Sains Malaysiana 51(11)(2022): 3765-3774

http://doi.org/10.17576/jsm-2022-5111-20

Effects of Electron Beam Irradiation on the Thermal Properties of Scrap Polytetrafluoroethylene

(Kesan Sinaran Elektron ke atas Sifat Terma Pepejal Politetrafluoroetilena)

SIVANESAN APPADU^1,*, CHANTARA THEVY RATNAM¹, SAHRIM AHMAD², RUEY SHAN CHEN², TEO MING TING¹ & THUMMALAPALLI C.S.M. GUPTA³

¹Radiation Processing Technology Division, Malaysian Nuclear Agency, 43000 Bangi, Selangor Darul Ehsan, Malaysia

²School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor Darul Ehsan, Malaysia

³Research and Development, Apar Industries Limited, Chembur 400071, Mumbai, India

Received: 10 February 2022/Accepted: 15 July 2022

Abstract

This study is focused on analyzing the effects of electron beam (EB) irradiation at high doses and normal atmospheric conditions on the thermal stability of scrap polytetrafluoroethylene (PTFE) solid to facilitate the recycling process of the material by grinding it into micro-powder additives for various applications. In this work, PTFE scrap with thickness not exceeding 1 mm was irradiated in doses between 0 - 1500 kGy using an electron beam accelerator machine (EBM) with a voltage energy of 3 MeV and current of 10 mA and grinded into powder by using a laboratory mill. The changes in morphology of the grinded powder, crystallinity and thermal properties of PTFE with increasing irradiation dose was studied by using scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The photomicrographs obtained from SEM showed that the particle size of the grinded micro-powder decreases with increasing irradiation dose with best results observed at 1500 kGy dose. DSC analysis showed that the crystallization temperature (T_c) and melting temperature (T_m) decreases with increasing irradiation doses as a result of lower molecular weight.  XRD analysis of the irradiated PTFE indicated that the intensity of the peak had increased with increasing doses of irradiation due to the increase in crystallinity of the material. The distinctly shorter derivative thermogravimetric (DTG) peak height at 1500 kGy shows higher rate of mass loss at that dose due to the rapid loss of mechanical properties caused by degradation.

Keywords: Degradation; electron beam; irradiation; micro-powder; polytetrafluoroethylene

Abstrak

Kajian ini ditumpukan kepada analisis kesan sinaran elektron (EB) pada dos sinaran yang tinggi dan dalam keadaan atmosfera biasa terhadap kestabilan terma sisa bahan pepejal politetrafluoroetilena (PTFE) untuk memudahkan proses pengitaran semula dengan mengisarkannya kepada bahan tambahan dalam bentuk serbuk bersaiz mikron untuk digunakan dalam pelbagai jenis aplikasi. Sisa bahan PTFE dalam bentuk kepingan dengan ketebalan tidak melebihi 1 mm disinarkan pada dos antara 0 - 1500 kGy dengan menggunakan mesin pemecut alur elektron (EBM) dengan tenaga voltan sebanyak 3 MeV dan arus alur elektrik 10 mA dan dikisarkan menjadi serbuk dengan menggunakan mesin pengisar makmal. Perubahan morfologi serbuk yang dikisarkan, sifat kehabluran dan sifat terma bahan PTFE dengan peningkatan dalam dos sinaran dikaji dengan menggunakan mikroskop elektron pengimbasan (SEM), analisis pembelauan sinar-X (XRD), analisis termogravimetri (TGA) dan kalorimetri pengimbasan pembezaan (DSC). Fotomikrograf yang diperoleh daripada analisis SEM menunjukkan bahawa saiz partikel serbuk mikro yang dikisar menjadi lebih kecil dengan peningkatan dalam dos penyinaran sehingga 1500 kGy. Analisis DSC menunjukkan bahawa suhu penghabluran (T_c) dan suhu lebur (T_m) berkurangan dengan peningkatan dalam dos penyinaran disebabkan nilai berat molekul yang menjadi lebih rendah. Analisis XRD bagi bahan PTFE yang disinarkan menunjukkan bahawa keamatan puncak meningkat dengan peningkatan dalam dos penyinaran disebabkan oleh peningkatan dalam sifat kehabluran bahan tersebut. Keamatan puncak termogravimetrik terbitan (DTG) yang jauh lebih rendah pada 1500 kGy juga menunjukkan kadar kehilangan jisim yang lebih tinggi disebabkan oleh degradasi serta kehilangan sifat mekanikal yang ketara pada dos berkenaan.

Kata kunci: Alur elektron; degradasi; penyinaran; politetrafluoroetilena; serbuk bersaiz mikro

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^*Corresponding author; email: siddhar131@gmail.com