اثر پارامترهای شکل‌شناسی بر خواص الکترومغناطیسی اسفنج میکروسلولی پلی‌یورتان گرمانرم در محدوده بسامد نوار X

نوع مقاله: پژوهشی

نویسندگان

1 تهران،دانشگاه تربیت مدرس، دانشکده مهندسی شیمی،گروه مهندسی پلیمر، صندوق پستی 111-14115

2 تهران،دانشگاه تربیت مدرس،دانشکده مهندسی برق،گروه مهندسی مخابرات، صندوق پستی 111-14115

چکیده

در این پژوهش، خواص الکترومغناطیسی اسفنج‌­های میکروسلولی پلی­‌یورتان گرمانرم به­‌عنوان مواد جاذب رادار به روش تجربی در محدوده بسامد نوار (X (4/12-2/8GHz تحلیل شد. در چارچوب پژوهش حاضر، هدف این است که به ارتباط میان شکل‌شناسی اسفنج شامل اندازه و کسر حجمی سلول­‌های هوا و خواص الکترومغناطیسی آن شامل درصد جذب، عبور و بازتاب پی­برد. نانوکامپوزیت­‌ها با درصدهای مختلف دوده با روش انعقاد تهیه و نانوکامپوزیت %15 وزنی، با استفاده از روش اسفنج­‌سازی ناپیوسته و گاز CO2 ابربحرانی، در کسر حجمی و اندازه سلول­‌های مختلف به اسفنج میکروسلولی تبدیل شدند. شکل‌شناسی سلولی اسفنج‌­ها، با استفاده از تصاویر میکروسکوپ الکترونی و خواص الکترومغناطیسی با دستگاه Vector Network Analyzer ارزیابی شد. اثر پارامترهای شکل‌شناسی اسفنج شامل کسر حجمی و نیز اندازه سلول­‌های هوا روی خواص جذب بررسی شد که در طراحی اسفنج­‌های جاذب رادار نقش بسزایی دارند. در نهایت، ارتباط میان ساختار اسفنج و خواص الکترومغناطیسی آن بنا شد. اسفنج‌‌­سازی سبب کاهش آستانه شبکه‌ای‌شدن نانوکامپوزیت به علت کاهش متوسط فاصله میان نانوذرات می­‌شود. اسفنج­‌سازی با کاهش ثابت دی­‌الکتریک مقدار بازتاب را به مقدار قابل توجهی کاهش داده و افزایش کسر حجمی سلول­‌های هوا به علت تعدد پراش داخل ماده سبب افزایش درصد جذب به ازای واحد جرم اسفنج می­‌شود. حساسیت موج الکترومغناطیسی در برابر تغییرات اندازه سلول نسبت به تغییرات کسرحجمی اسفنج­‌های میکروسلولی به مراتب کمتر است. خواص الکترومغناطیسی اسفنج­‌های میکروسلولی از نظریه­‌های محیط مؤثر قدری انحراف دارد. کسر حجمی سلول­‌های هوا تابع اندازه سلول نیز هستند و سلول­‌های ریزتر خواص جذب بهتری نشان می‌دهند.

کلیدواژه‌ها


عنوان مقاله [English]

Morphological Parameters in Relation to the Electromagnetic Properties of Microcellular Thermoplastic Polyurethane Foam in X-Band Frequency Ranges

نویسندگان [English]

  • Mohammad Hassan Moeini 1
  • Mohammad Hossein Navid Famili 1
  • Kayvan Forooraghi 2
  • Mazyar Soltani Alkouh 1
  • Mozafar Mokhtari Motameni Shirvan 1
1 Polymer Engineering Group, Faculty of Chemical Engineering, Tarbiat Modares University, P.O. Box: 14115-111, Tehran, Iran
2 Communication Engineering Group, Faculty of Electrical Engineering, Tarbiat Modares University, P.O. Box: 14115-111, Tehran, Iran
چکیده [English]

Microcellular thermoplastic polyurethane foams are examined as absorbing materials in the X-band (8.2-12.4 GHz) frequency range by means of experiment. In this work, we aim to establish relationships between foam morphology including cell size and air volume fraction and electromagnetic properties including absorption, transmission and reflection quality. Nanocomposites based on thermoplastic polyurethane containing carbon black were prepared by coagulation method. In this procedure 15 wt% carbon black-containing nanocomposite was converted to microcellular foams using batch foaming process and supercritical carbon dioxide as physical foaming agent. The morphology of the foams was evaluated by scanning electron microscopy. S-parameters of the samples were measured by a vector network analyzer (VNA) and the effect of morphological parameters such as cell size and air volume fraction on the absorbing properties was investigated. We also established structure/properties relationships which were essential for further optimizations of the materials used in the construction of radar absorbing composites. Foaming reduced the percolation threshold of the nanocomposites due to the reduction in the average distance between nanoparticles. Foaming and dielectric constant reduction dropped the reflection percentage significantly. The increase in air volume fraction in the foam increased absorption per its weight, because of multiple scattering in composite media. The sensitivity of electromagnetic wave toward the variation of cell size is strongly weaker than that toward the variation of air volume fraction. Electromagnetic properties of the microcellular foams deviated a little from effective medium theories (EMTs). Air volume fraction of the cells was a function of cell size and smaller cells showed higher absorption.

کلیدواژه‌ها [English]

  • microcellular foam
  • radar absorbing materials
  • thermoplastic polyurethane
  • foam morphology
  • electromagnetic properties

1.Tran M.P., Detrembleur C., Alexandre M., Jerome C., and Thomassin J.M., The Influence of Foam Morphology of Multi-Walled Carbon Nanotubes/Poly(methyl methacrylate) Nanocomposites on Electrical Conductivity, Polymer, 54, 3261-3270, 2013.

2.Zhang H.B., Yan Q., Zheng W.G., He Z., and Yu Z.Z., Tough Graphene-Polymer Microcellular Foams for Electromagnetic Interference Shielding, Appl. Mater. Interfaces, 3, 918-924, 2011.

3.Park K.Y., Lee S.E, Kim C.G., and Han J.H., Fabrication and Electromagnetic Characteristics of Electromagnetic Wave Absorbing Sandwich Structures, Compos. Sci. Technol., 66, 576-584, 2006.

4.Huo J., Wang L., and Yu H., Polymeric Nanocomposites for Electromagnetic Wave Absorption, Mater. Sci., 44, 3917-3927, 2009.

5.Jung W.K., Kim B., Won M.S., and Ahn S.H., Fabrication of Radar Absorbing Structure (RAS) Using GFR-Nanocomposite and Spring-Back Compensation of Hybrid Composite RAS Shells, Compos. Struct., 75, 571-576, 2006.

6.Oh J.H., Oh K.S., Kim C.G., and Hong C.S., Design of Radar Absorbing Structures Using Glass/Epoxy Composite Containing Carbon Black in X-Band Frequency Ranges, Composites: Part B, 35, 49-56, 2004.

7.Gurunathan T., Rao Chepuri R.K., Narayan R., and Raju K.V.S.N., Polyurethane Conductive Blends and Composites: Synthesis and Applications Perspective, Mater. Sci., 48, 67-80, 2013.

8.Peng M., Zhou M., Jin Z., Kong W., Xu Z., and Vadillo D., Effect of Surface Modifications of Carbon Black (CB) on the Properties of CB/Polyurethane Foams, Mater. Sci., 45, 1065-1073, 2010.

9.Li F., Qi L., Yang J., Xu M., Luo X., and Ma D., Polyurethane/Conducting Carbon Black Composites: Structure, Electric Conductivity, Strain Recovery Behavior, and Their Relationships, J. Appl. Polym. Sci., 75, 68-77, 2000.

10.Xiong C., Zhou Z., Xu W., Hu H., Zhang Y., and Dong L., Polyurethane/Carbon Black Composites with High Positive Temperature Coefficient and Low Critical Transformation Temperature, Carbon, 43, 1778-1814, 2005.

11.Chodak I., Omastova M., and Pionteck J., Relation Between Electrical and Mechanical Properties of Conducting Polymer Composites, J. Appl. Polym. Sci., 82, 1903-1906, 2001.

12.Novak I., Krupa I., and Chodak I., Relation Between Electrical and Mechanical Properties in Polyurethane/Carbon Black Adhesives, Mater. Sci. Lett., 21, 1039-1041, 2002.

13.Quievy N., Bollen P., Thomassin J.M., Detrembleur C., Pardoen T., Bailly C., and Huynen Isabelle, Electromagnetic Absorption Properties of Carbon Nanotube Nanocomposite Foam Filling Honeycomb Waveguide Structures, IEEE Trans. Electromagn. Compat., 54, 43-51, 2012.

14.Thomassin J.M., Pagnoulle C., Bednarz L., Huynen I., Jerome R., and Detrembleur C., Foams of Polycaprolactone/MWNT Nanocomposites for Efficient EMI Reduction, Mater. Chem., 18, 792-796, 2008.

15.Lee S.T. and Ramesh N.S., Polymeric Foams, CRC, USA, 1st ed., 1-6, 2004.

16.Rende D., Schadler L.S., and Ozisik R., Controlling Foam Morphology of Poly(methyl methacrylate) Via Surface Chemistry and Concentration of Silica Nanoparticles and Supercritical Carbon Dioxide Process Parameters, Chemistry, 2013, 1-13, 2013.

17.Foresta C., Chaumonta P., Cassagnaua P., Swobodab B., and Sonntag P., Polymer Nano-Foams for Insulating Applications Prepared from CO2 Foaming, Prog. Polym. Sci., 41, 122-145, 2015.

18.Soltani Alkouh M., Famili M.H.N., and Moeini M.H., The Investigation of Foaming Effect on Radar Absorbing Properties of PMMA/MWCNT Composites, Iran. J. Polym. Sci. Technol. (Persian), 28, 189-195, 2015.

19.Mokhtari Motameni Shirvan M. and Famili M.H.N., Effect of Stabilization on the Morphology of Polystyrene and Supercritical Carbon Dioxide Thermoplastic Foam, Iran. J. Polym. Sci. Technol. (Persian), 28, 505-515, 2016.

20.Mokhtari Motameni Shirvan M., Famili M.H.N., Soltani Alkouh M., and Golbang A., The Effect of Pressurized and Fast Stabilization on One Step Batch Foaming Process for the Investigation of Cell Structure Formation, J. Supercrit. Fluids, 112, 143-152, 2016.

21.Hong Y.K., Lee C.Y., Jeong C.K., Lee D.E., and Kim K., Method and Apparatus to Measure Electromagnetic Interference Shielding Efficiency and Its Shielding Characteristics in Broadband Frequency Ranges, Rev. Scie. Instrum., 74, 1098-1102, 2003.

22.Zhanga T., Huangb D., Yangd Y., Kanga F., and Gub J., Fe3O4/Carbon Composite Nanofiber Absorber With Enhanced Microwave Absorption Performance, Mater. Sci. Eng. B, 178, 1-9, 2013.

23.Zeng C., Hosseiny N., Zhang C., and Wang B., Synthesis and Processing of PMMA Carbon Nanotube Nanocomposite Foams, Polymer, 51, 655-664, 2010.

24.Balanis C.A., Advanced Engineering Electromagnetics, John Wiley and Sons, USA, 1st ed., 180-229, 1989.

25.Zhang H., Zhang J., and Zhang H., Electromagnetic Properties of Silicon Carbide Foams and Their Composites with Silicon Dioxide as Matrix in X-Band, Composites, Part A, 38, 602-608, 2007.

26.Kolokolova L. and Gustafson B.A.S., Scattering by Inhomogeneous Particles: Microwave Analog Experiments and Comparison to Effective Medium Theories, J. Quantitative Spectrosc. Radiat. Transf., 70, 611-625, 2001.

27.Zhang H., Zhang J., and Zhang H., Numerical Predictions for Radar Absorbing Silicon Carbide Foams Using a Finite Integration Technique with a Perfect Boundary Approximation, Smart Mater. Struct., 15, 759-766, 2006.

28.Aghajari E., Morady S., Famili M.H.N., Zakiyan E., and Golbang A., Responses of Polystyrene/MWCNT Nanocomposites to Electromagnetic Waves and the Effect of Nanotubes Dispersion,Iran. J. Polym. Sci. Technol. (Persian), 27, 193-201, 2014.

29.Arab-Baraghi M., Mohammadizadeh M., and Jahanmardi R., A Simple Method for Preparation of Polymer Microcellular Foams by In-Situ Generation of Supercritical Carbon Dioxide from Dry Ice, Iran. Polym. J., 23, 427-435, 2014.

30.Wee D., Seong D.G., and Youn J.R., Processing of Microcellular Nanocomposite Foams by Using a Supercritical Fluid, Fiber. Polym., 5, 160-169, 2004.

31.Zakiyan E., Famili M.H.N., and Ako M., Heterogeneous Nucleation in Batch Foaming of Polystyrene in Presence of Nanosilica as a Nucleating Agent, Iran. J. Polym. Sci. Technol. (Persian), 25, 231-240, 2012.