In-situ polymerization method was used to prepare palm-based polyurethane (PU) composites loading with 15 wt% magnetite (Fe3O4), polyaniline (PANI) and Fe3O4 coated with PANI labeled as PU15, PP and PPM, respectively. FTIR spectroscopy analysis indicated a shift in the carbonyl, C=O and NH in PP. The shift of the peak indicated that there was hydrogen bonding between the C=O (proton acceptor) of urethane with NH (proton-donator) of PANI. PPM gave the highest impact and flexural strengths at 4875 kJ/ m2 and 42 MPa, respectively but with the lowest flexural modulus (1050 MPa). Two-stage degradation behavior was observed in the TGA thermogram.
Structural and magnetic properties of type-M barium ferrite (BaFe12O19) nanoparticles (~ 20 nm) embedded in nonmagnetic 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.
Kajian ini telah dijalankan dengan menghasilkan dua sistem komposit iaitu komposit epoksi berpengisi montmorillonite (MMT) dengan dan tanpa cecair getah asli terepoksida (LENR) secara kaedah pencampuran in situ. Komposit telah di pra-matang pada tiga suhu iaitu pada suhu 30 °C, 50 °C atau 70 °C . Kedua dua sistem dimatang pada suhu 130 °C atau 140 °C. Ujian hentaman Izod dan ujian keliatan patah ke atas komposit yang dihasilkan menunjukkan peningkatan maksimum sebanyak 44% dengan penambahan MMT dan 29% peningkatan dengan penambahan getah asli terepoksida. Selain kandungan MMT, suhu pra matang 70 °C memberikan kesan yang ketara terhadap kekuatan hentaman dan keliatan patah sistem epoksi berpengisi MMT. Suhu pra-matang 50 °C merupakan suhu yang optimum dan berupaya memberikan kekuatan hentaman dan keliatan patah yang baik kepada sistem epoksi berpengisi MMT getah asli terepoksida. Suhu matang bagi kedua dua sistem tidak memberikan kesan yang ketara kepada sifat mekanikal kedua dua sistem komposit ini. Pemeriksaan mikrostruktur melalui mikroskop elektron transmisi menunjukkan MMT tertabur dengan susunan interkalasi. Peningkatan kandungan MMT melebihi 1 % berat menunjukkan kehadiran taktoid dan penggumpalan silikat.
UV-curable hyperbranched urethane acrylate (HBPUA) from oleic acid of palm oil has been synthesized through a medium aided by p-toluene sulfonic acid as a catalyst. This mixture was then used as the core (HBP) and reacted with palm oil oleic acid to form the hyperbranched polyol (HBP-1). HBPUA was prepared by reacting HBP-1 resin with diisocyanate and hydroxyl-containing acrylate monomer with the presence of 0.1-2 wt% dibutyltin dilaurate as a catalyst. The reaction was confirmed by several analytical data i.e. hydroxyl value (OHV), Fourier Transform infrared (FTIR) spectroscopy, gel permeation chromatography (GPC) and nuclear magnetic resonance (NMR) spectroscopy analyses. The HBPUA was easily curable when subjected to ultraviolet (UV) radiation.
In this study, graphene oxide (Go) filled epoxy nanocomposites were prepared using hot pressed method. The GO was produced using modified Hummers' method. The produced GO at different compositions (0.1, 0.3 and 0.5 wt%) were mixed with epoxy before the addition of hardener using ultra-sonication. The produced epoxy nanocomposites were characterized in terms of mechanical and thermal properties. The mechanical properties of the nanocomposites were significantly enhanced by the addition of GO. About 50% of increment in the flexural strength of the composite sample filled with 03 wt% of GO as compared to the neat epoxy sample. However, only slight improvement in the impact strength of the composite were obtained by adding 0.1 wt% of GO.
Kaedah tindak balas permukaan (RSM) telah digunakan untuk mengoptimumkan penyediaan biokomposit rHDPE berpenguat sekam padi sebagai pengisi. Sekam padi adalah sisa pertanian yang mempunyai ciri-ciri kayu dan digunakan secara pesat dalam bidang komposit kayu plastik. Kesan parameter suhu, tekanan serta masa proses tekanan panas ke atas kekuatan tegangan telah dikaji. Reka bentuk Box Bechken telah digunakan untuk menentukan parameter optimum biokomposit yang mempunyai kekuatan tegangan yang tinggi. Model tertib kedua telah dibangunkan untuk meramalkan kekuatan tegangan berdasarkan reka bentuk komposit. Didapati bahawa komposit sesuai digunakan apabila model regresi kuadratik dengan pekali penentu bilang (R2) yang tinggi. Keadaan proses menekan yang optimum dicapai pada suhu 180°C, tekanan 1000 psi dan masa 9 min dengan pekali penentu berbilang mencapai 97%. Di bawah keadaan yang optimum ini, komposit yang mengandungi 10, 20, 30, 40 dan 50% gentian RH telah disediakan. Kekuatan tegangan dan modulus tegangan biokomposit menunjukkan peningkatan apabila kandungan gentian RH ditambah.
Ferit NiZn dan nanotiub karbon diadunkan ke dalam getah asli termoplastik mengikut nisbah campuran 1:1. Kesan penambahan pengisi ke atas sifat magnet, struktur dan morfologi nanokomposit dikaji. Dua parameter magnet, iaitu pemagnetan tepuan dan daya koersif nanokomposit didapati bergantung kepada penambahan pengisi dalam matriks. Interaksi antara kedua-dua pengisi dalam matriks TPNR juga mempengaruh sifat magnet. Pengisi hibrid (ferit NiZn dan nanotiub karbon) bertabur sekata dalam matriks termoplastik getah asli. Kehabluran semi-amorfus fasa polipropilena didapati berlawanan dengan peningkatan kehabluran pengisi apabila kandungan pengisi bertambah.
Moldability of metal injection molding (MIM) is dependent on the outward appearance of the resultant feedstock. Properties of the binders used will influence the properties of the feedstock. Stainless steel powder 316L with mean size 22 μm and the binder system consists of three major fractions of paraffin wax, thermoplastic natural rubber and stearic acid with a powder loading of 65 vol. % was investigated. Comparison was also made with existing palm stearin in the binder system replacing the paraffin wax. Kinetic solvent extractions were done to determine the differences between the binder systems. The feedstock was then injected into tensile bar using vertical injection machine. The results showed that there is a slightly time extension during the solvent extraction as a comparison. The feedstock has been successfully injection molded at 190-200°C. Study of thermal analysis such as DSC and TGA has been done as a preparation for the thermal debinding and sintering process. This study demonstrated that a backbone polymer; thermoplastic natural rubber performs best in term of flow stability and compact quality and also saves in processing time.
The complex scattering parameters (S11* and S21*), relative dielectric permittivity (er* = er' - jer"), relative magnetic permeability (mr* = mr' - jmr") and absorption characteristics of some thermoplastic natural rubber (TPNR) – Fe3O4/YIG composites were investigated by means of a microwave vector network analyser and specular absorber method. The measurements were performed in the frequency range of 1 – 13 GHz with and without the presence of a transverse external magnetic field with magnitude of 1 T. The specular absorber method is used in determining the reflection loss (RL) of the composites and its dependence on material properties, thickness and the external magnetic field. In toroidal form, the composites under study seem to transmit more (Pt > 60%) but absorb and reflect less (Pa + Pr < 30%) microwave power in the frequency range used in this study and in both unmagnetised and magnetised states. The external magnetic field is seen to have the effects of reducing S11*, S21*, er', er", mr' and mr". The suppression of the relaxation and resonance behaviours on the mr' and mr" plots for all samples are observed for measurements performed in the presence of the external field. The composites, as revealed by the specular absorber method, show conditions of minimal reflection on RL versus frequency plot for all sample thickness where more than 95% of the microwave power is not reflected back. The location of the dips of minimal reflection on the frequency domain depend on the thickness, the dielectric and magnetic properties of the materials. The conditions of minimal reflection was found to occur when the thickness (t) of the sample equals the odd number multiple of a quarter wavelength in the material (lm), t = nlm/4 (n = 1, 3, 5, 7 …), where a geometrical cancellation took place at the surface of the absorber between the reflected waves, resembling a thin filem inteference phenomenon. The dips are suppressed and shifted to a higher frequency in the presence of the external magnetic field. With the knowledge of the dielectric permittivity and magnetic permeability of a material, the specular absorber method may provides a simple theoretical graphic aids in determining the absorption characteristics and location of the matching condition in the frequency domain.
Oil palm empty fruit bunch (EFB) fibres were pretreated by gamma irradiation followed by sodium carbonate (Na2
CO3
)
before the acid hydrolysis process to produce reducing sugars using diluted sulphuric acid (H2
SO4
). In this study, EFB
fibres were irradiated at different doses, i.e. 0, 100 and 200 kGy. Meanwhile, the gamma irradiated sample were then
subjected to Na2
CO3 pretreatment with 0 and 5% total titratable alkali (TTA). The effect of the pretreatment using gamma
irradiation and Na2
CO3
on the physical and chemical properties of the EFB fibres and the yield of the reducing sugar
obtained from the acid hydrolysis process was investigated. The obtained results showed that the content of holocellulose
was increased significantly with the increase of irradiation doses combined with Na2
CO3 pretreatment, whereas lignin
content of the EFB was decreased. The gamma irradiation and Na2
CO3 pretreatment resulted in structure breakage
and removal of silica of EFB fibres which can be due to the swelling of the fibres. A synergistic effect between gamma
irradiation and Na2
CO3 was observed, in which the yield of reducing sugars was increased by combining the gamma
irradiation and Na2
CO3 pretreatment.
Thermoplastic natural rubber sample is found isotropic based on SAXS pattern. Morphological parameter was obtained based on ideal lamellar morphology using 1-D correlation function. The fitting was carried out using Porod tail model and Vonk for back-extrapolated model. It is found that the long period value is 15.7nm which is comparable to results obtained from Lorents corrected profile, 20nm. Crystalline thickness and amorphous thickness was found as 13.4 and 2.31nm respectively
Magnetite (Fe3O4) nanoparticles have been synthesized using the chemical coprecipitation method. The Fe3O4 nanoparticles were likely formed via dissolution-recrystallization process. During the precipitation process, ferrihydrite and Fe(OH)2 particles formed aggregates and followed by the formation of spherical Fe3O4 particles. The synthesized Fe3O4 nanoparticles exhibited superparamagnetic behavior and in single crystal form. The synthesis temperature and the degree of agitation during the precipitation were found to be decisive in controlling the crystallite and particle size of the produced Fe3O4 nanoparticles. Lower temperature and higher degree of agitation were the favorable conditions for producing smaller particle. The magnetic properties (saturation magnetization and coercivity) of the Fe3O4 nanoparticles increased with the particle size.
The effects of liquid natural rubber (LNR) on the morphology and mechanical properties of rubber modified epoxy were investigated. Epoxy composites were prepared in four different compositions of LNR (3, 5, 7 and 9phr) by using twin screw extruder. The samples for tensile, fracture toughness and impact tests were prepared according to ASTM D 638, D 5045 and D 256. The elastomeric nature of rubber can act as energy dissipating centre to cause the ductile fracture for the rubber modified epoxy. They was an obvious increment of fracture toughness where maximum value was observed with 3 phr LNR. A clear increment of impact strength at 3 phr LNR was observed, followed by a small increment at 5 phr and no further increment at 7 and 9 phr LNR. The tensile strength showed a similar trend with impact strength and Young’s modulus. SEM micrographs showed an increment of rubber particle size when the amount of LNR was increased and caused the mechanical properties to drop.
L18 orthogonal array in mix level of Taguchi robust design method was carried out to optimize experimental conditions for the preparation of polymer blend composite. Tensile strength and neutron absorption of the composite were the properties of interest. Filler size, filler loading, ball mixing time and dispersion agent concentration were selected as parameters or factors which are expected to affect the composite properties. As a result of Taguchi analysis, filler loading was the most influencing parameter on the tensile strength and neutron absorption. The least influencing was ball-mixing time. The optimal conditions were determined by using mix-level Taguchi robust design method and a polymer composite with tensile strength of 6.33 MPa was successfully prepared. The composite was found to fully absorb thermal neutron flux of 1.04 x 105n/cm2/s with only 2 mm in thickness. In addition, the filler was also characterized by scanning electron microscopy (SEM) and elemental analysis (EDX).
The thermal conductivity of boron carbide filled thermoplastic natural rubber blend composite is studied experimentally as a function of filler loading and filler size. A polymer blend of 60/40 NR/HDPE was used as matrix for incorporation of particulate nano- and micro-sized B4C as filler to form the composite. As the filler loading is increased from 2-10%wt, a reduction and increment of thermal conductivity was observed. The results show at lower filler loading, HDPE crystallinity affects the thermal conductivity up to 4 and 6%wt of filler for nano- and micro-composite respectively. Further increase the loading do not much alter the crystallinity as the filler is distributed in continues phase of NR. The increment of filler amount in the amorphous NR causes the thermal conductivity to gradually increase which indicates the formation of interconnecting filler network structures
Penyelidikan ini dijalankan bagi mengkaji sifat mekanik nanokomposit epoksi berpenguat gentian hibrid nano tiub
karbon berbilang dinding (MWCNT) dan nanozarah tanah liat (NC). Nanokomposit berpenguat hibrid nanozarah telah
disediakan melalui kaedah kacauan mekanik dan sampel dengan jumlah nanozarah berbeza dibentuk menggunakan
pengacuan mampatan. Dalam ujian lenturan yang dijalankan, didapati sampel hibrid memberikan nilai kekuatan
yang lebih tinggi berbanding sampel tunggal. Ujian terhadap sifat hentaman nanokomposit epoksi berpenguat gentian
nanozarah menunjukkan bahawa penambahan gentian terhadap sampel tidak dapat meningkatkan sifat ketahanan daya
hentaman yang dikenakan. Namun demikian, sampel yang mengandungi gentian hibrid nano merekodkan nilai daya
tahan hentaman yang lebih tinggi berbanding sampel tunggal. Mikrograf pengimbas elektron (SEM) mengesahkan kesan
serakan pengisi hibrid dan ikatan antara muka dalam matriks yang baik. Ini membuktikan bahawa gentian hibrid antara
nanotiub karbon dan nanozarah tanah liat pada kandungan komposisi tertentu dapat menambahbaik sifat mekanik
bahan nanokomposit.
The effect of various multi-walled carbon nanotubes (MWNTs) on the tensile properties of thermoplastic natural rubber (TPNR) nanocomposite was investigated. The nanocomposite was prepared using melt blending method. MWNTs were added to improve the mechanical properties of MWNTs/TPNR composites in different compositions of 1, 3, 5, and 7 wt.%. The results showed that the mechanical properties of nanocomposites were affected significantly by the composition and the properties of MWNTs. SEM micrographs confirmed the homogenous dispersion of MWNTs in the TPNR matrix and promoted strong interfacial adhesion between MWNTs and the matrix which was improved mechanical properties significantly.