Biodegradable films composed of starch and chitosan plasticized by palm oil were fabricated via a solvent casting technique. In this study, the influence of the ratio of brown rice starch and ...chitosan on the mechanical, thermal, antimicrobial, and morphological properties of the films was investigated. Antimicrobial films with a smooth surface and a compact structure of brown rice starch were obtained. The results showed that a higher proportion of chitosan in the polymer blends resulted in a substantial enhancement in the tensile strength (TS) and thermal stability of the film. The TS values for BRS100, BRS30CH70, BRS50CH50, BRS70CH30, and CH100 were 3.7, 15.2, 10.2, 9.3, and 8.8 MPa, respectively, and the elongation at break (EB) values of the BRS100, BRS30CH70, BRS50CH50, BRS70CH30, and CH100 samples were 39.5%, 34.7%, 7.3%, 11.5%, and 6.9%, respectively. The addition of chitosan to the brown rice starch samples resulted in a reduced water uptake of the film. The film with a balanced ratio of brown rice starch and chitosan exhibited excellent water resistance, with its water absorption being the lowest among all of the studied compositions.
•chitosan/brown rice starch films have been fabricated by solvent casting technique•Surface roughness characterization was performed by using atomic force microscopy.•chitosan has improve tensile strength of the films•Antimicrobial activity of the film against both gram-negatif and gram-positive bacteria was influenced by chitosan•chitosan/brown rice starch films are a promising candidate for sustainable packaging application
Oil palm wood is the primary biomass waste produced from plantations, comprising up to 70% of the volume of trunks. It has been used in non-structural materials, such as plywood, lumber, and ...particleboard. However, one aspect has not been disclosed, namely, its use in thermal insulation materials. In this study, we investigated the thermal conductivity and the mechanical and physical properties of bio-insulation materials based on oil palm wood. The effects of hybridization and particle size on the properties of the panels were also evaluated. Oil palm wood and ramie were applied as reinforcements, and tapioca starch was applied as a bio-binder. Panels were prepared using a hot press at a temperature of 150 °C and constant pressure of 9.8 MPa. Thermal conductivity, bending strength, water absorption, dimensional stability, and thermogravimetric tests were performed to evaluate the properties of the panels. The results show that hybridization and particle size significantly affected the properties of the panels. The density and thermal conductivity of the panels were in the ranges of 0.66–0.79 g/cm3 and 0.067–0.154 W/mK, respectively. The least thermal conductivity, i.e., 0.067 W/mK, was obtained for the hybrid panels with coarse particles at density 0.66 g/cm3. The lowest water absorption (54.75%) and thickness swelling (18.18%) were found in the hybrid panels with fine particles. The observed mechanical properties were a bending strength of 11.49–18.15 MPa and a modulus of elasticity of 1864–3093 MPa. Thermogravimetric analysis showed that hybrid panels had better thermal stability than pure panels. Overall, the hybrid panels manufactured with a coarse particle size exhibited better thermal resistance and mechanical properties than did other panels. Our results show that oil palm wood wastes are a promising candidate for thermal insulation materials.
Oil palm wood is one of the solid wastes available in large quantities, which has been used as non-structural material. Many researchers focus on their material strength and binder selection. ...However, limited studies investigate oil palm wood as insulation materials. Therefore, this study aimed to evaluate the thermal and sound characteristics of oil palm wood binderless panels as insulation materials. Panels were manufactured from oil palm wood using hot presses with different particle sizes and pressing times. The results indicated that the particle size had a significant effect on the characteristics of the binderless panels but not on pressing times. The coarser particle size enhanced the thermal and sound resistance but decreased density, water resistance, and flexural strength. In addition, the panels with large particles had the least thermal conductivity (0.050 W/mK) and the highest sound absorption coefficient of 0.33. The study also showed that the flexural strength and water absorption of the panels ranged from 4.21 to 8.18 MPa and 84.51%–119.06%, respectively. The findings of this study indicate the feasibility of binderless panels from oil palm wood as insulation materials.
•Oil palm wood can be used as an insulating material other than a non-structural material.•The particle size has a significant effect on the properties of binderless panels.•The binderless panels with large particles have good thermal resistance performance and sound absorption.•The coarser particle size decreased physical and mechanical properties.•The binderless panels made of palm oil are feasibility of replacing synthetic materials as insulation materials.
The sustainable use of agricultural waste to generate valuable products while minimizing environmental burdens is increasing rapidly. Multiple sources of fibers have been intensively studied ...concerning their application in various fields and industries. However, few publications have extensively discussed the property's performance of oil palm empty fruit bunches (OPEFB) composites. With main properties similar to composites currently listed for industrial applications, OPEFB is worth listing as a potential composite for industrial applications and non-structural material alternatives. OPEFB-reinforced polymer composites are expected to be applied to automotive interior parts. This study aims to determine the effect of adding zinc oxide (ZnO) and polyurethane on OPEFB-reinforced polymer composites for automotive interior parts. This composite was produced using the hand lay-up method with 70% resin, 15% OPEFB fiber, 15% polyurethane as a blowing agent, and four variations of ZnO at 5%, 10%, 15%, and 20%. The OPEFB particle sizes are 40, 60, 80, and 100, respectively. The composite was examined to determine mechanical, morphology, chemical, and thermal characteristics. It was observed that the addition of 20% ZnO caused ZnO agglomeration, weakening the interfacial bond between OPEFB particles, polyester, polyurethane, and ZnO filler. Overall, the results showed that adding ZnO and polyurethane to the composite increased tensile, compressive, flexural, and impact strength, as well as thermal stability with more significant values up to 160%, 225%, 100%, 100%, and 4.3%, respectively. This result depicted that the best composition was specimens with 15% ZnO and 149 microns OPEFB fibers particle size. It is considered a promising candidate to be applied in automotive interior components.
A biopolymer-based aerogel has been developed to become one of the most potentially utilized materials in different biomedical applications. The biopolymer-based aerogel has unique physical, ...chemical, and mechanical properties and these properties are used in tissue engineering, biosensing, diagnostic, medical implant and drug delivery applications. Biocompatible and non-toxic biopolymers such as chitosan, cellulose and alginates have been used to deliver antibiotics, plants extract, essential oils and metallic nanoparticles. Antibacterial aerogels have been used in superficial and chronic wound healing as dressing sheets. This review critically analyses the utilization of biopolymer-based aerogels in antibacterial delivery. The analysis shows the relationship between their properties and their applications in the wound healing process. Furthermore, highlights of the potentials, challenges and proposition of the application of biopolymer-based aerogels is explored.
The degradation and mechanical properties of potential polymeric materials used for green manufacturing are significant determinants. In this study, cellulose nanofibre was prepared from ...Schizostachyum brachycladum bamboo and used as reinforcement in the PLA/chitosan matrix using melt extrusion and compression moulding method. The cellulose nanofibre(CNF) was isolated using supercritical carbon dioxide and high-pressure homogenisation. The isolated CNF was characterised with transmission electron microscopy (TEM), FT-IR, zeta potential and particle size analysis. The mechanical, physical, and degradation properties of the resulting biocomposite were studied with moisture content, density, thickness swelling, tensile, flexural, scanning electron microscopy, thermogravimetry, and biodegradability analysis. The TEM, FT-IR, and particle size results showed successful isolation of cellulose nanofibre using this method. The result showed that the physical, mechanical, and degradation properties of PLA/chitosan/CNF biocomposite were significantly enhanced with cellulose nanofibre. The density, thickness swelling, and moisture content increased with the addition of CNF. Also, tensile strength and modulus; flexural strength and modulus increased; while the elongation reduced. The carbon residue from the thermal degradation and the glass transition temperature of the PLA/chitosan/CNF biocomposite was observed to increase with the addition of CNF. The result showed that the biocomposite has potential for green and sustainable industrial application.
Synthetic inhibitor is commonly used to decelerate corrosion rate but the application has a detrimental effect on the environment. To address this limitation, organic inhibitor, specifically Crown ...Flower (Calotropis Giganteen) plant, has become the preferred due to the effectiveness. Therefore, this study aimed to investigate Calotropis Giganteen plant (CGP) using the linear polarization method in sodium chloride solution on low-carbon steel to determine the potential corrosion rate and inhibitor efficiency. The CGP was extracted by drying the stems, flowers, and leaves in the sun, followed by grinding with a blender to obtain a powder form. Furthermore, the extraction process was carried out through distillation to convert Calotropis Giganteen extract (CGE) into a liquid using Soxhlet Extractor. Corrosion rate measurement was conducted using electrochemical methods in 3.5 % NaCl aqua solution and the addition of extracts at 100, 200, 300, 400, and 500 ppm concentrations. The results showed that corrosion rate of low-carbon steel in a 3.5 % NaCl aqua solution could be reduced by CGE. The corrosion rate showed a minimum of 1.197 mpy at 400 ppm with inhibitor efficiency of 66.34 %, while the highest value of 3.131 mpy was obtained at 100 ppm with efficiency of 14 %. Based on these results, CGE has shown potential as effective corrosion inhibitor for low-carbon steel in a hydrochloric acid solution.
Background: The decrease of immunity acquired from COVID-19 vaccines is a potential cause of breakthrough infection. Understanding the dynamics of immune responses of vaccine-induced antibodies ...post-vaccination is important. This study aimed to measure the level of anti-SARS-CoV-2 receptor-binding domain (RBD) total antibody in individuals at different time points upon the receipt of the second dose of CoronaVac vaccine, as well as evaluate the plausible associated factors.
Methods: A cross-sectional study was conducted among CoronaVac-vaccinated residents in Banda Aceh, Indonesia. The level of anti-SARS-CoV-2 RBD total antibody was measured using Elecsys immunoassay. A set of standardized and validated questionnaires were used to assess the demographics and other associated factors.
Results: Our results showed waning anti-SARS-CoV-2 RBD total antibody titres over time post-vaccination. Compared to samples of the first month post-vaccination, the antibody titres were significantly lower than those of five-months (mean 184.6 vs. 101.8 U/mL, p = 0.009) and six-months post-vaccination (mean 184.6 vs. 95.59 U/mL, p = 0.001). This suggests that the length of time post-vaccination was negatively correlated with titre of antibody. A protective level of antibody titres (threshold of 15 U/mL) was observed from all the samples vaccinated within one to three months; however, only 73.7% and 78.9% of the sera from five- and six-months possessed the protective titres, respectively. The titre of antibody was found significantly higher in sera of individuals having a regular healthy meal intake compared to those who did not (mean 136.7 vs. 110.4 U/mL, p = 0.044), including in subgroup analysis that included those five to six months post-vaccination only (mean 79.0 vs. 134.5 U/mL, p = 0.009).
Conclusions: This study provides insights on the efficacy of CoronaVac vaccine in protecting individuals against SARS-CoV-2 infection over time, which may contribute to future vaccination policy management to improve and prolong protective strategy.
Natural fiber composites have been widely used for various applications such as automotive components, aircraft components and sports equipment. Among the natural fibers
have gained considerable ...attention to replace synthetic fibers due to their unique nature. The untreated and alkali-treated fibers treated in different durations were dried under the sun for 4 h prior to the fabrication of
fiber reinforced epoxy composites. The chemical structure and crystallinity index of composites were examined via FT-IR and XRD respectively. The tensile, flexural and impact tests were conducted to investigate the effect of the alkali treated Typha fibers on the epoxy composite. From the microscopy analysis, it was observed that the fracture mechanism of the composite was due to the fiber and matrix debonding, fiber pull out from the matrix, and fiber damage. The tensile, flexural and impact strength of the
fiber reinforced epoxy composite were increased after 5% alkaline immersion compared to untreated
fiber composite. From these results, it can be concluded that the alkali treatment on
fiber could improve the interfacial compatibility between epoxy resin and
fiber, which resulted in the better mechanical properties and made the composite more hydrophobic. So far there is no comprehensive report about
fiber reinforcing epoxy composite, investigating the effect of the alkali treatment duration on the interfacial compatibility, and their effect on chemical and mechanical of
fiber reinforced composite, which plays a vital role to provide the overall mechanical performance to the composite.
Beverages are one of the most accessible liquid foods, can provide nutrients such as vitamins, minerals, antioxidants, organic acids and other bioactive substances for the body. To meet this need, ...the development of synbiotic drinks made from local grains is urgently needed. Synbiotic drink which is a combination of grain-based probiotics and prebiotics also has advantages for consumption for people with lactose intolerance as a substitute for dairy milk. This study was aimed to evaluate the effect of Lactobacillus casei with various concentration on synbiotic drinks based on local grains and cereals and oyster mushroom. Another aim from this study was to find out the best treatment for the characteristics according to SNI 7552:2018. In this study, 6 levels formulation of L. casei concentration (0%, 2%, 3%, 4%, 5%, 6%) were used. The experiment was non-factorial and arranged in Completely Randomized Block Design with 4 replications. The data homogeneity was tested using the Bartletts test and data additivity was tested with the Tukey test. The data were then analyzed for variance and further processed using Least Significant Difference test (LSD) at 5% level. The results showed synbiotic drink with 4% of L. casei found to be the best treatment which had a total LAB of 9.83 log CFU/mL, 0.76% lactic acid, 3.52 pH with a color score of 3.53 (rather like), a aroma score of 3.32 (neutral), a taste score of 2.34 (neutral) and an overall acceptance score of 2.83 (neutral). Keywords: Lactic acid bacteria, L. casei, Prebiotics, Probiotics, Synbiotics
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