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Topic Review
High Performance Polymer Composites
Summarize data on the structure, mechanical and tribological properties, and wear patterns of composites based on high-performance polymers (HPPs) intended for use in friction units. The three key sections, divided according to the tribological contact schemes regardless of the polymer matrix. In the second part, the analysis of composites is carried out in point contacts. The third section is devoted to the results of studies of HPP-based composites in linear ones. The fourth section summarizes information on flat contacts. Particular attention is paid to the formation of transfer films (TFs) in the contacts and their influence on the tribological patterns of the studied rubbing materials.
  • 1.9K
  • 16 Mar 2022
Topic Review
Friction Spot Stir Welding
In the last decade, the friction stir welding of polymers has been increasingly investigated by the means of more and more sophisticated approaches. Since the early studies, which were aimed at proving the feasibility of the process for polymers and identifying suitable processing windows, great improvements have been achieved. This owes to the increasing care of academic researchers and industrial demands. These improvements have their roots in the promising results from pioneer studies; however, they are also the fruits of the adoption of more comprehensive approaches and the multidisciplinary analyses of results. The introduction of instrumented machines has enabled the online measurement of processing loads and temperature, and critical understanding of the principal aspects affecting the material flow and welds quality. Such improvements are also clearly demonstrated by the increase of the strength of recent joints (up to 99% of joining efficiency) as compared to those reached in early researches (almost 47%). This article provides a comprehensive review of the recent progresses on the process fundamentals, quality assessment and the influence of process parameters on the mechanical behavior. In addition, emphasis is given to new developments and future perspectives.
  • 1.8K
  • 28 Oct 2020
Topic Review
Hybrid Reinforced Polymer Matrix Composites
The use of composite materials has seen many new innovations for a large variety of applications. The area of reinforcement in composites is also rapidly evolving with many new discoveries, including the use of hybrid fibers, sustainable materials, and nanocellulose.
  • 1.8K
  • 22 Feb 2023
Topic Review
Joint-Design Strategies for Additive Manufacturing
Here, we aim to assess the current modelling and experimental achievements in the design for additive manufacturing of bonded joints, providing a summary of the current state of the art. To limit its scope, the document is focused only on polymeric additive manufacturing processes. As a result, this work contains a structured collection of the tailoring methods adopted for additively manufactured adherends and adhesives with the aim of maximizing bonded joint performance. 
  • 1.8K
  • 17 Sep 2020
Topic Review
High Performance Bioplastics
Biomass provides a wealth of renewable and bio-waste resources for bioplastics synthesis. Many of these bio-based plastics, encompass capacities for biodegradation and bioprocessing with high performance features akin to petroleum-based plastics. The realisation of bioplastics that exhibit a complete set of mechanical and biodegradability, hold the promise of delivering material of ecologically sustainable, low carbon footprint circularity.
  • 1.8K
  • 14 Jul 2021
Topic Review
Positronium as a Probe of Polymer Free Volume
Positron annihilation lifetime spectroscopy (PALS) is a valuable technique to investigate defects in solids, such as vacancy clusters and grain boundaries in metals and alloys, as well as lattice imperfections in semiconductors. In the case of polymers, PALS is able to give information on the holes forming the free volume; this quantity, is correlated to important mechanical, thermal, and transport properties of polymers. PALS supplies a quantitative measure of the free volume by probing the corresponding sub-nanometric holes. The system used is positronium (Ps), an unstable atom formed by a positron and an electron, whose lifetime can be related to the typical size of the holes.
  • 1.8K
  • 18 Sep 2023
Topic Review
PEDOT:PSS/Nonionic WPU
Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) has the merits of high electrical conductivity and solution processability, and can be dispersed in water. To improve the stretchability of PEDOT:PSS-based transparent electrode films, the intrinsically conducting polymer PEDOT:PSS was blended with highly stretchable nonionic waterborne polyurethane (WPU) and coated on a thermoplastic polyurethane (TPU) film. Nonionic WPU has good compatibility with PEDOT:PSS, without affecting the acidity. 
  • 1.8K
  • 16 Mar 2022
Topic Review
Tire Rubber and Its Degradation Behavior
The use of ground tire rubber (GTR) for modifying asphalt is very promising and is a sustainable development strategy. The addition of GTR to asphalt shows many improvements in the physical, chemical and mechanical properties of the rubber asphalt binder, such as enhanced stiffness, increased skid resistance, extended service life, mitigated fatigue cracking and so on.
  • 1.8K
  • 01 Nov 2022
Topic Review
Poly(Ionic Liquid) Materials-Based Advanced Formulations for Additive Manufacturing
Innovation in materials specially formulated for additive manufacturing is of great interest and can generate new opportunities for designing cost-effective smart materials for next-generation devices and engineering applications. Nevertheless, advanced molecular and nanostructured systems are frequently not possible to integrate into 3D printable materials, thus limiting their technological transferability. In some cases, this challenge can be overcome using polymeric macromolecules of ionic nature, such as polymeric ionic liquids (PILs). Due to their tuneability, wide variety in molecular composition, and macromolecular architecture, they show a remarkable ability to stabilize molecular and nanostructured materials. The technology resulting from 3D-printable PIL-based formulations represents an untapped array of potential applications, including optoelectronic, antimicrobial, catalysis, photoactive, conductive, and redox applications.
  • 1.8K
  • 08 Dec 2022
Topic Review
Ultrasonic Welding
The ultrasonic welding (UW) technique is an ultra-fast joining process used to join thermoplastics, metals and thermoplastic polymer matrix composites.
  • 1.8K
  • 27 Oct 2020
Topic Review
Bio-Inspired Hierarchical Fibres
Several naturally occurring biological systems, such as bones, nacre or wood, display hierarchical architectures with a central role of the nanostructuration that allows reaching amazing properties such as high strength and toughness. Developing such architectures in man-made materials is highly challenging, and recent research relies on this concept of hierarchical structures to design high-performance composite materials. This review deals more specifically with the development of hierarchical fibres by the deposition of nano-objects at their surface to tailor the fibre/matrix interphase in (bio)composites. Fully synthetic hierarchical fibre reinforced composites are described, and the potential of hierarchical fibres is discussed for the development of sustainable biocomposite materials with enhanced structural performance. Based on various surface, microstructural and mechanical characterizations, this review highlights that nano-objects coated on natural fibres (carbonnanotubes, ZnO nanowires, nanocelluloses) can improve the load transfer and interfacial adhesion between the matrix and the fibres, and the resulting mechanical performances of biocomposites. Indeed, the surface topography of the fibres is modified with higher roughness and specific surface area, implying increased mechanical interlocking with the matrix. As a result, the interfacial shear strength (IFSS) between fibres and polymer matrices is enhanced, and failure mechanisms can bemodified with a crack propagation occurring through a zig-zag path along interphases.
  • 1.8K
  • 29 May 2021
Topic Review
Electrospun Polymer Nanofibers
Electrospun polymer nanofibers constitute one of the most important nanomaterials with diverse applications. Nanofibers are classified as fibers with a ratio of length to thickness in the order of one thousand, or nanomaterials that have at least one dimension of 100 nm or less. A nanofiber with a diameter of ∼100 nm can have a specific surface area up to 1000 m2/g. Nanofibers can be produced by selecting the proper combination of polymers and additives, and using appropriate production techniques based on several essential characteristics that impact criteria of the intended particular application area. Electrospinning of polymer nanofibers is a widely used for investigation of their properties for uses in quite diverse applications. Attractive properties of electrospun nanofibers include the extremely high specific surface area, high porosity (typically 90%), light weight, controllable pore size, flexibility in surface functionalities, large permeability, excellent mechanical properties, high aspect ratio, and length up to many centimeters. Due to their exceptional characteristics, electrospun polymer nanofibers are used in many applications, which include biomedical technology, such as tissue engineering, wound healing and dressing, and drug delivery systems. In addition they have diverse uses in  sensors and biosensors applications, air filtration, defense applications, energy devices and protective textiles.
  • 1.8K
  • 12 Jan 2023
Topic Review
Concrete Incorporated with Recycled HDPE
Incorporating recycled plastic waste in concrete manufacturing is one of the most ecologically and economically sustainable solutions for the rapid trends of annual plastic disposal and natural resource depletion worldwide. This paper comprehensively reviews the literature on engineering performance of recycled high-density polyethylene (HDPE) incorporated in concrete in the forms of aggregates or fiber or cementitious material. Optimum 28-days’ compressive and flexural strength of HDPE fine aggregate concrete is observed at HDPE-10 and splitting tensile strength at HDPE-5 whereas for HDPE coarse aggregate concrete, within the range of 10% to 15% of HDPE incorporation and at HDPE-15, respectively. Similarly, 28-days’ flexural and splitting tensile strength of HDPE fiber reinforced concrete is increased to an optimum of 4.9 MPa at HDPE-3 and 4.4 MPa at HDPE-3.5, respectively, and higher than the standard/plain concrete matrix (HDPE-0) in all HDPE inclusion levels. Hydrophobicity, smooth surface texture and non-reactivity of HDPE has resulted in weaker bonds between concrete matrix and HDPE and thereby reducing both mechanical and durability performances of HDPE concrete with the increase of HDPE.
  • 1.8K
  • 07 Jun 2021
Topic Review
Anthocyanin-Based Polymers for Healthcare Applications
Anthocyanins are a specific group of molecules found in nature that have recently received increasing attention due to their interesting biological and colorimetric properties that have been successfully applied in several fields such as food preservation and biomedicine. Meanwhile, the incorporation of anthocyanins into polymeric systems has become an interesting strategy to widen the applicability of these molecules and develop new smart and functional polymers in the above-cited areas. 
  • 1.7K
  • 14 Mar 2024
Topic Review
High-Temperature PEM Fuel Cells
This review summarizes the current status, operating principles, and recent advances in high-temperature polymer electrolyte membranes (HT-PEMs), with a particular focus on the recent developments, technical challenges and commercial prospects of the HT-PEM fuel cells. A detailed review of the most recent research activities has been covered by this work, with a major focus on the state-of-the-art concepts describing the proton conductivity and degradation mechanisms of HT-PEMs. Also, the fuel cell performance and the lifetime of HT-PEM fuel cells as a function of operating conditions have been discussed. In addition, the review will highlight the important outcomes found in recent literature about the HT-PEM fuel cell. The main objectives of this review paper will be as follows: (1) the latest development of the HT-PEMs, primarily based on polybenzimidazole membranes, (2) the latest development of the fuel cell performance and the lifetime of the HT-PEMs.
  • 1.7K
  • 28 Aug 2021
Topic Review
Classification of Advanced Polymers by Application in Food/Beverages
Polymers are extensively used in food and beverage packaging to shield against contaminants and external damage due to their barrier properties, protecting the goods inside and reducing waste.  In addition to protecting the edible goods inside any package, researchers in polymers for food and beverage applications have leapt to develop polymers for advanced applications.
  • 1.7K
  • 01 Dec 2022
Topic Review
Non-Fullerene Acceptors of IDIC/ITIC Families
IDIC/ITIC families of non-fullerene acceptors has boosted the photovoltaic performances of bulk-heterojunction organic solar cells. The fine tuning of the photophysical, morphological and processability properties with the aim of reaching higher and higher photocurrent efficiencies has prompted uninterrupted worldwide research on these peculiar families of organic compounds.
  • 1.7K
  • 17 Nov 2020
Topic Review
Hydrogels and Dentin–Pulp Complex Regeneration
Abstract Dentin–pulp complex is a term which refers to the dental pulp (DP) surrounded by dentin along its peripheries. Dentin and dental pulp are highly specialized tissues, which can be affected by various insults, primarily by dental caries. Regeneration of the dentin–pulp complex is of paramount importance to regain tooth vitality. The regenerative endodontic procedure (REP) is a relatively current approach, which aims to regenerate the dentin–pulp complex through stimulating the differentiation of resident or transplanted stem/progenitor cells. Hydrogel-based scaffolds are a unique category of three dimensional polymeric networks with high water content. They are hydrophilic, biocompatible, with tunable degradation patterns and mechanical properties, in addition to the ability to be loaded with various bioactive molecules. Furthermore, hydrogels have a considerable degree of flexibility and elasticity, mimicking the cell extracellular matrix (ECM), particularly that of the DP. The current review presents how for dentin–pulp complex regeneration, the application of injectable hydrogels combined with stem/progenitor cells could represent a promising approach. According to the source of the polymeric chain forming the hydrogel, they can be classified into natural, synthetic or hybrid hydrogels, combining natural and synthetic ones. Natural polymers are bioactive, highly biocompatible, and biodegradable by naturally occurring enzymes or via hydrolysis. On the other hand, synthetic polymers offer tunable mechanical properties, thermostability and durability as compared to natural hydrogels. Hybrid hydrogels combine the benefits of synthetic and natural polymers. Hydrogels can be biofunctionalized with cell-binding sequences as arginine–glycine–aspartic acid (RGD), can be used for local delivery of bioactive molecules and cellularized with stem cells for dentin–pulp regeneration. Formulating a hydrogel scaffold material fulfilling the required criteria in regenerative endodontics is still an area of active research, which shows promising potential for replacing conventional endodontic treatments in the near future.
  • 1.7K
  • 28 Sep 2021
Topic Review
Shape-Memory Polymeric Artificial Muscles
Shape-memory polymers (SMPs) are intelligent materials capable of sensing an external stimulus and entering a transient state according to a stimulus-response, and finally recovering to the initial state through a recovery process, known as the shape memory effect. 
  • 1.7K
  • 26 Oct 2020
Topic Review
The Ubiquity of Microplastics in the Environment
Plastic is an indispensable material in modern society; however, high production rates combined with inadequate waste management and disposal have resulted in enormous stress on ecosystems. In addition, plastics can become smaller particles known as microplastics (MPs) due to physical, chemical, and biological drivers. MP pollution has become a significant environmental problem affecting terrestrial and aquatic ecosystems worldwide.
  • 1.7K
  • 28 Aug 2023
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