Articoli di riviste: "MICROBALLOONS"

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Dando, Kerrick R., William M. Cross, Marc J. Robinson e David R. Salem. "Characterization of mixture epoxy syntactic foams highly loaded with thermoplastic and glass microballoons". Journal of Composite Materials 53, n. 13 (27 novembre 2018): 1737–49. http://dx.doi.org/10.1177/0021998318810782.

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Syntactic foams comprising glass or thermoplastic microballoons have gained considerable attention in recent years due to mechanical and thermal properties that are advantageous for naval and aerospace applications. This work reports a method for producing syntactic foams with unusually high-volume fraction microballoon loadings (>0.74) and its utilization for the creation of “hybrid” epoxy resin-based syntactic foams comprising various mixtures of glass and thermoplastic microballoons. Microstructural analyses using X-ray micro-computed tomography provided non-destructive quantitative characterization of microballoon packing, confirming the high loading levels suggested by density measurements. By systematically varying the glass/thermoplastic microballoon ratio, it was shown that a range of mechanical properties can be engineered into these lightweight materials. The peak impact force of these syntactic foams can be significantly reduced (∼30% reduction) through combining glass and thermoplastic microballoons in a ratio where the thermoplastic microballoons are the dominant fraction but not the sole microballoon component.

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Ullas, A. V., Devendra Kumar e Prasun Kumar Roy. "Epoxy-Glass Microballoon Syntactic Foams: Rheological Optimization of the Processing Window". Advances in Polymer Technology 2019 (1 aprile 2019): 1–12. http://dx.doi.org/10.1155/2019/9180302.

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In this paper, we discuss the chemorheology of epoxy based syntactic foams containing glass microballoons of varying density, with an aim of establishing the effect of microballoon loading on its processability. The primary objective is to determine the maximum microballoon loading that disperses uniformly in the resin without the aid of any diluent. The viscosity and dynamic mechanical properties of epoxy formulations containing varying amounts of glass microballoons were established by parallel plate rheometry. Our studies reveal that solventless processing of formulations with microballoon loading > 60% poses practical difficulties due to prohibitively high viscosities, although a packing efficiency of 74% is theoretically allowed in the case of hexagonal close packing. The presence of microballoons does not alter the curing mechanism. The mechanical properties of syntactic foams were inversely proportional to the loading and type of glass microballoons.

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Dando, Kerrick R., William M. Cross, Marc J. Robinson e David R. Salem. "Production and characterization of epoxy syntactic foams highly loaded with thermoplastic microballoons". Journal of Cellular Plastics 54, n. 3 (23 marzo 2017): 499–514. http://dx.doi.org/10.1177/0021955x17700093.

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Glass microballoon syntactic foams consisting of 60–70 vol% hollow glass microballoons and epoxy resin matrix have gained considerable attention in recent years due to their unique combination of mechanical properties and low density, with applications in the naval and aerospace industries. An important limitation of these materials is the volume fraction ceiling (∼0.74) and subsequent density limit (0.36 g/cm3). Utilizing thermoplastic microballoons, syntactic foams were produced with densities as low as 0.067 g/cm3, achieved by developing a method that produces epoxy/microballoon compositions comprising an unusually high volume fraction of microballoons (0.75–0.95). The resulting morphology features microballoons which, having expanded in a restricted volume, are deformed into irregular shapes that efficiently pack together and are encapsulated by a thin coating of epoxy. The compressive yield strength, tensile strength and initial modulus of these highly loaded syntactic foams exhibit a non-linear decrease with increasing microballoon volume fraction to values typical of highly porous polymers, but display a high degree of recovery, or rebound, from large compressive strain compared with glass microballoon syntactic foams.

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Kannan, Sathish, Salman Pervaiz, Abdulla Alhourani, Robert J. Klassen, Rajiv Selvam e Meysam Haghshenas. "On the Role of Hollow Aluminium Oxide Microballoons during Machining of AZ31 Magnesium Syntactic Foam". Materials 13, n. 16 (11 agosto 2020): 3534. http://dx.doi.org/10.3390/ma13163534.

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The role played by hollow ceramic thin-walled aluminium oxide microballoons on the shear deformation characteristics of AZ31 Magnesium syntactic foam is studied through high-speed machining. The ceramic microballoons embedded in the AZ31 matrix provides the necessary stiffness for these novel foams. The effect of hollow ceramic microballoon properties, such as the volume fraction, thin wall thickness to diameter ratio, and microballoon diameter, profoundly affects the chip formation. A novel force model has been proposed to explain the causes of variation in cutting forces during chip formation. The results showed an increase in machining forces during cutting AZ31 foams dispersed with higher volume fraction and finer microballoons. At a lower (Davg/h) ratio, the mode of microballoon deformation was a combination of bubble burst and fracture through an effective load transfer mechanism with the plastic AZ31 Mg matrix. The developed force model explained the key role played by AZ31 matrix/alumina microballoon on tool surface friction and showed a better agreement with measured machining forces.

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Zhi, Chao, e Hairu Long. "Flexural Properties of Syntactic foam Reinforced by Warp Knitted Spacer Fabric". Autex Research Journal 16, n. 2 (1 giugno 2016): 57–66. http://dx.doi.org/10.1515/aut-2015-0028.

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Abstract The aim of this study was to investigate the flexural behaviours of syntactic foam reinforced by warp knitted spacer fabric (SF-WKSF). Seven kinds of SF-WKSF samples were fabricated by warp knitted spacer fabric (WKSF) with structural parameters including surface layer structures, inclination-angle and fineness of spacer yarns, different microballoons types and contents. The flexural tests were carried out and the bending properties of SF-WKSF were analysed based on the strength and modulus values obtained from the test results. It is indicated that the SF-WKSF shows higher flexural strength and modulus compared to neat syntactic foam with almost no impact on the density of composites. The results also demonstrate that the surface layer structure, inclination-angle of spacer yarns, microballons content and type have significant effects on the flexural responses of SF-WKSF. The composites exhibit better antibending capacities by selecting larger inclination-angle, closer surface layer structure, higher density and relatively higher content of S60HS microballoons.

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Rafeichik, Sergey. "Dependence of Critical Diameter of Emulsion Explosive on Density in Steel Confinement". Siberian Journal of Physics 8, n. 3 (1 ottobre 2013): 128–34. http://dx.doi.org/10.54362/1818-7919-2013-8-3-128-134.

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Emulsion explosives (EMX) based on fine emulsion matrix are characterized by high detonation ability. Critical diameter (as minimum diameter when detonation occurs) and reaction zone length are known in the case of thin confinement with low acoustic impedance. The dependence of critical diameter of EMX in steel confinement with high acoustic impedance was examined in the range of initial density 0,75–1,37 g/cm3 . Density was varied by the concentration of glass microballoons, which were used as the sensitizer. It was shown experimentally, that characteristic value is /2 1 cr R d a  in the case of strong confinement. This can be due to the decrease of detonation front curvature. Comparison was made between the values of critical diameter in weak and strong confinement. The main distinction is that such dependence in strong confinement is lower and almost monotonic. This can indicate the influence of some processes besides lateral rarefaction wave. Period of reaction is closely connected with critical diameter and reaction zone length. Model based on heterogeneous kinetic of heating of emulsion surrounding single microballoon was proposed to describe the experimental dependence of the reaction zone time of EMX on concentration of microballons

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7

Srivastava, Ankita, Ruchi Shukla, Kusum Sharma, Hitesh Jain e D. B. Meshram. "Microballoons: A Gastro Retentive Drug Delivery System". Journal of Drug Delivery and Therapeutics 9, n. 4-s (15 agosto 2019): 625–30. http://dx.doi.org/10.22270/jddt.v9i4-s.3274.

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Oral route is most preferable and widely used route for the administration of drug. Microballoons becomes novel technology in pharmaceutical field in the floating drug delivery for achieving the gastric retention. Microballoons are also called as hollowspheres which are porous smooth in nature and thus show good floating properties in gastric fluid. Microballoons release the drug in controlled manner at the targeted site. Microballoons are spherical empty vesicles without core and that can remain buoyant in gastric region for prolong period of time without irritation in gastrointestinal tract. Multiparticulate particles having a low density system that can efficiently prolong the gastric retention time of the drugs, thus enhanced bioavailability and thus improve the dosing frequency. These are less soluble at higher pH environment. As microballoons delivery systems provide longer retention in gastric pH and enhance the solubility of drugs that are less soluble in high pH environment. The formation of cavity inside the microballoons depend on the preparation, temperature and the surface smoothness determine the floatability and the release rate of microballoons. Keywords: Microballoons, Gastro retentive drug delivery system, Hollowspheres, Controlled release

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8

John, Bibin, C. P. Reghunadhan Nair e K. N. Ninan. "Low-Density Phenolic Syntactic Foams: Processing and Properties". Cellular Polymers 26, n. 4 (luglio 2007): 229–44. http://dx.doi.org/10.1177/026248930702600401.

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Low-density phenolic syntactic foams with different volume percentages of microballoons were processed and their mechanical performance has been evaluated in terms of tensile, flexural, compressive and the corresponding specific properties. Tensile and flexural strength increased with volume fraction of microballoon and optimized at 72–74 percentage by volume of microballoon. Both the properties decreased with further addition of microballoon. The corresponding specific properties also manifested a similar order. Compressive and specific compressive strength decreased with increase in microballoon volume percentage. The flexural and compressive modulus values followed the same trend as the strength values. The properties of phenolic syntactic foams were compared with syntactic foams based on an addition cure phenolic resin, Propargyl Ether Novolac resin (PN). The mechanical properties of the latter were inferior to those of phenolic syntactic foams. The morphology of the failed samples as examined by SEM showed that failure occurred by a combination of matrix and microballoon failure at low microballoon loading whereas it occurred by microballoon cracking and resin to microballoon debonding at high concentration of filler. The dynamic mechanical analysis of phenolic and PN resin syntactic foams showed a higher use temperature for PN system in comparison to phenolic.

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Ferreira, S. C., Alexandre Velhinho, L. A. Rocha e Francisco Manuel Braz Fernandes. "Microstructure Characterization of Aluminium Syntactic Functionally Graded Composites Containing Hollow Ceramic Microspheres Manufactured by Radial Centrifugal Casting". Materials Science Forum 587-588 (giugno 2008): 207–11. http://dx.doi.org/10.4028/www.scientific.net/msf.587-588.207.

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Syntactic functionally graded metal matrix composites (SFGMMC) are a class of metallic foams in which closed porosity results from the presence of hollow ceramic microspheres (microballoons), whose spatial distribution varies continuously between the inner and the outer section of the part, thus resulting in a continuous variation in properties. In this work, aluminiumbased SFGMMC rings were fabricated by radial centrifugal casting. The graded composition along the radial direction is controlled mainly by the difference in the centrifugal forces which act on the molten metal matrix and the ceramic particles, due to their dissimilar densities. In this case where the density of the SiO2-Al2O3 microballoons is lower than that of molten aluminium, the particles show a tendency to remain closer to the inner periphery of the ring. Thus the microballoon volume fraction increases along the radial direction of the ring from the outer to the inner periphery; in other words, the particle-rich zone is limited to an inner layer of the ring. Precursor conventional MMCs were prepared by stir-casting from the constituent materials, by homogeneously dispersing commercial SiO2-Al2O3 microballoons (particle size: 50 µm; particle volume fraction: 5 and 10 %) within a molten commercial Al-7Si-0.3Mg (A356) alloy. The resulting MMCs were then re-melt and centrifugally cast in order to produce the functionally graded composites. Particle gradients in the centrifugally cast composites were investigated by quantitative image analysis of optical micrographs (for the estimation of the particle volume fraction, mean particle diameter and porosity volume fraction).

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Penjuri, S. C. B., R. Nagaraju, S. Shaik, S. Damineni e S. R. Poreddy. "GASTRORETENTIVE MICROBALLOONS OF RIBOFLAVIN: FORMULATION AND EVALUATION". INDIAN DRUGS 54, n. 04 (28 aprile 2017): 47–52. http://dx.doi.org/10.53879/id.54.04.10708.

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Gastroretentive dosage forms are useful to extend release of drugs having a narrow window of absorption in the upper intestine and for drugs degraded by higher pH or for drugs with local action in the proximal part of the GI tract. In the present study, an attempt was made to prepare microballoons of riboflavin by emulsion solvent diffusion method by using HPMC and ethylcellulose in order to extend the drug release in the upper GIT, which may result in enhanced absorption and thereby improved bioavailability. The size and surface morphology of riboflavin microballoons were characterized by optical and scanning electron microscopy. FTIR and DSC studies revealed no drug excipient interaction. Average particle size of microballoons was found to be between 126.8±2.26 to 163.4±2.52 μm. Microballoons were found to be spherical in shape with smooth surface texture. Percentage yield of the microballoons was satisfactory. In vitro buoyancy of the optimized riboflavin microballoons was found to be 96.24±0.08%, indicating good floating in stomach. Cumulative amount of drug release from microballoons at the end of 12 hr was 99.78±2.78 % and followed Highuchi diffusion kinetics and super case II transport.

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Negia, Rakhi, Laxmi Goswamia e Preeti Kothiyal. "Microballoons: A better approach for gastro retention". Indian Journal of Pharmaceutical and Biological Research 2, n. 02 (30 giugno 2014): 100–107. http://dx.doi.org/10.30750/ijpbr.2.2.17.

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The purpose of this review is to accumulate the recent study on floating drug delivery system with special emphasis on microballoons as drug delivery. Microballoons are emerging as the most promising drug delivery as it overcome many limitations of conventional drug delivery system. As microballoons delivery system provides longer retention in gastric pH, hence longer is the residence time and therefore enhance the solubility of drugs that are less soluble in high pH environment. The formation of cavity inside the microsphere depends upon the preparation temperature and the surface smoothness determines the floatability and the drug release rate of the microballoons. The review includes the classification, advantages, disadvantages, method of preparation and future aspects of microballoons. Basic anatomy and physiology of stomach is also studied.

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Manivannan, Subramanian, Akshay M, Bhuvaneswari S e Nify F. "FORMULATION AND EVALUATION OF GASTRORETENTIVE MICROBALLOONS OF ACEBROPHYLLINE FOR THE TREATMENT OF BRONCHIAL ASTHMA". Asian Journal of Pharmaceutical and Clinical Research 9, n. 5 (1 settembre 2016): 105. http://dx.doi.org/10.22159/ajpcr.2016.v9i5.12603.

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ABSTRACTObjective: Gastroretentive dosage forms are an approach for prolonged and predictable drug delivery in the upper gastrointestinal tract to controlthe gastric residence time. Microballoons are considered as one of the most promising buoyant drug delivery systems as they possess the advantagesof both multiple-unit systems and good floating properties. Acebrophylline is a xanthine derivative with potent bronchodilator, mucosecretolytic, andanti-inflammatory property. It is used to treat bronchial asthma and chronic obstructive pulmonary diseases.Methods: Microballoons of acebrophylline were prepared by emulsion solvent diffusion method using hydroxypropyl methylcellulose (HPMC) andethyl cellulose (EC) as polymer. The microballoons were evaluated with their micromeritic properties, particle size, tapped density, compressibilityindex, angle of repose, percentage yield, in vitro buoyancy, entrapment efficiency, drug-polymer compatibility, scanning electron microscopy (SEM),and drug release kinetics.Results: The mean particle size of the microballoons formulation MB1 to MB6 containing HPMC and EC was in the range between 226±16 and 577±10,respectively. The mean particle size of microballoons was found to increase with increasing polymer concentration. The micromeritic properties werefound be good, and SEM confirmed their hollow structure with smooth and dense which helped to prolong floating to increase residence time instomach. The in vitro drug release studies showed controlled release of acebrophylline microballoons in the simulated gastric fluid more than 12 hrs.Conclusions: The results showed that the prepared floating microballoons of acebrophylline prove to be potential multiple-unit delivery devicesadaptable for safe and effective sustained drug delivery.Keywords: Microballoons, Acebrophylline, Bronchial asthma, Hydroxypropyl methylcellulose, Ethyl cellulose.

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Pandey, Chandra Prakash, e ,. Archana. "Development and Evaluation of Gastro Retentive Mucoadhesive Microballoons of Esomeprazole to Treat Peptic Ulcer". Journal of Drug Delivery and Therapeutics 12, n. 4-S (25 agosto 2022): 128–39. http://dx.doi.org/10.22270/jddt.v12i4-s.5552.

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The Gastro-retentive medication delivery method may increase patient compliance by lowering drug plasma level fluctuations1. The absorption maxima (max) of esomeprazole magnesium in 0.1 N HCl solution were found to be at 291 nm. Correlation coefficient values better than 0.99 suggest that the calibration curves provide strong linearity data. The results showed that the medication was soluble in 0.1 N HCl and had the maximum solubility in water. Magnesium esomeprazole was found to have a partition coefficient of (0.2442). The prepared mucoadhesive microballons percentage yield was calculated, with a range of 88.2 to 96.5 percent. The shape and surface morphology of produced mucoadhesive microballons photographed using a scanning electron microscope. The effectiveness of drug entrapment was in the region of 81.71 % - 93.51 % . The swelling rate and percent mucoadhesion of Esomeprazole Magnesium mucoadhesive microballons ranged from 75.63 percent to 88.64 percent. The in-vitro buoyancy % of mucoadhesive microballons used to determine the floating ability of all formulations. All of the developed formulations were floated for at least 7 to 12 hours. The best formulations incorporate naturally occurring polysaccharide polymeric blends as Drug: HPMC: Carbopol 934 (1:1:1) that release more than 98.13 percent of the drug in a regulated and sustained manner in the stomach environment for up to 24 hours. Keywords: Gastroretention, mucoadhesive microballoons, Esomeprazole, HPMC, Carbopol

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Hajare, Pranit P., e Punit R. Rachh. "FORMULATION AND DEVELOPMENT OF NOVEL GASTRORETENTIVE MICROBALLOONS OF REPAGLINIDE". Journal of Advanced Scientific Research 12, n. 04 Suppl 1 (31 dicembre 2021): 193–204. http://dx.doi.org/10.55218/jasr.s1202112421.

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The present study involves preparation and evaluation of Microballoons of Repaglinide which is having poor solubility in water and low oral bioavailability. Repaglinide, an oral hypoglycemic agent, is rapidly absorbed and eliminated from the body after oral administration. The peak plasma level occurs within an hour of oral administration with elimination half life of 1 hr. The objective of the present work is to prepare floating microballoons of Repaglinide for delivering the drug in controlled manner which will help to reduce dosing frequency and maintain the plasma concentration of drug for longer time without fluctuations. This will be helpful in having better control over clinical maintenance of the type 2 diabetic condition. The Microballoons were prepared by solvent evaporation emulsification technique using Sodium Alginate as coating agent and Calcium Chloride as cross-linking agent. The formation of spherical and hollow Microballoons was confirmed by SEM studies ranging from 220 to 310 μm. The percentage of drug entrapment was found to be 70-80%. The Micromeritic properties indicated better flowability of the spheres. The Buoyancy test showed good floatability for more than 12 hrs. Formulation B5, C5 and D3 showed higher buoyant percentage after 12 hours and percentage yield. Microballoons of Repaglinide were designed to increase the Solubility, Bioavliability and to improve the patient compliance. The microballoons with the smaller particle size enhanced the in vitro drug release of the Repaglinide. Thus, microballoons approach may be a promising carrier for Repaglinide and other BCS class II drugs.

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Chen, Zhuo, Zhi Xiong Huang, Yan Qin, Min Xian Shi, Qi Lin Mei e Ming Zhang. "Effect of Glass Microballoons Size on Compressive Strength of Syntactic Foams". Advanced Materials Research 321 (agosto 2011): 7–10. http://dx.doi.org/10.4028/www.scientific.net/amr.321.7.

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In this work, syntactic foams made of microballoons having same wall thickness ratio but with different particle size was prepared. Microballoons of three size distribution ranges were selected .The property of the syntactic foams were studied by quasi-static compression test. The experimental results show the microballoons size doesn’t influent the mechanical properties of the syntactic foam significantly. The failure mode of the syntactic foams was also studied in this work.

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Mae, Hiroyuki, Masaki Omiya e Kikuo Kishimoto. "Dynamic Mechanical Properties of Polypropylene Syntactic Foam with Polymer Microballoons". Applied Mechanics and Materials 7-8 (agosto 2007): 289–94. http://dx.doi.org/10.4028/www.scientific.net/amm.7-8.289.

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The main objective of this study is to measure and characterize the mechanical properties of the thermoplastic syntactic foams at the intermediate and high strain rates. The syntactic foam consists of the elastically deformable microballoons in the polypropylene matrix. The four types of syntactic foams and one polypropylene bulk specimen are prepared at same manufacturing process: 0, 20, 30, 40 and 50 volume percent of microballoons. Tensile tests are conducted at nominal strain rates ranging from 10-1 to 102 (1/sec). Elastic modulus, yield stress and rupture strain are measured and the effects of microballoons on the mechanical properties are studied. In addition, fracture surfaces are observed with ESEM (Environmental Scanning Electron Microscopy). Finally, the changes of fracture mode due to microballoons are discussed.

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Kaneko, Katsumi, Hiroshi Isobe, Takamine Katori, Ichiro Tokunaga, Takashi Gouda, Takaomi Suzuki, Sumio Ozeki e Kouji Okuda. "Microporous silica microballoons". Colloids and Surfaces A: Physicochemical and Engineering Aspects 74, n. 1 (luglio 1993): 47–55. http://dx.doi.org/10.1016/0927-7757(93)80397-w.

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Isobe, Hiroshi, Ichiro Tokunaga, Noriyoshi Nagai e Katsumi Kaneko. "Characterization of hydrated silicate glass microballoons". Journal of Materials Research 11, n. 11 (novembre 1996): 2908–15. http://dx.doi.org/10.1557/jmr.1996.0368.

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Glass microballoons (GB) of about 1 μm in diameter were prepared by ultrasonic spray pyrolysis from sodium silicate solution. A silica-rich type of glass microballoons (SB) was prepared by acid treatment of GB. The structural changes of both microballoons with thermal treatment up to 973 K were examined. Both GB and SB showed properties similar to hydrated sodium silicate glass, to some extent. SB was more thermally stable than GB, but the spherical structures of both microballoons were collapsed by heating at 973 K; cristobalite was observed in samples heated at 973 K. The loosely and tightly incorporated water molecules evolved up to 573 K and near 850 K, respectively. The crystallization of cristobalite caused tightly incorporated water molecules to develop. The ultramicropores accessible only to H2O molecules in SB gradually decreased by heating and disappeared by heating at 773 K.

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Salleh, Z., M. M. Islam, J. A. Epaarachchi e M. T. I. Khan. "Thermo-mechanical properties of fused borosilicate syntactic foams". Journal of Mechanical Engineering and Sciences 13, n. 2 (28 giugno 2019): 4898–910. http://dx.doi.org/10.15282/jmes.13.2.2019.10.0407.

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The coefficient thermal expansion, a (CTE) of glass microballoon/vinyl ester syntactic foam was determined using dimensional changes of a temperature gradient plot. The CTE was measured and found to be up to 53-63 % lower than the vinyl ester resin matrix when mixing with different weight percentages of the glass microballoon ranging from 2 wt.% to 10 wt.% using a thermomechanical analyzer (TMA). The results of CTE showed that it has a strong relationship with the syntactic foam density (r), radius ration (h) ,cavity porosity (fg) and matrix porosity (fm). Experimental results showed that the CTE decreases when glass microballoons are added into the composites measured at different temperatures ranging from 30 oC to 70 °C. The CTE from the experimental results were also compared with Turner’s modification model for composites for its suitability for thermal expansion of syntactic foams. The results indicate that Turner’s modification model exhibits a close correlation with the reduction up to 80 % of CTE based on experiment.

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R. Lankapalli, Sasidhar, Vidyadhara Suryadevara, Sowjanya L. Battula e Ramu Anne. "DEVELOPMENT AND EVALUATION OF CAPTOPRIL CONTROLLED RELEASE FLOATING MICROBALLOONS". Indian Drugs 59, n. 08 (16 settembre 2022): 31–38. http://dx.doi.org/10.53879/id.59.08.11130.

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The objective of the present study was to develop floating microballoons of captopril in order to achieve an extended gastric retention in the upper GIT which may enhance the absorption and improve bioavailability. The floating microballoons were formulated with calcium silicate as porous carrier, Eudragit L100 and ethyl cellulose 7 cps as coating polymers and captopril as model drug. The prepared microballoons were evaluated for particle size, angle of repose, Carr’s index, buoyancy studies, drug content and for in vitro drug release. Based upon the dissolution data obtained and various physical parameters evaluated, formulation containing drug to polymer ratio at 1:9 was optimised and further trials were carried out by changing the parameters like temperature, rpm and surfactant concentration to obtain more uniform and stable microballoons. In the optimized formulation, the drug release form was at a steady state manner when compared to the other formulations. The floating drug delivery system of captopril is a promising alternative way of achieving prolonged release with potential for achieving enhanced absorption and bioavailability.

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Dando, Kerrick R., e David R. Salem. "The effect of nano-additive reinforcements on thermoplastic microballoon epoxy syntactic foam mechanical properties". Journal of Composite Materials 52, n. 7 (21 giugno 2017): 971–80. http://dx.doi.org/10.1177/0021998317716267.

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Syntactic foams comprising glass microballoons have gained considerable attention over the past several years due to mechanical and thermal properties that are advantageous for use as a core material in naval and aerospace applications. Recent advancements in the production of thermoplastic microballoon syntactic foams have allowed for an increase in microballoon volume fraction (up to 0.9 volume fraction), with correspondingly lower densities but reduced mechanical properties. In this work, carbon nanofibers and halloysite nanotubes were incorporated in thermoplastic microballoon-based syntactic foam to enhance the mechanical properties and the relative effects of these two nanoscale reinforcements were compared. X-ray micro-computed tomography was employed to analyze the microstructure of the materials produced, and scanning electron microscopy was used to assess the dispersion of nano-additives within the resin. Compressive strength and modulus enhancements as large as 180% and 250% respectively were achieved with a 0.25 wt% addition of carbon nanofiber and increases of 165% and 244% respectively were achieved with a 0.5 wt% addition of halloysite nanotube. Tensile strength and modulus enhancements as large as 110% and 165% respectively were achieved with a 0.125 wt% addition of carbon nanofiber and increases of 133% and 173% respectively were achieved with a 0.125 wt% addition of halloysite nanotube.

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Singh, Rajan, Gaurav Kumar, Harsh Sachan e Avadesh K. Sharma. "Synthesis and Characterization of Syntacticfoam". International Journal of Engineering Research in Mechanical and Civil Engineering (IJERMCE) 9, n. 7 (13 luglio 2022): 30–32. http://dx.doi.org/10.36647/ijermce/09.07.a007.

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'syntactic' means 'putting together'. A composite material synthesized by putting a metal or polymer or a ceramic matrix with hollow spheres (microballoons). This composite material known as syntactic foam. It is used in the field where weight is a constrain as well as it is used for the purpose of energy absorption and for the purpose of heat resistant. Submarines, aircrafts where weight is constrained but also energy absorption capability of the material is a necessity factor. Microballoons have a drawback of low mechanical properties, so to overcame this limitation microballoons are filled with filler materials. This project focuses on the study of different syntactic foam and todetermine their behaviour and characteristics. Also find the different mechanical properties (stress,strain,fracture point, yield).

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Malik, Prashant, Upendra Nagaich, Raj Kaur Malik e Neha Gulati. "Pentoxifylline Loaded Floating Microballoons: Design, Development and Characterization". Journal of Pharmaceutics 2013 (9 maggio 2013): 1–5. http://dx.doi.org/10.1155/2013/107291.

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The floating microballoons have been utilized to obtain prolonged and uniform release in the stomach. The objective of the present study involves design, development, and characterization of pentoxifylline loaded floating microballoons to prolong their gastric residence time. Pentoxifylline (trisubstituted xanthine derivative) loaded microballoons were prepared by the solvent evaporation technique using different concentrations of polymers like HPMC K4M and ethyl cellulose (EC) in ethyl alcohol and dichloromethane organic solvent system. Microballoons were characterized for their particle size, surface morphology, production yield, loading efficiency, buoyancy percentage, and in vitro drug release studies. From the characterization it was observed that increases in amount of polymers (HPMC K4M and EC) led to increased particle size, loading efficiency, and buoyancy percentage, and retarded drug release. The particle size, particle yield, loading efficiency, buoyancy percentage and in vitro drug release for optimized formulation (F3) were found to be 104.0±2.87 µm, 80.89±2.24%, 77.85±0.61%, 77.52±2.04%, and 82.21±1.29%, respectively. The data was fitted to different kinetic models to illustrate its anomalous (non-Fickian) diffusion. The in vitro result showed that formulations comprised of varying concentrations of ethyl cellulose in higher proportion exhibited much retarded drug release as compared to formulations comprised of higher proportion of varying concentrations of HPMC K4M.

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Chen, Zhuo, Yan Qin, Zhi Xiong Huang, Qiang Shen e Lian Meng Zhang. "Preparation and Characterization of Novel Functional Gradient Syntactic Foam". Advanced Materials Research 66 (aprile 2009): 284–87. http://dx.doi.org/10.4028/www.scientific.net/amr.66.284.

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Low density syntactic foam monolayer slices, which were made of epoxy resin matrix and plastic microballoons (MB), were fabricated by rolling process with thickness controlled at 200μm. Density of monolayer slice ranges from 0.500g/cm3 to 0.996g/cm3 and it is designed to fit power law equation. The volume percentage of plastic microballoons in the monolayer pellets varies from 16.61% to 58.06%. The slices were characterized by optical and scanning electron microscopy, and measurement of density and sound wave velocity. The density, glass transition temperature and acoustic impedance were observed to vary with the volume percentage of plastic microballoons in the composite. Graded syntactic foams were fabricated by stacking slices of different density in a sequence of density gradient and the slices were bound together with adhesive made of epoxy resin-hardener under the pressure of 5MPa.

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25

Salleh, Zulzamri, Md Mainul Islam e Jayantha Ananda Epaarachchi. "Thermal Expansion Properties of Fused Borosilicate Syntactic Foams". Nano Hybrids and Composites 23 (dicembre 2018): 39–45. http://dx.doi.org/10.4028/www.scientific.net/nhc.23.39.

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The thermal properties such the coefficient thermal expansion, α (CTE) of fused borosilicate syntactic foam was determined using dimensional changes of a temperature gradient plot. The CTE was measured and found to be achieved the value lower than the vinyl ester resin matrix when mixing with different weight percentages of the glass microballoon ranging from 2 wt.% to 10 wt.% using a thermomechanical analyzer (TMA). These results showed that it has a strong relationship with the syntactic foam physical properties such density, radius ration,cavity porosity and matrix porosity. Experimental results showed that the CTE decreases when glass microballoons are added into the composites measured at different temperatures ranging from 30 °C to 70 °C. The CTE from the experimental results were also analysed using Turner’s modification model for composites for its suitability for thermal expansion of syntactic foams.

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26

Wang, En Yang, e Masaki Omiya. "A Microscopic Study on Local Strain Rate Sensitivity of Polypropylene Syntactic Foam with Microballoons". Advanced Materials Research 160-162 (novembre 2010): 1280–84. http://dx.doi.org/10.4028/www.scientific.net/amr.160-162.1280.

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27

Ghosh, Bijaya, Arka Chatterjee, Moumita Das Kirtania e Sankha Chattopadhyay. "Development of Cinnarizine Microballoons by Sequential Optimization and In Vivo Imaging by Gamma Scintigraphy". Current Drug Therapy 15, n. 4 (30 novembre 2020): 369–80. http://dx.doi.org/10.2174/1574885514666191119105908.

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Abstract (sommario):

Background: The drug cinnarizine is used in the treatment of vertigo and migraine. The main drawback is its very low water solubility which causes unpredictable bioavailability. Solubility is better in acidic pH. Therefore, gastro-retentive formulation would be beneficial to improve the bioavailability of the drug. Objective: The objective of the study was to prepare floating microballoons of cinnarizine which would float in the gastric fluid and release the drug in a sustained manner. Methods: Microballoons were prepared by diffusion solvent evaporation technique using polymers (Eudragit® S100, Eudragit® RLPO, Eudragit RL®100), characterised by FTIR, XRD, DSC and optimized by sequential simplex design. For optimization, formulations were graded with respect to formulation efficiency (percentages of yield, sphericity and drug content) and performance index (buoyancy and dissolution efficiency), from which the overall response of the formulations was determined. Finally, the optimized formulation was radiolabelled with 99mTc-MIBI and fed to Wistar albino rats and was evaluated for gastric retention by gamma scintigraphic study. Results: FTIR studies indicated drug and polymers were compatible. DSC and XRD analysis confirmed that the drug was in amorphous state in the formulation. SEM studies confirmed the sphericity of the microballoons. Formulation N7 showed the best overall response (65.61) which was the nearest to the target. Gamma scintigraphic study confirmed that the formulation was retained in the stomach for more than 5 h. Conclusion: The results indicated that floating microballoons of cinnarizine would stay in the stomach for prolonged period and thereby improve the bioavailability of the drug.

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28

Piriz, A. R., G. E. Giudice e J. G. Wouchuk. "Laser implosion of gas‐filled microballoons". Physics of Fluids B: Plasma Physics 4, n. 3 (marzo 1992): 693–700. http://dx.doi.org/10.1063/1.860267.

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29

SCHNEIDER, MICHEL, PHILIPPE BUSSAT, MARIE-BERNADETTE BARRAU, MARCEL ARDIT, FENG YAN e EVA HYBL. "Polymeric Microballoons as Ultrasound Contrast Agents". Investigative Radiology 27, n. 2 (febbraio 1992): 134–39. http://dx.doi.org/10.1097/00004424-199202000-00008.

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30

Prussin, S. G., S. M. Lane, M. C. Richardson e S. G. Noyes. "Debris collection from implosion of microballoons". Review of Scientific Instruments 57, n. 8 (agosto 1986): 1734–36. http://dx.doi.org/10.1063/1.1139165.

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31

Garçonnet, J.-P., O. Delage, D. Schirmann, A. Bertin, G. Grenier, B. Guilpart e A. Rouyer. "Neutron penumbral imaging of inertial confinement fusion targets". Laser and Particle Beams 12, n. 3 (settembre 1994): 563–71. http://dx.doi.org/10.1017/s0263034600008429.

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Abstract (sommario):

The first 14-MeV neutron images of imploded microballoons have been obtained on the Phébus laser facility at CEL-V. The sizes of the source have been measured, in direct-drive experiments, by means of a coded-aperture imaging system. The principle is to use a thick aperture with a diameter larger than that of the source to image the microballoon. The deconvolution of the recorded image allows one to reconstruct the image of the neutron source, and this technique allows one to obtain images at a lower neutron yield than with a conventional pinhole camera. The choice of the experimental conditions is a trade-off between the Phébus conditions, the spatial resolution, and the image reconstruction method that is related to the signalto-noise ratio. The sensitivity of the diagnostic is strongly dependent on the number of scintillator photons that are collected by the recording system. The neutron measurement threshold of our experimental setup is typically 2 × 1010 neutrons/shot for neutron source sizes of 800 μm.

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32

Gomathi, J., T. Muthukumaran, Kavitha C, Priyanka Sinha e Sabbathyan Balla. "Formulation and In- Vitro Evaluation of Baclofen Gastroretentive Microballoons for Sustained Drug Delivery". International Journal for Research in Applied Science and Engineering Technology 10, n. 9 (30 settembre 2022): 1322–29. http://dx.doi.org/10.22214/ijraset.2022.46820.

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Abstract: A sustained release drug delivery system for baclofen was designed to increase its residence time in the stomach without establishing contact with the mucosa. This was made possible through the preparation of microballoons by emulsion solvent diffusion-evaporation technique. The prepared microballoons were characterized for physical characteristics such as particle size, particle shape and surface morphology by scanning electron microscopy. Further, percentage yield determination, drug entrapment efficiency, in vitro buoyancy test, micromeritic investigations and in vitro drug release studies were carried out. The obtained microspheres were free flowing, spherical and displayed a particle size ranging from 50.15 to 67.0µm suitable for oral delivery. The drug entrapped in the hollow microspheres increased with the increase in eudragit RSPO content. Scanning electron microscopy and particle size analysis revealed differences in the formulations in respect to their appearance and size distribution. The FTIR spectroscopy technique and DSC were carried out to rule out drug – excipients interactions. From the results obtained, it was concluded that there was no interaction between drug and the excipients. The formulation containing Baclofen:Eudragit RSPO (1:3 and 1:4) exhibited higher percentage values for buoyancy time. The drug release was found to follow Higuchi kinetics with non-fickian diffusion mechanism, from all the four batches. These preliminary results indicate that baclofen loaded microballoons could be effective in sustaining drug release for prolonged periods of time

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33

Sirotinkin, N. V., M. G. Davudov, V. V. Bestuzheva, J. V. Omel’chuk e A. V. Tokarev. "Glass microballoons: Filling agents for polyurethane elastomers". Russian Journal of Applied Chemistry 84, n. 2 (febbraio 2011): 334–37. http://dx.doi.org/10.1134/s1070427211020297.

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34

AKUNETS, A., N. BASOV, V. BUSHUEV, V. DOROGOTOVTSEV, A. GROMOV, A. ISAKOV, V. KOVYLNIKOV, Y. MERKULEV, A. NIKITENKO e S. TOLOKONNIKOV. "Super-high-strength microballoons for hydrogen storage". International Journal of Hydrogen Energy 19, n. 8 (agosto 1994): 697–700. http://dx.doi.org/10.1016/0360-3199(94)90157-0.

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35

Ramadin, Y., M. Al-Haj Abdallah, M. Ahmad, A. Zihlif, S. K. J. Al-Ani e S. G. K. Al-Ani. "Optical properties of epoxy-glass microballoons composite". Optical Materials 5, n. 1-2 (gennaio 1996): 69–73. http://dx.doi.org/10.1016/0925-3467(95)00033-x.

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36

Gasser, M. S. "Preparation and Application of Inorganic Microballoons Membrane". Separation Science and Technology 43, n. 3 (febbraio 2008): 682–94. http://dx.doi.org/10.1080/01496390701812384.

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37

Carlisle, K. B., M. Koopman, K. K. Chawla, R. Kulkarni, G. M. Gladysz e M. Lewis. "Microstructure and compressive properties of carbon microballoons". Journal of Materials Science 41, n. 13 (luglio 2006): 3987–97. http://dx.doi.org/10.1007/s10853-006-7574-8.

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38

Zhang, Qiang, e Gao Hui Wu. "Microstructure and Compression Behavior of Cenosphere Filled Aluminum Syntactic Foams". Materials Science Forum 706-709 (gennaio 2012): 704–8. http://dx.doi.org/10.4028/www.scientific.net/msf.706-709.704.

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Abstract (sommario):

Aluminum syntactic foams were fabricated by pressure-inﬁltrating liquid pure aluminum into packed preforms of cenosphere fly ash. The morphology, true density and porosity of fly ash microballoons were characterized. The microstructure of the syntactic foams demonstrated uniform distribution of the microballoons in the aluminum matrix and seldom infiltration of cenosphere fly ash. These foams were subjected to quasi-static uniaxial compression tests and behaved like high strength aluminum foams under compressive deformation, exhibiting an extended plateau region in the stress–strain curves. With the decreasing of fly ash diameter, the plateau stress and absorbed energy of the syntactic foams increased. X-ray microcomputed tomography was used to examine the foam microstructures after interrupted compression and reveal the damage evolution. The current work provides a better understanding on the structure and mechanical properties of aluminum matrix syntactic foams.

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39

Suchańska, R., e W. Muniak. "Laser targets fabrication technologies". Laser and Particle Beams 8, n. 1-2 (gennaio 1990): 203–7. http://dx.doi.org/10.1017/s0263034600007965.

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The paper describes different types of plane targets, the method for obtaining metal microballoons from Au, Ag, and Cu with diameters of 600–1200 μm and wall thickness of 5–20 μm, and spherical cascade and cannonball type targets.

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40

Mohbe, Manoj, e D. P. Mondal. "Properties of Zn foam filled with cenosphere microballoons". Materials Today: Proceedings 46 (2021): 7448–51. http://dx.doi.org/10.1016/j.matpr.2021.01.073.

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41

Yadav, Akash, e DineshKumar Jain. "Gastroretentive microballoons of metformin: Formulation development and characterization". Journal of Advanced Pharmaceutical Technology & Research 2, n. 1 (2011): 51. http://dx.doi.org/10.4103/2231-4040.79806.

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42

Carlisle, K. B., K. K. Chawla, M. Koopman, G. M. Gladysz e M. Lewis. "Uniaxial Compressive Properties of Bismaleamid-coated Carbon Microballoons". Journal of Cellular Plastics 43, n. 6 (novembre 2007): 417–29. http://dx.doi.org/10.1177/0021955x06076060.

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43

Ullas, A. V., e Balram Jaiswal. "Halloysite nanotubes reinforced epoxy- glass microballoons syntactic foams". Composites Communications 21 (ottobre 2020): 100407. http://dx.doi.org/10.1016/j.coco.2020.100407.

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44

Medvedev, A. E., V. M. Fomin e A. Yu Reshetnyak. "Mechanism of detonation of emulsion explosives with microballoons". Shock Waves 18, n. 2 (27 maggio 2008): 107–15. http://dx.doi.org/10.1007/s00193-008-0141-2.

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45

Raju, Tina, Tanushree Sarkar, Bhagyashree S. Patil e Amol A. Raskar. "Microballoons-Novel Carriers in Gastro Retentive Drug Delivery". Research Journal of Pharmaceutical Dosage Forms and Technology 7, n. 4 (2015): 266. http://dx.doi.org/10.5958/0975-4377.2015.00038.5.

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46

Botas, J. D., e H. Águas. "The Stiffness of Syntactic Metal-Matrix Composites: A Statistical Model". ISRN Ceramics 2011 (6 febbraio 2011): 1–9. http://dx.doi.org/10.5402/2011/510474.

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Abstract (sommario):

Stiffness estimates of unloaded isotropic particulates are made by a new analytical model, when reinforcements are either compact or hollow spheres. A statistical extension of this model is described when stiffness predictions involve loading of syntactic composites. A simple experimental routine is also proposed for monitoring the microballoons fracture upon brittle syntactic metal-matrix composites tensile loading.

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47

Varia, Umang, Mohanlal Gupta, Hitesh Katariya e Krunal Hakim. "Febuxostat Loaded Microballoons: A Novel Approach for Gastric Retention". International Journal of Pharmaceutical Sciences and Drug Research 13, n. 04 (30 marzo 2020): 438–47. http://dx.doi.org/10.25004/ijpsdr.2021.130410.

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Abstract (sommario):

Febuxostat loaded microballoons (FEB-MBs) were formulated using a non-aqueous solvent evaporation method using Eudragit RS 100, HPMC K4 M as a polymer, and span 80 as a surfactant. The ratio of solvents like methanol and dichloromethane, liquid paraffin as a processing medium. The formulation was optimized by the Box-Behnken design. Optimized formulation was evaluated for particle size, entrapment efficiency, % buoyancy, Percentage yield, in-vitro release studies, and stability study. Mean particle size 80.11 ± 0.349, entrapment efficient 83.25 ± 0.526, and % buoyancy 92.41 ± 0.57 were found for optimized formulation. Scanning electron microscopy (SEM) image of formulation shows discrete particle size with smooth surface texture with a hollow space and spherical shape and particle size is less than 200 µm. The result of in-vitro study shows an improved rate of drug release for a longer period from FEB-MBs compared with pure drugs. This is due to increases in the surface area leads to increases in absorption. The stability study shows no significant change in microballoons of the optimized formulation after 30 days of storage as per ICH guidelines. This multi particulate system provides an excellent approach for sustained release of a medicament for longer, thereby reducing dose frequency.

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48

Park, Yong Kuk, Jin-Gon Kim e Jae-Kon Lee. "Prediction of Thermal Conductivity of Composites with Spherical Microballoons". MATERIALS TRANSACTIONS 49, n. 12 (2008): 2781–85. http://dx.doi.org/10.2320/matertrans.mra2008139.

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49

Juraszek, D., D. Billon, M. Bernard, J. L. Bocher, M. Decroisette, J. P. Garconnet, J. P. Le Breton, D. Meynial e Ph Schneider. "High‐velocity laser‐driven implosions with gold‐coated microballoons". Journal of Applied Physics 62, n. 9 (novembre 1987): 3595–97. http://dx.doi.org/10.1063/1.339261.

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50

Matsugu, R. S., J. C. Lehman, L. Borowski e P. Ladd. "Tritium Fill Station to Charge Microballoons for Fusion Experiments". Fusion Technology 19, n. 3P2B (maggio 1991): 1634–39. http://dx.doi.org/10.13182/fst91-a29575.

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