ABSTRACT
Polylactic-acid-starch-based polymer composite (PLA/TPS) has good thermal stability for biocomposites. However, the physical and mechanical properties of PLA/TPS do not meet the standards. It needed additives to enhance its physical and mechanical properties. The aim was to improve the physical and mechanical properties of PLA/thermoplastic starch using sucrose. In addition, this study evaluated the enhancement of thermal properties of PLA/thermoplastic starch using sucrose. This study used sucrose as an additive to enhance the PLA/TPS composite. The addition of sucrose inhibits the degradation of biocomposites. This means that thermal stability increases. The thermal stability increased because the degree of crystallinity increased with the addition of sucrose, which was also proven in the XRD result. The addition of sucrose caused the morphology of the biocomposite to have pores. The FESEM results showed that biocomposites with the addition of sucrose had pores and gaps. These gaps result from low adhesion between polymers, causing a decrease in the mechanical and physical properties of the sample. Based on the FTIR spectra, biocomposite PLA/TPS blends with the addition of sucrose still have many hydroxyl groups that will lead to attracting other molecules or ions, such as oxygen or water. This phenomenon affects the physical and mechanical properties of materials. The physical and mechanical properties increased with sucrose addition. The best composite was prepared using 3% sucrose. This is because sucrose has a crystalline structure that affects the properties of biocomposites. However, the addition of 3% sucrose was not as effective as that of neat PLA.
ABSTRACT
The suitability of bamboo's basic characteristics is very important for more specific purposes, such as composite raw materials. Anatomical, physical, mechanical, and chemical characteristics are some of bamboo's fundamental characteristics. This study analyses the basic properties, such as physical, mechanical, and chemical properties of bamboo from the Forest Area with Special Purpose (FASP) Pondok Buluh Sumatera Island, Indonesia (I); analyses the relationship between the properties of each type of bamboo (II); and chooses the type of bamboo with the best properties that have the potential to be applied to composite materials, such as laminated bamboo (III). This study used materials consisting of six species of bamboo from the FASP Pondok Buluh. The manufacture of physical and mechanical test samples refers to the ISO 22157 standard, 2004, while the chemical properties test refers to the TAPPI 1999 standard. The chemical, physical, and mechanical properties of bamboo vary widely among species. The lowest holocellulose and α-cellulose content were found in the Kuning Bamboo (B. vulgaris var. vittata). The content of holocellulose and α-cellulose causes the lowest density in Kuning Bamboo (B. vulgaris var. vittata). The Dasar Bamboo (Bambusa vulgaris) has the highest levels of lignin. The substances have an impact on moisture content, T/R ratio, and shear strength. The Dasar Bamboo (Bambusa vulgaris) has the lowest moisture content, the highest T/R ratio, and the highest shear strength. However, Betung Bamboo (Dendrocalamus asper) has the highest density in this study. The compressive strength of the Betung Bamboo (Dendrocalamus asper) has the highest value. Therefore, Betung bamboo and Dasar Bamboo in this study were potentially utilized for composite materials, such as laminated bamboo.
ABSTRACT
The purpose of this study is to address students' views of EIL in various circumstances by concentrating on the perspectives of Indonesian and Japanese university students about their EIL experiences, including their perception of current status of English (CSE), varieties of English (VE), strategies for multilingual/multicultural communication (SMC), and English speakers' identity (ESI). A total of 220 participants took part in this survey research. With the help of IBM SPSS Statistics 22, we conducted an EFA on the newly acquired data. Varimax rotations and Principle Components Analysis (PCA) were employed to extract data and we looked at three factors such as eigenvalues, factor loadings, and communalities. Using the criteria of Cronbach's alpha and Composite Reliability (CR), as well as Average Variance Extracted (AVE), the reliability and validity had been examined and the thresholds were reached. All items of CSE, VE, SMC, and ESI were employed in each construct. Descriptive statistics were obtained for the four constructs using their pooled mean and standard deviation (SD). At last, we used an independent samples t-test to evaluate whether the groups differed significantly in how Indonesian and Japanese students viewed EIL. The findings indicated that both groups had no differences in perceiving current status of English, varieties of English, strategies for multilingual/multicultural communication, and English speakers' identity. The implications for the deployment of EIL teaching methodologies and resources are highlighted.
ABSTRACT
The use of natural fibers or particles as alternative raw materials for particleboard production is essential due to the shrinking forest area. Currently, dung waste from the Sumatran elephant (Elephas maximus sumatranus) is being used as a raw material for particleboard due to its high fiber content. Although the product still has inferior mechanical and physical characteristics, it can be improved by layering bamboo. Therefore, this study aimed to enhance the mechanical and physical qualities of elephant dung particleboard by adding layers of bamboo. The particleboard constructed had three layers; namely, the face and back in the form of a bamboo layers, as well as the core, which was in the form of elephant dung. The elephant dung was evenly mixed with isocyanate adhesive using a spray gun, and the bamboo layers were coated with adhesive on one side of the surface. The sample was subjected to a hot press at a temperature of 150 °C and 30 kg/cm2 pressure for 10 min. Generally, JIS A 5908-2003 is the specification used to test the physical and mechanical properties of particleboard. During the experiment, the characteristics examined include density, moisture content, water absorption, thickness swelling, modulus of elasticity, modulus of rupture, and internal bonding, which were enhanced by using layers of bamboo. The results showed that the physical properties of the particleboard with bamboo layers were a density of 0.62-0.69 g/cm3, a moisture content of 7.87-10.35%, water absorption of 38.27-68.58%, and a thickness swelling of 10.87-30.00%, which met the minimum standards of JIS A 5908-2003. The mechanical characteristics had values for the modulus of elasticity of 1952-7282 MPa, the modulus of rupture of 20.44-68.27 MPa, and the internal bonding of 0.16-0.38 MPa, which met the JIS A 5908-2003 standard. Based on these results, the particleboard with Belangke bamboo layers was the best in this study.
ABSTRACT
Sumatran elephants (Elephas maximus sumatranus) are the world's largest living land mammals. The elephant's digestive system can only absorb 40% of the nutrients in digested feed, and the remainder is excreted as dung. Elephant dung waste can be used as a particleboard material due to its high fiber content. The objectives of this study are: (i) to prepare elephant dung waste as raw material for particleboard, (ii) to improve elephant dung particleboard's physical and mechanical properties using wood shavings, and (iii) to study the influence of several parameters on the physical and mechanical properties of particleboard. The particleboard dimensions and density were set at 20 cm × 20 cm × 1 cm and 0.8 g/cm3, respectively. The mixture ratio of elephant dung and wood shavings was 100/0, 90/10, 80/20, 70/30, 60/40, and 50/50 (% w/w). This mixture ratio of particles was sprayed with 7% isocyanate adhesive. The pressing at a pressure of 30 kg/cm2 for 5 min and 160 °C was used in this study. The physical and mechanical properties of particleboard were tested according to JIS A 5908 (2003) standard. The result shows that the addition of wood shaving improved the elephant dung particleboard's physical and mechanical properties. Except for moisture content and water absorption, the addition of wood shavings has a significant effect on elephant dung particleboard's physical and mechanical properties. The best ratio of elephant dung and wood-shaving for this research is 50/50 and has fulfilled the JIS A 5908-2003 standard, except for thickness swelling.
ABSTRACT
This physical and mechanical properties of a table tennis blade made from sorghum bagasse particleboard (TTBSB-particleboard) bonded maleic acid adhesive was investigated under pressing temperature and time variations. The TTBSB-particleboard was produced via a two-stage process in this study. A pressing temperature of 170-200 °C was used to prepare the first stage for 10 min. Following this, the second stage of the TTBSB-particleboard was produced with a different pressing time of 5-20 min. The TTBSB-particleboard had a specified target density of 0.6 g/cm3 and a size of 30 cm × 30 cm × 0.6 cm, respectively. For references concerning the tested quality of TTBSB-particleboard, the JIS A 5908-2003 standard has been used. For comparison, the commercial blades of Yuguan Wooden 1011 and Donic Original Carbo Speed were tested under the same conditions. The quality of the TTBSB-particleboard was successfully enhanced by increasing the pressing temperature (170 to 200 °C) and time (5 to 20 min). As a result, the pressing condition of 200 °C and 20 min were effective in this study. The TTBSB-particleboard in this study has a greater weight than the commercial blades of Yuguan and Donic. However, the TTBSB-particleboard in this study had a ball rebound comparable to that of the Donic blade.
