Thermal Conductivity of Graphite-Based Polymer Composites

It is well known that polymers are insulators, which limit their usage in other applications where thermal conductivity is essential for heat to be efficiently dissipated or stored. In the past, the improvement in the thermal conductivity of polym.rs with conductive fillers has been investigated by researchers. Carbon-based materials such as graphite, graphene and carbon nanotube, which feature excellent properties such as a high mechanical strength, a high thermal conductivity and a tailorable electronic configuration, have been added to different polymer matrices to enhance their thermal conductivity. Amongst others, graphite more especially expanded graphite merits special interest because of its abundant availability at a relatively low cost and lightweight when compared to other carbon allotropes. Herein, we describe the thermal conductivity of polymer/graphite composites and their applications

Effect of LDHs and Other Clays on Polymer Composite in Adsorptive Removal of Contaminants: A Review

ArticleRecently, the development of a unique class of layered silicate nanomaterials has attracted considerable interest for treatment of wastewater. Clean water is an essential commodity for healthier life, agriculture and a safe environment at large. Layered double hydroxides (LDHs) and other clay hybrids are emerging as potential nanostructured adsorbents for water purification. These LDH hybrids are referred to as hydrotalcite-based materials or anionic clays and promising multifunctional two-dimensional (2D) nanomaterials. They are used in many applications including photocatalysis, energy storage, nanocomposites, adsorption, di usion and water purification. The adsorption and di usion capacities of various toxic contaminants heavy metal ions and dyes on di erent unmodified and modified LDH-samples are discussed comparatively with other types of nanoclays acting as adsorbents. This review focuses on the preparation methods, comparison of adsorption and di usion capacities of LDH-hybrids and other nanoclay materials for the treatment of various contaminants such as heavy metal ions and dyes

Morphology, Thermal Stability, and Flammability Properties of Polymer-Layered Double Hydroxide (LDH) Nanocomposites: A Review

ArticleThe utilization of layered nanofillers in polymer matrix, as reinforcement, has attracted great interest in the 21st century. This can be attributed to the high aspect ratios of the nanofillers and the attendant substantial improvement in di erent properties (i.e., increased flammability resistance, improved modulus and impact strength, as well as improved barrier properties) of the resultant nanocomposite when compared to the neat polymer matrix. Amongst the well-known layered nanofillers, layered inorganic materials, in the form of LDHs, have been given the most attention. LDH nanofillers have been employed in di erent polymers due to their flexibility in chemical composition as well as an adjustable charge density, which permits numerous interactions with the host polymer matrices. One of the most important features of LDHs is their ability to act as flame-retardant materials because of their endothermic decomposition. This review paper gives detailed information on the: preparation methods, morphology, flammability, and barrier properties as well as thermal stability of LDH/polymer nanocomposites

Effects of annealing time on the structure and optical properties of ZnAl2O4/ZnO prepared via citrate sol-gel process

ZnAl2O4 nano-powders have been successfully prepared via citrate sol-gel technique. All powder samples were annealed at 600 °C for 1, 2, and 3 h. Thermogravimetric analysis (TGA) confirmed that the minimum annealing temperature of crystallization is ∼400 °C. Fourier Transform Infrared (FTIR) results showed a series of absorption peaks in the range of 810–4000 cm−1. The X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HR-TEM) results showed that the prepared nano-crystals consists of the mixture of both cubic (ZnAl2O4) and hexagonal (ZnO) structures. Ultra violet visible (UV–vis) spectroscopy revealed that the annealing time (AT) influences the band gap of the prepared phosphor materials. When the samples were excited at 275 nm, two emission peaks at 428 nm (violet) and 561 nm (green-yellow) were observed and they are attributed to the defects levels within the ZnO and ZnAl2O4 band gaps. The Commission Internationale de l’Elcairage (CIE) colour coordinates confirmed that all the prepared samples exhibit the violet emission and varying the AT does not influence the emission colour.The South African National Research Foundation (NRF) Thuthuka Programme (fund number: UID99266).https://www.elsevier.com/locate/mtcomm2019-03-01hj2018Physic

The Effect Of Filler Localization On The Properties Of Biopolymer Blends, Recent Advances: A Review

ArticleIn recent times, the field of biopolymer (BP) blends has been the focus of intensive fundamental and applied researches. Such BP combinations possess unique properties that are different from those of the individual components. However, most polyester polymers are thermodynamically immiscible because of their poor interactions. In the past, a third component, known as a welldefined diblock or triblock copolymer, whose chemical structure is identical to that of the main components, was usually used as a compatibilizer in order to emulsify the interfacial phase, decreasing the interfacial tension and refining the phase size. Currently, nanofillers are used to improve the phase morphologies of immiscible BP blends. The main advantage of using nanofillers, when compared to copolymers, is that the former can simultaneous act as nanoreinforcements and compatibilizers. In this review, the addition of nanofillers as the third component in the BP blend systems are reported in relation to their morphologies, barrier properties, shape memory, thermal, and mechanical properties. The effects of selectively localized nanofillers on the properties of the BP blends are also explored, with the aim of establishing the relationships between the localization of the fillers and the overall properties of the BP blends. Furthermore, the effect of the processing techniques on the localization of the nanofillers/BP blend is also reported. The review article discusses recent progress from 2014 up to 2019 on filler localization of BP blend nanocomposites

Morphology and Properties of Electrospun PCL and Its Composites for Medical Applications: A Mini Review

Polycaprolactone (PCL) is one of the most used synthetic polymers for medical applications due to its biocompatibility and slow biodegradation character. Combining the inherent properties of the PCL matrix with the characteristic of nanofibrous particles, result into promising materials that can be suitable for different applications, including the biomedical applications. The advantages of nanofibrous structures include large surface area, a small diameter of pores and a high porosity, which make them of great interest in different applications. Electrospinning, as technique, has been heavily used for the preparation of nano- and micro-sized fibers. This review discusses the different methods for the electrospinning of PCL and its composites for advanced applications. Furthermore, the steady state conditions as well as the effect of the electrospinning parameters on the resultant morphology of the electrospun fiber are also reported

Morphology and Photocatalytic Activity of Zinc Oxide Reinforced Polymer Composites: A Mini Review

There is an approximately 3% of fresh water available globally for utilization, while the rest of the water is not available for usage, leaving billions of people with less water. Less water availability means that the majority of water consists of pollutants either in ground water or drinking water, which in turn may have a negative impact on the environment and people. Various methods such as plasma technology, flocculation, neutralization, and disinfection have been utilized for wastewater treatment. The wastewater treatment methods have been found to be selective in terms of the removal of other pollutants, as a result, the majority of them are unable to remove pollutants such as antibiotics at a trace level. In order to ensure that there is a complete removal of pollutants from water, there is a need for the development of alternative wastewater treatment methods. The use of solar light by photocatalysis is an alternative method for the degradation of toxic pollutants. Different photocatalysts such as zinc oxide (ZnO), titanium dioxide (TiO2), and silver (Ag) have been used in the process of photocatalysis. However, the above photocatalysts were found to have drawbacks such as agglomeration at higher contents and health problems during transportation. To solve the above problem, the nanoparticles were immobilized in various matrices such as polymers and ceramics, with polymers being preferred because of low cost, chemical inertness, and high durability. The current review discusses various methods for the preparation of ZnO and its synergy with other nanoparticles incorporated in various polymer matrices. Because it is known that the preparation method(s) affects the morphology, the morphology and the photocatalytic activity of various ZnO/polymer composites and hybrid systems of ZnO/other nanoparticles/polymer composites are discussed in depth

Morphology and Photocatalytic Activity of Zinc Oxide Reinforced Polymer Composites: A Mini Review

There is an approximately 3% of fresh water available globally for utilization, while the rest of the water is not available for usage, leaving billions of people with less water. Less water availability means that the majority of water consists of pollutants either in ground water or drinking water, which in turn may have a negative impact on the environment and people. Various methods such as plasma technology, flocculation, neutralization, and disinfection have been utilized for wastewater treatment. The wastewater treatment methods have been found to be selective in terms of the removal of other pollutants, as a result, the majority of them are unable to remove pollutants such as antibiotics at a trace level. In order to ensure that there is a complete removal of pollutants from water, there is a need for the development of alternative wastewater treatment methods. The use of solar light by photocatalysis is an alternative method for the degradation of toxic pollutants. Different photocatalysts such as zinc oxide (ZnO), titanium dioxide (TiO2), and silver (Ag) have been used in the process of photocatalysis. However, the above photocatalysts were found to have drawbacks such as agglomeration at higher contents and health problems during transportation. To solve the above problem, the nanoparticles were immobilized in various matrices such as polymers and ceramics, with polymers being preferred because of low cost, chemical inertness, and high durability. The current review discusses various methods for the preparation of ZnO and its synergy with other nanoparticles incorporated in various polymer matrices. Because it is known that the preparation method(s) affects the morphology, the morphology and the photocatalytic activity of various ZnO/polymer composites and hybrid systems of ZnO/other nanoparticles/polymer composites are discussed in depth

A Review on Bast-Fibre-Reinforced Hybrid Composites and Their Applications

The development of eco-friendly products to protect the environment has become a topical subject in the research and industrial communities. This is a result of strict environmental regulations necessitating the development of novel strategies to reduce our reliance on petroleum-based products, which exert a negative effect on our ecosystem. Bast-fibre-based hybrids have been extensively studied for various applications due to their eco-friendliness and cost effectiveness. There is a very limited number of review articles covering the properties and preparation of bast-fibre-based hybrid composites. This review is designed to provide an overview of the preparation and application of bast-fibre-based hybrid composites. It covers the thermal properties, mechanical properties, moisture absorption and flame-retardant properties of bast hybrid composites. This review not only summarises recent advances on the use and preparation of bast hybrid composites, it also presents a future outlook