Applied Mechanics and Materials Vols. 548-549

Abstract: The recycling of plastic products is gaining widespread attention because of its significance in the reduction of petroleum consumption and in the conservation of limited resources. It is also an effective method of handling plastic waste, as opposed to traditional landfill and incineration waste disposal methods. This study attempts to find a method by which to manage the increasing amount of PA66-GF waste generated by the gear industry through the recycling method. By adopting the L₂₇ Taguchi orthogonal array, S/N ratio and ANOVA are conducted to evaluate the impact of recycled materials on various compositions. The different settings of injection parameters on the gears’ Young’s modulus and elongation at break are also identified and examined.

Abstract: As non-uniform color and complex texture exist on the polycrystalline silicon solar cell, manual surface inspection adopted by most domestic factories suffers from low efficiency and poor repetitive detection ability. To overcome the shortcomings of manual inspection, based on machine vision and SVM, an automatic silicon wafer surface defect detection and classification system has been developed in this paper: through feature extraction of color images and defect areas, a series of wafer classifiers are trained and used to separate the defective products from qualified ones. Experiments on samples and actual application in the enterprise show that the system has achieved high accuracy and fast run-time performance, indicating that machine vision is an effective and promising method for polycrystalline silicon solar cell inspection.

Abstract: In order to produce good functional Laser Sintering (LS) parts, it is important that the powder on the part bed surface receives a sufficient amount of power energy through the laser sintering process. The reason is that sufficient energy density is produced when the energy input increases and is applied to the part bed surface, which causes a higher temperature, and thus better melt flow. The objective of this research is to investigate the thermal properties of polymer materials used in Selective Laser Sintering (SLS) processes. In this experiment, there were five different thermoplastics powders known as polyamide 12 (PA2200), Glass Fill Polyamide (GF3200), Alumide, Duraflex and CastForm were tested using Differential Scanning Calorimetry (DSC). This outcome of this research would assist the SLS users to improve the sintering process and quality of the part surface finish.

Abstract: A series of novel stable polyurethane emulsion with high-solid-content and low-viscosity were prepared by self-emulsification. They were prepared by the reaction of poly (tetrahydrofuran-co-oxidation of propylene) glycol (Ng210), isophorone isocyanate (IPDI) with 1,2-dihydroxy-3-propanesulfonic acid salt (DHPA) as hydrophilic chain-extending agents. Influence of the content of DHPA on properties of polyurethane emulsion and film were analyzed .The results show that obtained emulsion were multivariate distribution in particle size and were spherical particles by measurement of grain size and electron microscopic photo. It is noticed that with increasing content of DHPA and, average particles diameter of polyurethane emulsion became smaller, poly-dispersion became narrower and solid-content became bigger. when the content of DHPA is 7%, solide-concent of emulsion reaches 61%. In addition, Polyurethane emulsion are endowed stability of emulsion are good at high temperature and low temperature as well as storage stability.

Abstract: Asbestos is the trade name of material widely used in construction, especially in BRICS members. The high usage of asbestos due to its low cost coupled with their properties, such as electrical resistance, tensile strength, heat resistance and some acids, in addition to its flexibility derived from its fibrous feature, which allows it to be woven. However, it is also known that asbestos in the process of extraction and production is extremely dangerous for workers. Very thin fibers tend to turn into powder that is deposited in the lungs of workers, which may lead to loss of breathing capacity, pleural plaques, some cancers, and most often a disease called asbestosis. Although there is a tendency to ban asbestos in all regions and countries, as already occurs in the European Union, Brazil, and other countries with large housing deficit, maintains the use of asbestos in the production of fiber cement tiles. The article aims to discuss the dilemma of controlled use and ban asbestos, and present the progress of the search for alternative materials to asbestos in Brazil.

Abstract: Foam stability can be uttered in foamability measurement and bubble size dispersal. The higher the foamability, the more stable it is. The addition of nanosilica particle to the foam system will further improve the rigidity of the lamellae interface by providing stickiness force between foam lamellae and its surface, halting the film thinning and prevent it from rupture. This paper aims to investigate the stability of CO₂ foam with addition of nanoparticle, to find the optimum surfactant and nanoparticle concentration that achieved higher foam stability, to determine the relationship between the foamability and the nanoparticle concentration within the carbon dioxide foam system and also to analyze the effect of crude oil on foam stability. For this experiment, foam generator was used. The concentrations of surfactant were prepared at ranges from 500 ppm to 5000 ppm. The foam stability test was conducted at constant pressure, temperature and flowrate. The nanoparticle was used with set of different concentrations such as 1000 ppm, 3000 ppm and 5000 ppm. It was found that the increases in both surfactant and nanoparticle concentration have boosted up the stability of the foam produced from 92% to 100% foamability and foam durability extended to maximum of 5 hours. The optimum concentration of both surfactant and nanoparticle was 5000 ppm. It is important to determine the relationship between foamability and nanoparticle concentration, so that foam stability, mobility and the morphology of the foam produced can be forecasted with the newly breakthrough nanoparticles technology.

Abstract: Hydroxyapatite (HAP) composite coatings with interlayer of TiO₂ on Ti6Al4V alloy were prepared by microarc oxidation and electrochemical potentiostatic method. Platelet adhesion test and electrochemical behaviors of the HAP coatings were investigated in platelet-rich plasma, Ringer's solution, Tyrode's solution and human blood at 37°C. The HAP coating was characterized by scanning electron microscope (SEM), X-ray diffraction (XRD). TiO₂ coating has round ostioles on the surface with the element of O, Na, Al, Si and Ti. The HAP coating has sheet-like, column-like and batten-like crystal with the Ca/P 1.6689. The biocompatibility of HAP coating was better than the initial coating. The results indicated that the HAP coating had better characters of anticorrosion and biocompatibility.

Abstract: Alpha-amylase, glucoamylase and cellulase were immobilized onto calcium alginate-waste clay (alg-WC) beads by using encapsulation technique. The clay was obtained from palm oil mill clay bath processing waste that was collected from FELDA Serting Hilir Palm Oil Mill, Malaysia. The aim of this study is to characterize and investigate the performance of waste clay as a supporting material for the tapioca starch hydrolysis. The encapsulated enzymes were characterized by using analytical equipment such as Fourier Transform Infrared Spectroscopy (FTIR) and Field Emission Scanning Electron Microscopy (FESEM). The FTIR results showed the interaction of functional groups between alginate and waste clay in the alg-WC beads. The alginate beads characterized at peaks 1615 cm^-1, 1417 cm^-1 and 1027 cm^-1, and peaks 1396 cm^-1, 873 cm^-1 and 712 cm^-1 characterized the waste clay. The FESEM analysis also revealed that the different surface morphology of alginate beads and alg-WC beads. It also showed that the enzymes were successfully encapsulated within the alg-WC beads. The activity of the immobilized enzymes was studied at different clay concentrations. The highest immobilization yield was obtained at 2% (w/v) of clay concentration and the highest enzyme loading was 98.29 %. The immobilized enzymes also retained 33% of its activity after seven usage cycle with 1 hour of each reaction time.

Abstract: Removal of acid gases from natural gas is very important as to meet the sale’s specifications and environmental regulations. It is also a measure to minimize the corrosion effects. The most common process to remove the acid gases is amine process. There are some operating parameters which can be considered to optimize amine sweetening plant such as inlet gas temperature, lean amine circulation rate, lean amine temperature, amine concentration, number of trays and others. The objectives of the project are to study the optimum number of trays of absorber and amine circulation rate in removing acid gases in absorption unit using HYSYS simulator which capable in designing the process. By using HYSYS software, a base case of amine sweetening unit was created and di-ethanolamine (DEA) is used as the amine solvent. Four samples at different concentrations of acid gases were tested. The rules evaluated include 20 trays in the absorber and higher circulation rate. Although these rules of thumb are excellent as the starting points, violating these rules could offer considerable advantages to process efficiency. Depending on the concentration of the acid gases at the feed stream, every situation is different and requires a thorough investigation whether some changes are beneficial or not.

Abstract: In this study, an effect of leaching treatment on the mechanical properties of natural rubber latex (NRL) products was investigated. The products were prepared by compounding the NRL dispersion system with modified kaolin as fillers then it was formed by dipping method. It was found that incorporation of fillers in NRL would result in lowering mechanical properties of vulcanizates when the leaching was performed. The results were confirmed further by characterization of Fourier-Transform Infra-Red (FTIR) and Scanning Electron Microscopy (SEM).