Applied Mechanics and Materials Vol. 679

Abstract: Polylactic acid (PLA) is the most promising material in the biodegradable category. However, brittleness and poor thermal stability restrict its application. To overcome this limitation, PLA may be blended with other biodegradable materials to tailor its properties while maintain biodegradability. In this study a series of blends of PLA and poly (ε-caprolactone) (PCL) with various mass fractions were prepared by solution method and solvent casting. Films of each blend were formed when the solvent evaporated. Subsequently, tensile test samples were punched out of the film for testing and tensile testing, Fourier transform infrared spectrometry (FTIR), Differential scanning Calorimetry (DSC) and contact angle measurements were carried out. Since PCL is a ductile material, the two materials were blended together in an effort to improve the mechanical properties. However, on thermal analysis of the blends, two individual melting peaks were observed in the DSC thermograms. Furthermore, no significant shift in peaks was observed on the FTIR spectra, and clear droplets and boundaries between two components of the blend can be observed in morphology study, all indicated the immiscibility of PLA and PCL. Tensile test showed poor mechanical properties due to the poor adhesion of the two immiscible components of the blend, and the addition of PCL did not influence the wettability of the surface of the blends as there were no significant differences in contact angle measurements.

Abstract: In this study, xanthan gum and poly (ethylene oxide) (PEO) were blended via hot melt extrusion. Results showed that PEO acted as a plasticiser and lowered the melt viscosity of xanthan gum/PEO blends. For example, melt flow rate and torque level were observed to decrease at increasing percent compositions of PEO in the blend. Breakdown testing demonstrated that xanthan gum accelerates the breakdown rates compared to the breakdown rate of 100 % PEO extrudate samples.

Abstract: Novel photopolymerised composite hydrogels based on PEGDMA, maleic chitosan and maleic PVA were investigated for their suitability in bone tissue engineering applications. Initial swelling and compression studies revealed that the hydrogels permitted the retention of aqueous solution while still maintaining structural integrity. Promising cytotoxicity data was obtained during direct and indirect contact exposure of composite hydrogels to pre-osteoblast (MC3T3-E1) cells. Hybrid hydrogels displayed minimal cytotoxic properties and allow tailoring of mechanical properties by variation of the loading of the maleic component in the composite. Scanning electron microscopy and live-dead staining of composite hydrogels also revealed that maleic chitosan based gels supported the adhesion of MC3T3-E1 cells and may have potential as bone tissue engineering scaffolds.

Abstract: The effect of isophathalic acid-maleic anhydride (IAMA) as a compatibilizer on the tensile properties and swelling behavior of ethylene vinyl acetate /natural rubber/ feldspar (EVA/NR/PF) composites were studied. The EVA/NR/PF composites with and without IAMA were prepared using Brabender Plasticoder at 160oC with 50rpm rotor speed. The results indicated that EVA/NR/PF/IAMA showed higher value of tensile strength and M100 but lower elongation at break and percentage mass swell compared to EVA/NR/PF composites.

Abstract: Radical science and innovation in farming is vital to produce the food that the world will need by 2050. To feed an estimated world population of nine billion people in 2050, 70 % to 100 % increase in food production will be required if it continues rising at the current rate. The aim of this project is to develop novel revolutionary super absorbent hydrogel coatings for agricultural use. Hydrogel seed coatings improve the rate of seed germination and emergence and enhance seed survival during critical development periods, especially under less than optimal conditions. Preliminary work with ι-carrageenan hydrogel showed a promising results including higher seed germination rates, faster plant emergence, lower water requirement, enhanced root development and potential carrier of nutrients. Two hydrogel blends – agar/ι-carrageenan and xanthan/κ-carrageenan/ι-carrageenan – were synthesised and characterised in this project as potential seed coating materials based on their biodegradable, non-toxic sugar based natural polymers and their excellent water absorbing/holding capability. The newly formulated hydrogels were characterised by swelling studies, rheological measurements and infrared spectroscopy. It was found that the addition of xanthan/κ-carrageenan into ι-carrageenan hydrogel improved the water absorbing capacity from 117.90 % to 139.05 %, the life-span of the hydrogel from 6 hr to 24 hr in excess water and the gel strength from 108.4 Pa to 267.98 Pa. The addition of agar into ι-carrageenan showed an increase in gel strength and a greater improvement in water holding capacity giving 67.33 % water content while ι-carrageenan on its own had only 39.64 % after 72 hr of incubation at 30 °C, which showed higher potential to be used in drought conditions. The ATR-FTIR results proved that the hydrogels were physically cross-linked. A further evaluation such as the germination profile test is required to test the effectiveness of the hydrogel coatings on seeds. It is anticipated that this work will be extended to coating different seed varieties in the future with these newly developed hydrogels.

Abstract: There is an urgent and unmet requirement for biocompatible and biodegradable implants that gradually resorb when implanted in vivo. This study examines the potential of melt extruded thermoplastics polyethylene oxide (PEO) and polycaprolactone (PCL) in the area of regenerative medicine. Various ratios of PEO and PCL were melt blended and analysed in order to obtain an optimised breakdown rate. Subsequently the effect of varying the molecular weight of PCL using a constant molecular weight PEO was also examined. Samples were characterised using melt flow index (MFI), differential scanning calorimetry (DSC) and breakdown analysis. It was found that by altering both the concentrations of PEO/PCL and the molecular weight of PCL, melt viscosity, breakdown rate and thermal properties could be modulated to produce potential implant materials with a tailored breakdown rate.

Abstract: This article studies the numerical simulation of power generation in four different tidal stations in the East Coast region of Malaysia. The tidal stations are Tanjung Sedili, Tanjung Gelang, Tioman and Cendering. The simulation model is based on power generation using tidal barrage. Ebb, flood and double-mode generations were studied. The tidal basin area was estimated by approximation to generate sufficient electricity for local community consumption. Thus, a different basin area was estimated for every location as each location has different population size. Single-flow generation was assumed for ebb and floor generations with 40% barrage efficiency while bi-directional generation was assumed for double-mode generation with 30% barrage efficiency. Double-mode generation has the highest power generation among the three different methods. Tanjung Gelang has the highest average tidal range difference. However, Pulau Tioman is more suitable to have the tidal barrage as the local community population is smaller, thus, requiring a smaller basin area to generate sufficient electricity to meet the demand of local community. On average, tidal barrage with a basin area of 0.3km² in Pulau Tioman will be able to generate 13.74 GWh annually.

Abstract: This article studies the GIS simulation of yearly power generation in five different tidal stations in the East Coast region of Malaysia. The tidal stations are Geting, Tanjung Gelang, Tioman, Tanjung Sedili and Cendering. The tidal station in Geting is not analysed in this study because the tidal range is insignificant. After analysing the lagoons nearby to the four tidal stations, Tanjung Gelang and Tanjung Sedili are chosen in this study based on their natural characteristics and geomorphology of lagoons. The simulation model is based on yearly power generation using tidal barrage. This article also looks into the model in terms of mapping using GIS software to obtain bathymetry and tidal range data. Bathymetry data in GIS format is obtained from NOAA (National Oceanic and Atmospheric Administration) and tidal range data is obtained from ‘Jabatan Ukur dan Pemetaan Malaysia’. The latest tidal data up to date is the year 2011. The minimum depth of tidal basin should be 3.0 meter. Using GIS software to analyse bathymetry and tidal range data, the results are then combined to find yearly generation power output in the two tidal stations and are plotted in one map for each tidal station. The area of basin in Tanjung Gelang and Tanjung Sedili are 17.736 km2 and 27.919 km2. The calculation includes the important parameters such as area of basin, tidal range, number of tide cycles per year, and number of hours per tide. From the results and analysis, it is concluded that Tanjung Sedili and Tanjung Gelang produce 1.528 x 108 kWh and 1.294 x 108 kWh as their yearly power generation in 2011.

Abstract: – Decrease the iron loss, total loss and thicknesses of steel sheets will produce high efficiency of the induction motor This paper studies, a rotor construction with different thickness was investigated thoroughly and analyzed in the case of efficiency, torque, all losses and distribution field. All result simulation was done by MotorSolve (IM) which allows the user to produce more design of induction motor with a decision within a short time. According to simulation result, the 0.35 mm showed that a best performance and efficient compared to 0.50 mm thickness of rotor frame.

Abstract: Hydrogel soft contact lenses have been investigated as delivery systems for ophthalmic drug products in response to the need for more efficient ophthalmic drug delivery systems. Ocular drugs delivered via eye drops have a low residence time in the eye resulting in as low as 5% bioavailability of the therapeutic agent. This study investigates the effect of varying concentrations of the photoinitiator diphenyl (2,4,6-trimethylbenzoyl)-phosphine oxide (TPO) on the physicochemical properties of hydrogel soft contact lenses for ophthalmic drug delivery purposes. Contact lens samples were synthesised via photopolymerisation with a range of initiator concentration. Gel fraction and swelling results indicated that increasing the photoinitiator concentration increased the efficiency of the gel network and reduced the water content of contact lens samples. Fourier transform infra-red spectroscopy (FTIR) analysis was employed to confirm polymerisation of the lenses and also indicated the presence of residual photoinitiator in lenses with higher TPO concentrations.