clinical commentary (1) describes the neurophysiological foundation for visual-cognitive compensation after ACL-R, (2) provides a theoretical rationale for implementing visual-cognitive challenges throughout the return to sport (RTS) continuum, and (3) presents a framework for implementing visual-cognitive challenges from the acute phases of rehabilitation. The 'Visual-Cognitive Control Chaos Continuum (VC-CCC) framework consists of five training difficulties that progress visual-cognitive challenges from high control to high chaos, to better represent the demands of sport. CLINICAL APPLICATION: The VC-CCC framework augments traditional rehabilitation so that each exercise can progress to increase difficulty and promote sensorimotor and visual-cognitive adaptation after ACL-R.

Comparative Study of Multi‐objective Bayesian Optimization and NSGA‐III based Approaches for Injection Molding Process

AbstractInjection molding is a prevalent method for producing plastic components, yet determining the ideal process parameters has predominantly relied on heuristic approaches. In this research, a data‐driven injection molding process optimization framework is developed to simultaneously minimize warpage, cycle time, and clamping force. Employing multi‐objective Bayesian optimization (MBO), the framework is applied to a fan blade model for verification. Incorporating those objectives enables the selection of an injection molding machine with the proper maximum clamping force within acceptable tolerance and production time. Furthermore, non‐moldable regimes are considered in design space, which allows less prior knowledge for setting design space. The optimized results are compared with those obtained using NSGA‐III, a well‐established genetic algorithm‐based optimization technique, as a benchmark. The optimization frameworks produce a Pareto front for the three‐dimensional outputs, revealing distinct trade‐off relationships between cycle time and warpage, as well as clamping force and warpage. The MBO framework demonstrates a superior Pareto front compared to NSGA‐III when utilizing a limited data set, underscoring its benefits in scenarios where costly simulations or experiments are necessary. These findings are anticipated to contribute to the optimization of manufacturing processes, ultimately enhancing productivity in real‐world industries.

Synergistic co-pyrolysis of corn stover and refuse-derived fuel with microplastics: Kinetic and thermodynamic study

Biomass and refuse-derived fuel are prevalent constituents of municipal solid waste worldwide, exerting persistent pressures on environmental ecosystems. Consequently, there arises a critical necessity for their effective recycling and management. This study investigates the co-pyrolysis of corn stover (CS) and Refuse-Derived Fuel (RDF) in a 1:1 mass ratio through kinetic and thermodynamic analyses. Using a thermogravimetric analyzer and differential scanning calorimetry (DSC), the co-pyrolysis process is examined within a temperature range of 25–900 °C, under varying heating rates of 5, 10, and 20 °C/min in a nitrogen atmosphere. Kinetic analysis is conducted employing model-free methods, including Kissinger-Akahira-Sunose (KAS), Flynn-Wall-Ozawa (FWO), Starink, and Tang, with subsequent estimation of thermodynamic parameters such as enthalpy change (ΔH), entropy change (ΔS), and Gibbs free energy (ΔG). Additionally, mass and energy balances specific to the blended feedstock are calculated to evaluate future operational efficiency. The investigation reveals the higher heating values (HHV) of CS and RDF as 17.879 and 20.035 kJ/kg, respectively. Notably, the DTG and DSC curves indicate a positive interaction between CS and RDF's plastic component at temperatures exceeding 400 °C. Kinetic analysis yields average activation energies for CS, RDF, and the CS-RDF blend (1:1) as 202.26, 235.87, and 212.60 kJ/mol, respectively, suggesting a reduction in activation energy for the blend. In summary, these findings offer valuable insights into the co-pyrolysis of CS and RDF, thereby contributing to the optimization of co-pyrolysis as an effective waste-to-energy conversion process.

Environmental-friendly extraction of di(2-ethylhexyl) phthalate from poly(vinyl chloride) using liquefied dimethyl ether

Poly(vinyl chloride) (PVC) is one of the most widely used plastics. However, a major challenge in recycling PVC is that there is no economical method to separate and remove its toxic phthalate plasticizers. This research made a breakthrough by extracting PVC with liquefied dimethyl ether (DME) and successfully separating the plasticizer components. Nearly all (97.1 %) of the di(2-ethylhexyl) phthalate plasticizer was extracted within 30 min by passing liquefied DME (285 g) through PVC at 25 °C. The compatibility of PVC with organic solvents, including liquefied DME, was derived theoretically from their Hansen solubility parameters (HSP), and actual dissolution experiments were conducted to determine the optimal PVC solvents. A liquefied DME mixture was used to dissolve PVC, and the extract was diluted with ethanol to precipitate the dissolved PVC. We demonstrated that liquefied DME is a promising method for producing high quality recycled products and that the process retains the fundamental properties of plasticizers and PVC without inducing degradation or depolymerization. Because of its low boiling point, DME can be easily separated from the solute after extraction, allowing for efficient reuse of the solvent, extracted plasticizer, and PVC. DME does not require heat and produces little harmful wastewater, which significantly reduces the energy consumption of the plasticizer additive separation process.

High-temperature mechanical properties of additively manufactured 420 stainless steel

Martensitic stainless steels are indispensable alloys in various high stress and temperature applications such as plastic injection molds and components in steam generators. Subtractive manufacturing methods used to fabricate these parts, however, limits its functionality and performance due to design constraint of cooling channels. This limitation can be resolved by means of additive manufacturing while ensuring that acceptable high-temperature properties can be achieved. In this work, the mechanical behavior of additively manufactured 420 stainless steel (AM420SS) is explored through material constitutive modeling to determine the mathematical model that best describes its flow stress in extreme conditions. This is accomplished by subjecting the samples to hot compression under the strain rates of 0.1–1.0 s−1, and temperatures between 973–1423 K (700 °C–1150 °C) via Gleeble thermomechanical test. The experimental data were used to generate the predictive flow stress curves of constitutive models which includes Johnson-Cook, Zerilli-Armstrong, Zener-Hollomon, and Hensel-Spittel equations. Results showed that Zener-Hollomon and Hensel-Spittel models are the most accurate material constitutive equations with relatively high R values of 0.986 and 0.976, and low average absolute relative error values of 6.96% and 7.69%, respectively. The material constants derived from these models can be applied in finite element analysis simulations to assess the performance of using AM420SS parts at high temperature and strain conditions.

Metallization of polypropylene substrates through surface functionalization and physical vapor deposition of chromium coatings

Physical vapor deposition (PVD) of chromium coatings represents an interesting alternative to electroplating to obtain metallized plastic parts for a variety of manufacturing sectors. This process is however hampered by the limited adhesion of the metallic layer on the underlying polymeric substrates. Within this context, PVD metallization of polypropylene substrates has so far been particularly challenging given the low surface energy and poor wettability of this commodity plastics. To address this issue, a comprehensive approach is proposed here to enable the production of PVD-metallized PP substrates with excellent and stable interlayer adhesion. The adhesive properties of the PP substrate are modified by a selective UV-induced photografting process in which vinyl-, glycidyl- or 2-hydroxyethyl methacrylate species are covalently attached to the PP surface, as confirmed by Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy and surface wettability measurements. Based on the chemistry of the photografted functionality, different resin systems are selected and investigated for use as primers to enable subsequent chromium deposition, including acrylic, epoxy and polyurethane systems. The effect of the photografting process on the adhesion between PP and the primers is systematically assessed by means of pull-off tests, highlighting a significant improvement of the adhesion force after surface functionalization with appropriate grafting agents. Finally, functionalized PP substrates are chromated through PVD, obtaining homogeneous and crack-free chromium surfaces upon judicious selection of suitable primer-grafting agent combinations. This also led to outstanding interlayer adhesion and micromechanical performance. This work provides the first demonstration of chromium-metallization of PP substrates via PVD for metallized plastic components with excellent surface characteristics, and paves the path for the design of mechanically durable and aesthetically-compliant PVD-metallized PP components.