Nowadays, epoxy composites are elements of engineering materials and systems. Although they are known as versatile materials, epoxy resins suffer from high flammability. In this sense, flame ...retardancy analysis has been recognized as an undeniable requirement for developing future generations of epoxy-based systems. A considerable proportion of the literature on epoxy composites has been devoted to the use of phosphorus-based additives. Nevertheless, innovative flame retardants have coincidentally been under investigation to meet market requirements. This review paper attempts to give an overview of the research on flame retardant epoxy composites by classification of literature in terms of phosphorus (P), non-phosphorus (NP), and combinations of P/NP additives. A comprehensive set of data on cone calorimetry measurements applied on P-, NP-, and P/NP-incorporated epoxy systems was collected and treated. The performance of epoxy composites was qualitatively discussed as
,
, and
cases identified and distinguished by the use of the universal Flame Retardancy Index (FRI). Moreover, evaluations were rechecked by considering the UL-94 test data in four groups as V0, V1, V2, and nonrated (NR). The dimensionless FRI allowed for comparison between flame retardancy performances of epoxy composites. The results of this survey can pave the way for future innovations in developing flame-retardant additives for epoxy.
Recent Trends in Nanomedicine and Tissue Engineering covers numerous recent technological and research accomplishments in the area of Nanomedicine and Tissue Engineering. The introduction of ...nanomaterials and nanotechnology have led to crucial advancements in the fields of nanomedicine and tissue engineering, as well as cancer therapies and drug delivery systems.
The book follows recent trends in drug delivery systems, wound healing fields, cancer therapies, protection of teeth and also other health care systems.
Technical topics discussed in the book include:
Nanorobots
Tissue engineering
Gene therapy
Drug delivery
Nanomotors
Nanogels
ZnO nanoparticles were synthesized from chitosan and zinc chloride by a precipitation method. The synthesized ZnO nanoparticles were characterized by Fourier transform infrared spectroscopy, X-ray ...diffraction peak profile analysis, Scanning electron microscopy, Transmission electron microscopy and Photoluminescence. The X-ray diffraction results revealed that the sample was crystalline with a hexagonal wurtzite phase. We have investigated the crystallite development in ZnO nanoparticles by X-ray peak profile analysis. The Williamson–Hall analysis and size–strain plot were used to study the individual contributions of crystallite sizes and lattice strain
ϵ
on the peak broadening of ZnO nanoparticles. The parameters including strain, stress and energy density value were calculated for all the reflection peaks of X-ray diffraction corresponding to wurtzite hexagonal phase of ZnO lying in the range 20°–80° using the modified form of Williamson–Hall plots and size–strain plot. The results showed that the crystallite size estimated from Scherrer’s formula, Williamson–Hall plots and size–strain plot, and the particle size estimated from Transmission electron microscopy analysis are very much inter-correlated. Both methods, the X-ray diffraction and Transmission electron microscopy, provide less deviation between crystallite size and particle size in the present case.
The viscoelastic behavior and reinforcement mechanism of nano ZnO reinforced natural rubber (NR) nanocomposites were investigated in this study. Dynamic mechanical analysis was performed to ...investigate the nature of the constrained polymer region in NR–nano ZnO nanocomposites, and the constrained polymer region is responsible for the reinforcement mechanism. The viscoelastic and tensile properties of NR nanocomposites were investigated with respect to the effect of nanofiller loading. All the nanocomposites showed a significant increase in storage modulus in the glassy and rubbery regions, the shift of the tan δ peak to the higher temperature region, and the lowering of the tan δ peak intensity compared to neat NR. The enhancement in the modulus is related to the weight % of the added nano ZnO as well as the volume of the constrained rubber chains in the proximity of ZnO nanoparticles. The study of the constrained volume of the polymer indicates that the structure of the nanocomposite possesses a moderately strong interfacial interaction between rubber chains and ZnO nanoparticles. The type of rubber–nanofiller interaction strongly influences the amount and modulus of the constrained region and contributes to the enhancement in the storage modulus of the resulting nanocomposites. The volume fraction of the constrained region of the NR nanocomposites was found to have good linear correlation with the weight % of nano ZnO. It was also understood that there should exist an optimum cross-linking density for a certain nanofiller reinforced rubber system, as well as partial physical adsorption of macromolecular rubber chains on the nanofiller surface. An optimum nanofiller loading is necessary for moderately strong rubber–nanofiller interaction and hence for the enhancement in the mechanical properties of the NR nanocomposites. A core–shell morphology model and constrained polymer model have been proposed to explain the constrained polymer chains in the NR–nano ZnO nanocomposite system on the basis of these results.
Research on nanocellulose has significantly increased over the past few decades, owing to the various attractive characteristics of this material, such as renewability, widespread availability, low ...density, excellent mechanical properties, economic value, biocompatibility, and biodegradability. Nanocellulose categorized into two main types, namely cellulose nanofibrils (CNFs) and cellulose nanocrystals (CNCs). In this review, we present the recent advances made in the production of CNFs and CNCs. In addition to the conventional mechanical and chemical treatments used to prepare CNFs and CNCs, respectively, other promising techniques as well as pretreatment processes have been also proposed in recent times, in an effort to design an economically efficient and eco-friendly production route for nanocellulose. Further, while the hydrophilic nature of nanocellulose limits its use in polymeric matrices and in some industrial applications, the large number of hydroxyl groups on the surface of nanocellulose provides a suitable platform for various kinds of modification treatments. The various chemical and physical surface treatment procedures reported for nanocellulose have been reviewed in this paper. Finally, in this review, we summarize the life cycle assessment studies conducted so far on nanocellulose, which quantify the environmental impact of nanocellulose products. The current paper is a comprehensive review of the recent literature on nanostructured cellulose.
This article examines the effect of the addition of hexagonal boron nitride (h-BN) nanopowder on the polymer chain confinement, thermal, morphological and mechanical properties of the epoxy system. A ...series of epoxy resin/h-BN (EPBN) nanocomposites with varying compositions (0.1, 0.25, 0.5 and 1 wt%) of h-BN was prepared using 4,4′-diaminodiphenyl sulfone (DDS) as the curing agent. The amount of epoxy chains confined at the h-BN nanofillers was determined and quantified using the results obtained by dynamic mechanical analysis (DMA). h-BN 0.5 wt%/epoxy (EPBN0.5) exhibited the highest volume fraction of the constrained region among the h-BN/epoxy nanocomposites and the presence of h-BN increases the glass transition temperature (
T
g
) of the epoxy matrix by 10 °C. Furthermore, h-BN/epoxy nanocomposites showed a higher storage modulus when compared to the neat epoxy. The incorporation of the h-BN nanopowder into the epoxy system resulted in an excellent improvement in the impact strength and tensile strength of the system, especially with 0.5 wt% h-BN concentration. This could be ascribed to the uniform distribution of the h-BN nanoparticle in the epoxy matrix. Although epoxy nanocomposites exhibited a higher activation energy (which is related to the thermal stability) compared to that of the neat epoxy, thermal analysis revealed that the incorporation of the h-BN nanopowder does not have much influence on the thermal stability of the system. However, fractured surface analysis of the nanocomposites indicated that the surface roughness increases with an increase in h-BN content.
This article examines the effect of the addition of hexagonal boron nitride (h-BN) nanopowder on the polymer chain confinement, thermal, morphological and mechanical properties of the epoxy system.
The usage of polymer composites in various engineering fields has increased. However, the long-term service performance of such materials under aggressive conditions is still poorly understood, which ...limits the development of safe and economically effective designs. In this study, the aging of an epoxy resin and its carbon fiber-reinforced polymer (CFRP) composites upon immersion in water, acidic, and alkaline solutions was evaluated at different temperatures. The service life of the CFRP composites under various conditions could be predicted by the Arrhenius theory. The thermal and mechanical analysis results indicated that the CFRP composites were more vulnerable to HCl owing to the higher moisture absorption and diffusion of HCl into their cracks. The scanning electron microscopy results showed that the polymer matrix was damaged and degraded. Therefore, to allow long-term application, CFRP composites must be protected from acidic environments.
Elastomer composites have established a unique position among technologically important materials because of their extensive and potential applications. Considerable interest has been devoted to ...graphite derived elastomer composites, known as new generation materials, due to their exceptional electrical, mechanical and permeability properties. The discovery of graphene opened a promising aspect towards the synthesis of elastomer nanocomposites. A thorough investigation of the properties of various graphitic fillers, such as natural graphite flakes, expanded graphite (EG), graphite nanoplatelets (GNP) and graphene is undertaken in this review. The dependence of these fillers on the rheological, electrical (sensing), mechanical, thermal, dielectric and barrier properties of elastomer composites is discussed, giving special emphasis to particle size and mode of interactions with the matrix. A systematic evolution from microcomposites to nanocomposites is shown to give definitive evidence of the importance of graphene nanocomposites. Most preparation methods of these composites are covered, including, solution blending, latex compounding, in situ polymerization, and melt intercalation. Graphene exhibits very good dispersion in most elastomers and substantially improves the mechanical and electrical properties of the matrix compared to all other graphite derivative composites. A review of the potential applications of these composites and current challenges is provided in order to guide future progress on the development of more promising materials.
Various NCDs with antimicrobial, anticancer and neurodegenerative drug delivery applications. a) Pleurotus species, b) Hylocereus undatus, c) Curcuma longa L., d) Manilkara zapota (L.) P. Royen, e) ...Banana leaf, f) Carica papaya, g) Ocimum Sanctum, h) Foeniculum vulgare Mill seeds, i) Azadirachta indica, j) Aloe vera (L.) Burm.f.
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•The source and rationale behind natural carbon quantum dots (NCDs) are carefully discussed.•The various synthesis method and their merits have been summarized.•The optical properties and toxicological profile of NCDs are highlighted.•The drug delivery applications of NCDs are detailed.•The clinical status of NCDs are presented.
Natural carbon based quantum dots (NCDs) are an emerging class of nanomaterials in the carbon family. NCDs have gained immense acclamation among researchers because of their abundance, eco-friendly nature, aqueous solubility, the diverse functionality and biocompatibility when compared to other conventional carbon quantum dots (CDs).The presence of different functional groups on the surface of NCDs such as thiol, carboxyl, hydroxyl, etc., provides improved quantum yield, physicochemical and optical properties which promote bioimaging, sensing, and drug delivery. This review provides comprehensive knowledge about NCDs for drug delivery applications by outlining the source and rationale behind NCDs, different routes of synthesis of NCDs and the merits of adopting each method. Detailed information regarding the mechanism behind the optical properties, toxicological profile including biosafety and biodistribution of NCDs that are favourable for drug delivery are discussed. The drug delivery applications of NCDs particularly as sensing and real-time tracing probe, antimicrobial, anticancer, neurodegenerative agents are reviewed. The clinical aspects of NCDs are also reviewed as an initiative to strengthen the case of NCDs as potent drug delivery agents.
In this review, few established cell printing techniques along with their parameters that affect the cell viability during bioprinting are considered. 3D bioprinting is developed on the principle of ...additive manufacturing using biomaterial inks and bioinks. Different bioprinting methods impose few challenges on cell printing such as shear stress, mechanical impact, heat, laser radiation, etc., which eventually lead to cell death. These factors also cause alteration of cells phenotype, recoverable or irrecoverable damages to the cells. Such challenges are not addressed in detail in the literature and scientific reports. Hence, this review presents a detailed discussion of several cellular bioprinting methods and their process‐related impacts on cell viability, followed by probable mitigation techniques. Most of the printable bioinks encompass cells within hydrogel as scaffold material to avoid the direct exposure of the harsh printing environment on cells. However, the advantages of printing with scaffold‐free cellular aggregates over cell‐laden hydrogels have emerged very recently. Henceforth, optimal and favorable crosslinking mechanisms providing structural rigidity to the cell‐laden printed constructs with ideal cell differentiation and proliferation, are discussed for improved understanding of cell printing methods for the future of organ printing and transplantation.
This review article highlights the effects of processing parameters of established 3D bioprinting techniques on the cellular activity of bioinks and advanced methods to improve the cell viability. This review helps to precisely identify the associated problems for cell viability that will help to improve the future technology of organ printing before transplantation.
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