Papers by Keyword: Polymer

Abstract: Latent heat storage is one of the most efficient ways of storing thermal energy. Compared with other kinds of PCMs, solid-solid PCMs have obvious advantages and have drawn more attention from the public. This paper reviews previous work on solid-solid PCMs. The advantages and disadvantages, as well as the preparation of three kinds of solid-solid PCMs were discussed. The problems associated with the application of PCMs with regards to the material and the methods used to contain them are also discussed. It is clear that solid-solid PCMs are promising, but possess the disadvantages as long phase transition time, low thermal conductivity, complexity and high cost. Therefore, there still much to do for solid-solid PCMs towards practical application in the future.

Abstract: In order to study the regularity of shear degradation of polymer solution, the artificial core is used to simulate the flow of polymer formation^[1]. The influence of mass concentration, molecular weight and shear rate on the rheological of polymer solution is studied. And the stability of the polymer solution after degradation were analyzed through method of indoor simulation experiment Research shows that Polymer solution is degraded after shearing , the viscosity reduced and it will not rebound with the passage of time. When the solution was sheared through the porous medium, degradation rate increases with the increase of shear rate. Also it can be seen, in the case of the same concentration, the degradation rate increases with the increase of relative molecular mass. In the case of the same relative molecular mass, the degradation rate increases with the increase of the mass concentration.

Abstract: Clay-nanoplatelets have emerged among the other nanomaterials for over the past few years due to their good thermal stability and mechanical properties. This paper presents the X-ray diffraction (XRD) analysis of nanoclay filled epoxy nanocomposites. In this study XRD was used to measure the dispersion state of clay particles in epoxy. A series of nanocomposites with 1 wt%, 3 wt% and 5 wt% nanoclay was fabricated using mechanical stirring and three roll mill methods. The overlaid of XRD patterns of pure Epikote 828 polymer, Cycom 977-20 polymer and polymer-nanoclay nanocomposites were produced. It was found that, there were no peak of diffraction pattern appeared for pure Epikote 828 and Cycom 977-20. Based on XRD results, the polymer is able to intercalate between the clay layers because the interlayer spacing between the clay platelets increased significantly. In addition, the results showed that the dispersion of clay in epoxy was more uniform using three-roll mill method compared to mechanical stirring method.

Abstract: As the development of nanotechnology has extended to the world of biomolecules, a revolution has occurred in the design and assembly of nanomaterials for drug delivery with a significant potential to impact drug efficacy and patient outcomes. Currently a number of nanomaterials are under investigation for their suitability as sustained, controlled and targeted drug carriers. Leading edge of the rapidly developing nanosciences is the development and assessment of these nanomaterials, with specific physicochemical properties different from their larger/ bulk counterparts, as vehicles for transport of small and large drug molecules. The characteristics such as size, shape, chemical composition, surface structure and charge, aggregation and agglomeration, and solubility, can greatly influence interactions of these nanostructured systems or carriers with biomembranes and cells. The selectivity and reactivity achieved due to the very small size assigns these systems with a wide spectrum of applications. In this review, nanomaterials are considered in terms of the physical attributes or pharmaceutical effects allocated by them to the all-inclusive carrier or vehicle system (s). However we will limit our discussion to lipidic and polymeric nanomaterials, the two most commonly promoted, and safe nanosystems for delivery of both, the chemical or small molecular entities (SME) and the macromolecules including genes and siRNA.Contents of Paper

Abstract: To reduce the cost of solar electricity, there is an enormous potential of thin-film photovoltaic technologies. An approach for lowering the manufacturing costs of solar cells is to use organic (polymer) materials that can be processed under less demanding conditions. Organic/polymer solar cells have many intrinsic advantages, such as their light weight, flexibility, and low material and manufacturing costs. But reduced thickness comes at the expense of performance. However, thin photoactive layers are widely used, but light-trapping strategies, due to the embedding of plasmonic metallic nanoparticles have been shown to be beneficial for a better optical absorption in polymer solar cells. This article reviews the different plasmonic effects occurring due to the incorporation of metallic nanoparticles in the polymer solar cell. It is shown that a careful choice of size, concentration and location of plasmonic metallic nanoparticles in the device result in an enhancement of the power conversion efficiencies, when compared to standard organic solar cell devices.Contents of Paper

Abstract: The use of natural fibers in making a variety of synthetic material has attracted attentions due to mainly two causes. 1. Making use of waste material into usable composites and 2. To tide over disposal of waste which otherwise causes degradation of environment. In the present study raw coir fiber was chemically treated with nitro compounds. It is a kind of chemical modification of fiber. Treated fiber was reinforced with epoxy polymer in the 1:1:1(resin: hardener: treated fiber). Dielectric estimation of the resulting composite was done with Wayne Kerr impedance analyzer in the temperature range of 30^O to 180^O C at different frequencies. Systematic variation in properties was found from pure epoxy composite to fiber reinforced epoxy composite. XRD study reveals that composite is crystalline in nature. Change in morphology of the fiber was found when compared with untreated fiber, which is confirmed by Scanning Electron Microscopy. The objective of this study is to utilize the coir fiber, a waste product found in abundance in nature. If natural fibres could be used as reinforcement material in polymers, it may lead to new dimensions to research in the area of embedded materials. It might prove as an asset in electronic, automobile and engineering fields. It is lightweight; bio-degradability makes it a potential in new arena when India goes green.Keywords: coir, fiber, reinforcement, polymer

Abstract: In order to investigate the surface potential decay tendency of the insulator polymers such as Polypropylene (PP) and Polyvinyl Chloride (PVC), the high voltage corona triode was applied to inject the charge into the surface and volume of the samples. Due to that the surface potential decay tendency is of utmost important to the investigation of space charge storage mechanism in those polymers, the decay tendency of each sample was tested and observed. The results show that the polypropylene with cellular structure can stored larger amount of the surface charges than the polyvinyl chloride. The results could be put into industrial application of insulation materials in the related fields of electrical insulation engineering.

Abstract: Due to ecological and sustainability constraints, in late years we see great achievements in green technology in the field of materials science. The development of high-performance biocomposites (made from natural resources) is increasing worldwide. The challenge in working with natural fiber reinforced composites is the large spectrum of possibilities for making them.Biocomposites properties are influenced by a number of variables, including the fiber type, environmental conditions (where the plant fibers are sourced), processing methods, and any modification of the fiber. It is well known that recently exists a large interest in the industrial applications of composites containing biofibers reinforced with biopolymers. The characteristics of reinforcing fibers used in biocomposites, including source, type, structure, composition, as well as mechanical properties, will be reviewed. The variety of biocomposite processing techniques as well as the factors (moisture content, fiber type and content, coupling agents and their influence on composites properties) affecting these processes will be discussed.Techniques for processing the natural fiber reinforced composites will be discussed based on thermoplastic matrices (compression molding, extrusion, injection molding, and thermoforming), and thermosets (resin transfermolding, sheet molding compound). Their influence on mechanical performance (tensile, flexural and impact properties) will be evaluated. Finally, the work will conclude with recent developments and future trends of biocomposites.

Abstract: The paper aims a comparison with respect to the dynamic mechanical properties of few hybrid polymer based composite architectures based on experimental data against micro-mechanical models based numerical predictions. The hybrid polymer based composites considered were particle-fiber combinations reinforced within an unsaturated polyester resin to provide different architectures. Variations in storage modulus (E’), loss modulus (E’’) and damping factor (tan δ) with temperature increase and different particle volume fraction were investigated. Data comparison reveals the herein composite architectures’ performances over the benchmark and enables further insight into the material development and characterization issues.

Abstract: A kind of N-substituted maleimide - having two olefinic bonds with different reactivities, (S)-N-Maleoyl-L-leucine allyl ester ((S)-ALMI), was synthesized from maleic anhydride, L-leucine and allyl alcohol. Radical polymerizations were carried out to obtain optically active polymers using 2,2′-azobisisobutyronitrile. Structures of the monomer and polymers obtained were investigated by NMR measurements. In radical polymerizations, the solvents strongly affect the radical polymerization behaviors of (S)-ALMI.