Silanol groups that are present on the surface of rice hull ash or silica ash fillers can positively influence the reinforcing character of the filler. However, being hydrophilic, they present the ...problem of aggregation and moisture absorption. Physicochemical contributions to reinforcement, provided by silanol groups, influence the filler-polymer and filler-filler interactions. In this study, we investigated the surface energetics of silica ash particles and the effect of chemical surface modification on the free surface energy of silica ash particles was studied.Inverse Gas Chromatography (IGC), a successful evaluation technique for the surface energy of solids, has been used at infinite dilution to determine the nature of surface interaction of various probes with a silica ash surface. The Gibbs free energies and enthalpies of specific interactions were also determined to estimate the acid-base characteristics of the surface of silica ash particles. The influence of heat treatment and surface modification upon the physicochemical parameters was also investigated. It was found that the silica ash surface is acidic in nature. Modification of the surface, by hydrophobization using silane agents, reduces the specific component of surface energy and could be expected to positively affect the reinforcing character. Surface modification reduced the specific component of surface energy by 80% and positively affects the filler-matrix interaction.
Polylactic acid (PLA) and organically modified layered silicates (organoclay) with concentrations of 2-10 wt% were prepared by melt intercalation technique. The effects of organoclay on the ...mechanical and thermal properties of PLA were studied. Tensile properties were evaluated using an Instron Universal Tester. Modulated differential scanning calorimetry (MDSC) and Thermogravimetric analyses (TGA) were performed to study the thermal behaviour of the prepared composites. The nanocomposites exhibited superior improvement of practical materials properties such as Young's modulus and thermal stability, as compared to the neat PLA. The Young's modulus drastically increased, whereas tensile strength and elongation at break decreased. The maximum degradation temperature of the hybrid increased linearly with an increasing amount of organoclay. However, MDSC has determined that the glass transition, cold crystallisation, and melting point temperatures were not significantly influenced by the presence of organoclay.
In an increasingly globalized environment, engineering graduates must be able to work in diverse teams which may span nations. This means that engineering qualifications must embrace transnational ...perspectives and different local contexts within which engineering is practiced. One way to assure quality at the transnational level is to develop “dual accreditation”: degrees offered offshore are accredited by both the offering education provider's accrediting body and the professional body of the country in which the offering is being delivered. In light of this change to the engineering industry, The International Engineering Alliance has modified the Washington Accord, which controls the accreditation of all engineering degrees offered within signatory nations. Pre-2014 any engineering program delivered offshore needed accreditation from the offering education provider's professional body, however, by 2014, the Washington accord was altered to require dual accreditation: in other words, accreditation must be a collaborative endeavor between the accrediting body from the country offering the program and the local accrediting body of the nation where the program is being offered. This change in the agreement has some significant implications for the future accreditation of offshore engineering programs and this paper will examine some of these emerging issues.
Hardwood saw mill residues have traditionally not been favoured by the particleboard industry (or indeed other forest product industries) owing to their high density and extractives content. However, ...re-growth and plantation of timber industry has been producing hardwood saw mill residues with lower extractive contents and lower densities in recent years. The work presented here deals with investigating the use of hardwood saw mill residue, which is currently treated as solid waste, in producing industry-grade particleboard. A crossed experimental design covering seven process parameters with two levels was performed to manufacture three-layer particleboards in the laboratory to investigate effects of processing parameters on physical and mechanical properties of final boards. Although, resin surface and pressing time are significantly influencing both mechanical and physical properties of hardwood particleboard, moisture core increases the thickness swelling and reduces the mean density. However, the need for higher moisture content and resin load compared to those of softwood particleboard need to be addressed further to achieve an economically feasible product.
Polypropylene (PP) was used to study filler-polymer interactions when rice hull ash (silica ash) is used as a microfiller. Two sizes (47 and 20 μm) of silica ash particles were studied to obtain ...quantitative data on the composites' mechanical performance. The smaller particle size was obtained after communizing the original size. Nucleating effects were found, suggesting that there is a moderate polymer-filler interaction during melt-processing. A comparison of the effects of increasing filler loading and increasing surface treatment indicated that at higher filler loadings, the effect of surface treatment was not dominant. Reducing the filler particle size was found to improve tensile modulus and impact strength.
Removal of silica ash impurity by burning it off resulted in a significant increase in the above mentioned properties; however, similar results were not obtained after surface treatment of the unburnt ash. The results indicate that there is a possible trade-off between using the silica ash without burning, thus saving on the cost of burning off the impurities, and using the “burnt” ash and saving on the cost of surface modification.
Towards a Framework for Employability Teaching and Learning Ranaraja, Iresha; Jollands, Margaret; Date, Abhijit
2022 IEEE International Conference on Teaching, Assessment and Learning for Engineering (TALE),
2022-Dec.
Conference Proceeding
Future of work requires a workforce ready to face dynamic and turbulent market conditions. Despite decades of focus on graduates' employability, higher education institutes are under-prepared for ...this challenge. This study presents a draft conceptual framework for HE teachers to incorporate employability learning into curriculum development and delivery, a novel contribution to the literature. The theoretical underpinning for the study is drawn from employability and psychology literature. Another novel aspect of this study is that it captures both individual and institutional responsibility towards employability, for effective employability teaching and learning.
This paper focuses on the application of silica rich, rice hull ash (RHA) from the rice industry as filler in polypropylene (PP). The dynamic rheological behaviour and the crystallinity of its ...composites with semi-amorphous polypropylene were used as performance indicators. The effect of coupling agents on RHA/PP compatibility was also investigated. Addition of RHA increased storage modulus (G′), and the onset (Tco) and peak (Tc) crystallinity temperatures, and decreased the degree of crystallinity of the system. Two coupling agents, maleated polypropylene (MAPP) and an amino functional silane, were used to improve the interfacial adhesion of RHA and PP. Addition of MAPP increased G′, Tc and Tco and the crystalline phase of the system. Addition of silane had mixed effects. It increased the rheological properties at higher concentrations, it increased Tc and Tco at all the concentrations and increased crystallinity at lower concentrations and decreased it at higher concentrations. Results from a thermogravimetric analyser were useful in revealing the mechanism by which silane bond to RHA and its effect on the rheology and crystallisation behaviour of the composites.
Annually, sawmills and other wood-processing factories generate a significant amount of scrap materials which are sent to landfills or incinerated. The amount of residue generated in Australia ...annually is estimated at 200,000 tonnes. A research project conducted at RMIT University explored utilizing these waste materials as particleboard furnish. The research team has now established a methodology for making particleboard in the laboratory using 100% hardwood sawmill residues, developing a particleboard product made in the laboratory which has acceptable mechanical properties and density profiles in accordance with the Australian Standards. However, this board product has some perceived issues which have been hindering ready commercial uptake. The current product requires a 10% higher resin load, has a 10% higher board density, and requires 10% longer pressing times compared to normal softwood particleboard. The paper presents an analysis of the current production process of particleboard to investigate the economic feasibility of particleboard production using hardwood sawmill residues. A major challenge in the analysis is converting the environmental benefit of utilizing large quantities of sawmill residue to a monetary term. Investigation of the global impact of particleboard by considering emission of carbon dioxide to the atmosphere is also included. A comparison is presented between different methods of disposing wood residues to understand the environmental benefit of using hardwood residue in particleboard.
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