Materials Science Forum Vol. 1114

Abstract: For a long time, rayon has been produced using dissolving pulp (DP). DP is typically made from wood or cotton, but it takes a long time to collect wood, and high-quality cotton must be imported from afar. Sansevieria trifasciata (ST) fiber, which contains more than 50% cellulose, offers potential as a raw material and a substitute for cotton and wood. It is simple to develop and grow. It can endure a wide range of light and temperature conditions. By using the water-pre-hydrolysis, soda-Anthraquinone cooking (soda-AQ), and elementary-chlorine-free (ECF) bleaching sequences, this work aims to convert ST into DP. Results, The DP was produced with a yield of 43.69%, a kappa value of 4.73, a viscosity of 9.3 cP, an alpha-cellulose content of 97.7% and a brightness of 90.7%, which was higher than the ISO brightness of 88%. The DP quality corresponds to the minimum DP level for rayon according to the Indonesian National Standard (SNI). It is very promising for further development, such as being used for viscose fiber production.

Abstract: A hybrid composite is a combination of two or more reinforced in a matrix. Hybrid composite will give better properties as compared to individual fiber-reinforced polymer composites. This research aims to study the effect of different fiber layer orientations on the properties of hybrid kenaf/fiberglass polyester matrix composite. Two types of the composite were produced which are Sample 1, the fiber layer orientation is fiberglass, kenaf fiber, kenaf fiber and fiberglass (FG-K-K-FG), and Sample 2, the fiber layer orientation is fiberglass, kenaf fiber, fiberglass, and kenaf fiber (FG-K-FG-K). The composite is manufactured using the hand lay-up technique and hot pressed. 50 g of unsaturated polyester resin and 12 g of hardener, Methyl Ethyl Ketone Peroxide (MEKP) were mixed and applied on top of every layer of fiber before being compressed at 100°C for 10 minutes. The properties of the hybrid composite were determined by completing five types of tests which are tensile test, impact test, water absorption test, thermogravimetric analysis (TGA), and scanning electron microscope (SEM). The results showed that Sample 2 (FG-K-FG-K) has higher tensile strength compared to Sample 1 (FG-K-K-FG) with the value of 30.97 MPa and 0.23 MPa respectively. For the water absorption test, Sample 1 (FG-K-K-FG) with a value of 239.21% has the highest water absorption properties compared to Sample 2 (FG-K-FG-K) with a value of 180.22%. Samples 1 and 2 have no obvious differences in terms of their thermal stability characteristics for the TGA test. For SEM, it is observed that both samples showed an attachment of adhesive between fiber layers and matrix. The overall conclusion is Sample 2 (FG-K-FG-K) has high mechanical properties but needs improvement for low water absorption.

Abstract: Biodegradable films demand increases due to the awareness of the environmental effects of synthetic plastics. However, biodegradable films based on starch have high water sensibility and poor mechanical properties. This led to an interest among the scientist in improving the properties of biodegradable films. The objectives of this study were to investigate the effect of lotus root starch content on the water solubility, water absorption, water vapor permeability and biodegradability of cassava bioplastic films. The lotus root starch was added at 10%, 20%, 30%, 40% and 50% of cassava starch. The results showed that the water absorption properties decreased by 122% to 21% and the water vapor permeability showed a decreasing trend as the lotus starch content increased. The water solubility increased from 4% to 36% with the increase of lotus starch content and biodegradability increased by 87.5% at 50% of lotus starch content. The results exposed the potential of cassava/ lotus starch bioplastic films for food packaging applications.

Abstract: In this paper, the performance of microstrip patch antenna that is made of fully biodegradable materials has been studied. The polymer resins of Polyurethane as a binder agent were produced using polyol extracted from palm oil while the host composites were made from oil palm empty fruit bunch fiber. The performance of Polyurethane – Oil Palm (PolyOP) Empty Fruit Bunch composite as a microwave dielectric substrate was tested by fabricating microstrip patch antenna on it. The performance of fabricated patch antenna was measured using Vector Network Analyzer (VNA) and is compared with simulation results obtained from High Frequency Structure Simulator (HFSS) simulator. The difference of percentage in resonant frequency, return loss, bandwidth and VSWR between simulation and measurement were found to be 0.4%, 75.2%, 67.9%, and 12.7%, respectively.

Abstract: Lignocellulosic biomass, such as sorghum stalk fiber, has received a lot of interest as reinforcement in polymer composites because of its renewable nature, low cost, and potential environmental benefits. This is due to crystalline cellulose fibrils embedded in hemicellulose, lignin, wax, and other impurities in the lignocellulosic fiber. As a result, treatment to remove non-cellulosic components, expose cellulose fibrils, and improve the adhesion with polymer matrices is critical for their usage as reinforcement in polymer composites. This study investigates the effects of environmentally friendly steam treatment on sorghum stalk fiber's structural and morphological properties. Sorghum stalk fiber was subjected to steam treatment conditions at different durations. Fourier transform infrared (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and sessile drop tests were used to examine the structural and morphological changes generated by steam treatment. It was observed that the steam treatment of sorghum fiber was successful in eliminating part of the amorphous lignin and hemicellulose components as well as contaminants such as wax, causing the crystallinity ratio to rise. Defibrillation also occurs, and the fiber surface becomes rougher. Due to the rough fiber surface and the space created by defibrillation, the polymer matrix can penetrate the fiber and increase its adhesion by a mechanical interlocking mechanism.

Abstract: The development of bioplastics is currently increasing, because bioplastics are an effort to reduce landfill waste. One of the bioplastics that has good degradation ability is cornstarch. The addition of nanoparticles was carried out to improve the properties of bioplastic packaging. One example of the application of nanotechnology in food packaging is silver nanoparticles (AgNP), known as antimicrobial substances. This research was conducted to determine the effect of adding AgNP (0%, 1%, and 2%) on the antimicrobial and biodegradation of cornstarch bioplastics. Bioplastics are made by casting method. AgNP was used from the synthesis of silver nitrate (AgNO₃) and trisodium citrate dihydrate (C₆H₅Na₃O₇.2H₂O) as a reducing agent and stabilizer by chemical reduction method, which was then analyzed by FTIR. The results obtained showed that cornstarch bioplastic AgNP 1% has the ability to estimate the fastest degradation time among other concentrations with an addition of 103 days. Cornstarch bioplastic AgNP 2% had the best ability to inhibit bacterial growth, with antibacterial inhibition zone diameters of 11.03 mm (Staphylococcus aureus) and 10.61 mm (Escherichia coli). However, AgNP could not inhibit the mold growth of Aspergillus niger. The addition of AgNP to cornstarch bioplastics can increase the degradation capabilities and antibacterial activity of bioplastics.

Abstract: The purpose of this research is to investigate the mechanical effects of polypropylene using sorghum fiber as nucleating agent. Alkalization, bleaching, and acid hydrolysis are all used to chemically modify sorghum fiber. This modified sorghum fiber was then mixed with polypropylene as a polymer matrix for 10 minutes in a rheomix at 100 rpm at 165°C and molded in a hot press. The results of this study suggest that acid hydrolysis can improve the crystallinity and compatibility of sorghum fiber. Furthermore, at 23.44 MPa, the optimum mechanical characteristics of a mixture of polypropylene and micro fibrillated cellulose (MFC) from sorghum fiber were achieved from 0.5% MFC resulting from acid hydrolysis.

Abstract: Plastic is an important necessity with the characteristics of being light, strong, relatively cheap, and durable. However, plastic cannot decompose in a short time so that it becomes a pollutant. The using of Poly lactic acid (PLA) is an alternative to synthetic plastics substitute such as Low-Density Polyethylene (LDPE) because it is degradable. However, PLA is brittle, so it requires a plasticizer in the form of additives, namely Polyethylene glycol (PEG) 200 and fillers in the form of clay and CaCO₃ to improve the mechanical properties of PLA which is brittle and has poor toughness. The purpose of this study was to determine the effect of adding additives to mechanical properties of PLA. The method used is solvent blending using chloroform as a solvent, stirring at 200 rpm for 6 hours at 30 . The research was conducted through testing the effect of the ratio of filler addition on the condition that the ratio of PLA/Additives was constant, i.e., 70%PLA/30% Additives. The resulting film is white and slightly transparent and has a smooth surface. The effect of adding additives in the form of plasticizers and fillers was tested through Dynamic Mechanical Analysis (DMA) analysis to determine the value of tensile strength, Young's modulus, and elongation break. The best result was obtained at a ratio of 25%CaCO₃/Clay, which was increasing elongation at break 7.62%. It also indicated with best decreased percentage value of Young’s modulus, and highest crystallinity index of 39.86%. The worst value is obtained in variant of 50%CaCO₃/Clay that indicated with lowest tensile strength and decreased of % elongation at break. From this study, the best variant was recommended as a laminating plastic, that does not require high tensile strength for application.

Abstract: Additive manufacturing, or 3D printing, is a key technology driving Industry 4.0. via the formation of three-dimensional objects from a computer-aided design model which can be done through layer-by-layer technique. Polylactic acid (PLA) ranks as one of the most favored materials as a 3D printing filament. Despite its unique properties, PLA took about 12 weeks to biodegrade which is slow degradation leads to an increased rate of plastic pollution in the environment. The aim of this study was to provide an alternative method for bioplastic waste management through biodegradation process using potting mix soil at different incubation temperatures and times. The PLA was designed in coupon shapes and eventually, 3D printed, respectively. Consequently, potting mix soil was prepared in a container and coupon, as all PLA samples were then planted 7 cm from the soil surface. Eventually, PLA samples were subjected to biodegradation process in the soil at 25 °C and 50 °C. Subsequently, each sample was drawn from the soil at different incubation times up to 65 days. The results show that prolong incubation time has resulted in PLA coupon losing weight up to 10.4% and 1.4% for the incubation time of 25 °C and 50 °C, respectively. Meanwhile, the physical structure has deteriorated to powder form and the fragility decreases proportionally as prolonged incubation time. Functional groups analysis showed the functional groups altered after the biodegradation process of PLA and soil. Ergo, this method can be utilized for the community to execute self-degradation of their PLA waste generated even at their own facility.

Abstract: Non-isothermal DSC has been used to investigate the curing kinetics of epoxy adhesives (DGEBA-cycloaliphatic amine). The epoxy samples were scanned on DSC with five heating rates (5°C/min, 7.5°C/min, 10°C/min, 12.5°C/min, and 15°C/min). The curing kinetics were obtained through ASTM standards E2890 and E698 (the Ozawa and Kissinger methods). The kinetic parameters obtained include Ea (activation energy), A (pre-exponential factor), and n (reaction order). The activation energy calculated from the Kissinger and Ozawa method was slightly different but insignificant. The reaction rate (dα/dt) and degree of curing/conversion (α) relationship towards temperature (T), and time (t) was also investigated. The curing process's reaction rate (dα/dt) has maximum value; it can no longer increase after a specific conversion rate (α).