Pusat Pengajian Kejuruteraan Bahan dan Sumber Mineral - Tesis

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Modelling And Simulation Of Air Classifier Cement Manufacturing
(2014)
Ishak, Ku Esyra Hani Binti
The cement finish grinding circuit in cement manufacturing consumed the most electrical power in the cement industry. The total power consumption, however depends on the fineness of the grind, the particle size distribution and also the efficiency of the separation process of the ground particles. Improving the efficiency of the grinding and separation of the particles can give an improvement in the energy saving and cost reduction. The separation of particles is usually done by air classifier in a closed circuit. This thesis presents the development of a mathematical model that can describe the behavior of air classifier in the cement finish grinding circuit. Efficiency curves were used to model the high efficiency air classifier. The modelling work involves the taking of data in the full-scale plant. Industrial surveys were done to obtain data at the air classifier feed, air classifier reject and air classifier product. These data are important information in understanding how the air classifier behaves and helped in the development of the air classifier model. First, a review of mathematical modelling of air classifier is presented. Then, the results of the particle size distribution of from the testing are discussed. The efficiency curve was also developed. The simulator used is mainly based on the Whiten function to model the air classifier and predicts the reject and product output streams particle size distributions. The modelling of air classifier can be modelled in terms of dsoe, bypass, the fish hook and the sharpness of the curve.
Effect Of Stand-Off Distance And Plasma Current On The Properties Of Hydroxyapatite Coatings Produced By Plasma Spray
(2014-12)
Sulaiman, Wan Ruzaini Wan
Plasma sprayed hydroxyapatite (HA) coatings on metallic implants for biomedical applications are attracted significant researchers interest due to accelerated rate of bone bonding that occurs following their implantation. This present work aims to produce plasma sprayed HA coatings with varying spray parameters (i.e.; stand-off distance, SOD and plasma current, PC) in order to control the coatings crystallinity. The substrate used is 316L stainless steel. Five SODs were selected i.e. 80 mm, 100 mm, 120 mm, 140 mm and 160 mm combined with two different PCs (500 A and 600 A), respectively. The coatings then divided into two groups (as sprayed and heat treated). Both coating was subjected to in vitro test through immersion in SBF solution up to 28 days to determine their bioactivity. The coating properties before and after immersion in SBF were analyzed using FESEM and XRD. The analysis showed coatings morphology consists of type III, V and VIII splats with lamella and non-lamella structures. The crystallinity of as-sprayed coatings is in vicinity of 50%. However, the crystallinity increases more than 90% after heat treatment process. The in vitro analysis proved that the highest apatite layer precipitations on surface with coatings surface was from the assprayed coatings rather than the one being heat treated. Therefore, the quality of HA coating via plasma spray coating technique can be modified through the suitable combination is at SOD 120 mm and PC 600 A.
Preparation And Properties Of Polyvinyl Alcohol/Soya Bean Flour Biodegradable Film
(2014-09)
Suki, Fairus Mazlia Mat
In this research, a new polymer blend based on soya bean flour (SBF) and polyvinyl alcohol (PVA) was prepared using solution casting method. Initially, the SBF content was varied from 10 to 40 wt %. Tensile strength and elongation at break of the PVAlSBF blend films were lower, but the tensile modulus was higher than that of unfilled PVA film. This was mainly because of the presence of SBF in the blend. The PVAlSBF blend films showed higher water barrier properties with increasing SBF content. Biodegradability tests revealed that the presence of SBF stimulated the degradation rate and caused the weight loss of the PVAlSBF blend films. Secondly, the effectiveness of hexamethylenetetramine (HMTA) as crosslinker on PVAlSBF blend films was compared to the non crosslinked PVA/SBF blend films. The crosslinked PVAlSBF blend films showed better tensile and water barrier properties. This was attributed to the effectiveness of HMTA in the blend. Natural weathering test revealed that the presence of HMTA did not significantly affect the weatherability of the PVAlSBF blend films. But, in soil burial test the weight loss of non-crosslinked blend films was higher than crosslinked blend films. Thirdly, banana frond flour (BFF) and halloysite nanotubes (I-INT) were added as filler to form ternary blend system. PVAlSBF/HNT blend films show better properties in tensile and water barrier because HNT have higher aspect ratio and provided more interaction sites. Degradability for both blend films were increased with increasing filler content after subjected to degradation test. Lastly, BFF was treated by alkaline treatment. Better tensile and water barrier properties were obtained by the treated PVAlSBF/BFF blend films. This result might due to the better compatibility and interaction of treated BFF and PVAlSBF matrix. Besides that, the higher water barrier properties of treated PVAlSBFIBFF blend films were contributed to reduction of the film degradation.
Preparation And Properties Of Rubber Seed Shell Flour (Rssf)Filled Polypropylene (Pp) Composites
(2014-09)
Shafiq, Mohamad Danial
In this research, rubber seed shell flour (RSSF) was incorporated in polypropylene (PP) to determine the composites with optimum properties. RSSF loadings were varied from 10 php to 40 php to study the effect of adding RSSF on processing, tensile, morphological, flexural, impact, water absorption and thermal properties of PP/RSSF composites. In the second series, the effect of adding polyethylene copolymerized with acrylic acid (PE-co-AA) was studied, on the properties of PPIRSSF composites. Phthalic anhydride (PA) was added as a compatibilizer separately in PPIRSSF composites in the third series. In the next series, epoxidized vegetable oil (EVO) was added as a compatibilizer in PP/RSSF with fixed amount of 7 php. Preparation of the composites has been conducted in Haake Polydrive internal mixer with the temperature of 180°C using rotor speed of 50 rpm. The addition of RSSF in the composites increased the stabilization torque in PP composites. Furthermore, compatibilization of PPIRSSF composites with PE-co-AA and p A increased the stabilization torque of PPIRSSF. Somehow, the presence of EVO reduced the stabilization torque resulted from flexible and long chain of EVO. The addition of RSSF in PP reduced the tensile strength and elongation at break, somehow, the Young's modulus is improved. This is mainly caused by incompatibility of PP and RSSF resulted to poor interfacial adhesion. Clear observations were presented in SEM micrograph of tensile fracture surface. The incorporation of RSSF in PP has increased the water absorption of the composites xxiv due to the presence of lignocelluloses in RSSF, which possibly creates hydrogen bonding with water.
The Effect Of Natural Weathering Exposure And Hygrothermal Aging On The Properties Of Pultruded Hybrid Glass/Kenaf Fibre Reinforced Unsaturated Polyester Composites
(2014-06)
Osman, Muhammad Razak
By using pultrusion technique, three types of pultruded composites at 70 V/V% fibre loading have been produced which are pultruded kenaf fibre reinforced unsaturated polyester composites (PKRC), pultruded glass fibre reinforced unsaturated polyester composites (PGRC) and pultruded glass/kenaf fibre hybrid reinforced unsaturated polyester composites (PGKRC). The objective of this study is to determine the behavior of PGKRC as compared to PKRC and PORC after being subjected to natural weathering exposure of 200 days and six weeks of hygrothermal aging in distilled water at 65°C. In natural weathering exposure study, PGRC specimens recorded the least absorbed moisture while PKRC specimens showed the highest. PGKRC specimens took place in between these two specimens but closer to the PGRC instead of PKRC. Similar pattern were observed in the hygrothermal aging study. Flexural and compression tests carried out on all the three types of specimen had shown a decrement in mechanical properties after a prolonged exposure. Moisture invasion is the major factor that weakened the fibre-matrix interfaces which led to mechanical properties reduction and it acts differently for different types of pultruded composites due to the nature of the constituent fibres and the arrangement of the pultruded hybrid composites. The effects of different layering pattern in PGKRC were also studied and concluded based on the resulted mechanical properties.

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