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Abstract:The main objective of this work is to develop film and study the thermal characteristics of polysaccharides films at various concentration of carrageenan in the mixture by calculating activation energy of polysaccharides films. There were four (4) film samples of two polysaccharides combination; arabic gum (AG) and carrageenan (C) with different formulations; sample A, sample B, sample C and sample D prepared. Sample A film is the control sample that contained only arabic gum and distilled water (DI) with 40% weight arabic gum per volume DI water (w/v%). Meanwhile for sample B and C were prepared with concentration 40 w/v% of Arabic gum and two differents of carrageenan concentrations; 1 w/v% and 10 w/v% respectively. Polyethylene glycol 400 (PEG 400) as a plasticiser was added into sample D film. The sample films were thermally characterized using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) under nitrogen atmosphere. The major thermal transitions as well as, activation energies of the major decomposition stages were determined. Sample A and B films exhibited the highest (112.43 kJ/mol) and the lowest (102.89 kJ/mol) activation energy of thermal decomposition, respectively. The activation energies were lower at larger amounts of sulfate groups from carrageenan on the degradation reactions. The DSC trend for all samples shows two (2) major intense peaks recorded in the DSC thermograms; an endothermic transition at temperature around 100 °C and followed by an exothermic transition at temperature around 300 °C. The endothermic transition is due to the heat absorption for dehydration of water, H 2 O and the decomposition of samples process. Meanwhile, the exothermic transition is caused by the formation of H 2 O, CO and CH 4 in polysaccharide film from dehydration, depolymerisation and decomposition at the high-temperature stages.

At present, plant-based hard capsule such as hydroxypropyl methylcellulose (HPMC) has a high demand in drug delivery application but the production process is expensive with limited reactant supply. κ-carrageenan has been used as a gelling agent in HPMC hard capsule production. This study aims to develop gum Arabic (GA)-κ-carrageenan biocomposite, a potential material to produce hard capsule. The GA-κ-carrageenan biocomposite films were prepared at different κcarrageenan weight ratios of 33% (GC33), 50% (GC50) and 67% (GC67) at constant concentration of polyethylene glycol and alginate. The control films of GA film and κ-carrageenan film were compared. The film and hard capsule formed from GC67 shows the highest tensile strength and capsule loop of 36.21 MPa and 34.11 N, respectively at 1058 mPa.s solution viscosity at 300 rpm shear rate. The hard capsule disintegrated at 7.30 min. The addition of GA is compatible to make the hard capsule surface smoother. Thus, this biocomposite has the potential to be developed for future hard capsule.

Anaerobic digestion (AD) involves a series of biological processes in which organic material is broken down and transformed into biogas. A simulation model of the AD process in treating food waste to produce biogas was developed using Aspen Plus software. The components list, thermodynamic property package, reaction list, reactor model, and process condition were specified in Aspen Plus. Sensitivity analysis was performed to study the effect of hydraulic retention time and changes in food waste composition on the biogas production. The methane composition in biogas decreased when the hydraulic retention time was increased which is due to the reduction of substrate consumption during the AD process. The process model is able to represent the AD process and provides a good approximation on the production of biogas under various process operating conditions.

It was believed that fluid flow and the laminar to turbulent transition delay were more easily controlled on smooth surfaces until the discovery of the grooved shark skin surface that changed the whole idea of how smooth the surface should be to have high flow in submerged surfaces. Riblets have gained renewed interest in academic fields of study and in industry due to several advantages in manipulating the turbulence boundary layer. Drag reduction using small, longitudinally grooved surface provides up to 10 % lower energy consumption in several applications. This review provides an overview of the mechanism of drag reduction with riblets, the different geometries and types, and the latest developments in drag reduction riblet technology.