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Ultrasonic testing is widely used for defect detection in polymer composites owing to advantages such as fast processing speed, simple operation, high reliability, and real-time monitoring. However, defect information in ultrasound images is not easily detectable because of the influence of ultrasound echoes and noise. In this study, a stable three-dimensional deep convolutional autoencoder (3D-DCA) was developed to identify defects in polymer composites. Through 3D convolutional operations, it can synchronously learn the spatiotemporal properties of the data volume. Subsequently, the depth receptive field (RF) of the hidden layer in the autoencoder maps the defect information to the original depth location, thereby mitigating the effects of the defect surface and bottom echoes. In addition, a dual-layer encoder was designed to improve the hidden layer visualization results. Consequently, the size, shape, and depth of the defects can be accurately determined. The feasibility of the method was demonstrated through its application to defect detection in carbon-fiber-reinforced polymers. [ABSTRACT FROM AUTHOR]

The mechanical properties of both polymethyl methacrylate (PMMA) and polyethylene terephthate (PET) were examined in tensile and three-point bending tests, as well as their bond and interlayer shear strengths were assessed. The results obtained were employed in computer simulation of mechanical loading of temporary removable complete dentures (TRCDs). It was shown that the variations of the elastic moduli of the dental materials studied did not exceed 15.6%; the ultimate strength of PET was higher than that of PMMA by ~2.2 times in tension and by ~1.9 times in bending. Elongation at break was greater for the PET specimens than those for the PMMA ones by ~2.3 times in tension and by ~3.1 times in bending. Computer simulation has shown that when the load was applied at the angle of 90°, the tooth fractured in all cases. Stresses were much lower in the denture base concerning the critical levels. Therefore, the adhesion conditions considered did not affect the pattern of their failure, and the critical load was the same for both denture base materials. When the load was applied to canines at the angle of 45°, the critical load was below the specified level of 100 N in the PMMA denture base due to the peculiarities of TRCD design and the lower strength of PMMA. When both canines and incisors were loaded at the angle of 45°, the PET denture base could withstand the greater critical load than the PMMA one. Both mechanical tests and computer simulation results enabled to conclude that PET is the prospect denture base material for the manufacture of TRCDs and dental orthopedic treatment. [ABSTRACT FROM AUTHOR]

This letter was to present an attempt of large‐wavelength Gaussian deconvolution phase‐contrast computed tomography (LW‐GD‐PCCT) for promotion of image quality reconstructed in low‐frequency band of terahertz (THz) spectrum at 0.11 THz. The interaction between the imaging samples and the THz Gaussian beam were formulated firstly in this paper, where the unwrapped phase was extracted specifically to portray the spatial structure distribution of the samples. Additionally, a Gaussian deconvolution was employed for the further reduction of spatial distortions. Moreover, an image reconstruction was carried out with the obtained phase sinograms based on phase‐used inverse Radon transform from the different positions on the sample. For an experimental assessment of the concept of LW‐GD‐PCCT, a single ellipsoid reflector‐based THz Gaussian beam generating system was established and samples such as polystyrene (PS) foam cuboid (Sample 1), and cylinder (Sample 2) with hollow defects (air holes and triangles) were prepared carefully in this work. To experimentally evaluate the performance of the contributing to the structural imaging over soft samples. Two‐dimensional topographies of each sample were reconstructed successfully, and the obtained cross root‐mean‐square error (cross‐RMSE), cross peak signal‐to‐noise ratio (cross‐PSNR), and cross structural similarity (cross‐SSIM) were 151.6451, 26.3225, and 0.9616 for Sample 1 with a high dose of 180 projections respectively, as well as 30.3242, 33.3129, and 0.9711 for Sample 2 with a low dose of 36 projections, respectively. The obtained imaging indicators of this work showed a superiority of imaging quality over those of recent works. Furthermore, the investigation of the bearing capacity has shown promise in enhancing image quality even in low‐dose conditions. The presented results suggest that the unwrapped phase combining with Gaussian deconvolution in low‐frequency band of THz imaging would be useful to improve the reconstructed image quality, potential to highly feasible non‐destructive testing of polymer foam via large wavelength. [ABSTRACT FROM AUTHOR]

This study delves into the mechanical characteristics of polyamide PA2200 components crafted using selective laser sintering (SLS) technology. Our primary objective is to analyze the tensile behavior of the components printed at various orientations, showing its response to diverse loading conditions. Finite element method (FEM) modeling was employed to analyze the tensile behavior of these details. The time determined for breaking the detail is 9 s. In addition we forecast key properties, such as tensile behavior and strength, using machine learning (ML) techniques, and the best models are for predicting relative elongation are KNeighborsRegressor and SVR. [ABSTRACT FROM AUTHOR]

Wear is the leading cause of nozzle failure. The durability of the nozzle is affected by the material it is made from. Traditional materials are ceramics, stainless steel, brass, and polymers. One of the possible ways to improve the wear resistance of polymer nozzles is through the incorporation of dispersed fillers into them. This paper presents the results of testing polymer composites for their chemical resistance to pesticides, examining the effects of different types and amounts of fillers on the chemical and abrasion resistance. When silicon carbide was used as a filler, the strength increased by 30.2%. The experiments on chemical resistance to pesticides revealed that the nature, shape, and volume content of filler particles do not significantly affect the resistance of the compounds obtained. Tests on hydro-abrasive wear have shown that graphite and silicon carbide are effective fillers capable of reducing wear by up to 7.5 times. Based on previous research, it is recommended to use a composite compound with 15% volume of silicon carbide for nozzle manufacturing. [ABSTRACT FROM AUTHOR]

The article titled "Topical section 'Advanced Testing of Soft Polymer Materials'" discusses the importance of using advanced testing methods to characterize and analyze soft polymer materials. The increasing demand for enhanced properties and capabilities in various industries, such as e-mobility, energy generation, information technology, soft robotics, and medical engineering, has led to the need for predictive and advanced laboratory testing. The article emphasizes the importance of accuracy, relevance, productivity, and cost-effectiveness in laboratory testing, as well as the development of new concepts for soft polymeric materials, including nanotechnology, self-healing, and eco-design. The scope of the article includes the development and application of advanced testing methods for chemical, rheological, mechanical, thermal, electrical, and magnetic analysis, as well as concepts for predictive testing and realistic load simulation. The article highlights the potential of simulation tools and artificial intelligence in predicting the behavior and durability of soft polymer materials. [Extracted from the article]

While 3‐dimensional (3D) printing technology is advancing rapidly, commonly used filament materials are struggling to meet growing expectations. Polyamide (PA) is a material with high potential to replace commonly used low‐performance filament materials, thanks to its cost‐effectiveness and optimal material properties compared to advanced engineering materials. To explore this potential, the thermal, thermomechanical, and mechanical properties (at different temperatures), as well as the wear characteristics, of PA, short carbon fiber reinforced‐PA (SCFR‐PA), and short glass fiber reinforced‐PA (SGFR‐PA) filaments were comparatively examined in this study. Differential scanning calorimeter analysis (DSC), Dynamic Mechanical Thermal Analysis (DMA), uniaxial tensile tests, and Shore D hardness tests were conducted on the 3D printed specimens. The yield strength decreased by 48% and 73%, respectively, for neat PA as compared to room temperature when tested at 40 °C and 60 °C, while for SCFR‐PA, it decreased by 40% and 60%, and for SGFR‐PA, it decreased by 33% and 48%, respectively. The findings obtained from wear tests conducted on both bottom and top surfaces have demonstrated that glass reinforcement yields better results than carbon reinforcement. The experimental findings have been compared with SEM images, revealing their consistency. Highlights: This study focuses on the performance evaluation of 3D printed PA and its composites.The mechanical properties of the materials at different temperatures were compared.Adhesive wear behavior is not directly related to fiber type, wear surface or hardness.Morphological analysis was conducted to elucidate the influence of fiber type on mechanical properties and wear behavior. [ABSTRACT FROM AUTHOR]

In this work, three cyanoalkyl silicone GC stationary-phase polymers, namely OV-105, OV-225, and OV-275, were investigated as potential extractants for dispersive liquid–liquid microextraction (DLLME). The OV-225 polymer (cyanopropylmethyl-phenylmethylsilicone) exhibited the cleanest chromatographic background and was extensively studied. The proposed polymer was tested through the DLLME of four non-steroidal anti-inflammatory drugs from aqueous samples, followed by HPLC separation with UV detection at 230 nm. To achieve the maximum enrichment, the experimental conditions that influence the DLLME process were optimized using one-factor-at-a-time and design-of-experiment (DoE) approaches. The extraction variables (polymer mass, dispersive solvent volume, buffer pH, and mixing time) were screened by implementing a two-level full factorial design (FFD). Significant variables were fine-tuned using response surface methodology based on a face-centered central composite design (CCD). The optimum conditions were 10 mg of polymer (extraction medium); 50 µL of tetrahydrofuran (dispersive solvent); 100 µL of phosphate buffer pH 2.75 ([PO43−] = 100 mM); and 3 min of vortex mixing. The addition of salt had a minimal effect on the enrichment factors. In the optimum conditions, enrichment factors up to 46 were achieved using 1.5 mL samples. Calibration curves exhibited correlation coefficients > 0.999 using 4-pentylbenzoic acid as an internal standard. The limits of quantitation were 5 ng/mL for naproxen, 10 ng/mL for diflunisal, 25 ng/mL for indomethacin, and 75 ng/mL for ibuprofen. The analysis of spiked tap water samples showed adequate relative recoveries and precision. In conclusion, the proposed polymer (OV-225) is a potential greener alternative to traditional organic extractants used in DLLME. [ABSTRACT FROM AUTHOR]

Recycling concrete with reinforcement made of basalt fibre polymers: investigations on the composite and tensile load‐bearing behaviour The use of recycling concrete is subject to restrictions in Germany, which prevent its use in environmental conditions containing de‐icing salt of exposure classes XD3 and XS3. To overcome these normative barriers, the Munich UAS is conducting research on the use of alternative reinforcement materials that completely eliminate reinforcement corrosion induced by chlorides. In this regard, non‐corrosive fibre composite bars, made of basalt, are employed, which offer ecological advantages over reinforcements made of stainless steel, glass fibre or carbon. The investigations presented here on the composite and tensile load‐bearing behaviour of basalt fibre‐reinforced polymers have arisen as part of a current research project examining the use of this type of reinforcement in bridge caps made of recycling concrete. In addition to preliminary concrete technology studies on the use of up to 100 % recycled aggregates, composite specimens made of recycled concrete and basalt fibre reinforced polymer were tested to provide insights on the load‐bearing behaviour under static and cyclic conditions. [ABSTRACT FROM AUTHOR]

The relationships between gas permeability and free volume fraction, intersegmental distance, and glass transition temperature, are investigated. They are analyzed for He, CO2, O2, CH4, and N2 gases and for five similar polyimides with a wide range of permeabilities, from very low to extremely high ones. It has been established here that there is an exponential relationship between permeability and the free volume fraction, and between permeability and the most probable intersegmental distance as measured by WAXS; in both cases, with an exponential coefficient that depends on the kinetic gas diameter as a quadratic polynomial and with a preexponential positive constant. Moreover, it has been proven that the intersegmental distance increases linearly with the free volume fraction. Finally, it has been established that the free volume fraction increases with the glass transition temperature for the polymers tested, and that they depend on each other in an approximate linear way. [ABSTRACT FROM AUTHOR]

Tuff has been used as a natural building stone in the construction industry since the earliest times. Tuff is slight, simple to manufacture, and has good isolation qualities, which is why it is used so frequently despite its low strength characteristics and high porosity. In this study, samples of white and pink tuff from the regions of Derbent and Gümele districts of Eskisehir province were treated with a water-based (water-soluble) copolymer bath to evaluate their endurance to atmospheric conditions. Spherical samples were subjected to 30-minute slake durability index testing in a water-based copolymer bath. The index values of the initial spherical samples were contrasted with the index values from the fourth cycle of the spherical samples that had received the copolymer bath treatment. Although the index values of the original spherical samples were determined to be 92.22% and 95.32%, respectively, the index values of the spherical sample sets treated with a water-based copolymer bath were determined to be 98.29% and 98.83%, respectively. The study results indicate that spherical samples with a water-based copolymer bath treatment had a greater impact on improving the slake durability index values compared to spherical samples without treatment. [ABSTRACT FROM AUTHOR]

[Display omitted] • Progress and promises of predictive gas transport models for polymers are surveyed. • Agreement between experimental and predicted properties is highlighted. • Developments in handling the extensive polymer database is emphasized. • Advantages and challenges of models to identify novel structures are addressed. Membrane-based gas separation is a commercially practiced technology dominated by polymeric materials. Nevertheless, as established through the accumulation of large datasets of various polymers tested for decades, polymeric membranes suffer from an inherent permeability-selectivity trade-off. The natural culmination of such trade-off behavior has been the construction of chemical/molecular structure-transport property relationships, fueling an ongoing search for new and improved polymers. Yet, considering the time and financial costs of experimental research, it seems hard to fully harness the potential of polymer technology for developing membranes unless we switch towards data-driven prediction as a mainstream approach. Particularly the predictive models capable of estimating polymer permeation properties with high accuracy could propel the field. However, the data presence and accessibility issues hamper such a transition. Here, we provide a historical overview of the predictive models, highlighting the main incentive behind: Facilitating advanced membrane research by identifying chemical structures not studied or synthesized yet. To this end, we specifically focus on the gas transport properties of existing polymers and provide insights into their use and further development. Then, we discuss the establishment of predictive methods, which are mainly based on the representation of structural fragments constituting polymers, analysis of existing transport data, and estimation of increments for corresponding fragments. Within these predictive methods, the models based on the concept of additive contributions and machine learning approaches are particularly instrumental for handling extensive polymer databases. Still, since they complement the semi-empirical models, we also briefly touched upon non-equilibrium thermodynamics-based models for glassy polymers in our analysis. Overall, we address the advantages and challenges of using these models as a tool to identify novel polymer structures for designing high-performance membranes. We hope this review will help initiate new collaborations between membrane scientists/technologists and polymer informaticians. [ABSTRACT FROM AUTHOR]

Poly(N -isopropylacrylamide) (PNIPAM) is a highly versatile thermo-responsive hydrogel with immense potential for applications in biomedicine and tissue engineering. While PNIPAM has been extensively researched, there remains a significant gap in understanding its mechanical behavior at the atomistic scale. To address this challenge, this study employs molecular dynamics (MD) simulations to delve into the mechanical response of cross-linked PNIPAM hydrogels. The uniqueness of this research lies in our emphasis on providing atomic-level insights into the influence of chemical cross-linking and physical entanglements, as well as quantifying their effects during the application of strain. This represents a novel contribution to the study of hydrogels. MD simulations enable us to scrutinize the behavior of individual polymer chains and their intricate interactions in unprecedented detail, shedding light on microscale phenomena that are often inaccessible through experiments alone. To tackle the complexities associated with atomistic simulations of cross-linked hydrogels, we introduce a dynamic cross-linking algorithm. This innovative approach incorporates a nonreactive force field to construct realistic three-dimensional hydrogel microstructures, employing a stepwise bond formation strategy. Our findings underscore the remarkable impact of increasing the Degree of Cross-linking (DoC) and/or the Degree of Polymerization (DoP) on enhancing the robustness and elastic modulus of PNIPAM hydrogels. Additionally, we uncover the stochastic nature of chemical cross-linking, leading to the formation of anisotropic super-fragments when DoC exceeds a critical threshold. Furthermore, this research highlights the pivotal role of low strain rates on the order of 106 s−1 in accurately modeling the mechanical properties of hydrogels using MD simulations. This approach enables us to obtain meaningful quantitative mechanical properties that align with experimental results reported in the existing literature. In summary, this paper offers an unprecedented level of insight into the intricate interplay of chemical cross-linking and physical entanglements, providing a foundation for future research in this domain. [Display omitted] • Presented a dynamic crosslinking algorithm for MD simulations of hydrogels and polymers. • Explored the effect of chain length and cross-linking on mechanical properties of PNIPAM. • Identified the role of fragmentation on mechanics of PNIPAM hydrogel. • Quantified chain entanglements in cross-linked hydrogel during application of strain. • Clarified the crucial role of low strain rates in MD mechanical tests on polymers. [ABSTRACT FROM AUTHOR]

Digital image correlation (DIC) techniques have been widely used for experimentally characterizing the mechanical behavior of polymer materials. However, practical applications of DIC for tensile testing of polymers often face serious image decorrelation caused by crazing and excessive deformation. In this work, a fluorescent three-dimensional digital image correlation (3D-DIC) with an adaptive incremental calculation strategy is proposed to realize reliable large deformation measurement of polymers by eliminating or mitigating the image decorrelation caused by these issues. The proposed technique first utilizes fluorescent 3D-DIC to eliminate image decorrelation caused by the crazing effect. Then, an adaptive incremental calculation strategy that can automatically update reference images is adopted to mitigate image decorrelation due to excessive deformation. The effectiveness and practicality of the proposed technique were demonstrated by measuring the full-field deformation in chloroprene rubber samples subjected to large tensile deformation. Also, the proposed method was applied to investigate the mechanical behavior of a specific waterproof coating material. Experimental results indicate that the combination of fluorescent 3D-DIC and adaptive incremental calculation strategy can effectively address image decorrelation problems in large deformations of polymers, yielding high-accuracy displacement and strain measurements. This technique holds potential for broader applications in studying the mechanical behavior of other materials or structures undergoing large or super-large deformations. • Propose a fluorescent 3D-DIC with an adaptive incremental calculation strategy to measure large deformations in polymers. • Fluorescent stereovision imaging effectively avoids decorrelation problem caused by "crazing" in strained polymers. • Adaptive incremental calculation strategy mitigates image decorrelation problem caused by large deformation. [ABSTRACT FROM AUTHOR]

• Highest nanoindentation strain rate reported on a polymer: 103 s−1. • Nanoindentation and micropillar compression of SU-8 polymer from 10-3 to 103 s−1. • Novel nanoindentation protocol to obtain reliable modulus and hardness at 103 s−1. • High strain rate properties of SU-8 reported for first time. In situ micropillar compression and nanoindentation were performed on photolithographically fabricated SU-8 polymer inside a scanning electron microscope (SEM), covering seven orders of strain rates from 10-3 to 103 s−1. The extracted mechanical properties – modulus, hardness, yield strength, strain rate sensitivity (SRS) exponent – were systematically compared from both microscale tests and showed excellent agreement. No change in deformation mechanism was observed at high strain rates. We report a novel experimental protocol for high strain rate nanoindentation, comprising of input profile smoothing, that minimizes resonance amplitude during unloading and allows reliable extraction of modulus and hardness using standard Oliver-Pharr analysis. To the best of our knowledge, this is the first report of mechanical properties of SU-8 beyond 1 s−1 strain rate using nanoindentation based tests. [ABSTRACT FROM AUTHOR]