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Title:	Kesan sinaran elektron terhadap sifat magnet dan penyerapan gelombang mikro bahan komposit TPNR berpengisi nanozarah ferit nikel
Authors:	Sivanesan Appadu @ Applasamy (P48245)
Supervisor:	Sahrim Hj. Ahmad, Prof. Dr.
Keywords:	Thermoplastics Composite materials
Issue Date:	3-Oct-2013
Description:	Kesan sinaran elektron dalam julat dos 0 hingga 300 kGy ke atas sifat magnet dan sifat penyerapan gelombang mikro nanokomposit getah asli termoplastik (TPNR) berpengisi nanozarah ferit nikel (NiFe2O4) dikaji. Nanokomposit TPNR-NiFe2O4 disediakan dengan menggunakan mesin pengadun leburan mengikut nisbah jisim (wt) 92:8, 88:l2, 84:16 dan 80:20. TPNR adalah terdiri daripada 70% polietilena berketumpatan tinggi (HDPE), 20% getah asli (NR) dan 10% cecair getah asli (LNR). Kajian penentuan pecahan gel dijalankan untuk menanggarkan darjah taut-silangan yang berlaku ke atas sampel polimer selepas dikenakan sinaran elektron. Pencirian mikrostruktur ditentukan melalui teknik pembelauan sinar-X (XRD). Kajian morfologi sampel dijalankan dengan menggunakan mikroskop elektron imbasan (SEM). Mikroskop transmisi elektron (TEM) digunakan untuk mengkaji morfologi sampel serta taburan partikel nanozarah dalam komposit. Ujian imbasan kalorimetri kebezaan (DSC) dijalankan bagi menentukan kestabilan terma nanokomposit. Pencirian sifat magnet dijalankan dengan menggunakan magnetometer sampel bergetar (VSM) dan sifat penyerapan gelombang mikro dikaji melalui teknik pengukuran S-parameter penganalisis rangkaian vektor gelombang mikro (VNA). Kajian penentuan pecahan gel menunjukkan peningkatan dalam dos sinaran elektron meningkatkan darjah taut-silangan yang berlaku ke atas matriks polimer dalam sampel TPNR tulen dan nanokomposit. Hasil kajian juga menunjukkan penambahan pengisi nanozarah NiFe2O4 dalam matriks TPNR meningkatkan nilai pecahan gel jika dibandingkan dengan TPNR tulen. Kajian mikrostruktur XRD menunjukkan sampel NiFe2O4 tulen berstruktur spinel kubus dengan nilai parameter kekisi, a = 8.339 Å. Peningkatan dalam dos sinaran elektron dari 0-300 kGy didapati menurunkan nilai saiz hablur (D) dari 13.158 nm ke 6.582 nm. Pemeriksaan SEM menunjukkan peningkatan dalam dos sinaran elektron terhadap nanokomposit TPNR mewujudkan kecacatan atau lekukan yang lebih jelas dan bertaburan pada dos yang lebih tinggi. Mikrograf TEM menunjukkan nanozarah NiFe2O4 tidak wujud berasingan tetapi tertarik antara satu sama lain dan membentuk aglomerasi nanozarah yang disebabkan oleh tenaga permukaan yang tinggi. Peningkatan dalam dos sinaran elektron didapati mengaruhkan pemecahan nanozarah NiFe2O4 kepada saiz yang lebih kecil. Analisis DSC menunjukkan peningkatan dalam dos sinaran elektron meningkatkan nilai suhu peralihan kaca (Tg) manakala suhu penghabluran (Tc) dan nilai darjah kehabluran (Xc) menurun dalam TPNR tulen dan TPNR berpengisi 12% berat NiFe2O4. Suhu peleburan (Tm) meningkat dari 0 - 100 kGy dan menurun semula pada 200 dan 300 kGy bagi TPNR tulen, manakala bagi TPNR berpengisi 12% berat NiFe2O4, nilai Tm meningkat dari 0 - 200 kGy dan menurun sedikit pada 300 kGy. Analisis graf histerisis VSM NiFe2O4 tulen menunjukkan penambahan dos sinaran elektron telah meningkatkan nilai pemagnetan tepu (Ms), pemagnetan baki (Mr) dan nilai daya koersif (Hc) dalam medan magnet. Sampel nanokomposit menunjukkan penambahan dos sinaran elektron meningkatkan nilai Ms dan Mr tetapi nilai Hc adalah tidak konsisten iaitu berubah-ubah dalam julat 21 - 31 Oe. Keputusan VNA menunjukkan nilai kehilangan pantulan (RL) nanokomposit TPNR berpengisi 12% berat NiFe2O4 pada dos 300 kGy adalah yang terbaik iaitu -40.92 dB pada frekuensi sepadan 7.5 GHZ. Peningkatan dalam dos sinaran bagi sampel nanokomposit TPNR berpengisi 16% dan 20% berat NiFe2O4 didapati meningkatkan nilai RL manakala bagi sampel nanokomposit berpengisi 8% dan 12% berat NiFe2O4 RL menurun,The effects of electron beam (EB) irradiation in dose rate of 0 to 300 kGy on the magnetic and microwave absorbing properties of thermoplastic natural rubber (TPNR) nickel ferrite nanocomposite (NiFe2O4) were studied. The TPNR-NiFe2O4 nanocomposite was melt blended in weight ratios of 92:8, 88:l2, 84:16 dan 80:20. TPNR consists of 70% high density polyethylene (HDPE), 20% natural rubber (NR) and 10% liquid natural rubber (LNR). The gel content of the nanocomposite samples were measured to determine the degree of radiation crosslinking. The microstructure characterization of the samples was done by using the X-ray diffraction (XRD) method. The morphological characterization was done by using the scanning electron microsope (SEM). The transmission electron microscope (TEM) was used to study the morphology and distribution of nanoparticles in the samples. The differential scanning calorimetry (DSC) thermogram was analyzed to determine the thermal properties of the nanocomposite. The magnetic properties were analyzed with the Vibrating Sample Magnetometer (VSM) and the microwave absorbing properties were measured with the S-parameter analysis technique by using the Vector Network Analyzer (VNA). Gel content studies showed that the increase in EB irradiation dose increased the degree of crosslinking in the polymeric chains of pure TPNR and nanocomposite samples. The study also showed that the increase in content of NiFe2O4 fillers in the TPNR matrix increased the gel content compared to pure TPNR. XRD microstructure analysis of pure NiFe2O4 sample revealed the presence of cubic spinel structure with the lattice parameter a = 8.339 Å. The calculated crystal size (D) decreased from 13.158 nm to 6.582 nm with increasing irradiation dose from 0-300 kGy. SEM micrograph analysis showed the presence of defects in both the irradiated TPNR and nanocomposite samples which is more visible and scattered with increasing dose rate. TEM micrograph analysis showed that the NiFe2O4 nanoparticles tended to agglomerate due to strong high surface energy attraction and decreased in particle size with increasing irradiation dose. DSC analysis showed that with the increase in dose of EB irradiation the glass temperature (Tg) increased while the crystallization temperature (Tc) and degree of crystallinity (Xc) decreased in pure TPNR and TPNR with 12% weight ratio of NiFe2O4. The melt temperature (Tm) increased from 0 - 100 kGy and decreased at 200 and 300 kGy. For TPNR with 12% weight ratio of NiFe2O4, the Tm value increased from 0 - 200 kGy and decreased at 300 kGy. Analysis of the VSM hysteresis loop graph for pure NiFe2O4 showed that with the increase in irradiation dose the magnetic saturation (Ms), magnetic retentivity (Mr) and coercivity (Hc) values in the magnetic field increased. For the nanocomposite samples the increase in irradiation dose showed that the Ms and Mr increased but the Hc value was found to be inconsistent in the range of 21 - 31 Oe. The VNA results showed that the reflection loss (RL) value for the TPNR nanocomposite with 12% NiFe2O4 at 300 kGy was the lowest at -40.92 dB corresponding to 7.5 GHZ frequency. The reflection RL value for the TPNR nanocomposite with 16% and 20% weight ratio of NiFe2O4 increased with increasing irradiation dose while the RL value for the TPNR nanocomposite with 8% and 12% weight ratio of NiFe2O4 decreased.,Master/Sarjana
Pages:	130
Call Number:	TA418.9.C6S588 2013 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Science and Technology / Fakulti Sains dan Teknologi

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