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Johnsy George R. Kumar C. Jayaprahash A. Ramakrishna S. N. Sabapathy A. S. Bawa 《应用聚合物科学杂志》2006,102(5):4514-4522
Rice bran was incorporated into low‐density polyethylene (LDPE) at different concentrations by compounding in a twin‐screw extruder and blown into films of uniform thickness. The rice bran incorporation influenced physical, mechanical, barrier, optical, thermal properties, and biodegradation of LDPE. The mechanical and optical properties decreased as the percentage of rice bran increased. The effect of rice bran on the morphology of LDPE blends was examined using scanning electron microscopy. Oxygen transmission rate and water vapor transmission rate increased with the increased content of rice bran. Addition of rice bran did not alter the melting temperature (Tm) of the blends; however the thermal stability decreased, while glass transition temperature (Tg) increased. Kinetics of thermal degradation was also investigated and the activation energy for thermal degradation indicated that for up to 10% filler addition, the dispersion and interfacial adhesion of rice bran particles in LDPE was good. Aerobic biodegradation tests using municipal sewage sludge and biodegradation studies using specific microorganism (Streptomyces species) revealed that the films are biodegradable. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4514–4522, 2006 相似文献
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CO2‐induced crystal engineering of polylactide and the development of a polymeric nacreous microstructure
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Nacre's biomineralization process and its self‐organizing brick‐and‐mortar crystalline microstructure have inspired many researchers to develop new materials derived from the natural world. In our study, we took a novel approach to two‐dimensional (2‐D) crystallization. That is, we applied the biomineralization self‐organizational principle that exists in natural materials to a biopolymer (polylactide). The CO2‐induced crystallization of poly(d ‐lactide), with its unique diffusion‐controlled crystallization mechanism, tends to produce distinct 2‐D spherulitic structures. We found that these 2‐D spherulites were self‐organizing in nature, and that they created a stack of 2‐D spherulitic structures. These crystalline microstructures, with their intervening amorphous phase, were foamed in situ due to the CO2‐induced crystallization self‐exclusion phenomenon. We compared the resultant crystalline structure with nacre's brick‐and‐mortar crystalline microstructure to confirm the biomimetic principle of self‐organization. To the best of our knowledge, this is the first time that a biopolymer has been crystallized in a 2‐D manner in a way that resembles nature's biomineralization process. The hierarchical crystalline microstructure is morphologically similar to that of nacre biomaterials. This novel crystallization technique is simple, absolutely non‐toxic and works swiftly to produce a brick‐and‐mortar crystalline microstructure with a high degree of order. © 2017 Society of Chemical Industry 相似文献
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Effect of Pasteurization and Retort Processing on Spectral Characteristics,Morphological, Thermal,Physico‐Mechanical,Barrier and Optical Properties of Nylon‐Based Food Packaging Materials
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Rajamanickam Ramalingam Sajeevkumar VA Johnsy George Sabapathy SN 《Packaging Technology and Science》2015,28(5):425-436
The effect of pasteurization and retort processing on spectral, morphological, thermal, physico‐mechanical, barrier and optical properties of three different packaging materials viz., PP/N6/PP, PET/N6/cPP and SiOx‐PET/N6/cPP were studied. These packaging materials were packed with distilled water, which acted as a food simulant. Subsequently, these pouches were subjected to different thermal processing conditions such as pasteurization and retort processing. Both the processing techniques found to have retained the mechanical properties of all packaging materials. Water vapour transmission rate (WVTR) and oxygen transmission rate (OTR) of nylon‐based combinations were increased after processing. Gloss found to decrease invariably irrespective of the material and increases with the severity of the treatment. XRD diffractogram shows changes in crystal structure as a result of thermal processing, and SEM analysis shows the crystal fragmentation. Absorption of water by the amide group of nylon 6 was observed, which could be a reason for the increase in OTR and WVTR. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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English RD Van Stipdonk MJ Sabapathy RC Crooks RM Schweikert EA 《Analytical chemistry》2000,72(24):5973-5980
We show that selected self-assembled monolayers (SAMs) and bilayers are readily characterized by the application of controlled photooxidation and spontaneous desorption mass spectrometry (SDMS) in the negative ion mode. Additionally, SDMS is used to characterize organic and inorganic anionic species adsorbed to the surface of a positively charged SAM surface, 2-aminoethanethiol (AET). Prominent peaks are observed that correspond both to the sulfonate form of each SAM and bilayer and to the anion form of each molecule adsorbed to AET. In addition, fragments of the oxidized thin films were also observed at m/z 80 (SO3-) and 97 (HSO4-). Other prominent fragment peaks more characteristic of the molecule are also seen in the mass spectra. 相似文献
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CO2‐induced crystallization of polylactide and its self‐templating ‘stack of coins’ crystalline microstructure
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Sabapathy Sankarpandi Chul B. Park Anup K. Ghosh 《Polymer Engineering and Science》2017,57(4):365-373
Can we learn from biomineralization process of natural materials to fabricate a three‐dimensional (3D) thick laminate microstructure by stacking of two‐dimensional (2D) crystalline structure? By adopting this self‐organization principle of biomineralization process, a polymer is crystallized two‐dimensionally into a multi‐layered architecture. Herein, we demonstrate a 2D crystallization method of polylactide and its principle of self‐organization to develop the discontinuous laminate microstructures. We find that instead of building a multilayered morphology layer‐by‐layer, the lamellar microstructures can be built in one step by using self‐organization principle of 2D crystallization. The biopolymer PLA is compression molded, and the molded samples are crystallized by using supercritical CO2 in a high pressure vessel. The CO2‐induced crystallization has a unique diffusion‐controlled crystallization mechanism, which tends to produce a disc‐shape spherultic structure. From microscopy analysis, we observe that these 2D spherulites are self‐organizing in nature and form 3D thick laminate structures with integrated amorphous phase in between. The obtained discontinuous laminate microstructure is comparable to “stack of coins” structure and we report the biomimetic approach of crystallization process. Thus, our study shows an innovative approach to engineer the crystalline microstructure of PLA. POLYM. ENG. SCI., 57:365–373, 2017. © 2016 Society of Plastics Engineers 相似文献
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Samir Salem Al-Bawri Mohammad Tariqul Islam Kabir Hossain Thennarasan Sabapathy Muzammil Jusoh 《计算机、材料和连续体(英文)》2022,71(1):611-628
This paper presents a textile-based C-shaped split-ring resonators (SRR) metamaterial (MTM) unit cells with an electrical tunability function. The proposed MTM was composed of two symmetrical C-shaped SRR combined with a central diagonal metal bar, whereas the RF varactor diode is placed on the backside of the splitted ground plane. Stopband behavior of single and array MTM unit cells were analyzed while the achieved negative index physical characteristics were widely studies. Though four different MTM arrays (i.e., 1 × 1, 1 × 2, 2 × 1, and 2 × 2) were analyzed in simulation, a 2 × 2-unit cell array was chosen to fabricate, and it was further undergone experimental validation. This proposed tunable MTM exhibits double negative (DNG)/left-handed properties with an average bandwidth of more than 2.8 GHz. Furthermore, attainable negative permittivity and negative permeability are within 2.66 to 9.59 GHz and within 2.77 to 15 GHz, respectively, at the frequency of interest (between 1 and 15 GHz). Moreover, the proposed tunable MTM also showed tunable transmission coefficient characteristics. The proposed electrically tunable textile MTM might function in a dynamic mode, making it suitable for a variety of microwave-wearable applications. A satisfactory agreement between simulations and experiments were achieved, demonstrating that the proposed MTM can operate over a wide bandwidth. 相似文献
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Siti Rahena Isa Muzammil Jusoh Thennarasan Sabapathy Jamel Nebhen Muhammad Ramlee Kamarudin Mohamed Nasrun Osman Qammer Hussain Abbasi Hasliza A. Rahim Mohd Najib Mohd Yasin Ping Jack Soh 《计算机、材料和连续体(英文)》2022,70(2):2699-2725
New requirements in communication technologies make it imperative to rehash conventional features such as reconfigurable antennas to adapt with the future adaptability advancements. This paper presents a comprehensive review of reconfigurable antennas, specifically in terms of radiation patterns for adaptation in the upcoming Fifth Generation (5G) New Radio frequency bands. They represent the key of antenna technology for materializing a high rate transmission, increased spectral and energy efficiency, reduced interference, and improved the beam steering and beam shaping, thereby land a great promise for planar antennas to boost the mid-band 5G. This review begins with an overview of the underlying principals in reconfiguring radiation patterns, followed by the presentations of the implemented innovative antenna topologies to suit particular advanced features. The various adaptation techniques of radiation pattern reconfigurable planar antennas and the understanding of its antenna design approaches has been investigated for its radiation pattern enhancement. A variety of design configurations have also been critically studied for their compatibilities to be operated in the mid-band communication systems. The review provides new insights on pattern reconfigurable antenna where such antennas are categorized as beam steering antenna and beam shaping antennas where the operation modes and purposes are clearly investigated. The review also revealed that for mid-band 5G communication, the commonly used electronic switching such as PIN diodes have sufficient isolation loss to provide the required beam performance. 相似文献
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Hossain Kabir Sabapathy Thennarasan Jusoh Muzammil Soh Ping Jack Ahmad R. Badlishah Jais Mohd Ilman Osman Mohamed Nasrun Yasin Mohd Najib Mohd Rahim Hasliza A. Saluja Nitin Abbasi Qammer H. 《Wireless Personal Communications》2022,123(2):1003-1024
Wireless Personal Communications - This work proposes a novel frequency-reconfigurable circular patch antenna incorporated with a rectangular slot and a narrow slot capable of producing constant... 相似文献
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Johnsy George V. A. Sajeevkumar R. Kumar K. V. Ramana S. N. Sabapathy A. S. Bawa 《应用聚合物科学杂志》2008,108(3):1845-1851
Bacterial cellulose produced by Gluconacetobacter xylinus was treated with sodium carbonate (Na2CO3) and sodium hydroxide (NaOH) to remove entrapped noncellulosic materials. Fourier transform infrared (FTIR) spectroscopy has been used to investigate the effect of alkali on the chemical structure of bacterial cellulose. The changes in the crystalline nature of these membranes were analyzed using X‐ray diffraction (XRD) technique. The morphology and the removal of noncellulosic impurities followed by alkali treatment were studied using scanning electron microscopy (SEM) and energy dispersive X‐ray spectrometry (EDS). The enhanced thermal stability of bacterial cellulose was evident from thermogravimetric analysis (TGA). Further, the alkali treatments resulted in relatively pure form of cellulose, which finds application in various spheres. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献