Papers by Keyword: Polymerization

Abstract: In order to develop sustainable materials for a variety of industries, hybrid polymer composites reinforced with natural fibers are emerging as a critical option. The various forms of hybrid composites and the employment of various polymers—such as thermoplastics, thermosets, and elastomers—when paired with natural fibers are the main topics of this narrative theoretical review. The article examines the applications of various composites in industries such consumer products, construction, automotive, and aerospace, providing insights into how polymer choice affects a composite's applicability for a given application. Through an examination of recent advancements in hybrid composite design and polymer utilization, this analysis offers a thorough grasp of the present trends and potential applications of these materials in promoting sustainable engineering practices.

Abstract: Herein, we have synthesized polypyrrole grafted graphene oxide (GO-g-PPy) nanohybrids by a free radical emulsion graft polymerization method. GO was used as the substrate for pyrrole grafting. The parameters of the graft polymerization reaction were optimized. The optimum concentrations of surfactant, monomer and initiator were 0.25 wt. %, 3 vol.%, and 7 wt.%, respectively. The maximum grafting percentage was 989.6% at these optimal reaction parameters. The formation of the grafted nanohybrids was confirmed by Fourier transform infrared spectroscopy (FTIR) and thermal stability studies were carried out by thermogravimetric analysis (TGA). GO-g-PPy naohybrids can be used as functional additives or conductive materials for EMI shielding applications.

Abstract: Hybrids of graphene oxide (GO) are emerged as multifunctional nanomaterials since the realization of their technological potential in EMI shielding, water treatment, sensors, catalysis, and more. They can be formed by combining organic species onto a GO substrate. Recently, the graft polymerization method has been used to develop nanohybrids of GO with varieties of monomers such as aniline, acrylonitrile, glycidyl methacrylate, and 4-vinyl pyridine at PIEAS. Graft polymerization can be done by chemical or radiation methods. This process offers quite a good control to tailor the properties of desired product by optimizing the reaction parameters. If possible chemical modifications of nanohybrids will also open new applications in different research areas. An overview of research recent work carried out at PIEAS on the graft polymerization of monomers on a GO substrate is presented. This work describes the published work on the successful synthesis of the grafted nanohybrids and the importance of optimizing the reaction conditions to obtain good yield of desired product. The practical prospects of the grafted GO nanohybrids in selected applications has also been presented. These polymer grafted GO nanohybrids can be seen as a green materials in many potential applications.

Abstract: Polylactic acid is a biodegradable polymer with wide range of applications in food packaging and medical industries. Polylactic acid is commonly derived from lactic acid which is made from sugar and starch via bacterial fermentation. Whereas the production of polylactic acid via ring opening polymerization uses lactide as its precursor. This method undergoes reaction with the presence of catalyst. In this research, polylactic acid is produced via ring opening polymerization using different catalyst. However, very few studies conducted on how the catalyst effects the molecular structure of the PLA produced. The main objective is to study the effect of using stannous octoate (SnOct₂) and anhydrous lithium chloride (LiCl) as catalyst in producing PLA. Lactide is reacted with SnOct₂ and LiCl at 130°C at different ratio of lactide to catalyst (Lac/Cat) of 25/1, 50/1 and 100/1 by weight. The resulting PLA is characterized using Fourier Transform Infrared Spectroscopy (FTIR) to analyse the molecular structure and UV-Visible Spectrometer (UV-VIS) to measure the concentration of the PLA obtained. The ratio of Lac/Cat shows significant difference on the PLA with SnOc_t2 as the catalyst but shows no significant difference on the PLA with LiCl as the catalyst. Nevertheless, LiCl can still be used as the catalyst in producing PLA which has been proved by the presence of certain peaks on the FTIR spectrum. However, further investigation needs to be carried out to understand the ROP mechanism when using LiCl as the catalyst.

Abstract: Heterogeneous metal complex catalyst such as Zinc glutarate (ZnGA) and Zinc-Ferum Double Metal Cyanide (Zn-Fe DMC) have been shown to improve reactivity for alternating copolymerization using CO₂ and epoxides. However, there are not lot of studies that have been done to study the effect of different parameter such as time and temperature on the catalytic activities of ZnGA and Zn-Fe DMC. ZnGA was treated with toluene while Zn-Fe DMC catalyst was treated with (complexing agent) tert-butanol. The main focus of this study is to synthesize ZnGA and Zn-Fe DMC at different parameter where the catalysts were produced at a variety of temperatures (50,60,70 °C) and reaction times (3h & 9h). Three different zinc-ferum ratios (1:4, 1:6, and 1:8) were developed for the Zn-Fe DMC catalyst to compare the effect of iron as metal and zinc on the active site. The catalyst was characterized using Fourier-transform infrared spectroscopy (FTIR) to determine their functional elements and Brunauer–Emmett–Teller analysis (BET) for surface characterization and pore size. The effects of reaction parameters such as time and reaction temperature were investigated using this catalyst in an auxiliary-batch reactor. FTIR result shows that GA was successful incorporation into ZnO and the production of ZnGA catalysts. The presence of typical functional groups in the Zn–Fe DMC catalysts was also confirmed. The surface area and pore volume of ZnGA increases as the temperature and reaction time increases while Zn-Fe DMC the surface area and pore volume decrease as the ratio increases. These surface-modified catalysts can generate high-molecular-weight polymers, which benefits both the environment and industry.

Abstract: Epoxy resin as a polymer material with good mechanical and electrical characteristics and resistance from corrosion and moisture resistance are considered to have the potential to be applied in defense field. The research aimed to investigate the kinetics of the reaction between bisphenol A diglycidyl ether (DGEBA) and terephthalic acid (TPA). The reaction between the DGEBA and TPA was carried out for 2 h. Then, the samples of the reaction product were taken at 15, 30, 45, 60, 90 and 120 min and were analyzed for their acid number. To determine the effect of temperature on the reaction, the reaction was carried out at various temperatures of 30 °C, 50 °C, 60 °C and 75 °C. Furthermore, the effect of variation of DGEBA and TPA mole ratio was carried out using the ratio of 0.8:1; 1:1; 1.2:1; 1.4:1. By comparing the experimental data with the calculated reaction kinetics equation data, the proposed reaction model had an average relative error of 4.63% for the temperature variation and a relative error of 7.02% for the variation of mole ratio reactants.

Abstract: Controlling the polymerization of polypyrrole (Ppy) in presence of Zr-based metal organic-framework (Zr-MOFs) using sodium dodecyl sulphonate (SDS) as a dopant, leads to the formation of a new class of thermoelectric materials based on conducting polymer and highly porous MOFs with enhanced properties for energy production applications. The polymerization of polypyrrole in the Zr-Fumerate pores leads to the formation of homogenously coated MOF-spheres with high crystalinity and a high degree of improvement in many electrical properties such as conductivity and carrier mobility. The figure shows the movement of the electrons from the hot to the cold side in the aligned polymer inside the MOF pores.

Abstract: Modelling and identification of the synthesis of SDRL rubber in the presence of toluene and modifier was carried out. The mechanism of the polymerization of butadiene on the lithium catalytic system. One of the most characteristic differences between the processes of ionic, in particular, anionic, polymerization and radical polymerization is that even when using initiators that seem to be individual, several forms of active centres, that differ in their reactivity, can simultaneously be present in systems.

Abstract: The reaction of spontaneous polymerization in the N, N-dialkylaminoethyl methacrylate - alkyl halide system in organic solvent solutions is considered. It is shown that polymerization in the system under study begins only after the formation of quaternary ammonium salt in the reaction medium (at a concentration of about 0.2 mol/L) by the Menshutkin reaction, as a result of quaternization of the unsaturated amine with an alkyl halide. For the explanation of the aggregate of the obtained experimental data, fundamental considerations were formulated, kinetic schemes were developed, and the corresponding mechanism of polymerization processes was proposed.

Abstract: Membrane technologies are currently among the most demanded. This is evidenced by their variety and a wide range of membrane applications in the most topical areas of human life. This work proposes a simple and inexpensive method for producing composite membranes for ultrafiltration and nanofiltration with a surface layer of cellulose acetate for water purification and water treatment processes. A nylon microfiltration membrane was used as a membrane base. The surface layer was obtained by immersion in a solution of cellulose acetate in acetone. Composite membranes with different retention properties were obtained depending on the number of deposited layers. The resulting membranes were examined for total porosity, water absorption, cellulose acetate content, contact angle, and IR absorption spectra. The specific productivity of the obtained membranes with respect to distilled water was also established.