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Title:	Physical, thermal, magnetic and microwave absorption properties of thermoplastic natural rubber nanocomposite filled with nickel zinc ferrite nanoparticles
Authors:	Moayad Husein Alhaj Mahmoud Flaifel (P30090)
Supervisor:	Sahrim Hj. Ahmad, Prof. Dr.
Keywords:	Thermoplastic composites
Issue Date:	13-Jul-2012
Description:	In this research, we focused on the preparation and characterization of nickel zinc ferrite nanoparticles as reinforcing filler being incorporated in thermoplastic natural rubber (TPNR) matrix. TPNR was prepared from high-density polyethylene (HDPE), natural rubber (NR) and liquid natural rubber (LNR) in a ratio of 70:20:10 mixed with 4,8,12 weight percent (wt %) of the filler using Thermo-Haake Polylab internal mixer by melt blending technique. Structural, thermal, magnetic and microwave absorption properties were investigated to determine the overall characteristics of the produced nanocomposites. Structural characterization obtained from XRD, TEM, and SEM showed that the magnetic nanoparticles were homogenously dispersed in the TPNR matrix. Further, the crystallinity of the nanocomposite sample was observed to increase with increasing filler content. Thermal properties were measured using DSC, TGA, DMA and thermal conductivity analyzer. The results have shown that the thermal stability had increased with increasing NiZn ferrite content in TPNR matrix, so as the value of Tg. Moreover, the thermal conductivity of all samples decreased with temperature due to interfacial phonon scattering effect, but was observed to increase with filler loading until 8 wt%, which was believed to be the threshold value of the percolated network of the filler. Magnetic characterization was also carried out using VSM. The obtained results revealed non-attainment of magnetization even at higher values of magnetic field explained in terms of core-shell morphology. The results further showed an absence of hysteresis loops at 300 K due to the prevailing superparamagnetic phenomenon, while a tremendous enhancement in the values of remanence and coercivity was achieved at 10 K due to the increased effect of magnetic anisotropy, which was able to overcome spins' fluctuations with decreasing temperature. In addition, the increased TB distribution width with decreasing filler content illustrated by ZFC and FC splitting curves, has implied reduced magnetostatic interparticle interactions. Finally, microwave absorption properties of the nanocomposites were investigated using MVNA. The results revealed that the complex permittivity values (ε',ε'') decreased gradually with frequency, but showed a peak at different frequencies due to dipolar polarization effect. The complex permeability values (μ',μ'') demonstrated a peak at about 6 GHz indicating spin rotational effect. The influence of NiZn ferrite was observed to increase the values of (ε',ε'') and (μ',μ'') with increasing its loadings, as it is conclusive of larger dipole displacement and larger anisotropy field respectively. Microwave absorption properties revealed multi absorbing peaks behaviour in the frequency range of 0.5-12 GHz. The influence of NiZn ferrite has reported an increase in the value of RL minimum with increasing filler rates, especially in the X-band frequency and affected the peak position, while the operating bandwidth frequency reported an increase until 8 GHz. The effect of increasing sample thickness of the nanocomposite samples has affected the position of the RL minimum with a gradual attenuation of its value. Taken together, the synergistic interaction of the magnetic and dielectric losses could be the reason behind the modification of the previously mentioned microwave absorption properties.,Certification of Master's/Doctoral Thesis" is not available
Pages:	155
Call Number:	TA418.9.C6F563 2012 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Science and Technology / Fakulti Sains dan Teknologi

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