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This study aims to investigate the thermo-physical and morphological morphology of cornhusk fiber-reinforced polyester composites. The content of corn husk fiber (CHFs) has been varied, namely 20, 30, 40, and 50 (% vol.) in the polyester composite, respectively. The hot press technique has been used in the manufacture of these composites, then properties were investigated through thermo-physical tests including differential scanning calorimetry, thermogravimetry, Fourier transforms infrared, impact strength properties, and morphology using SEM. The results showed that the composite containing 30% CHF (KJP2) was found to have the most optimal impact strength (4.25 KJ/m 2 ), and the best thermal resistance properties were found in the KJP3 composite, compared with other composites; due to CHF dispersion and good interfacial adhesion between CHF and polyester. SEM images of the fracture of the impact test specimens of the composites show better interfacial bonding between CHFs and polyester.

This study describes the relationship between elementary school students' critical thinking and writing skills. The main objective of this research is to describe students' writing and critical thinking skills through project-based learning models. This study uses a quantitative approach with a quasi-experimental type. The research design used was a nonequivalent pretest-posttest control group design. The sample of this study was 50 students who were divided into 25 experimental groups and 25 students in the control class. This research selects 6th-grade students from one school in Bandung. The data collection instrument in this study used a description test to determine students' critical thinking and an assignment test to make persuasive texts to assess students' writing skills. The ANOVA test was used to determine the relationship between critical thinking and students' writing skills. The T-test was used to determine the differences in students' ability to write persuasive texts before and after receiving treatment with the project-based learning model. The results showed a good correlation between critical thinking and students' writing skills. In addition, there is a significant difference in students' writing skills before and after learning using the project-based learning model. It can be seen from the significance value of 0.00 <0.05. Thus the project-based learning model has a positive impact on improving students' critical thinking in learning to write and writing skills for elementary school students.

Abstract. The modification of the characteristics of natural fiber composites with components derived from abundant and environmentally beneficial horse dung waste has piqued interest. The purpose of this investigation was to see how adding horse dung particles (DN) to pineapple leaf fiber (DN)/polyester composites affected the results. To create new samples, different percentages of HF (5–30%) are utilized. Hand-layup method was used to create the DN/HF composite. The results revealed that adding 30% (vol. percent) HF to the composite improved elongation, flexural strength, and flexural modulus, while adding 5% (vol. percent) HF improved impact strength, tensile strength, and tensile modulus of elasticity. At 30% HF concentration, maximum flexural strength values of 63.91 5.1 MPa were recorded. The composite's fracture morphology revealed weak interfacial interactions between DN-polyester-HF, and particle accumulation.