A review on thermophysical evaluation of alkali-activated geopolymers

Recent progress in research on the key thermal expansion properties of amorphous, silica-based, alkali-activated geopolymers and their potential applications are here reviewed and addressed. Besides having great potential as thermal insulators and fire resistant materials since they are not combustible, geopolymers can be applied as interior aircraft components to improve fire resistance, and as coatings for insulator applications and many other potential applications. The raw materials used to make geopolymers are alumino silicates such as fly ash, granulated blast furnace slag, and calcined kaolinite clays. The raw materials can be obtained from biomass waste such as rice husk ash, palm oil ash, and rice husk bark ash. Different raw materials will exhibit different thermal expansion/shrinkage due to their different chemical compositions. In addition, processing of geopolymer material will result in diverse thermal properties due to the different molarity of the alkaline activated solutions used and method of preparation. Interestingly, it was found that the dilatometer curve is influenced by many factors such as aluminosilicate source, silica to alumina ratio, geopolymer mixing ratio, chemical composition and type of geopolymer—such as composite, coating or hybrid. These characteristics are investigated further in this review paper

Mechanical analysis of a wedge device in sawing technology

The oil palm trunk (OPT) currently represents a massive volume of agricultural waste with great potential to be rapidly developed in the wood composite industry. An improvement in sawing technology has potential to improve the yield of the commercially hard outer core of the OPT by about 27 % thus replacing the present sub-optimal square sawing pattern with a more efficient and higher-yielding polygon sawing pattern. To achieve this, a 'wedge' device was designed to be mounted on the existing sawing carriage. The proper methodology was followed including extraction of the design layout of the machine, development of the schematic drawing and wireframe model, modification of the design in computer-aided design (CAD) environment, the performance of stress, total deformation, and fatigue analysis, and production of a complete drawing for fabrication purpose. Results from the analysis showed that the designed part was safe to be fabricated with a small maximum equivalent stress of 2.546 MPa, maximum total deformation of 0.007935 mm and total life cycle of one million cycles. These evaluation results indicate that the material used for the wedge device (including the base part) satisfies the design requirements of static strength and is safe within its designed fatigue life

Optimization of adhesion strength and microstructure properties by using response surface methodology in enhancing the rice husk ash-based geopolymer composite coating

As a result of their significant importance and applications in vast areas, including oil and gas, building construction, offshore structures, ships, and bridges, coating materials are regularly exposed to harsh environments which leads to coating delamination. Therefore, optimum interfacial bonding between coating and substrate, and the reason behind excellent adhesion strength is of utmost importance. However, the majority of studies on polymer coatings have used a one-factor-at-a-time (OFAT) approach. The main objective of this study was to implement statistical analysis in optimizing the factors to provide the optimum adhesion strength and to study the microstructure of a rice husk ash (RHA)-based geopolymer composite coating (GCC). Response surface methodology was used to design experiments and perform analyses. RHA/alkali activated (AA) ratio and curing temperature were chosen as factors. Adhesion tests were carried out using an Elcometer and a scanning electron microscope was used to observe the microstructure. Results showed that an optimum adhesion strength of 4.7 MPa could be achieved with the combination of RHA/AA ratio of 0.25 and curing temperature at 75 °C. The microstructure analysis revealed that coating with high adhesion strength had good interfacial bonding with the substrate. This coating had good wetting ability in which the coating penetrated the valleys of the profiles, thus wetting the entire substrate surface. A large portion of dense gel matrix also contributed to the high adhesion strength. Conversely, a large quantity of unreacted or partially reacted particles may result in low adhesion strength

Physical and mechanical properties of unripe Nipah banana fruit (Musa acuminata balbisiana)

This paper describes the properties determined to acquire physical and mechanical properties of unripe Nipah banana. In Malaysia, most of the banana chips processing companies use a variety from Nipah Banana,also known as Musa acuminata balbisiana a triploid hybrid banana cultivar. The physical (diameter, weight and peel thickness on edge and side) and mechanical properties (penetration and compression test) of Nipah Banana variety were determined through five consecutive days to evaluate its behaviour throughout its ripening period. The average diameter is 38.78±5.77 mm x 29.25±4.92 mm. The average thickness of peel at the edge and side are 5.3±0.93 mm and 3.65±1.01 mm respectively. The average weight of the Nipah banana variety is 77.85±28.61 g. Penetration force through 5 ripening days was found to decrease from 7.53N to 6.59 N (top position), 7.59N to 6.40N (middle position) and 8.31N to 6.43N (bottom position). The compressive force decreases through 3 days from 1704 N to 1630 N with the sudden increase in day 4 to 1380 Using the following properties accumulated, the machine components specification can be obtained which are the blade force required to slit the banana peel, the thickness of the blade needed for the slitting of banana peel, the roller force to hold the banana in place and the peeler size

Fire retardant performance of rice husk ash-based geopolymer coated mild steel - a factorial design and microstructure analysis

Higher content of silica in geopolymer coating resulted in better thermal properties. Since rice husk ash (RHA) has the highest silica content compared to other aluminosilicate sources available, it offers the best potential to be an alternative silica source in producing geopolymer coating binder. In this study, five factors including ratio of alkaline activator (AA) (A), ratio of RHA/AA (B), curing temperature (C), curing time (D) and concentration of NaOH (E) were analyzed using statistical analysis to identify the significant factors that mostly influence fire retardant performance of RHA-based geopolymer coating. The fire retardant tests were conducted and results recorded included (i) time taken to reach 300°C and (ii) temperature at equilibrium. Sample S7 (coating composition of A=5.5, B=0.3, C=50°C, D=7days, E=8M) which produced the best fire retardant performance was selected for further detailed investigation using thermogravimetry analysis (TGA) and scanning electron microscopy (SEM). It was found that the back temperature of mild steel plate of sample S7 reached 300°C after 17 minutes and achieved an equilibrium state at 398°C. SEM micrographs showed the presence of needle-like structures formed after fire test might be the reason for the best fire performance of sample S7

Optimizing the processing factor and formulation of oat-based cookie dough for enhancement in stickiness and moisture content using response surface methodology and superimposition

Despite the utilization of dusting flour and oil to reduce dough stickiness during the production process in food industry, they do not effectively help in eliminating the problem. Stickiness remains the bane of the production of bakery and confectionery products, including cookies. In addition, the high moisture content of cookie dough is unduly important to obtain a high breaking and compression strengths (cookies with high breaking tolerance). This study was conducted in light of insufficient research hitherto undertaken on the utilization of response surface methodology and superimposition to enhance the stickiness and moisture content of quick oat-based cookie dough. The study aims at optimizating, validating and superimposing the best combination of factors, to produce the lowest stickiness and highest moisture content in cookie dough. In addition, the effect of flour content and resting time on the stickiness and moisture content of cookie dough was also investigated, and microstructure analysis conducted. The central composite design (CCD) technique was employed and 39 runs were generated by CCD based on two factors with five levels, which comprised flour content (50, 55, 60, 65, and 70%), resting time (10, 20, 30, 40, and 50 min) and three replications. Results from ANOVA showed that all factors were statistically significant at p < 0.05. Flour content between 56% and 62%, and resting time within 27 and 50 min, resulted in dough with high stickiness. High-region moisture content was observed for flour content between 60% and 70%, and within 10 and 15 min of resting time. The optimized values for flour content (V1) = 67% and resting time (V2) = 10 min. The predicted model (regression coefficient model) was found to be accurate in predicting the optimum value of factors. The experimental validation showed the average relative deviation for stickiness and moisture content was 8.54% and 1.44%, respectively. The superimposition of the contour plots was successfully developed to identify the optimum region for the lowest stickiness and highest moisture content which were at 67–70% flour content and 10–15 min resting time

Design And Development Of Ergonomic Table And Analyze Using Rula Analysis

Ergonomics and design have made the greatest relation in producing an artifact or creating a workplace. A computer table is widely used in classrooms in universities. However, the problems of the current computer table have been detected through the results of RULA analysis. In this project, a survey of the questionnaire was done and the anthropometric data have also been collected. The dimensions of the current computer table are then collected and the deficiencies of the current computer table have been focused on RULA analysis. A new structural design of the computer table has been designed, in order to meet the requirements of ergonomics. A product of the new design of ergonomics computer table is made and has been focused on RULA analysis to define the improvement between both tables. The paper showed a comparison between the current computer table and the new ergonomics computer table were analyzed. The improvement of the new ergonomics computer table was identified and reduced the injuries and disorders. A further investigation on better working posture when using a computer table is required, while further improvement for the product design of a new ergonomics computer table is needed, as well as the application of the ergonomics design aspect in our life

Effects of different fluting medium geometries on von-mises stress and deformation in single fluted board: a three-dimensional finite element analysis

Paperboard box produced in large volume for packaging purpose either to pack light or heavy product. When a heavy product is packed, high strength and structural stability against compression and deformation of the paperboard box are demanded. This paper investigates the effects of different shape of fluting mediums on the von Mises stress and deformation using finite element analysis (FEA) tool. Solidworks and ANSYS software were used to design a 3-D model and perform static structural analysis, respectively. The result from the analysis and simulation revealed that common s-shape geometry experienced the lowest von Mises stress and deformation. Honeycomb geometry experienced the highest von Mises stress of 0.19576 MPa while triangle fluting medium recorded the highest deformation at 1.8695E-4mm

Design For Manufacturability (DFM) Of 3D Printed Parts Fabricated Using Open Source 3D Printer

Fused deposition modeling (FDM) is one of the well-known additive manufacturing (AM) techniques to fabricate the part using layer-by-layer concept. Recently, an open source 3D printer is become widely available used by 3D printer user because of its affordability and portability. In this study, the performance of an open source 3D printer was evaluated based on the dimensional accuracy of the printed parts. The test model was fabricated using two types of printer, which is low cost 3D printer, Prusa and mid-end 3D printer, Cubepro. Then, the dimension of every model structure was measured using Rexscan 3D laser scanner and was compared

A review on antimicrobial packaging from biodegradable polymer composites

The development of antimicrobial packaging has been growing rapidly due to an increase in awareness and demands for sustainable active packaging that could preserve the quality and prolong the shelf life of foods and products. The addition of highly efficient antibacterial nanoparticles, antifungals, and antioxidants to biodegradable and environmentally friendly green polymers has become a significant advancement trend for the packaging evolution. Impregnation of antimicrobial agents into the packaging film is essential for impeding or destroying the pathogenic microorganisms causing food illness and deterioration. Higher safety and quality as well as an extended shelf life of sustainable active packaging desired by the industry are further enhanced by applying the different types of antimicrobial packaging systems. Antimicrobial packaging not only can offer a wide range of advantages, but also preserves the environment through usage of renewable and biodegradable polymers instead of common synthetic polymers, thus reducing plastic pollution generated by humankind. This review intended to provide a summary of current trends and applications of antimicrobial, biodegradable films in the packaging industry as well as the innovation of nanotechnology to increase efficiency of novel, bio-based packaging systems