Advanced Industrial and Engineering Polymer Research最新文献

In the present study, we investigated the possibility of value-added recycling of ultrafine ground tire rubber (uGTR) produced from water jet milling, with an average particle size of a few tens of microns. Our goal was to compare the properties of blends with different uGTR and conventional fine ground tire rubber (fGTR) contents prepared by blending with low-density polyethylene (LDPE). We also aimed to explore the property changes caused by the larger specific surface area due to the size effect. Samples were prepared with a hydraulic press after internal mixing. In the case of ground tire rubber (GTR) filled mixtures, the tensile properties showed rubber-like characteristics: with a significant decrease in modulus, elongation at break remained high, and tensile strength slightly decreased. The fracture surfaces of the samples were analyzed by scanning electron microscopy (SEM), wherein the case of materials made with uGTR showed better adhesion between the phases. In order to investigate the interfacial adhesion between the GTR and LDPE, we performed dynamic mechanical thermal analysis (DMTA). The glass transition peak of the uGTR shifted to a higher temperature and the storage modulus was higher than in the case of samples containing fGTR. Finally, we determined the Shore D hardness of the materials, which decreased with increasing GTR content, but hardness was greater in the case of uGTR samples. The better mechanical properties of blends containing uGTR were explained by better interfacial adhesion between the two phases due to the significantly higher specific surface area compared to fGTR.

Sulfobetainic polymers were synthesized by polymeranalogous reaction of new amino celluloses starting from cellulose tosylate. To obtain different amino celluloses as starting building blocks, a comprehensive study with a selection of asymmetric and symmetric N-alkylated diamines was performed. For reaction with asymmetric diamines, it turned out that the primary amino moiety reacts preferably. Derivatives thus obtained consist in a neutral main structural unit and a cationic side structural unit, which is not described up to now. In order to investigate the reactivity of the amino celluloses 6-deoxy-6-(N,N,N′,N′-tetramethylethylenediamino) cellulose was used as uniform starting material for the design of novel polyampholytes by conversion with 1,3-propansultone. Detailed structure characterization was implemented by means of 1D and 2D-NMR spectroscopy.

Laser sintering of polymers (LS) is one of the most promising additive manufacturing technologies as it allows for the fabrication of complexly structured parts with high mechanical properties without requiring additional supporting structures. Semi-crystalline thermoplastics, which are preferably used in LS, need to be processed within a certain surface temperature range enabling the simultaneous presence of the material in both, the molten and solid state. In accordance with the most common processing models, these high temperatures are held throughout the entire building phase. In the state of the art, this leads to high cooling times and delayed component availability.

In this paper, process-adapted methods, in-situ experiments and numerical simulations were carried out in order to prove that this drawback can be overcome by material-adapted processing strategies based on a deepened model understanding. These strategies base on the fact, that the crystallization and solidification of polyamide 12 is initiated a few layers below the powder bed surface at high temperature and quasi-isothermic processing conditions. Therefore, isothermal crystallization and consolidation behaviour is analyzed by process-adapted material characterization. The influence of temperature fields during laser processing was analyzed in dependence of part cross-section, layer number and fabrication parameters and correlated to the resulting part properties. Furthermore, the possibility to homogenize the parts thermal history by controlling the part cooling is highlighted by a simulational approach. The authors show that the material-dependent solidification behavior must be taken into account as a function of the geometry- and layer-dependent temperature fields and demonstrate a major influence on the material and component properties. From these findings, new processing strategies for the laser exposure process as well as for the temperature control of the build chamber in z-direction arise, which allow for the acceleration of the LS process and earlier availability of components with more uniform part properties.

For many years, 3D Printing technologies have created significant advancements in the fields of engineering and healthcare. 4D printing is also introduced, which is the advanced version of 3D printing. The process of 4D printing is when a printed 3D object becomes another structure due to the influence of outside energy inputs such as temperature, light, or other environmental stimuli. This technology uses the input of smart materials, which have the excellent capability of shape-changing. The self-assembly and programmable material technology aim to reimagine building, production, assembly of products, and performance. 4D printing is applied in various sectors such as engineering, medicine, and others. 4D printed proteins could be a great application. With this new dimension, 3D printed objects can change their shape by themselves over the influence of external stimuli, such as light, heat, electricity, magnetic field, etc. This paper discussed a brief about 4D printing technology. Various characteristics of 4D Printing for enhancing the manufacturing domain, its development, and applications are discussed diagrammatically. Conceptualised the Work Process Flow for 4D Additive Manufacturing and finally identified ten major roles of 4D printing in the manufacturing field. Although reversible 4D Printing itself is a fantastic development, it is innovative, and it employs durable and accurate reversal material during the shapeshift. It helps us create complicated structures that cannot be accomplished easily by traditional manufacturing technologies. It seems to be a game-changer in different industries by depending on natural factors instead of energy and changes the way to produce, develop, bundle, and ship goods entirely.

Continuous lattice fabrication is a newly introduced method for additive manufacturing of fiber-reinforced thermoplastic composites that allows to deposit material where it is needed. The success of this technology lies in a printing head in which unconsolidated continuous fiber-reinforced composite is pulled through a pultrusion die before the material is extruded and deposited out of plane without the use of supporting structures. However, state-of-the-art composite feedstock like commingled yarns shows limits in achievable material quality and part dimensions due to the underlying fiber architecture where thermoplastic fibers are mingled with reinforcement filaments. Hybrid bicomponent fibers overcome these constraints because each individual reinforcement filament is clad in a thermoplastic sheath. This results in absence of time-consuming fiber impregnation steps that would negatively effect void content and material quality.

This study compares the material quality of pultrudates made from hybrid bicomponent fibers to that of commercially available commingled yarns at various processing conditions. Experiments are reported in which polycarbonate composite profiles with a diameter of 5 mm containing 50 vol% to 60 vol% E-glass fibers are pultruded at different die filling degrees, mold temperatures and pultrusion speeds. The results show that the pultrudates obtained from hybrid bicomponent fibers have lower void content than those manufactured under the same conditions from commingled yarns. We assess this to be caused by the difference in consolidation mechanism which in the case of the hybrid bicomponent fibers is dominated by coalescing of the thermoplastic sheaths compared to the Darcian flow-dominated consolidation of commingled yarns.

Ultra-high molecular weight polyethylene (UHMWPE) possesses distinctive properties, but has an extremely low melt flow rate (MFR) of about zero, which makes it unsuitable for processing by standard methods for polymers. The aim of this paper was to investigate the tribological properties of two-component UHMWPE-based composites with different content of isotactic PP. The composites were fabricated by three methods: a) hot pressing of the powder mixtures; b) hot compression of granules; and c) 3D printing (FDM). It was shown that the UHMWPE-based composites obtained by extrusion compounding (hot compression of granules and 3D printing) in terms of the mechanical and tribological properties (wear resistance, the friction coefficient, Young's modulus, and yield strength) were superior to the ones manufactured by hot pressing of the powder mixtures. The most effective was the ‘UHMWPE+20% PP’ composite in terms of maintaining high tribological and mechanical properties and the necessary melt flow rate (MFR) in a wide range of loads. It was recommended as a feedstock for additive manufacturing of complex-shaped products (joint components) for friction units in orthopedics.

Laser sintering is a commonly used Additive Manufacturing (AM) technique applicable to a variety of applications in fields such as the automotive industry, healthcare, and consumer goods. As well as offering mechanical properties suitable for end-use part production, polymer laser sintering can produce more complex structures than many other AM techniques since it does not require support structures, and parts can be stacked in the build area for more efficient processing. A wide range of polymers should theoretically be processable by laser sintering. However, in practice this is not the case, with only a small number of polymers currently able to be processed reliably and consistently. This paper reviews research that has been undertaken to increase the processability, mechanical properties and functionality of laser sintering polymers through the addition of a range of organic and inorganic nanofillers. It examines key challenges, including dispersion of the nanophase, and methods that have been developed to overcome them. The effects of the nanophase on processability are explored, as well as the importance of key processing parameters. The latest developments on techniques for production of nanocomposite powders and characterisation of parts are discussed. The final properties of laser sintered parts that have been achieved and their potential applications are highlighted, and the current challenges and potential directions for future research are discussed.

Locally bendable solid plates were manufactured in a single 3D-printing operation, using a single material, i.e., short carbon fiber reinforced plastic (CFRP). The locally bendable CFRP plates included solid and bendable parts, which were connected seamlessly using double-stepped lap configuration. A parallel cross shape structure and 100% infill structure was adopted for the bendable and solid parts, respectively. The bendability could be controlled by varying the girder angle of the parallel cross shape structure. The bending stiffness was reduced to nearly 98% compared to that of the solid plate. The cyclic bending tests indicated that the locally bendable CFRP plate underwent reversible bending deformation. The bending stiffness decreased by approximately 8–14%. However, visible damage was not observed even after 100 cycles of bending deformation.

Additive manufacturing (AM) produces a complex shaped product from its data, layer by layer, with high precision and much less material wastage. As compared to the conventional manufacturing process, there are many positive environmental advantages of additive manufacturing technologies. Most importantly, there is less waste of raw material and the use of new and smart materials. It appears to concentrate on the output of a component on lesser material waste, energy usage, and machine emissions. There is a need to study the environmental sustainability of additive manufacturing technologies and their applications. As more businesses aim to strengthen their eco-footprint, sustainability in AM is gaining momentum. Visionary leaders of the industry are continually challenging their employees to find new ways to reduce waste, improving their workforce's manufacturing environment, and find innovative ways to use new materials to become more sustainable. The growth in value-added components, goods, and services has resulted from these initiatives. This paper discusses the significant benefit of additive manufacturing to create a sustainable production system. Finally, the paper identifies twelve major applications of AM for sustainability. Although additive manufacturing and technological dominance are being established with crucial industries, their sustainability advantages are visible in the current manufacturing scenario. The main goal is to identify the environmental benefits of additive manufacturing technologies over conventional manufacturing. Industries can now decide on suitable technologies to meet environmental goals.