Composite fabricated from the combination of biodegradable polymer and bioactive filler is beneficial for bone tissue
engineering if the biomaterial can perform similar characteristics of the natural inorganic-organic structures of bone.
In this study, we have investigated the thermoplastic starch (TPS)/sol-gel derived bioglass composite as new biomaterial
for bone tissue engineering. The composites were produced using selected TPS/bioglass mass ratio of 100/0, 95/5, 90/10,
85/15 and 80/20 by a combination of solvent casting and salt leaching techniques. Tensile test results showed the addition
of bioglass increased the tensile strength and Young’s modulus, but reduced the elongation at break of the samples. The
modulus of all samples were higher than the requirement for cancellous bone (10-20 MPa). The SEM imaging showed
the presence of porous structure on the surface of all samples. XRD results confirmed the formation of hydroxycarbonate
apatite (HCA) layer on the surface of bioglass containing samples; indicating the occurrence of surface reactions when
the samples were immersed in Simulated Body Fluid (SBF). Furthermore, the presence of P-O stretch band in FTIR
spectrum between 1000 and 1150 cm-1 and Si-O-Si stretch band at 1000 cm-1 also proved the bioactivity of TPS/bioglass
composite. The in vitro biodegradability analysis shows the biodegradability of TPS/bioglass composite decreases with
increasing mass ratio of the bioglass.
Al-Si/SiC composites with the fraction of 5 and 15 wt. % fine SiC particles were fabricated using stir casting process by which SiC powders were poured into aluminium melt and cast in a stainless steel mould to form ingot. Characterization by X-ray diffraction (XRD) analysis showed the presence of constituent and intermetallic materials in the composites. Microstructure study revealed that both fine and course particles scattered in the Al-Si matrix. The characterization of thermal properties showed that the thermal conductivity and coefficient of thermal expansion decreased with the increase in SiC content. The conductivity and expansion behavior is correlated to the microstructure and weight fraction of the SiC particles. Meanwhile, the hardness of the composite increased with the increasing of SiC particles in the composites.
Kajian ini meliputi penyediaan simen kalsium fosfat yang terdiri daripada campuran serbuk brushit (DCPD) dan hidroksiapatit (HA) yang dihasilkan secara sintesis dalam makmal. Larutan penimbal digunakan sebagai fasa cecair dan dicampurkan dengan campuran serbuk DCPD dan HA bagi menghasilkan simen tulang secara in situ dengan nisbah cecair kepada serbuk (L/P) antara 0.26 – 0.36 mL g-1. Sodium alginat dan protein soya ditambahkan ke dalam simen kalsium fosfat dan dikaji kesannya terhadap simen yang dihasilkan. Keputusan kajian menunjukkan simen kalsium fosfat dapat dihasilkan pada nisbah L/P 0.32 mL g-1 dengan penambahan 1%bt sodium alginat dan 1%bt protein soya dengan kebolehsuntikan yang maksimum (100%) dan tempoh pengerasan selama 26 min. Penambahan protein soya juga telah meningkatkan kekuatan mampatan simen tulang daripada 2.90 MPa (tanpa protein) kepada 3.98 MPa pada 1.5%bt protein. Simen kalsium fosfat-protein soya yang dihasilkan juga menunjukkan sifat kebioaktifan. Pertumbuhan apatit berlaku pada hari ke-3 selepas rendaman di dalam larutan simulasi badan (SBF) dan membesar dengan perlanjutan tempoh rendaman.
Mekanisme pembentukan apatit pada permukaan β-wolastonit dikaji. β-wolastonit dihasilkan daripada teknik sol-gel menggunakan abu sekam dan batu kapur terkalsin sebagai bahan pemula dengan nisbah CaO:SiO2 adalah 55:45. Kebioaktifan sampel β-wolastonit dikaji dengan merendam sampel berbentuk silinder dalam larutan simulasi badan (SBF) untuk tempoh yang ditetapkan iaitu 1, 3, 7 dan 14 hari. Komposisi permukaan, morfologi dan perubahan struktur sampel sebelum dan selepas direndam dianalisis melalui pembelauan sinar-X (XRD) dan mikroskop elektron imbasan (FESEM) yang digabungkan dengan EDX. Keputusan XRD menunjukkan fasa β-wolastonit berjaya dihasilkan selepas dimasukkan ke dalam autoklaf untuk 8 jam pada suhu 135°C pada tekanan 0.24 MPa dan disinter 2 jam pada suhu 950°C. Apatit didapati tumbuh pada permukaan sampel β-wolastonit selepas 7 hari rendaman dalam larutan SBF. Semasa proses rendaman dalam larutan SBF, 2 jenis kumpulan kalsium fosfat dihasilkan iaitu amorfus kalsium fosfat (ACP) selepas 3 hari rendaman dengan julat nisbah Ca/P 1.2-2.02 dan pada hari ke-14 membentuk hidroskiapatit kurang kalsium (CDHA) dengan nisbah Ca/P 1.63. Perubahan fasa sampel β-wolastonit daripada keadaan hablur kepada amorfus jelas terbukti daripada keputusan XRD selepas direndam dalam SBF dengan penurunan puncak keamatan bagi sampel β-wolastonit pada sudut belauan 30°. Ini mengukuhkan mekanisme pembentukan lapisan apatit pada permukaan sampel β-wolastonit dan ianya bersifat bioaktif.
The mechanical strength of magnetic lumen loaded handsheets was reported to be lower than the unloaded handsheets. This effect is due to the deposition of filler inside the fiber lumen and some on the fibre surface which interfere with the fibre to fibre bonding. Hence, in order to improve the handsheets strength, cationic starch is used as a dry strength additive. In this study, mixed tropical hardwood pulps were used throughout the experiment. The magnetite particles were deposited in the fibre lumen via the lumen loading technique. The addition of cationic starch was found to increase the handsheet strength. However, it disturbed and influenced the location and distribution of the magnetic fillers. Some of the magnetite particles were observed to be displaced from the fiber lumen and pit apertures. The charges of the filler particles and cationic starch played an important role in producing charge repulsion and pulling effect which lead to filler dislocation.
Porous hydroxyapatite (HAp) as a bone graft substitute was produced via gas technique with three different concentrations of hydrogen peroxide (H2O2) namely 20, 30 and 50%. Hydroxyapatite(HA) slurries with different concentration were produced by mixing between H2O2 solutions and HA powder (L/P) with different ratio i.e. 0.9 to 2.20 ml.g-1. Different L/P ratio and H2O2 concentration affected the porosity, interconnectivity and compressive strength of HAp sample. Changes in L/P ratio between 0.9 to 2.20 ml.g-1, increases the porosity around 50 - 65% at 20% H2O2 concentration. Porosity increases with the L/P values and H2O2 concentration which 76% of porosity was obtained at 50% H2O2 and 2.20 mlg-1 of L/P. The compressive strength of HAp is in the range of 0.5 to 2.15 MPa and is found decreasing with the increasing of L/P values.
Tujuan kajian ini adalah untuk mengenal pasti kesan rawatan suhu yang berbeza terhadap kebioaktifan wolastonit
yang disintesis menggunakan teknik sol gel. Abu sekam padi dan batu kapur digunakan sebagai bahan awalan untuk
menghasilkan wolastonit. Nisbah campuran kalsium oksida dan silika dioksida CaO/SiO2 ditentukan pada 55:45 dan
dimasukkan ke dalam autoklaf pada suhu 135°C dengan tekanan 0.26 MPa selama 8 jam. Campuran serbuk CaO dan
SiO2 tersebut disinter pada suhu yang berbeza (1150°C dan 1250°C) dan diuji sifat kebioaktifan secara rendaman
dalam larutan cecair badan tersimulasi (SBF) selama 1,3,5,7 dan 14 hari secara in vitro. Sifat fizikal dan kebioaktifan
wolastonit sebelum dan selepas direndam dalam larutan SBF dan beberapa pencirian telah dijalankan menggunakan
teknik analisis XRD, FESEM, EDX dan FTIR. Campuran serbuk CaO-SiO2 yang telah diautoklaf dan disinter pada suhu
1250°C menghasilkan puncak tunggal pseudowolastonit. Ujian kebioaktifan menunjukkan lapisan amorfus kalsium
fosfat (ACP) dengan julat nisbah Ca/P 1.9-1.51 terbentuk lebih pantas pada sampel wolastonit yang disinter pada suhu
1250°C berbanding pembentukan ACP pada sampel tersinter 1150°C.
The purpose of this study was to prepare macroporous glass ceramic scaffold by sol-gel glass synthesis and powder
sintering method. Sodium nitrate was added during sol-gel process to obtain glass ceramic with mol composition of
42.11% SiO2
- 18.42% CaO - 29.82% Na2
O - 9.65% P2
O5
. The glass particles were found to be thermally stable above
900°C as indicated by TGA/DTA analysis. The dried glass particles obtained from sol-gel process were compacted and
sintered at 1000°C for 3 h soaking time. Sintering crystallized the glass by 71.5% of crystallinity with tetracalcium catenahexaphosphate
(V) (Ca4
(P6
O19) as the main crystalline phase as revealed by XRD analysis. Although glass crystallized
during sintering, it showed a good in vitro bioactivity as apatite-like layer were deposited on the glass ceramic surface
when immersed in simulated body fluid (SBF) for 14 days. SEM analysis proved the macroporous structure formation with
pore size ranges between 30 and 350 µm due to foaming effect which occurred during sintering. Besides that, the glass
ceramic surface formed into vitrified-like due to fluxing effect during sintering thus affected the porosity and densification
measurement done by Archimedes test. In conclusion, the presence of sodium oxide in sol-gel glass ceramic composition
by 29.82 mol % with sintering temperature at 1000°C is able to produce bioactive and macroporous glass ceramic that
potentially be used as medical scaffold material.
Kajian ini bertujuan untuk mengkaji kesan kandungan fosfat berbeza (X = 10, 15 dan 20% mol) terhadap pembentukan
morfologi permukaan, ikatan kimia, penghabluran, fasa dan kekuatan mampatan kaca sol-gel tersinter. Serbuk kaca
gel dengan komposisi 50SiO2
.(50-X).CaO.XP2
O5 (dalam peratusan mol) disediakan melalui kaedah sol-gel, dimampat
membentuk pelet dan disinter pada suhu 1200°C selama 3 jam. Didapati bahawa dengan peningkatan kandungan fosfat,
mikrostruktur kaca tersinter yang lebih padat terhasil disebabkan peningkatan pemadatan jasad, pengurangan keliangan
ketara dan pembentukan butiran dan sempadan butiran berhablur yang lebih besar. Peningkatan sebanyak 20% mol
kandungan fosfat meningkatkan vitrifikasi (fasa kekaca) pada permukaan kaca tersinter yang mana meningkatkan
pemadatan jasad kepada 83.56%, kekuatan mampatan pada 113 MPa dan penurunan peratusan penghabluran pada
sekitar 66%. Analisis EDS menunjukkan peningkatan kandungan fosfat menyebabkan peningkatan unsur Si-O pada fasa
amorfus dan unsur P-O pada fasa berhablur. Analisis FTIR menunjukkan berlaku pemisahan fasa kaya fosfat dan fasa
kaya silikat dan pada masa sama meningkatkan rangkaian tetrahedra silikat (Si-O-Si) dan fosfat (P-O-P) kaca tersinter.
Peningkatan kandungan fosfat meningkatkan kumpulan berfungsi berkaitan fosfat hablur dan mengurangkan kumpulan
berfungsi berkaitan silikat hablur. Ini menyebabkan peningkatan pembentukan fasa silikokarnotit, Ca5 (PO4)2 (SiO4)
dalam matriks kaca tersinter dengan peningkatan kandungan fosfat yang ditunjukkan melalui analisis XRD.
Hydroxyapatite (HA) powder was synthesized via wet method using calcium nitrate hydrate (Ca(NO3)2.H2O) and diammonium hydrogen phosphate ((NH4)2HPO4) as raw materials. Powder obtained was milled using various milling speed ranging from 250 to 400 r.p.m. and sintered at 1300°C for 2hrs. Due to the nature of HA powder that decomposed at high temperature, XRD technique have been used in this work to determine the phase composition of the HA powder and also the crystallite size. The unmilled sample was used as the control group. Results show that sufficient heat supply generated from the milling process, initiates the decomposition of HA phase into ȕ-tricalcium phosphate (ȕ-TCP). Decomposition of HA starts to occur at the milling speed of 300 rpm, i.e the formation of ȕ-TCP was occurred at lower sintering temperature. It was believed that the decomposition of HA was associated with the formation of an intermediate phase, oxyapatite. Moreover, the crystallinity and particle size of the produced powder is very much affected by the milling speed and the stability of the HA. All milled powders possess spherical shape particle.
Nitridation behaviour of Al-Mg-Si alloys was studied as a function of temperature by means of thermogravimetry method. A reactive gas, N2-4%H2 at a rate of 10 ml/min was purged into the thermogravimetry analyser chamber. The Al alloys were heated from 25oC to 625oC at the heating rate of 15oC/min and then reduced to 3oC/min until it reached 1500oC. It was found that by varying the amount of Mg and Si in Al-Mg-Si alloys significantly influenced the growth of the composites. A differential thermogravimetric curve shows the Mg containing alloys experienced many steps of chemical reactions. This indicates that besides AlN presence as a major phase, other compounds also exist in the final product. The X-ray diffraction results confirmed the existence of oxide phases such as a-Al2O3, MgAl2O4 and MgO in addition to residual Si and Al metal. The presence of oxide compounds is believed to be due to the reaction between the alloying elements and residual oxygen gas left in the reaction atmosphere. It was also found that Si could play a role in promoting the weight gain of the composite produced. The heating rate has also a profound effect on the weight gain, whereby higher heating rate resulted in low yielded of AlN during the nitridation reaction of the Al-Mg-Si alloys.
Sifat isoterma dan kinetik penjerapan formaldehid ke atas komposit serbuk serat kelapa sawit-TiO2 yang melibatkan sistem gas-pepejal adalah dikaji. Komposit serbuk serat kelapa sawit-TiO2 dihasilkan dengan mencampurkan serbuk kelapa sawit dan serbuk TiO2 dengan nisbah 8:2 menggunakan teknik pengisaran mekanik. Pengujian dijalankan di dalam kebuk ujian dengan komposit serbuk kelapa sawit-TiO2 dibiarkan untuk menjerap dan mengurangkan nilai kepekatan formaldehid secara pasif. Didapati nilai penjerapan maksima dan sifat kinetik penjerapan bergantung kepada kepekatan awal formaldehid. Kepekatan awal, Ci, 2.1 ppm dan 0.5 ppm masing-masing diwakili oleh pseudo-tertib pertama dan pseudo tertib kedua, manakala Ci = 0.75 dan 0.9 ppm diwakili oleh model Elovich. Isoterma penjerapan formaldehid diwakili oleh isoterma Freundlich dengan nilai korelasi tertinggi R2 = 0.9397 berbanding nilai korelasi isoterma Langmuir (R2 = 0.8692) dan isoterma Temkin (R2 = 0.8756). Parameter keseimbangan, 0
Al/B4C composites with 0 wt.%, 5 wt.% and 10 wt.% of B4C were prepared by powder metallurgy and their properties were characterised successfully. Investigation of the effect of milling times (4, 8, 12, 16 hours) on microstructure, phase identification, hardness and neutron attenuation coefficient of composites has been studied. The results showed that hardness increased with increased of milling time, with maximum hardness obtained at 16 hours milling time. The increment is slower as the composition of B4C increased. The hardness of Al/10%B4C, Al/5%B4C and Al/0%B4C were 81.7, 78.7 and 61.2 HRB respectively. Morphology of scanning electron microscopy (SEM) showed that microstructures play important role in controlling the hardness. Meanwhile, x-ray diffraction (XRD) analysis showed the phases and crystalline present in composites with an indication that crystalline of the grain increased as the milling time increased. Neutron absorption of Al/10%B4C composites showed that this composite has the highest attenuation coefficient, thus indicating that it is the best composites for neutron shielding.
The preparation, physical and mechanical properties of Al/B4C composites with 5 and 10 wt.% reinforcement content were investigated. In order to obtain the feedstock with a low powder loading, B4C mixtures containing fine powders were investigated to obtain the optimal particle packing. The experimental results indicated that the fine containing 5 and 10 wt.% particles are able to prepare the feedstock with a good flowability. The composites fabricated by powder metallurgy have low densities and homogeneous microstructures. Additionally there is no interface reaction observed between the reinforcement and matrix by XRD analysis. The hardness of Al/B4C composites prepared by powder metallurgy was high.
Bioactive composites consist of pseudowollastonite and mullite synthesized from natural resources was developed for
bone implant applications. To realize such applications, a mechanical test of these composites and in vitro bioactivity in
SBF solution were studied. The present paper reports pseudowollastonite synthesized from the rice husk ash and limestone
reinforced with 10, 20 and 30 wt. % of mullite. Influence of sintering temperature, phase composition, morphology towards
mechanical properties of various pseudowollastonite-mullite (PSW-M) composites was examined prior to the bioactivity
test. It was found that pseudowollastonite with the addition of 20 wt. % of mullite sintered at 1150°C gave the best result
for diametral tensile strength (DTS) and hardness with the value of 8.8 ± 0.15 MPa and 3.79 ± 0.13 GPa, respectively.
The obvious increment in the mechanical strength was due to the formation of liquid phase CaAl2
O3
during sintering at
1150°C. In addition, the formation of fibrous apatite (HA) layer of amorphous calcium phosphate (ACP) with Ca/P ratio
1.8 on PSW20M sample confirmed the good bioactivity of the composite.