Hasil untuk "Polymers and polymer manufacture"

Abhishek P. Dhand, M. D. Davidson, Hannah M. Zlotnick et al.

Incorporation of polymer chain entanglements within a single network can synergistically improve stiffness and toughness, yet attaining such dense entanglements through vat photopolymerization additive manufacturing [e.g., digital light processing (DLP)] remains elusive. We report a facile strategy that combines light and dark polymerization to allow constituent polymer chains to densely entangle as they form within printed structures. This generalizable approach reaches high monomer conversion at room temperature without the need for additional stimuli, such as light or heat after printing, and enables additive manufacturing of highly entangled hydrogels and elastomers that exhibit fourfold- to sevenfold-higher extension energies in comparison to that of traditional DLP. We used this method to print high-resolution and multimaterial structures with features such as spatially programmed adhesion to wet tissues. Editor’s summary When three-dimensional (3D) printing polymers, there is a trade-off between fast hardening, which ensures the strength and fidelity of the printed shape, and a slower reaction rate, which allows for more downstream processing but may not be compatible with some printing methods such as vat polymerization. Dhand et al. designed monomers that can be partially reacted using fast photo-initiated polymerization followed by a slow, redox initiated process, thus forming long polymer chains with dense entanglements. The key to the process is to keep the content of the initiators at a low level. The method enables the printing of objects with functional monomers, complex shapes, and multiple materials. —Marc S. Lavine

Bhuvaneshwaran Mylsamy, Senthil Kumar Marudhamuthu Shanmugam, Karthik Aruchamy et al.

High performance and durability are essential for goods to satisfy the needs of the expanding worldwide market. Wood plastic composites (WPCs) are materials made from a combination of wood, polymers, and additives. WPCs can be extruded, injected, compressed, or thermoformed. Presently, WPCs are manufactured using sophisticated processes including as laser sintering, fused layer modeling, and additive manufacturing. Properly managing the melt temperature and pressure is crucial in the manufacturing process of WPCs to ensure effective polymer incorporation. Natural fibers have distinct benefits for polymer composites, but they also have some serious drawbacks, like lower strength properties—especially lower impact strength than synthetic fibers—poor compatibility with hydrophobic polymers, poorer dimensional stability and moisture absorption due to hydroxly groups, a maximum processing temperature that is limited, thermal degradation above 200–220°C, and lower biological durability. The modification of the surface of the fibers improves the mentioned disadvantages of the natural fibers. High‐quality WPCs require the application of chemical or physical treatment to the wood fibers. This extensive review focused on the modification techniques applied to the surface of wood, manufacturing processes, and properties and applications of WPCs. Modification methods used in surface treatment of natural fibers was explained. Properties and recent applications of wood polymer composites were given. Optimum requirements of natural fibers and polymer matrices are given. Fabrication methods of natural fiber composites are extensively given.

Ruslan Melentiev, A. Yudhanto, R. Tao et al.

: Polymers and their composites are widely used for designing structures in aerospace, automotive, electronic, sport industries due to their lightweight, cost, and processing advantages. However, the surface of polymeric materials typically exhibits intrinsic deficiencies, limiting their durability and functionalities, e.g., low wear resistance, low thermal and electrical conductivity, low adhesion, low bioactivity, low reflectiveness, and weak photochemical resistance. Polymer metallization is an emerging concept that addresses these deficiencies by forming a metallic skin on polymeric surfaces. Herein, the working principles, recent advances, challenges, functional capabilities, and applications of the state-of-the-art polymer metallization methods in the fields of additive manufacturing, coating technologies, and material science are reviewed on nano-, micro-, and macroscales. The polymer metallization methods applied to polymeric and polymer composite substrates are physical vapor deposition, electrochemical plating, a family of thermal spray methods (such as flame spaying, arc spraying, plasma spraying, and cold spraying), and a series of polymer–metal direct bonding methods (such as adhesive bonding, injection overmolding, and fusion joining techniques, including ultrasonic joining, friction spot joining, electromagnetic induction joining, and laser joining). Understanding the key aspects within these approaches would guide scientist and engineers for optimizing the design and durability of structural materials made of polymers/composites.

G. D. Goh, K. Wong, N. Tan et al.

ABSTRACT Large-format 3D printing for polymers enables cost-effective mass customisation and production of structurally robust, large-scale components for industries like aerospace and automotive. This review analyses additive manufacturing scalability, including throughput, volume, and essential criteria for 3D printing techniques. Challenges in large-scale polymer additive manufacturing are explored, including material selection, interlayer bonding, surface quality versus production speed, recyclability of materials, and post-processing. Materials development is found to be crucial for addressing thermal shrinkage issues, with solutions involving process control and fibre reinforcement while considering rheological properties and nozzle clogging. Balancing production speed and surface finishing in material extrusion 3D printing involves factors like print speed, nozzle size, and innovative designs to optimise throughput and surface quality. In large-format 3D printing, meticulous process control and quality assurance are vital to ensure the expected printing outcomes and defect-free parts, given the substantial material and energy investment.

Nima Zohdi, R. Yang

Additive manufacturing (AM) is a sustainable and innovative manufacturing technology to fabricate products with specific properties and complex shapes for additive manufacturable materials including polymers, steels, titanium, copper, ceramics, composites, etc. This technology can well facilitate consumer needs on products with complex geometry and shape, high strength and lightweight. It is sustainable with having a layer-by-layer manufacturing process contrary to the traditional material removal technology—subtractive manufacturing. However, there are still challenges on the AM technologies, which created barriers for their further applications in engineering fields. For example, materials properties including mechanical, electrical, and thermal properties of the additively manufactured products are greatly affected by using different ways of AM methods and it was found as the material anisotropy phenomenon. In this study, a detailed literature review is conducted to investigate research work conducted on the material anisotropy phenomenon of additively manufactured materials. Based on research findings on material anisotropy phenomenon reported in the literature, this review paper aims to understand the nature of this phenomenon, address main factors and parameters influencing its severity on thermal, electrical and mechanical properties of 3D printed parts, and also, explore potential methods to minimise or mitigate this unwanted anisotropy. The outcomes of this study would be able to shed a light on improving additive manufacturing technologies and material properties of additively manufactured materials.

Stoyko Fakirov

The reason that the predicted mechanical properties of polymer nanocomposites often don't match what is observed in materials made by blending the matrix and reinforcement is primarily because the nano-sized material is not spread out well enough. Achieving good dispersion in polymer nanocomposites faces fundamental thermodynamic hurdles. Because of this, it is best to skip the dispersion step entirely when manufacturing these materials. New techniques for making genuine polymer nanocomposites without dispersion operate on the principle of “creating instead of adding.” This method entails commencing the manufacturing process with one component while producing the second component concurrently. The cold drawing process of a polymer blend transforms the minor component into uniformly dispersed nanofibrils, yielding a nanofibrillar polymer-polymer composite as the final material. The selective extraction of the matrix component from the cold drawn blend leads to the formation of neat nanofibrils. Post-compression molding, these nanofibrils are converted into nanofibrillar single polymer composites. Both categories are classified as genuine nanocomposites. To significantly boost the mechanical strength of polymer nanocomposites potentially increasing tensile strength and modulus by 300–400 %, or even up to ten times more than with older techniques two main elements are crucial: bypassing the dispersion step and ensuring the nano-sized reinforcement is optimally distributed throughout the polymer.

Vani Nigam, Achuth Chandrasekhar, Amir Barati Farimani

On-demand Polymer discovery is essential for various industries, ranging from biomedical to reinforcement materials. Experiments with polymers have a long trial-and-error process, leading to use of extensive resources. For these processes, machine learning has accelerated scientific discovery at the property prediction and latent space search fronts. However, laboratory researchers cannot readily access codes and these models to extract individual structures and properties due to infrastructure limitations. We present a closed-loop polymer structure-property predictor integrated in a terminal for early-stage polymer discovery. The framework is powered by LLM reasoning to provide users with property prediction, property-guided polymer structure generation, and structure modification capabilities. The SMILES sequences are guided by the synthetic accessibility score and the synthetic complexity score (SC Score) to ensure that polymer generation is as close as possible to synthetically accessible monomer-level structures. This framework addresses the challenge of generating novel polymer structures for laboratory researchers, thereby providing computational insights into polymer research.

Aref Yarahmadi, Behrooz Dousti, Mahdi Karami-Khorramabadi et al.

Increased mass manufacturing and the pervasive use of plastics in many facets of daily life have had detrimental effects on the environment. As a result, these worries heighten the possibility of climate change due to the carbon dioxide emissions from burning conventional, non-biodegradable polymers. Accordingly, biodegradable gelatin and chitosan polymers are being created as a sustainable substitute for non-biodegradable polymeric materials in various applications. Chitosan is the only naturally occurring cationic alkaline polysaccharide, a well-known edible polymer derived from chitin. The biological activities of chitosan, such as its antioxidant, anticancer, and antimicrobial qualities, have recently piqued the interest of researchers. Similarly, gelatin is a naturally occurring polymer derived from the hydrolytic breakdown of collagen protein and offers various medicinal advantages owing to its unique amino acid composition. In this review, we present an overview of recent studies focusing on applying chitosan and gelatin polymers in various fields. These include using gelatin and chitosan as food packaging, antioxidants and antimicrobial properties, properties encapsulating biologically active substances, tissue engineering, microencapsulation technology, water treatment, and drug delivery. This review emphasizes the significance of investigating sustainable options for non-biodegradable plastics. It showcases the diverse uses of gelatin and chitosan polymers in tackling environmental issues and driving progress across different industries.

Kirstie R. Ryan, M. Down, Nicholas J. Hurst et al.

Samiullah Khan, Abdur Rehman, Syed Faisal Badshah et al.

Ibuprofen sodium (IBP) is a commonly used NSAID for multiple pain conditions. However, despite its extensive use, it is associated with multiple GIT adverse effects after oral administration. In the present study, we have fabricated thermoresponsive gel depot using Poly (N-vinylcaprolactam) and sodium alginate as polymers. The designed formulations are intended to be used as IBP depot after being administered subcutaneously. The sol-gel phase transition temperature and gelation time of gel samples were optimized by tube inversion, rheological exploration and optical transmittances. Temperature sweep experiments confirmed that optimized gel samples have sol-gel transition between 32°C and 37°C. Swelling and in vitro drug release displayed that optimized gels have maximum swelling and IBP release at pH 7.4 and at 35°C confirming their pH/thermo sensitivity. The degradation profile of hydrogels displayed controlled degradation for 6 days that with increasing contents. MTT assay showed L929 cells displayed more than 90% cell viability against blank and IBP-loaded PNVCL/NaAlg hydrogels at optimized concentrations. Fourier transform infrared spectroscopy confirmed the polymer blend hydrogels structure formation. Thermogravimetric analysis confirmed the presence of thermoresponsive moieties and thermal stability of polymer blend hydrogel sample. While scanning electron microscopy showed that hydrogel has channels in structure that might facilitate the diffusion of solvent. Results concluded that PNVCL/NaAlg hydrogels can be utilized as IBP sustained depot following subcutaneous application invivo and GIT adverse effects could be avoided associated with its oral administration.

Markus Schmidt, Günter Seyfried, Uliana Reutina et al.

This study investigates whether it is possible to simulate quantum entanglement with theoretical memristor models, physical memristors (from Knowm Inc.) and slime molds Physarum polycephalum as bioelectric components. While the simulation with theoretical memristor models has been demonstrated in the literature, real-world experiments with electric and bioelectric components had not been done so far. Our analysis focused on identifying hysteresis curves in the voltage-current (I-V) relationship, a characteristic signature of memristive devices. Although the physical memristor produced I-V diagrams that resembled more or less hysteresis curves, the small parasitic capacitance introduced significant problems for the planned entanglement simulation. In case of the slime molds, and unlike what was reported in the literature, the I-V diagrams did not produce a memristive behavior and thus could not be used to simulate quantum entanglement. Finally, we designed replacement circuits for the slime mold and suggested alternative uses of this bioelectric component.

Jiaxi Wang, Yaosen Min, Xun Zhu et al.

Polymers, composed of repeating structural units called monomers, are fundamental materials in daily life and industry. Accurate property prediction for polymers is essential for their design, development, and application. However, existing modeling approaches, which typically represent polymers by the constituent monomers, struggle to capture the whole properties of polymer, since the properties change during the polymerization process. In this study, we propose a Multimodal Infinite Polymer Sequence (MIPS) pre-training framework, which represents polymers as infinite sequences of monomers and integrates both topological and spatial information for comprehensive modeling. From the topological perspective, we generalize message passing mechanism (MPM) and graph attention mechanism (GAM) to infinite polymer sequences. For MPM, we demonstrate that applying MPM to infinite polymer sequences is equivalent to applying MPM on the induced star-linking graph of monomers. For GAM, we propose to further replace global graph attention with localized graph attention (LGA). Moreover, we show the robustness of the "star linking" strategy through Repeat and Shift Invariance Test (RSIT). Despite its robustness, "star linking" strategy exhibits limitations when monomer side chains contain ring structures, a common characteristic of polymers, as it fails the Weisfeiler-Lehman~(WL) test. To overcome this issue, we propose backbone embedding to enhance the capability of MPM and LGA on infinite polymer sequences. From the spatial perspective, we extract 3D descriptors of repeating monomers to capture spatial information. Finally, we design a cross-modal fusion mechanism to unify the topological and spatial information. Experimental validation across eight diverse polymer property prediction tasks reveals that MIPS achieves state-of-the-art performance.

Ilhan Aziz, Younes Chahid, Jennifer Keogh et al.

Additive manufacturing (AM; 3D Printing), a process which creates a part layer-by-layer, has the potential to improve upon conventional lightweight mirror manufacturing techniques, including subtractive (milling), formative (casting) and fabricative (bonding) manufacturing. Increased mass reduction whilst maintaining mechanical performance can be achieved through the creation of intricate lattice geometries, which are impossible to manufacture conventionally. Further, part consolidation can be introduced to reduce the number of interfaces and thereby points of failure. AM design optimisation using computational tools has been extensively covered in existing literature. However, additional research, specifically evaluation of the optical surface, is required to qualify these results before these advantages can be realised. This paper outlines the development & metrology of an AM mirror for a CubeSat platform with a targeted mass reduction of 60% compared to an equivalent solid body. This project aims to incorporate recent developments in AM mirror design, with a focus on manufacture, testing & evaluation. This is achieved through a simplified design process of a Cassegrain telescope primary mirror mounted within a 3U CubeSat chassis. The mirror geometry is annular with an external diameter of 84 mm and an internal diameter of 32 mm; the optical prescription is flat for ease of manufacture. Prototypes were printed in AlSi10Mg, a low-cost aluminium alloy commonly used in metal additive manufacturing. They were then machined and single-point diamond turned to achieve a reflective surface. Both quantitative & qualitative evaluations of the optical surface were conducted to assess the effect of hot isostatic pressing (HIP) on the optical surface quality. The results indicated that HIP reduced surface porosity; however, it also increased surface roughness and, consequently, optical scatter.

Sanghyeon Park, Yuseung Hong, Hyunseo Choi

The use of chemical warfare agents (CWAs) in modern warfare cannot be disregarded due to their ease of use and potential for large-scale incapacitation. An effective countermeasure involves the physical adsorption of these agents, preventing their entry through the respiratory tract by non-specific adsorption. In this study, we investigate the physical interaction between potential adsorbents and model gases mimicking CWAs, thereby identifying sufficient conditions for higher physical adsorption performance. Our findings reveal that the physical adsorption capacity is highly sensitive to the surface properties of the adsorbents, with uniform development of micropores, rather than solely high surface area, emerging as a critical factor. Additionally, we identified the potential of porous organic polymers as promising alternatives to conventional activated carbon-based adsorbents. Through a facile introduction of polar sulfone functional groups on the polymer surface, we demonstrated that these polar surface polymers exhibit physical adsorption capabilities for formaldehyde under ambient conditions comparable to high-performance activated carbons. Notably, the superior activated carbon possessed a high BET surface area of 2400 m^2/g and an exceptionally uniform micropore structure with an average pore size of approximately 11 Angstroms. This research paves the way for designing adsorbents with high physical adsorption capacities tailored for CWAs protection, offering a significant advancement in developing next-generation protective materials.

S. Nowfal, Vijaya Bhaskar Sadu, Sudhakar Sengab et al.

Sustainable Manufacturing Practices (SMP), particularly in the selection of materials, have become essential due to environmental issues caused by the expansion of industry. Compared to conventional polymers, biodegradable Polymer Materials (BPM) are growing more commonly as an approach to reducing trash pollution. Suitable materials can be challenging due to numerous considerations, like ecological impact, expenditure, and material properties. When addressing sophisticated trade-offs, standard approaches drop. To compete with such challenges, employing Genetic Algorithms (GA) may be more successful, as they have their foundation in the basic concepts of biological development and the natural selection process. With a focus on BPM, this study provides a GA model for optimal packaging substance selection. Out of the four algorithms for computation used for practical testing—PSO, ACO, and SA—the GA model is the most effective. The findings demonstrate that GA can be used to enhance SMP and performs well in enormous search spaces that contain numerous different combinations of materials.

Sundarakannan Rajendran, Geetha Palani, Arunprasath Kanakaraj et al.

This review examines the mechanical performance of metal- and polymer-based composites fabricated using additive manufacturing (AM) techniques. Composite materials have significantly influenced various industries due to their exceptional reliability and effectiveness. As technology advances, new types of composite reinforcements, such as novel chemical-based and bio-based, and new fabrication techniques are utilized to develop high-performance composite materials. AM, a widely popular concept poised to shape the development of Industry 4.0, is also being utilized in the production of composite materials. Comparing AM-based manufacturing processes to traditional methods reveals significant variations in the performance of the resulting composites. The primary objective of this review is to offer a comprehensive understanding of metal- and polymer-based composites and their applications in diverse fields. Further on this review delves into the intricate details of metal- and polymer-based composites, shedding light on their mechanical performance and exploring the various industries and sectors where they find utility.

Reema H. Alasfar, S. Ahzi, N. Barth et al.

Porous polymer-based nanocomposites have been used for various applications due to their advantages, including multi-functionalities, easy and known manufacturability, and low cost. Understanding of their mechanical properties has become essential to expand the nanocomposites’ applications and efficiency, including service-life, resistance to different loads, and reliability. In this review paper, the focus is on the modeling of the mechanical properties of porous polymer-based nanocomposites, including the effects of loading rates, operational temperatures, and the material’s porosity. First, modeling of the elastic modulus and yield stress for glassy polymers and polymer reinforced by nanofillers are addressed. Then, modeling of porosity effects on these properties for polymers are reviewed, especially via the use of the well-known power-law approach linking porosity to elastic modulus and/or stress. Studies related to extending the mechanical modeling to account for porosity effects on the elastic modulus and yield stress of polymers and polymer-nanocomposites are discussed. Finally, a brief review of the implementation of this modeling into 3D computational methods to predict the large elastic-viscoplastic deformation response of glassy polymers is presented. In addition to the modeling part, the experimental techniques to measure the elastic modulus and the yield stress are discussed, and applications of polymers and polymer composites as membranes for water treatment and scaffolds for bone tissue engineering are addressed. Some modeling results and validation from different studies are presented as well.

Abdullah Al Noman, Balaji Krishna Kumar, Tarik J. Dickens

ABSTRACT Additive manufacturing (AM) has emerged as a transformative technology capable of fabricating complex geometries and multi-material structures across various industries. Despite its potential, challenges persist in terms of limited material selection, anisotropic properties, and achieving functional microstructures in polymer and metal composites. Field-assisted additive manufacturing (FAAM) employs external fields like acoustic, magnetic, and electric fields. It has shown promise in addressing these limitations by controlling filler orientation and concentration in polymeric composites and improving surface finish and microstructure in metals. This review paper provides a comprehensive analysis of the state-of-the-art FAAM processes for polymer and metal composites, focusing on material compatibility, the mechanics of each field, and their integration with AM technologies as well as current applications, limitations, and potential future directions in the development of FAAM processes. Enhancing FAAM process understanding can create tailored anisotropic composites, enabling innovative applications in aerospace, automotive, biomedical fields, and beyond.

Sebastián Coba-Daza, Itziar Otaegi, Nora Aramburu et al.

The increasing global plastic production has created an urgent demand for energy-efficient processes to transform mixed plastic waste into value-added products via upcycling. Compatibilization of polypropylene (PP) and poly(ethylene terephthalate) (PET), two used semi-crystalline polymers in industry, is investigated in this study. We evaluate the effectiveness of an ethylene-butylene-acrylate terpolymer (PTW) at different contents in a 70/30 PP/PET blend, examining the resulting physico-chemical characteristics. Adding PTW as compatibilizer significantly reduces the droplet size in the PP/PET blend, improving rheological and mechanical properties. Remarkably, the blend containing 1.5 % PTW exhibits maximum enhancement in mechanical properties. To understand deeply the chemical compatibilization mechanism, Fourier transform infrared spectroscopy (FTIR-ATR), Atomic Force Microscopy combined with infrared spectroscopy (AFM-IR), and Proton Nuclear Magnetic Resonance Spectroscopy (1H NMR) techniques were employed. The compatibilizer was located at the interphase, and the chemical reaction using AFM-IR and 1H NMR was tracked. These advanced techniques prove the chemical compatibilization mechanism in PP/PET blends with PTW. These findings contribute to understanding the compatibilization processes, offering valuable guidance for developing efficient upcycling processes for mixed plastic waste.

Chirag Miglani, Jahanvi Ralhan, Maqsuma Banoo et al.