Advanced Industrial and Engineering Polymer Research最新文献

The increasing motorisation rate worldwide is responsible for the demand of huge quantities of tyres that, after their useful service life, become waste and should be properly managed. Due to the relative low cost of tyres and the complexity related to recycling, worldwide around 41% of the total amount of end-of-life tyres is discarded into landfills or stockpiles without any recovery of the material or of the energy. Moreover, the chemical composition of tyres makes them extremely resistant to degradation phenomena with a potential long-term permanence in the environment. The high energy amount required for the production of tyres and the related environmental impact should encourage the recycling of tyres and also promote the adoption of maintenance activities, such as retreading, that allow a considerable increase in the useful service life of tyres with consequent reduction in GHG emissions. In this article the relevant literature describing the current status of end-of-life options worldwide, the European legislation regarding tyre waste, their possible uses and the related environmental aspects are presented.

Waste tyres and their accumulation is a global environmental concern, as 1.5 billion of waste tyres are generated annually in the world. The products are not biodegradable and, if disposed of in landfills and stockpiles, are recognized for leaching toxic chemicals into the surrounding environment, acting as breeding grounds for mosquitoes, and fueling inextinguishable fires. The potential of using rubber from worn tyres in many civil engineering works has been studied for more than 30 years, and their application in construction materials comprises cementitious concrete, asphalts, and granulates for earth structures. Recycling of tyres in these field represents a suitable way of disposal for both environmental and economic reasons. Therefore, the aim of this review is to present the state of the art in tyre recycling in civil applications. In particular, the re-use of waste tyres in cement-based materials has been discussed, and then the recycling of waste tyres in bituminous mixtures and in geotechnical applications has been reviewed. This review is mainly focused on the physical properties of construction materials when recycled rubber is incorporated, trying to highlight the effects deriving from the interaction between rubber and these materials, and analyzing the proposed technological approaches from a material science perspective.

Collagen, crucial insoluble fibrous protein in connective tissue and extracellular matrix, plays an important role in the body structures of animals. It is most distinct for its triple helix structure. This triple helix structure can be dissolved with high temperature and enzymes. To seek out a possible solution for the stabilization of the triple-helix structure, a selective complex between a collagen model system and a macro cyclic crown ether was calculated using Spartan Student v8 Graphical User Interface, a computational molecular simulation program, to measure the energy difference. The complex reveals a lower energy than the sum of the energy of the initially separated collagen molecule and crown ether ring, indicating that the complex is more stabilized. The possible desired complex could be applied to surface materials with both a desired texture and durability.

This paper describes the effects of various alkali metal and alkaline earth metal compounds, as well as walnut shell ash (WNS ash), on the cure characteristics (ts₂, tc₉₀) of a chlorobutyl rubber (CIIR)-based heat resistance truck inner tube compound. We observed that CIIR-F (KOH) has a very high scorch safety and a very slow cure. As it is a strong base with a high pH (13.84), it cures very slowly. Despite having a pH of 10.6, a ts₂ of 6.36, and a tc₉₀ of 18.84 min, CIIR-D (CaCO₃) cures faster than CIIR-A (blank). The ts₂ and tc₉₀ values for CIIR-A (blank) were 6.55 and 18.88 min, respectively. Except for CIIR-D (CaCO₃), all of the materials used to have higher scorch safety (ts₂) and optimum cure time (tc₉₀) in rheometer than CIIR-A (blank). CIIR-C (BaCO₃) performed nearly as well as a blank. This study revealed that the trend of cure characteristics (ts₂, tc₉₀) in rheometer and Mooney scorch (t₅) in Mooney viscometer not only depends on pH but also depends on ionic radius, ionization enthalpy and oxidation number of alkali metal and alkaline earth metal and the type of compound of alkali metal and alkaline earth metal.

3D printing has evolved as a disruptive technology for fabrication of industrial components, however due to the intrinsic nature of the process, the mechanical strength of the parts developed by 3D printing is a subject of research. The economic and technical advantages offered by 3D printing makes it as a potential replacement for the conventional manufacturing processes, particularly for developing complex and optimized products. The current paper is structured to focus on the various processes of 3D printing used for the development of industrial products, the various process parameters involved in each process and their effect on the mechanical properties of these parts particularly fatigue, tensile, bending strength, etc. primarily focusing on polymeric materials. Further an important aspect of 3D printed parts i'e tribological properties have been highlighted. A systemic literature review related to these aspects has also been presented. A section highlights the various applications of these 3D printed parts particularly in medical, aerospace and automotive. A section also highlights the sustainability aspects of these 3D printed parts. The paper also highlights the possible future research areas, recommendations and challenges involved in developing 3D printed parts.

Polymer nanocomposite and its mechanical properties are the area of immense interest for material developers in academia and industry. Present study investigates mechanical behavior of novel hexagonal bipyramidal Silver-Poly (vinyl alcohol) nanocomposites (Ag/PVA NCs) thin film fabricated using aqua-mediated in-situ reduction at room temperature. Specimen was characterized through UV-Visible (λmax = 417 nm), PL (λ(em) = 482 nm), XRD (average crystallite size 29.7 nm and preferential growth of thin film along [111] plane), TEM (hexagonal bipyramidal morphology, size ∼26.25 nm), TGA (increased thermal stability), FTIR (peaks at 945, 604 cm^-1 confirms coordination of Ag and PVA matrix) and SAED. Depth sensing single-step and multi-step nanoindentation was employed to extract material’s sensitive mechanical property. Hardness (H: 0.352 to 0.192 GPa) and elastic modulus (Er: 8.718 to 6.72GPa) decreased with increasing single-step loads (from 50 μN to 10 mN), which can be attributed to indentation size effect (ISE). Cyclic nanoindentation (p∼5 mN, 23 cycles) was performed to deeply understand material sensitive degree of dislocation-structure interaction for fatigue analysis. The reduction in % elastic recovery was found at higher loads. On account of smooth surface, elastic unloading (stiffness) values linearly (y = 1.3944x + 3.8676 with R² = 0.9835) increased from cycle 1 to 23 and contact depth increases linearly (y = 0.0329x + 1.5697, R² = 0.9901) with the number of cycles. Interpretation of p-h profile indicated H and Er decreases with increasing load, along with proceeding cycles and no fracture or breakage/ weakening of NCs / progressive and localized structural damage was observed which evidenced that surface was completely uniform and defect free.

The purpose of this paper is to highlight the importance of the effective utilisation of internet-based technologies in Additive Manufacturing (AM) through its practical implications in various areas. The key technologies that comprise the Industry 4.0 paradigm and have been previously implemented into the AM process possess immense potential to bring about miraculous manufacturing changes. The ongoing pandemic situation, too, has pushed the industries into the deployment of advanced technologies to deal effectively with the major challenges that followed COVID-19 and to keep up with customers' expectations. Therefore, manufacturing industries need to adopt the latest internet-based technologies into AM, especially for lean and optimised manufacturing and perceived proficiency of advanced printing technologies. This paper identifies goals of sustainable manufacturing that can be accomplished as a result of implementation of Internet of Things (IoT) in 3D printing technology. Also, since the Internet of Things-enabled AM process is an entirely new concept, limited sources are available in this field. Pubmed, Scopus, and Google Scholar databases are used to conduct literature reviews. The study conducted is the most up-to-date information on Internet of Things-enabled AM and is rigorously analyzed to identify prospective application areas. Thus, IoT-enabled AM helps in producing sustainable solutions for humanity and in meeting customers' demands in the stipulated period, thereby contributing to mass personalisation, which is the ultimate goal of Industry 4.0.

In this work, multiwalled carbon nanotubes (MWNTs) are dispersed in 70/30 (wt/wt) polycarbonate (PC)/acrylonitrile butadiene styrene (ABS) (PC70ABS30) blends and their nanocomposites by the melt-processing method. The morphology observations suggest the development of matrix-droplet morphology. There exists an interaction between MWNTs and the PC phase, which is observed from Raman spectroscopic investigation. Dynamic mechanical analysis (DMA) studies show the increase in storage modulus values depicting the stiffening effect of MWNTs, tanδ value increase depicting the energy dissipation. The flexural and impact properties increase significantly. The mechanism of flexural fracture is craze formation in the skin layer with a shear band and facets formation in the bulk region as observed from the SEM investigation of a flexural fractured surface of MWNTs reinforced PC70ABS30 blends and their nanocomposites. In addition, the deformation at the edge, river-like pattern, striation associated shear bands, craze, cavitation, and facets formation are the impact fracture mechanism as observed from SEM investigation of impact fractured surface of MWNTs reinforced PC70ABS30 blends and its nanocomposites. Scratch studies reveal the improved dispersion of MNNTs at 0.5–1 wt% in PC70ABS30 blends and their nanocomposites with a slightly higher scratch coefficient of friction and scratching force.

In 1960, Treloar [1] published a seminal paper showing that the stiffness (E-Modulus) of an extended viz. fully stretched polyethylene and polyamide chain is close to 200 GPa, which is appr. the same stiffness as steel. In the 1970s, Zhurkov [2] and Boudreaux [3] estimated that the strength of an extended PE chain could be as high as 25 GPa. These theoretical calculations/predictions rose the interest of many scientists and engineers to pursue chain-extension which in practice implies that fibers are made in which a maximum degree of chain-extension, viz. chain alignment, in the fiber direction is attempted. These earlier publications were in fact not very realistic because even if polymer chains could be perfectly aligned in the fiber direction, then the maximum length of a polymer chain is limited to some 10 μm. In measuring fiber properties macroscopic dimensions are encountered with gauge length's in the order of several centimeters in the tensile tester. Consequently, in a tensile tester an ensemble of a larger number of parallel chains is tested and the stress-transfer and chain overlap between individual chains determine the tensile properties like strength and stiffness/E-Modulus. Consequently, the strength of a polyethylene fiber is determined by the rather weak intermolecular van der Waals interactions with important consequences for chain alignment and chain length.

In the case of the non-polar polyethylene with only weak van der Waals intermolecular interactions one would expect no impressive tensile fiber properties whereas in the case of more polar polymers, such as the polyamides, one would expect quite some interesting properties when the hydrogen-bonds between the individual chains could be aligned along the fiber axis. The reality turned out to be quite the opposite as will be discussed in this chapter for polyethylene and in the chapter on ‘high-performance fibers based on flexible polar molecules’ for the polyamides (nylons).