Search results for: polymer blend

Authors: Tamer M. Shehata, Heba S. Elsewedy, Mashel Al Dosary, Alaa Elshehry, Mohamed A. Khedr, Maged E. Mohamed

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Objective: 2,4-Dichlorophenoxy acetic acid (2,4-D) is a well-known herbicide widely used as a weed killer. Recently, 2,4-D was rediscovered as a new anti-inflammatory agent through in silico as well as in-vivo experiments. However, poor solubility of 2,4-D could represent a problems during pharmaceutical development in addition to lower bioavailability. Solid dispersion (SD) refers to a group of solid products consisting of at least two different components, usually a hydrophobic drug and hydrophilic matrix. It is well known technique for enhancing drug solubility. Therefore, selecting SD as a tool for enhancing 2,4-D could be of great interest to the formulator. Method: In our project, several polymers were investigated (such as PEG, HPMC, citric acid and others) in addition to drug polymer ratios and its effect on solubility. Evaluation of drug polymer interaction was investigated through both Fourier Transform Infrared (FTIR) and Differential Scanning Calorimetry (DSC). Finally, in-vivo evaluation was performed for the best selected preparation through inflammatory response of rat induce hind paw. Results: Results indicated that, citric acid 2,4-D and in ratio of 0.75 : 1 showed modified the dissolution profile of the drug. The FTIR resltes indicated no significant chemical interaction, however DSC showed shifting of the drug melting point. Finally, Carragenan induced rat hind paw edema showed significant reduction of the drug solid dispersion in comparison to the pure drug, indicating rapid and complete absorption of the drug in solid dispersion form. Conclusion: Solid dispersion technology can be utilized efficiently to enhance the solubility of 2,4-D.

Keywords: solid dispersion, 2, 4-D solubility, carragenan induced edema

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Authors: Kedar Nath Nepal, Dyutiman Choudhary, Naba Raj Pandit, Yam Gahire

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Crop fertilizer recommendations are outdated as these are based on the response trails conducted over half a century ago. Further, these recommendations were based on the response trials conducted over large geographical area ignoring the large spatial variability in indigenous nutrient supplying capacity of soils typical of most smallholder systems. Application of fertilizer following such blanket recommendation in fields with varying native nutrient supply capacity leads to under application in some places and over application in others leading to reduced nutrient-use-efficiency (NUE), loss of profitability, and increased environmental risks associated with loss of unutilized nutrient through emissions or leaching. Opportunities exist to further increase yield and profitability through a significant gain in fertilizer use efficiency with commercialization of affordable and precise application technologies. We conducted participatory trails in Maize (Zea Mays), Cauliflower (Brassica oleracea var. botrytis) and Tomato (Solanum lycopersicum) in Mid Hills of Nepal to evaluate the efficacy of Urea Deep Placement (UDP and Polymer Coated Urea (PCU);. UDP contains 46% of N having individual briquette size 2.7 gm each and PCU contains 44% of N . Both PCU and urea briquette applied at reduced amount (100 kg N/ha) during planting produced similar yields (p>0.05) compared with regular urea (200 Kg N/ha). . These fertilizers also reduced N fertilizer by 35 - 50% over government blanket recommendations. Further, PCU and urea briquette increased farmer’s net income by USD 60 to 80.

Keywords: high efficiency fertilizers, urea deep placement, briquette polymer coated urea, zea mays, brassica, lycopersicum, Nepal

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Authors: Z. Okay, M. Kalkan Erdoğan, M. Şahin, M. Saçak

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Polyacrylonitrile (PAN) is one of the most common and cheap fiber-forming polymers because of its high strength and high abrasion resistance properties. The result of alkaline hydrolysis of PAN fiber could be formed the products with conjugated sequences of –C=N–, acrylamide, sodium acrylate, and amidine. In this study, PAN fiber was hydrolyzed in a solution of sodium hydroxide, and this hydrolyzed PAN (HPAN) fiber was used to prepare conductive composite fiber by silver particles. The electrically conductive PAN fiber has the usage potential to produce variety of materials such as antistatic materials, life jackets and static charge reducing products. We monitored the change in the weight loss values of the PAN fiber with hydrolysis time. It was observed that a 60 % of weight loss was obtained in the fiber weight after 7h hydrolysis under the investigated conditions, but the fiber lost its fibrous structure. The hydrolysis time of 5h was found to be suitable in terms of preserving its fibrous structure. The change in the conductivity values of the composite with the preparation conditions such as hydrolysis time, silver ion concentration was studied. PAN fibers with different degrees of hydrolysis were treated with aqueous solutions containing different concentrations of silver ions by continuous stirring at 20 oC for 30 min, and the composite having the maximum conductivity of 2 S/cm could be prepared. The antibacterial property of the conductive HPAN fibers participated silver was also investigated. While the hydrolysis of the PAN fiber was characterized with FTIR and SEM techniques, the silver reduction process of the HPAN fiber was investigated with SEM and TGA-DTA techniques. The SEM micrographs showed that the surface of HPAN fiber was rougher and much more corroded than that of the PAN fiber. Composite, Conducting polymer, Fiber, Polyacrylonitrile.

Keywords: composite, conducting polymer, fiber, polyacrylonitrile

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Authors: Sajjad H. Kasanagh, Perviz Ahmedzade, Alexander Fainleib, Taylan Gunay

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Modification of asphalt is a fundamental method around the world mainly on the purpose of providing more durable pavements which lead to diminish repairing cost during the lifetime of highways. Various polymers such as styrene-butadiene-styrene (SBS) and ethylene vinyl acetate (EVA) make up the greater parts of the all-over asphalt modifiers generally providing better physical properties of asphalt by decreasing temperature dependency which eventually diminishes permanent deformation on highways such as rutting. However, some waste and low-cost materials such as recycled plastics and ground rubber tire have been attempted to utilize in asphalt as modifier instead of manufactured polymer modifiers due to decreasing the eventual highway cost. On the other hand, the usage of recycled plastics has become a worldwide requirement and awareness in order to decrease the pollution made by waste plastics. Hence, finding an area in which recycling plastics could be utilized has been targeted by many research teams so as to reduce polymer manufacturing and plastic pollution. To this end, in this paper, thermoplastic dynamic vulcanizate (TDV) obtained from recycled post-consumer polyethylene and ground tire rubber (GTR) were used to provide an efficient modifier for asphalt which decreases the production cost as well and finally might provide an ecological solution by decreasing polymer disposal problems. TDV was synthesized by the chemists in the research group by means of the abovementioned components that are considered as compatible physical characteristic of asphalt materials. TDV modified asphalt samples having different rate of proportions of 3, 4, 5, 6, 7 wt.% TDV modifier were prepared. Conventional tests, such as penetration, softening point and roll thin film oven (RTFO) tests were performed to obtain fundamental physical and aging properties of the base and modified binders. The high temperature performance grade (PG) of binders was determined by Superpave tests conducted on original and aged binders. The multiple stress creep and recovery (MSCR) test which is relatively up-to-date method for classifying asphalts taking account of their elasticity abilities was carried out to evaluate PG plus grades of binders. The results obtained from performance grading, and MSCR tests were also evaluated together so as to make a comparison between the methods both aiming to determine rheological parameters of asphalt. The test results revealed that TDV modification leads to a decrease in penetration, an increase in softening point, which proves an increasing stiffness of asphalt. DSR results indicate an improvement in PG for modified binders compared to base asphalt. On the other hand, MSCR results that are compatible with DSR results also indicate an enhancement on rheological properties of asphalt. However, according to the results, the improvement is not as distinct as observed in DSR results since elastic properties are fundamental in MSCR. At the end of the testing program, it can be concluded that TDV can be used as modifier which provides better rheological properties for asphalt and might diminish plastic waste pollution since the material is 100% recycled.

Keywords: asphalt, ground tire rubber, recycled polymer, thermoplastic dynamic vulcanizate

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Authors: Bakhtiar Ul Haq, R. Ahmed, A. Shaari, Mazmira Binti Mohamed, Nisar Ali

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The capability of exploiting the electronic charge and spin properties simultaneously in a single material has made diluted magnetic semiconductors (DMS) remarkable in the field of spintronics. We report the designing of DMS based on zinc-blend ZnO doped with Cr impurity. The full potential linearized augmented plane wave plus local orbital FP-L(APW+lo) method in density functional theory (DFT) has been adapted to carry out these investigations. For treatment of exchange and correlation energy, generalized gradient approximations have been used. Introducing Cr atoms in the matrix of ZnO has induced strong magnetic moment with ferromagnetic ordering at stable ground state. Cr:ZnO was found to favor the short range magnetic interaction that reflect the tendency of Cr clustering. The electronic structure of ZnO is strongly influenced in the presence of Cr impurity atoms where impurity bands appear in the band gap.

Keywords: ZnO, density functional theory, diluted agnetic semiconductors, ferromagnetic materials, FP-L(APW+lo)

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Authors: Hilal T. Sasmazel, Seda Surucu

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Skin tissue engineering is a promising field for the treatment of skin defects using scaffolds. This approach involves the use of living cells and biomaterials to restore, maintain, or regenerate tissues and organs in the body by providing; (i) larger surface area for cell attachment, (ii) proper porosity for cell colonization and cell to cell interaction, and (iii) 3-dimensionality at macroscopic scale. Recent studies on this area mainly focus on fabrication of scaffolds that can closely mimic the natural extracellular matrix (ECM) for creation of tissue specific niche-like environment at the subcellular scale. Scaffolds designed as ECM-like architectures incorporating into the host with minimal scarring/pain and facilitate angiogenesis. This study is related to combining of synthetic PCL and natural chitosan polymers to form 3D PCL/Chitosan core-shell structures for skin tissue engineering applications. Amongst the polymers used in tissue engineering, natural polymer chitosan and synthetic polymer poly(ε-caprolactone) (PCL) are widely preferred in the literature. Chitosan has been among researchers for a very long time because of its superior biocompatibility and structural resemblance to the glycosaminoglycan of bone tissue. However, the low mechanical flexibility and limited biodegradability properties reveals the necessity of using this polymer in a composite structure. On the other hand, PCL is a versatile polymer due to its low melting point (60°C), ease of processability, degradability with non-enzymatic processes (hydrolysis) and good mechanical properties. Nevertheless, there are also several disadvantages of PCL such as its hydrophobic structure, limited bio-interaction and susceptibility to bacterial biodegradation. Therefore, it became crucial to use both of these polymers together as a hybrid material in order to overcome the disadvantages of both polymers and combine advantages of those. The scaffolds here were fabricated by using electrospinning technique and the characterizations of the samples were done by contact angle (CA) measurements, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-Ray Photoelectron spectroscopy (XPS). Additionally, gas permeability test, mechanical test, thickness measurement and PBS absorption and shrinkage tests were performed for all type of scaffolds (PCL, chitosan and PCL/chitosan core-shell). By using ImageJ launcher software program (USA) from SEM photographs the average inter-fiber diameter values were calculated as 0.717±0.198 µm for PCL, 0.660±0.070 µm for chitosan and 0.412±0.339 µm for PCL/chitosan core-shell structures. Additionally, the average inter-fiber pore size values exhibited decrease of 66.91% and 61.90% for the PCL and chitosan structures respectively, compare to PCL/chitosan core-shell structures. TEM images proved that homogenous and continuous bead free core-shell fibers were obtained. XPS analysis of the PCL/chitosan core-shell structures exhibited the characteristic peaks of PCL and chitosan polymers. Measured average gas permeability value of produced PCL/chitosan core-shell structure was determined 2315±3.4 g.m-2.day-1. In the future, cell-material interactions of those developed PCL/chitosan core-shell structures will be carried out with L929 ATCC CCL-1 mouse fibroblast cell line. Standard MTT assay and microscopic imaging methods will be used for the investigation of the cell attachment, proliferation and growth capacities of the developed materials.

Keywords: chitosan, coaxial electrospinning, core-shell, PCL, tissue scaffold

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Authors: Y. H. Tshela Ntumba, A. Przepiórkowska, M. Prochoń

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Polymeric materials have become an integral part of every aspect of today's industry. They have wide applications, inter alia, in areas such as medicine, food industry and agriculture. In agriculture, for example, they are used for the production of pots, irrigation systems and for soil mulching. The aim of this study was the attempt to produce a biodecomposable agricultural mat, by coating cotton fabric with a blend of carboxylated styrene-butadiene latex (LBSK) containing the enzymatic hydrolyzate of keratin from cattle hair, which would serve as a material for mulching. The production of such material allows the beneficial management of burdensome tannery waste constituted by keratin from cattle hair and at the same time, the production of agricultural mats that much faster undergo decomposition than commonly used polyethylene mats.

Keywords: agricultural mat, biodecomposition, biodegradation, carboxylated butadiene-styrene latex, cellulosic-elastomeric material, keratin hydrolyzate, mulching, protein hydrolyzate

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Authors: Firas Al-Mahmoud, Jean-Michel Mechling, Mohamed Shaban

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The long-term durability of fibre reinforced polymer (FRP) composites is often stated as being the main reason for the use of these materials. Indeed, structures externally or Near Surface Mounted (NSM) reinforced with Carbon Fibre Reinforcement Polymer CFRP are often in contact with temperature cycles and salt water immersion and other environmental conditions that reduce the expected durability of the system. Bond degradation is a frequent cause of premature failure of structural elements and environmental conditions are known to relate to such failures. The purpose of this study is to investigate the effect of environmental exposure on the bond for different CFRP strengthening systems. Bending tests were conducted to evaluate the bond with and without environmental exposure. The specimens were strengthened with CFRP sheets, CFRP plates and NSM CFRP rods embedded in two filling materials: epoxy resin and mortar. Then, they were exposed to up to 300 freeze–thaw cycles. One freeze–thaw cycle consisted of four stages according to ASTM or immersed in 3.5% salted tap water. A total of thirty-six specimens were prepared for this purpose. Results showed a decrease in ultimate bond strength for specimens strengthened by CFRP sheets that were immersed in salt water for 120 days, while a reduction was shown for CFRP sheet and plate bonded specimens that were subjected to 300 freeze–thaw cycles. Exposing NSM CFRP rod strengthened specimens, embedded in resin or mortar, to freeze–thaw cycles or to immersion in salt water does not affect the bond strength.

Keywords: durability, strengthening, FRP, bond, freeze–thaw

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Authors: Milad Abbasi

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Carbon fiber-reinforced polymer (CFRP) composite structures are increasingly being utilized in the automotive industry due to their lightweight and specific energy absorption capabilities. Although it is impossible to predict composite mechanical properties directly using theoretical methods, various research has been conducted so far in the literature for accurate simulation of CFRP structures' energy-absorbing behavior. In this research, axial compression experiments were carried out on hand lay-up unidirectional CFRP composite tubes. The fabrication method allowed the authors to extract the material properties of the CFRPs using ASTM D3039, D3410, and D3518 standards. A neural network machine learning algorithm was then utilized to build a robust prediction model to forecast the axial compressive properties of CFRP tubes while reducing high-cost experimental efforts. The predicted results have been compared with the experimental outcomes in terms of load-carrying capacity and energy absorption capability. The results showed high accuracy and precision in the prediction of the energy-absorption capacity of the CFRP tubes. This research also demonstrates the effectiveness and challenges of machine learning techniques in the robust simulation of composites' energy-absorption behavior. Interestingly, the proposed method considerably condensed numerical and experimental efforts in the simulation and calibration of CFRP composite tubes subjected to compressive loading.

Keywords: CFRP composite tubes, energy absorption, crushing behavior, machine learning, neural network

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Authors: Nigus Maregu Demewoz, Shu-Kai Yeh

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Low-density nanocellular foam is a fascinating new-generation advanced material due to its mechanical strength and thermal insulation properties. In nanocellular foam, reducing the density increases the insulation ability. However, producing a nanocellular foam of densities less than 0.3 with a cell size of less than 100 nm is very challenging. In this study, poly (methyl methacrylate) (PMMA) was blended with Polyether block amide (PEBAX) to study the effects of PEBAX on the nanocellular foam structure of the PMMA matrix. We added 2 wt% of PEBAX in the PMMA matrix, and the PEBAX nanostructured domain size of 45 nm was well dispersed in the PMMA matrix. The foaming result produced a new generation special bouquet-like nanocellular foam of cell size less than 50 nm with a relative density of 0.24. Also, we were able to produce a nanocellular foam of a relative density of about 0.17. In addition to thermal insulation applications, bouquet-like nanocellular foam may be expected for filtration applications.

Keywords: nanocellular foam, low-density, cell size, relative density, PMMA/PEBAX blend

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Authors: I. Ramesha Mithanthaya, N. Bhavanishankar Rao

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In this study, the effect of glass powder (GP) and ground granulated blast furnace slag (GGBS) on the compressive strength of Fly ash based geopolymer concrete has been investigated. The mass ratio of fine aggregate (fA) to coarse aggregate (CA) was maintained constant. NAOH flakes dissolved in water was used as activating liquid and mixed with fly ash (FA) to produce geopolymer paste or cementing material. This paste was added to mixture of CA and fA to obtain geopolymer concrete. Cube samples were prepared from this concrete. The ranges of investigation parameters include GP/FA from 0% to 20%, and GGBS/ FA from 0% to 20% with constant amount of GP. All the samples were air cured inside laboratory under room temperature. Compressive strength of cube samples after 7 days and 28 days curing were determined. The test results are presented and discussed. Based on the results of limited tests a suitable composition of FA, GP and GGBS for constant quantity of CA and fA has been obtained to produce geopolymer concrete of M32. It is found that geopolymer concrete is 14% cheaper than concrete of same strength using OPC. The strength gain in the case of geo-polymer concrete is rather slow compared to that of Portland cement concrete. Tensile strength of this concrete was also determined by conducting flexure test on beam prepared using this concrete. During curing, up to 7days, greyish-white powder used to come out from all the surfaces of sample and it was found to be a mixture of Carbonates and Sulphides of Na, Mg and Fe. Detailed investigation is necessary to arrive at an optimum mixture composition for producing Geo-polymer concrete of required strength. Effect of greyish-white powder on the strength and durability of the concrete is to be studied.

Keywords: geopolymer, industrial waste, green material, cost effective material, eco-friendly material

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Authors: Yiorgos Hadjichristou

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The paper will focus on the strategic development deriving from the evolution of the traditional courtyard spatial organization towards a new, contemporary sustainable way of living. New sustainable approaches that engulf the social issues, the notion of place, the understanding of weather architecture blended together with the bioclimatic behaviour will be seen through a series of experimental case studies in the island of Cyprus, inspired and originated from its traditional wisdom, ranging from small scale of living to urban interventions. Weather and nature will be seen as co-architectural authors with architects as intelligently claimed by Jonathan Hill in his Weather Architecture discourse. Furthermore, following Pallasmaa’s understanding, the building will be seen not as an end itself and the elements of an architectural experience as having a verb form rather than being nouns. This will further enhance the notion of merging the subject-human and the object-building as discussed by Julio Bermudez. This eventually will enable to generate the discussion of the understanding of the building constructed according to the specifics of place and inhabitants, shaped by its physical and human topography as referred by Adam Sharr in relation to Heidegger’s thinking. The specificities of the divided island and the dealing with sites that are in vicinity with the diving Green Line will further trigger explorations dealing with the regeneration issues and the social sustainability offering unprecedented opportunities for innovative sustainable ways of living. The above premises will lead us to develop innovative strategies for a profound, both technical and social sustainability, which fruitfully yields to innovative living built environments, responding to the ever changing environmental and social needs. As a starting point, a case study in Kaimakli in Nicosia a refurbishment with an extension of a traditional house, already engulfs all the traditional/ vernacular wisdom of the bioclimatic architecture. It aims at capturing not only its direct and quite obvious bioclimatic features, but rather to evolve them by adjusting the whole house in a contemporary living environment. In order to succeed this, evolutions of traditional architectural elements and spatial conditions are integrated in a way that does not only respond to some certain weather conditions, but they integrate and blend the weather within the built environment. A series of innovations aiming at maximum flexibility is proposed. The house can finally be transformed into a winter enclosure, while for the most part of the year it turns into a ‘camping’ living environment. Parallel to experimental interventions in existing traditional units, we will proceed examining the implementation of the same developed methodology in designing living units and complexes. Malleable courtyard organizations that attempt to blend the traditional wisdom with the contemporary needs for living, the weather and nature with the built environment will be seen tested in both horizontal and vertical developments. A new social identity of people, directly involved and interacting with the weather and climatic conditions will be seen as the result of balancing the social with the technological sustainability, the immaterial and the material aspects of the built environment.

Keywords: building as a verb, contemporary living, traditional bioclimatic wisdom, weather architecture

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Authors: Yamina Boukari, Nashiru Billa, Andrew Morris, Stephen Doughty, Kevin Shakesheff

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Poly (lactic-co-glycolic) acid (PLGA) is a synthetic polymer that can be used in bone tissue engineering with the aim of creating a scaffold in order to support the growth of cells. The formation of microspheres from this polymer is an attractive strategy that would allow for the development of an injectable system, hence avoiding invasive surgical procedures. The aim of this study was to develop a microsphere delivery system for use as an injectable scaffold in bone tissue engineering and evaluate various formulation parameters on its properties. Porous and lysozyme-containing PLGA microspheres were prepared using the double emulsion solvent evaporation method from various molecular weights (MW). Scaffolds were formed by sintering to contain 1 -3mg of lysozyme per gram of scaffold. The mechanical and physical properties of the scaffolds were assessed along with the release of lysozyme, which was used as a model protein. The MW of PLGA was found to have an influence on microsphere size during fabrication, with increased MW leading to an increased microsphere diameter. An inversely proportional relationship was displayed between PLGA MW and mechanical strength of formed scaffolds across loadings for low, intermediate and high MW respectively. Lysozyme release from both microspheres and formed scaffolds showed an initial burst release phase, with both microspheres and scaffolds fabricated using high MW PLGA showing the lowest protein release. Following the initial burst phase, the profiles for each MW followed a similar slow release over 30 days. Overall, the results of this study demonstrate that lysozyme can be successfully incorporated into porous PLGA scaffolds and released over 30 days in vitro, and that varying the MW of the PLGA can be used as a method of altering the physical properties of the resulting scaffolds.

Keywords: bone, microspheres, PLGA, tissue engineering

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Authors: O. G. Onuoha, O. G. Akagu

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The potentials of acha (Digitaria exiles), aya (Cyperus esculentus) and defatted water melon seed (Citrullis lanatus) as a weaning formula was investigated using the following blends for acha, aya and defatted water melon seed respectively in percentage proportion to obtain the weaning formulae; WS1(20:50:30); WS2(30:40:30); WS3(40:30:30); WS4(50:20:30). The result of the chemical analysis showed that; the sample WS1 had the highest value (15.6%) for protein while sample WS4 had the least value (14.1%). The fat content sample WS4 having the highest value (30.8%) while sample WS1 had the least value (27.3%). The ash content sample WS4 had the highest value (3.22%) while sample WS1 had the least value (2.63%). The carbohydrate content showed that sample WS1 having the highest value (50.5%) while sample WS4 had the least value (46.58%). While sample WS4 had the highest energy value (528.32 Kcal) and sample WS2 had the least value (515.06 Kcal). However, all the sample results fell within the dietary daily reference intake for infants between 0-3 years and required only local technology in its production.

Keywords: weaning formula, acha, aya, deffted water melon seed

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Authors: Monalisa Halder, Amit K. Das, Ajit K. Meikap

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Polymer nanocomposites are very significant materials both in academia and industry for diverse potential applicability in electronics. Polymer plays the role of matrix element which has low density, flexibility, good mechanical strength and electrical properties. Use of nanosized multiferroic filler in the polymer matrix is suitable to achieve nanocomposites with enhanced magneto-dielectric effect and good mechanical properties both at the same time. Multiferroic terbium manganate (TbMnO₃) nanoparticles have been synthesized by sol-gel method using chloride precursors. Terbium manganate-polyvinyl alcohol (TbMnO₃-PVA) nanocomposite film has been prepared by solution casting method. Crystallite size of TbMnO₃ nanoparticle has been calculated to be ~ 40 nm from XRD analysis. Morphological study of the samples has been done by scanning electron microscopy and a well dispersion of the nanoparticles in the PVA matrix has been found. Thermogravimetric analysis (TGA) exhibits enhancement of thermal stability of the nanocomposite film with the inclusion of TbMnO₃ nanofiller in PVA matrix. The electrical transport properties of the nanocomposite film sample have been studied in the frequency range 20Hz - 2MHz at and above room temperature. The frequency dependent variation of ac conductivity follows universal dielectric response (UDR) obeying Jhonscher’s sublinear power law. Correlated barrier hopping (CBH) mechanism is the dominant charge transport mechanism with maximum barrier height 19 meV above room temperature. The variation of dielectric constant of the sample with frequency has been studied at different temperatures. Real part of dielectric constant at 1 KHz frequency at room temperature of the sample is found to be ~ 8 which is higher than that of the pure PVA film sample (~ 6). Dielectric constant decreases with the increase in frequency. Relaxation peaks have been observed in the variation of imaginary part of electric modulus with frequency. The relaxation peaks shift towards higher frequency as temperature increases probably due to the existence of interfacial polarization in the sample in presence of applied electric field. The current-voltage (I-V) characteristics of the nanocomposite film have been studied under ±40 V applied at different temperatures. I-V characteristic exhibits temperature dependent rectifying nature indicating the formation of Schottky barrier diode (SBD) with barrier height 23 meV. In conclusion, using multiferroic TbMnO₃ nanofiller in PVA matrix, enhanced thermal stability and electrical properties can be achieved.

Keywords: correlated barrier hopping, nanocomposite, schottky diode, TbMnO₃, TGA

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Authors: Temesgen Geremew

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ZnO is currently receiving a lot of attention in the semiconductor industry due to its unique characteristics. ZnO is widely used in solar cells, heat-reflecting glasses, optoelectronic bias, and detectors. In this composition, we provide an overview of the ZnO thin flicks' packages, methods of characterization, and implicit operations. They consist of Transmission spectroscopy, Raman spectroscopy, Field emigration surveying electron microscopy, and X-ray diffraction. This review content also demonstrates how ZnO thin flicks function in electrical components for piezoelectric bias, optoelectronics, detectors, and renewable energy sources. Zinc oxide (ZnO) thin films offer a captivating tapestry of possibilities due to their unique blend of electrical, optical, and mechanical properties. This review delves into the realm of their potential applications and future prospects, highlighting the pivotal contributions of research endeavors aimed at tailoring their functionalities.

Keywords: Zinc oxide, raman spectroscopy, thin films, piezoelectric devices

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Authors: Adel M. Al-Shutairi, Ahmed H. Al-Zahrani

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Tea is a popular beverage drunk by millions of people throughout the globe. Tea has considerable health advantages, in-cluding antioxidant, antibacterial, antiviral, chemopreventive, and anticarcinogenic properties. As a result of environmental pollution (atmospheric deposition) and the production process, tealeaves may also include a variety of dangerous substances, such as polycyclic aromatic hydrocarbons (PAHs). In this study, graphene oxide reinforced chitosan/poly-nitroaniline polymer was prepared to develop a sensitive and reliable solid phase extraction method (SPE) for extraction of PAH7 in tea samples, followed by high-performance liquid chromatography- fluorescence detection. The prepared adsorbent was validated in terms of linearity, the limit of detection, the limit of quantification, recovery (%), accuracy (%), and precision (%) for the determination of the PAH7 (benzo[a]pyrene, benzo[a]anthracene, benzo[b]fluoranthene, chrysene, benzo[b]fluoranthene, Dibenzo[a,h]anthracene and Benzo[g,h,i]perylene) in tea samples. The concentration was determined in two types of tea commercially available in Saudi Arabia, including black tea and green tea. The maximum mean of Σ7PAHs in black tea samples was 68.23 ± 0.02 ug kg-1 and 26.68 ± 0.01 ug kg-1 in green tea samples. The minimum mean of Σ7PAHs in black tea samples was 37.93 ± 0.01 ug kg-1 and 15.26 ± 0.01 ug kg-1 in green tea samples. The mean value of benzo[a]pyrene in black tea samples ranged from 6.85 to 12.17 ug kg-1, where two samples exceeded the standard level (10 ug kg-1) established by the European Union (UE), while in green tea ranged from 1.78 to 2.81 ug kg-1. Low levels of Σ7PAHs in green tea samples were detected in comparison with black tea samples.

Keywords: polycyclic aromatic hydrocarbons, CS, PNA and GO, black/green tea, solid phase extraction, Saudi Arabia

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Authors: Ajay V. Kolhe, R. E. Shelke, S. S. Khandare

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This study discusses the performance and combustion characteristics of a direct injection diesel engine fueled with Jatropha methyl ester (JME). In order to determine the performance and combustion characteristics, the experiments were conducted at the constant speed mode (1500rpm) under the full load condition of the engine on single cylinder 4-stroke CI engine. The result indicated that when the test engine was fuelled with JME, the engine performance slightly weakened, the combustion characteristics slightly changed when compared to petroleum based diesel fuel. The biodiesel caused reduction in carbon monoxide (CO), unburned hydrocarbon (HC) emissions, but they caused to increases in nitrogen oxides (NOx) emissions. The useful brake power obtained is similar to diesel fuel for all loads. Oxygen content in the exhaust is more with JME blend due to the reason that fuel itself contains oxygen. JME as a new Biodiesel and its blends can be used in diesel engines without any engine modification.

Keywords: biodiesel, combustion, CI engine, jatropha curcas oil, performance and emission

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Authors: Agnė Kairyte, Saulius Vaitkus

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The gradual depletion of fossil feedstock and growing environmental concerns attracted extensive attention to natural resources due to their low cost, high abundance, renewability, sustainability, and biodegradability. Lignin is a significant by-product of the pulp and paper industry, having unique functional groups. Recently it became interesting for the manufacturing of high value-added products such as polyurethane and polyisocyanurate foams. This study focuses on the development of high-performance polyurethane foams with various amounts of lignin as a filler. It is determined that the incorporation of lignin as a filler material results in brittle and hard products due to the low molecular mobility of isocyanates and the inherent stiffness of lignin. Therefore, the current study analyses new techniques and possibilities of liquid glass infusion onto the surface of lignin particles to reduce the negative aspects and improve the performance characteristics of the modified foams. The foams modified with sole lignin and liquid glass-infused lignin had an apparent density ranging from 35 kg/m3 to 45 kg/m3 and closed-cell content (80–90%). The incorporation of sole lignin reduced the compressive and tensile strengths and increased dimensional stability and water absorption, while the contrary results were observed for polyurethane foams with liquid glass-infused lignin particles. The effect on rheological parameters of lignin and liquid glass infused lignin modified polyurethane premixes and morphology of polyurethane foam products were monitored to optimize the conditions and reveal the significant influence of the interaction between particles and polymer matrix.

Keywords: filler, lignin waste, liquid glass, polymer matrix, polyurethane foam, sustainability

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Authors: Md. Belal Uudin Rabbi, Sakib Al Montasir, Saifur Rahman, Niger Nahid, Esmail Hossain Emon

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The practice of radiation shielding protects against the detrimental effects of ionizing radiation. Radiation shielding depletes radiation by inserting a shield of absorbing material between any radioactive source. It is a primary concern when building several industrial fields, so using potent (high activity) radioisotopes in food preservation, cancer treatment, and particle accelerator facilities is significant. Radiation shielding is essential for radiation-emitting equipment users to reduce or mitigate radiation damage. Polymer composites (especially epoxy based) with high atomic number fillers can replace toxic Lead in ionizing radiation shielding applications because of their excellent mechanical properties, superior solvent and chemical resistance, good dimensional stability, adhesive, and less toxic. Due to being lightweight, good neutron shielding ability in almost the same order as concrete, epoxy-based radiation shielding can be the next big thing. Micro and nano-particles for the epoxy resin increase the epoxy matrix's radiation shielding property. Shielding is required to protect users of such facilities from ionizing radiation as recently, and considerable attention has been paid to polymeric composites as a radiation shielding material. This research will examine the radiation shielding performance of epoxy-based nano-WO3 reinforced composites, exploring the performance of epoxy-based nano-WO3 reinforced composites. The samples will be prepared using the direct pouring method to block radiation. The practice of radiation shielding protects against the detrimental effects of ionizing radiation.

Keywords: radiation shielding materials, ionizing radiation, epoxy resin, Tungsten oxide, polymer composites

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Authors: Irdawati Bay Nalls

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This study looked at Bilingual First Language Acquisition (BFLA) Spanish-English Mexican Americans across an elementary public school in the United States and the possibility of maintaining harmonious bilingualism. Adopting a phenomenological approach, with a focus on the status of bilingualism in education within a marginalized community, classroom observations, and small group and one-on-one interviews were conducted. This study explored the struggles of these bilinguals as they acculturated in America through their attempt to blend heritage and societal languages and cultural practices. Results revealed that bilinguals as young as 5 years old expressed their need to retain Spanish as a heritage language while learning English. 12 years old foresee that Spanish will not be taught to them in schools and highlighted the need to learn Spanish outside the school environments. Their voices revealed counter-narratives on identity and the need to maintain harmonious bilingualism as these students strived to give equal importance to the learning of English and Spanish as first languages despite the setbacks faced.

Keywords: BFLA, Mexican-American, bilingual, harmonious bilingualism

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Authors: Sukanya Devi Ramachandran, Vaishnavi Muralidharan, Kavya Chandrasekaran

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Polycaprolactone is polymer belonging to the polyester family that has noticeable characteristics of biodegradability and biocompatibility which is essential for medical applications. Polycaprolactone is produced by the ring opening polymerization of the monomer epsilon-Caprolactone (ε-CL) which is a closed ester, comprising of seven-membered ring. This process is normally catalysed by metallic components such as stannous octoate. It is difficult to remove the catalysts after the reaction, and they are also toxic to the human body. An alternate route of using enzymes as catalysts is being employed to reduce the toxicity. Lipase enzyme is a subclass of esterase that can easily attack the ester bonds of ε-CL. This research paper throws light on the extraction of lipase from germinating sunflower seeds and the activity of the biocatalyst in the polymerization of ε-CL. Germinating Sunflower seeds were crushed with fine sand in phosphate buffer of pH 6.5 into a fine paste which was centrifuged at 5000rpm for 10 minutes. The clear solution of the enzyme was tested for activity at various pH ranging from 5 to 7 and temperature ranging from 40oC to 70oC. The enzyme was active at pH6.0 and at 600C temperature. Polymerization of ε-CL was done using toluene as solvent with the catalysis of lipase enzyme, after which chloroform was added to terminate the reaction and was washed in cold methanol to obtain the polymer. The polymerization was done by varying the time from 72 hours to 6 days and tested for the molecular weight and the conversion of the monomer. The molecular weight obtained at 6 days is comparably higher. This method will be very effective, economical and eco-friendly to produce as the enzyme used can be regenerated as such at the end of the reaction and can be reused. The obtained polymers can be used for drug delivery and other medical applications.

Keywords: lipase, monomer, polycaprolactone, polymerization

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Authors: Amir Nourbakhsh Habibabadi, Alireza Ashori

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Context: The growing concern over the management of plastic waste and the high demand for wood-based products have led to the development of wood-plastic composites. Agricultural residues, which are abundantly available, can be used as a source of lignocellulosic fibers in the production of these composites. The use of recycled polymers and nanomaterials is also a promising approach to enhance the mechanical and physical properties of the composites. Research Aim: The aim of this study was to investigate the feasibility of using recycled high-density polyethylene (rHDPE), polypropylene (rPP), and agricultural residues fibers for manufacturing wood-plastic nano-composites. The effects of these materials on the mechanical properties of the composites, specifically tensile and flexural strength, were studied. Methodology: The study utilized an experimental approach where extruders and hot presses were used to fabricate the composites. Five types of cellulosic residues fibers (bagasse, corn stalk, rice straw, sunflower, and canola stem), three levels of nanomaterials (carbon nanotubes, nano silica, and nanoclay), and coupling agent were used to chemically bind the wood/polymer fibers, chemicals, and reinforcement. The mechanical properties of the composites were then analyzed. Findings: The study found that composites made with rHDPE provided moderately superior tensile and flexural properties compared to rPP samples. The addition of agricultural residues in several types of wood-plastic nano-composites significantly improved their bending and tensile properties, with bagasse having the most significant advantage over other lignocellulosic materials. The use of recycled polymers, agricultural residues, and nano-silica resulted in composites with the best strength properties. Theoretical Importance: The study's findings suggest that using agricultural fiber residues as reinforcement in wood/plastic nanocomposites is a viable approach to improve the mechanical properties of the composites. Additionally, the study highlights the potential of using recycled polymers in the development of value-added products without compromising the product's properties. Data Collection and Analysis Procedures: The study collected data on the mechanical properties of the composites using tensile and flexural tests. Statistical analyses were performed to determine the significant effects of the various materials used. Question addressed: Can agricultural residues and recycled polymers be used to manufacture wood-plastic nano-composites with enhanced mechanical properties? Conclusion: The study demonstrates the feasibility of using agricultural residues and recycled polymers in the production of wood-plastic nano-composites. The addition of these materials significantly improved the mechanical properties of the composites, with bagasse being the most effective agricultural residue. The study's findings suggest that composites made from recycled materials can offer value-added products without sacrificing performance.

Keywords: polymer, composites, wood, nano

Procedia PDF Downloads 70

Authors: Ndidi F. Amulu, Calistus N. Ude, Patrick E. Amulu, Nneka N. Uchegbu

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The effects of temperature and enzyme concentration on the quality of mixed pineapple and pawpaw blended fruits juice were studied. Extracts of the two fruit juices were separately treated at 70  for 15 min each so as to inactivate micro-organisms. They were analyzed and blended in different proportions of 70% pawpaw and 30% pineapple, 60% pawpaw and 40% pineapple, 50% pineapple and 50% pawpaw, 40% pawpaw and 60% pineapple. The characterization of the fresh pawpaw and pineapple juice before blending showed that the juices have good quality. The high water content of the product may have affected the viscosity, vitamin C content and total soluble solid of the blended juice to be low. The effects of the process parameters on the quality showed that better quality of the blended juice can be obtained within the optimum temperature range of (50-70 °C) and enzyme concentration range (0.12-0.18 w/v). The ratio of mix 60% pineapple juice: 40% pawpaw juice has better quality. This showed that pawpaw and pineapple juices can blend effectively to produce a quality juice.

Keywords: clarification, pawpaw, pineapple, viscosity, vitamin C

Procedia PDF Downloads 303

Authors: Băilă Diana Irinel, Păcurar Răzvan, Păcurar Ancuța

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Although the volumes of fibre reinforced polymer composites (FRPs) used for aircraft applications is a relatively small percentage of total use, the materials often find their most sophisticated applications in this industry. In aerospace, the performance criteria placed upon materials can be far greater than in other areas – key aspects are light-weight, high-strength, high-stiffness, and good fatigue resistance. Composites were first used by the military before the technology was applied to commercial planes. Nowadays, composites are widely used, and this has been the result of a gradual direct substitution of metal components followed by the development of integrated composite designs as confidence in FRPs has increased. The airplane uses a range of components made from composites, including the fin and tailplane. In the last years, composite materials are increasingly used in automotive applications due to the improvement of material properties. In the aerospace and automotive sector, the fuel consumption is proportional to the weight of the body of the vehicle. A minimum of 20% of the cost can be saved if it used polymer composites in place of the metal structures and the operating and maintenance costs are alco very low. Glass fiber-epoxy composites are widely used in the making of aircraft and automobile body parts and are not only limited to these fields but also used in ship building, structural applications in civil engineering, pipes for the transport of liquids, electrical insulators in reactors. This article was establish the high-performance of composite material, a type glass-epoxy used in automotive and aeronautic domains, concerning the tensile and flexural tests and SEM analyzes.

Keywords: glass-epoxy composite, traction and flexion tests, SEM analysis, acoustic emission (AE) signals

Procedia PDF Downloads 103

Authors: S. Bouameur, S. Chirani

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The aim of this study was to evaluate the potential use of EthylCellulose in the preparation of microspheres as a Drug Delivery System for sustained release of phenobarbital. The microspheres were prepared by solvent evaporation technique using ethylcellulose as polymer matrix with a ratio 1:2, dichloromethane as solvent and Polyvinyl alcohol 1% as processing medium to solidify the microspheres. Size, shape, drug loading capacity and entrapement efficiency were studied.

Keywords: phenobarbital, microspheres, ethylcellulose, polyvinylacohol

Procedia PDF Downloads 361

Authors: Wei-Chia Huang, Jane Wang

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Damage to nerves is considered one of the most irreversible injuries. The regeneration of nerves has always been an important topic in regenerative medicine. In general, damage to human tissue will naturally repair overtime. However, when the nerves are damaged, healed flesh wound cannot guarantee full restoration to its original function, as truncated nerves are often irreversible. Therefore, the development of treatment methods to successfully guide and accelerate the regeneration of nerves has been highly sought after. In order to induce nerve tissue growth, nerve conduits are commonly used to help reconnect broken nerve bundles to provide protection to the location of the fracture while guiding the growth of the nerve bundles. To prevent the protected tissue from becoming necrotic and to ensure the growth rate, the conduits used are often modified with microstructures or blended with neuron growth factors that may facilitate nerve regeneration. Electrical stimulation is another attempted treatment for medical rehabilitation. With appropriate range of voltages and stimulation frequencies, it has been demonstrated to promote cell proliferation and migration. Biodegradability are critical for medical devices like nerve conduits, while conductive polymers pose great potential toward the differentiation and growth of nerve cells. In this work, biodegradability and conductivity were combined into a novel biodegradable, photocurable, conductive polymer composite materials by embedding conductive nanoparticles in poly(glycerol sebacate) acrylate (PGSA) and 3D-printed into nerve conduits. Rat pheochromocytoma cells and rat neuronal Schwann cells were chosen for the in vitro tests of the conduits and had demonstrate selective growth upon culture in the conductive conduits with built-in microchannels and electrical stimulation.

Keywords: biodegradable polymer, 3d printing, neural regeneration, electrical stimulation

Procedia PDF Downloads 104

Authors: Sapna Bhargav

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Contemporary fiction is an intricate exercise where novelist acquires the role of a philosopher, a sociologist and a psychologist. The dilemma of fragmented self that a man experiences, is a crucial subject of contemporary fiction. Paul Auster's fiction is exemplary of the merger of Existentialism and Postmodernism, and while both of these movements insist on isolation of the self from all aspects of social affiliation, Auster's unique blend of these concepts presents man in a state which is not just alienated, but stranded in a desolate abyss, rendering even the release of death as questionable. The conundrums of the self is a compulsory consequence of the existentialist alienation that postmodern man is subjected to, and is further accentuated by the fact that existentialist freedom dictates that not only are one's actions not dictated by any form of external entity, but also the onus of one's destiny lies on an individual's own deeds. This paper will analyse Auster's The Brooklyn Follies from an Existentialist perspective, and will attempt to trace the alienation and identity conflicts of the Auster’s characters along with some of the common Austerian themes. An emphasis will be laid on the characters’ endeavour to reconstruct their lost self.

Keywords: alienation, existentialism, identity, postmodernism, self

Procedia PDF Downloads 588

Authors: Hyehyeon Lee, Jiwon Yu, Juwon Kim, Raquel Kristina Leoni Tumiar, Taewon Kim, Juae Kim, Hongsuk Suh

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Photovoltaics, which have many advantages in cost, easy processing, and light-weight, have attracted attention. We synthesized pyrimidine-based conjugated polymers with 2-{4-[4,6-bis-(4-hexyl-thiophen-2-yl)-pyrimidin-2-yl]-phenyl}-thiazolo[5,4-b]pyridine (pPTP) which have an ability of powerful electron withdrawing and introduced into the PSCs. By Stille polymerization, we designed the conjugated polymers, pPTPBDT-12, pPTPBDT-EH, pPTPBDTT-EH and pPTPTTI. The HOMO energy levels of four polymers (pPTPBDT-12, pPTPBDT-EH, pPTPBDTT-EH and pPTPTTI) were at -5.61 ~ -5.89 eV, their LUMO (Lowest Unoccupied Molecular Orbital) energy levels were at -3.95 ~ -4.09 eV. The device including pPTPBDT-12 and PC71BM (1:2) indicated a V_oc of 0.67 V, a J_sc of 1.33 mA/cm², and a fill factor (FF) of 0.25, giving a power conversion efficiency (PCE) of 0.23%. The device including pPTPBDT-EH and PC71BM (1:2) indicated a V_oc of 0.72 V, a J_sc of 2.56 mA/cm², and a fill factor (FF) of 0.30, giving a power conversion efficiency of 0.56%. The device including pPTPBDTT-EH and PC71BM (1:2) indicated a V_oc of 0.72 V, a J_sc of 3.61 mA/cm², and a fill factor (FF) of 0.29, giving a power conversion efficiency of 0.74%. The device including pPTPTTI and PC71BM (1:2) indicated a V_oc of 0.83 V, a J_sc of 4.41 mA/cm², and a fill factor (FF) of 0.31, giving a power conversion efficiency of 1.13%. Therefore, pPTPBDT-12, pPTPBDT-EH, pPTPBDTT-EH, and pPTPTTI were synthesized by Stille polymerization. And We find one of the best efficiency for these polymers, called pPTPTTI. Their optical properties were measured and the results show that pyrimidine-based polymers especially like pPTPTTI have a great promise to act as the donor of the active layer.

Keywords: polymer solar cells, pyrimidine-based polymers, photovoltaics, conjugated polymer

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Authors: Parastou Kharazmi

Abstract:

Degradation of building materials particularly pipelines causes environmental damage during renovation or replacement and is a time consuming and costly process. Rehabilitation by polymer composites is a solution for renovation of degraded pipeline in heritage buildings and other structures which are less costly, faster and causes less damage to the environment; however, it is still not clear for how long these materials can perform as expected in the field and working condition. To study their service life, two types of composites based on Epoxy and Polyester resins have been evaluated by accelerated exposure and field exposure. The primary degradation agent used in accelerated exposure has been cycling temperature with half of the tests performed in presence of water. Thin films of materials used in accelerated testing were prepared in laboratory by using the same amount of material as well as technique of multi-layers application used in majority of the field installations. Extreme intensity levels of degradation agents have been used only to evaluate materials properties and as also mentioned in ISO 15686, are not directly correlated with degradation mechanisms that would be experienced in service. In the field exposure study, the focus has been to identify possible failure modes, causes, and effects. In field exposure, it has been observed that there are other degradation agents present which can be investigated further such as presence of contaminants and rust before application which prevents formation of a uniform layer of polymer or incompatibility between dissimilar materials. This part of the study also highlighted the importance of application’s quality of the materials in the field for providing the expected performance and service life. Results from extended accelerated exposure and field exposure can help in choosing inspection techniques, establishing the primary degradation agents and can be used for ageing exposure programs with clarifying relationship between different exposure periods and sites.

Keywords: building, renovation, service life, pipelines

Procedia PDF Downloads 188