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Sains
Malaysiana 41(9)(2012): 1125–1131
Structural and Magnetic Properties of
Type-M Barium Ferrite – Thermoplastic Natural Rubber Nanocomposites
(Sifat
Struktur dan Magnet Nanokomposit Ferit Barium Jenis-M – Getah Asli
Termoplastik)
Nurhidayaty Mokhtar
Physics Department, Faculty
of Science, Universiti Putra Malaysia, 43400 UPM Serdang
Selangor D.E. Malaysia
Mustaffa Hj.
Abdullah* & Sahrim Hj. Ahmad
School of
Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan
Malaysia
43600 UKM
Bangi, Selangor D.E. Malaysia
Received: 29 June 2011 / Accepted: 29
February 2012
ABSTRACT
Structural and magnetic properties
of type-M barium ferrite (BaFe12O19)
nanoparticles (~ 20 nm) embedded in non-magnetic thermoplastic natural rubber (TPNR)
matrices were investigated. The TPNR matrices were prepared
from high density polyethylene (HDPE)
and natural rubber (NR) in the weight ratios of 80:20 and
60:40, respectively, with 10 wt% of NR in the form of liquid
natural rubber (LNR) which act as a compatibiliser.
BaFe12O19 – filled nanocomposites with
2 – 12 wt% BaFe12O19 ferrite
were prepared using a melt- blending technique. Magnetic hysteresis was
measured using a vibrating sample magnetometer (VSM)
in a maximum field of 10 kOe at room temperature (25oC).
The saturation magnetisation (MS), remanence (MR)
and coercivity (Hc) were derived from the hysteresis
loops. The results show that the structural and magnetic properties of
nanocomposites depend on both the ferrite content and the composition of the
natural rubber or plastic in the nanocomposites. All the nanocomposites exhibit
an exchange bias-like phenomenon resulting from the exchange coupling of spins
at the interface between the core ferrimagnetic region and the disordered
surface region of the nanoparticles.
Keywords: Exchange bias; high
density polyethylene; hysteresis; magnetic properties; natural rubber
ABSTRAK
Sifat
struktur dan magnet nanozarah (~ 20 nm) ferit barium jenis-M (BaFe12O19)
yang dimasukkan ke dalam matriks getah asli termoplastik (TPNR)
tidak bermagnet telah dikaji. Matrik TPNR disediakan
daripada polietilena ketumpatan tinggi (HDPE) dan getah asli (NR)
dalam nisbah berat 80:20 dan 60:40, dengan 10% berat NR dalam
keadaan getah asli cecair (LNR) yang bertindak sebagai penserasi. Nanokomposit berpengisi BaFe12O19 sebanyak
2 – 12% berat disediakan menggunakan teknik adunan lebur. Histeresis magnet diukur menggunakan magnetometer sampel bergetar (VSM)
dalam medan maksimum 10 kOe pada suhu bilik (25oC). Pemagnetan tepu (Ms), remanens (MR)
dan koersiviti (Hc) diperoleh daripada gelung
histeresis. Keputusan menunjukkan bahawa sifat
struktur dan magnet nanokomposit bergantung kepada kandungan ferit dan
komposisi getah asli atau plastik dalam nanokomposit. Semua
nanokomposit menunjukkan fenomenon mirip pincang saling tukar yang terhasil
daripada gandingan saling tukar pada antaramuka di antara rantau teras
ferimagnet dan rantau tak tertib di permukaan nanozarah.
Kata
kunci: Getah asli; histeresis; pincang saling tukar; polietilena ketumpatan
tinggi; sifat magnet
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*Corresponding author; email: mha@ukm.my
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