اثر نانوذرات گرافن کاهش‌‌یافته گرمایی بر عملکرد حفاظت از تداخل الکترومغناطیسی، رفتار رئولوژی و پایداری گرمایی آمیخته PP/PET

نوع مقاله: پژوهشی

نویسندگان

قم، دانشگاه صنعتی قم، دانشکده فنی مهندسی، گروه مهندسی پلیمر، صندوق پستی: 1519-37195

چکیده

در پژوهش حاضر، اثر نانوذرات گرافن کاهش‌یافته گرمایی بر رسانندگی الکتریکی، ثابت دی‌الکتریک، قابلیت سپر حفاظت امواج الکترومغناطیسی، رفتار رئولوژی و پایداری گرمایی آمیخته PP/PET مطالعه شده است. بدین منظور، نانوکامپوزیت‌های آمیخته PP/PET با ترکیب درصد 50/50 در مجاورت مقادیر مختلف گرافن به روش اختلاط مذاب تهیه شدند. شکل‌شناسی نمونه‌ها هر دو فاز پیوسته بود که با جذب ترجیحی نانوذرات ساختار فراگیر دوگانه تشکیل  شد. این ساختار به‌طور شایان توجهی رسانندگی الکتریکی نانوکامپوزیت‌ها را افزایش داد. نتایج رئولوژی نشان داد، شبکه سه‌بعدی نانوذرات گرافن در کسر حجمی کم تشکیل شده است. در کسر حجمی حدود %1/0 از نانوذرات مقدار رسانندگی الکتریکی به‌دست آمده (S/m 10-6) معیارهای لازم برای فیلم‌های نازک را در کاربردهای ضدالکتریسیته ساکن برآورده می‌سازد. در مقدار %2 از نانوذرات مقدار رسانندگی الکتریکی به مقدار  درخور توجه 0.16S/m  می‌رسد که برای بسیاری از کاربردهای الکتریکی قابل قبول است. با افزودن گرافن ثابت دی‌الکتریک و  قابلیت حفاظت از تداخل امواج الکترومغناطیس آمیخته افزایش شایان ‌توجهی داشت، به‌طوری که با افزودن %2 نانوذرات در بسامد 10Hz ، ثابت دی‌الکتریک آمیخته خالص از حدود 4 به مقدار 107×9 و حفاظت از تداخل امواج الکترومغناطیس از 1dB  برای نمونه خالص  به مقدار 42dB افزایش یافت. این نتایج نشان می‌دهد، نانوکامپوزیت تهیه شده به‌خوبی قابلیت استفاده در کاربرد‌‌های حفاظت در برابر تداخل امواج الکترومغناطیس را دارد. نتایج آزمون تجزیه گرماوزن‌سنجی نشان داد، افزودن نانوصفحه‌های گرافن به‌طور چشمگیری باعث پایداری گرمایی آمیخته شده است، به‌طوری که دمای T10 و Tmax با افزودن گرافن و افزایش مقدار آن به دماهای بیشتر انتقال یافته و سرعت تخریب نیز کاهش یافته است.

کلیدواژه‌ها


عنوان مقاله [English]

Effect of Thermally-Reduced Graphene Nanoparticles on the Electromagnetic Interference Shielding Performance, Rheological Behavior and Thermal Stability of PP/PET Blend

نویسندگان [English]

  • Razieh Moeini
  • Arash Sadeghi
  • Jafar Khademzadeh Yeganeh
Department of Polymer Engineering, Qom University of Technology, P.O. Box: 37195-1519, Qom, Iran
چکیده [English]

Hypothesis: We investigated the effect of thermally-reduced graphene (TRG) nanosheets on electrical conductivity, dielectric constant, electromagnetic interference shielding performance, rheological behavior and thermal stability of polypropylene/polyethylene terephthalate (PP/PET) blend.
Methods: For this purpose, 50/50 PP/PET blends were prepared through melt compounding in presence of different volume fractions of TRG. The direct current (DC) conductivity, the AC electrical conductivity and EMI shielding effectiveness of composites were measured. The morphology of blends was examined by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM).
Findings: The morphology of the samples was co-continuous, and preferential localization of the nanoparticles led to a double percolated structure. This structure enhanced electrical conductivity of the samples considerably. The rheological analysis indicated that a percolated network was formed at low volume fractions of TRG. At 0.1 vol% loading, the conductivity of the composites satisfies the antistatic criterion (10−6 S/m) for thin films. At 2 vol% of graphene, a high electrical conductivity of
0.16 S/m was achieved which was considered sufficient for electronic device applications. The dielectric constant and the electromagnetic interference shielding efficiency (EMI SE) of the blends significantly increased with TRG addition. By incorporating 2 vol% of TRG, the dielectric constant increased from 4 (for neat sample) to 9×107 at 10 Hz and the EMI SE increased from 1 dB (for neat sample) to 42 dB at 10 GHz, satisfying the target value for commercial applications. Thermogravimetric analysis (TGA) indicated that addition of TRG effectively enhanced the thermal stability of the samples. Incorporation of TRG not only increased the initial decomposition temperatures but also decreased the rate of decomposition. The enhanced thermal stability of the composites was attributed to the high aspect ratio of TRGs, which served as a barrier and prevented the emission of gaseous molecules during thermal degradation.

کلیدواژه‌ها [English]

  • thermally reduced graphene
  • Rheology
  • electrical conductivity
  • electromagnetic interference shielding
  • thermal stability

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