China
Africa
Explore chapters and articles related to this topic
Polymers for Supercapacitors
Published in Soney C George, Sam John, Sreelakshmi Rajeevan, Polymer Nanocomposites in Supercapacitors, 2023
Sreelakshmi Rajeevan, Sam John, Soney C George
Polymers are macromolecules composed of several repeating subunits called monomers. The monomers are formed by atoms or grouped atoms linked together by chemical bonds. The process of formation of polymers is called polymerization. Polymers play an inevitable role in fabricating energy storage devices due to their exceptional structural, morphological, mechanical, thermal, and electrochemical properties, and all these properties depend on individual constituents or monomers (11). Polymers are promising candidates for the configuration of individual components of supercapacitors or any other energy storage devices and act as a multifunctional system to achieve high performance and highly durable energy storage systems. The most fascinating features of polymers are controllable geometrical shape as per the requirement, and tunable morphology and properties by incorporating appropriate fillers, especially nanofillers. The application of polymers in the fabrication of supercapacitors can be broadly classified into four groups, including electrodes, binders, electrolytes, and separators. These are the essential components of a supercapacitor’s cell design. The optimization and modification of properties of these components are significant tasks for the apprehension of achieving a high-performance energy storage system.
Plastic Waste in the Aquatic Environment
Published in Leo M. L. Nollet, Khwaja Salahuddin Siddiqi, Analysis of Nanoplastics and Microplastics in Food, 2020
Isangedighi Asuquo Isangedighi, Gift Samuel David, Ofonmbuk Ime Obot
The degradation of negatively buoyant plastics depends on very slow thermal oxidation, or hydrolysis, as a result of most wavelengths being readily absorbed by water. Hence, plastics residing in marine environments degrade at a significantly slower rate than they do on land. Polymer degradation can be categorized as any physical or chemical changes resulting from environmental factors, including light, heat, moisture, chemical conditions and biological activity [19]. It is not clear just how long plastic items remain in their original form. However, some plastic items appear to be broken up into smaller and smaller fragments over time [21]. At sea, this process is thought to occur because of wave action, oxidation and ultraviolet light. On the shore, plastic may break up into smaller pieces owing to grinding from rocks and sand [22]. The resulting plastic fragments may be mistaken for prey and ingested by marine organisms. Plastic debris in the oceans may eventually be broken up so much that it becomes microscopic in size like grains of sand, hence the term microplastics. These tiny fragments (about 20 μm in diameter) have been identified in marine sediments and in ocean waters [23].
Radial Tire Materials Technology and Rubber Compounding
Published in Brendan Rodgers, Tire Engineering, 2020
Polymers are produced by one of two chemical processes, addition or condensation polymerization. Addition polymerization occurs by one of three mechanisms, namely radical (e.g., low-density branched polyethylene), cationic (e.g., butyl rubbers), or anionic (e.g., polystyrene). Condensation polymerization of adipic acid and hexamethylene diamine, with the elimination of water, is used to produce nylon 6,6 that is used in tire reinforcements. Industrially, polymers are produced in bulk, solution, suspension, or emulsion processes. Elastomers are typically produced in a solution batch process, continuous solution process, or an emulsion process. Elastomers are then categorized according to a classification process defined by the International Institute of Synthetic Rubber Producers and ASTM. Briefly, an emulsion polymerized SBR polymer, such as IISRP SBR1500, has a bound styrene level of 23.5%, and bale Mooney viscosity of 50–55 Mooney units. The oil-extended version is classed as SBR 1712. Polymer/oil/carbon black masterbatches fall under either 1600 series or 1800 series classes (Table 6.12). Solution polymers similarly are classed as 1200 series for SBR and BR, and 2200 series for polyisoprene and copolymers of isoprene (Table 6.13).
Potentiality of high Z doped PVA polymer as a gamma, neutron and charged particles shielding material
Published in Radiation Effects and Defects in Solids, 2023
G. B. Hiremath, N. H. Ayachit, N. M. Badiger
Polymers properties are attractive, such as light weight, good workability, ease of process ability, and stability in harsh environments (33). The addition of high Z in the polymers can act as shielding materials. Recently, several investigators measured radiation shielding properties for polymers composites (34–39). PVA (polyvinyl alcohol) is a synthetic polymer that is water-soluble and has good elastic mechanical, flexible, ductile, and compressive properties, as well as biodegradability and biocompatibility (40,41). Mostafa et al., (40) found that 30 wt % Er+3 in PVA has better gamma shields than 30 wt% Dy+3 in PVA. Muthamma et al., (41) found that Bi-filled PVA polymers, which are lightweight, easily fabricated, and cost-effective composites, show good radiation shields with increases in filler weight. Issa et al., (42) discovered that increasing the mass attenuation coefficient values increases the BaTiO3 content in PVA from 0.65 to 3.57%.
A review on magnetic polymeric nanocomposite materials: Emerging applications in biomedical field
Published in Inorganic and Nano-Metal Chemistry, 2023
Combining various polymers with magnetic nanostructures made ready toward the design of multifunctional materials with outstanding magnetic responsive highlights. Polymers have extraordinary properties like simplicity of handling, adaptability, lightweight, high solidness, malleability, and low cost. The basic role of the polymer grid in magnetic composites is to tie the filler particles together. In addition, they structure a boundary among them to dodge agglomeration, reduce the toxicity, give assortments of surface properties, forestall opsonization and fast endocytosis, and thus delay plasma half-life. The expansion of the inorganic stage permits the adjustment of the polymer actual properties just as the usage of new qualities into the polymer framework.[122]
UHMWPE textiles and composites
Published in Textile Progress, 2022
Ashraf Nawaz Khan, Mohit Gupta, Puneet Mahajan, Apurba Das, R. Alagirusamy
Nowadays, greater attention is being paid to eco-friendly biodegradable polymeric materials. Starch is one of the natural polymers which can be converted to thermoplastic starch in the presence of plasticisers. The fibre formed from thermoplastic starch can be used to produce composite laminates including UHMWPE fibres. Also, a conventional matrix material such as PE or polypropylene can be blended with the starch-based polymer to induce additional properties (Guo et al., 2017). In comparison to stainless steel, biodegradable polymers such as poly (lactic acid), poly (glycolic acid), and their copolymers have only 36% of tensile strength and 54% of the flexural strength combined with just 3% of the stiffness in either test. However, with the inclusion of fibres, the strength increases significantly. Poly (lactic acid), and poly (ortho ester) are the slowest degrading biodegradable polymers and the unreinforced biodegradable polymer has been successfully used for clinical purposes where the requirement is for only low stiffness. The UHMWPE-reinforced biodegradable composite may be the best-available option for biomedical fields as well with improved stiffness and strength (Daniels, Chang, Andriano, & Heller, 1990).