In this research, the production of carbon fiber composite (CFC) with epoxy resin was carried out for biomedical application. The surface of the carbon fibers was previously oxidized with concentrated nitric acid at a temperature of 100 °C for 30–120 min to create a rough surface impression on the carbon fibers to enhance interfacial bonding in the composite, increase surface area, and reduce surface tension. The carbon fiber/epoxy composite was fabricated using the vacuum assisted resin infusion method. Characterization of the oxidized carbon fibers and the composite products was performed using a digital microscope, scanning electron microscope, and Fourier Transform Infrared (FTIR) analysis. FTIR analysis results indicated that the carbon fiber oxidation process introduced new chemical functional groups, such as –CN and –CO groups. Mechanical characterizations included tensile testing of non-oxidized and oxidized carbon fiber and tensile testing of carbon fiber/epoxy composite. The results showed that the composite formed from oxidized carbon fibers/epoxy resin exhibited higher tensile strength compared to non-oxidized CFC. The longer the carbon fiber oxidation process, the higher the tensile strength values obtained.

Bamboo particles as reinforcement in composite materials are prospective to be applied to particleboard products in the industry. This study aimed to synthesize bamboo particle reinforced polymer composites as a substitute for particleboard products, which still use wood as a raw material. The parameters of the composite synthesis process were varied with powder sizes of 50, 100, and 250 mesh, each mesh with volume fractions of 10, 20, and 30%, matrix types of polyester and polypropylene, Tali Bamboo, and Haur Hejo Bamboo as reinforcements. Characterization included tensile strength, flexural strength, and morphology. Particleboard products were tested based on JIS A 5908-2003, including density testing, moisture content, thickness expansion after immersion in water, flexural strength in dry and wet conditions, bending Young’s modulus, and wood screw holding power. The results showed that the maximum flexural and tensile strength values of 91.03 MPa and 30.85 MPa, respectively, were found in polymer composites reinforced with Tali bamboo with the particle size of 250 mesh and volume fraction 30%. Particleboard made of polypropylene and polyester reinforced Tali Bamboo with a particle size of 250 mesh and a volume fraction of 30% composites meets the JIS A 5908-2003 standard.

Jute is one of eco-friendly natural fiber with relatively low cost and high volume production. This study aimed to determine the effect of weight fractions of jute fiber as a reinforcement in polypropylene (PP) to obtain an optimum properties of PP/jute fiber composites. Jute fiber was pre-treated through alkalization. The PP was initially produced by extrusion process, followed by fabricated the composites by compiling the PP matrix and jute fibers into lamina using a hot-press method. The results of tensile test and heat deflection temperature test showed that the addition of 40wt% jute fiber to the PP increased the tensile strength about 19.7 % up to (38.2±4.9)MPa, the Young modulus about 79.8 % up to (3.20±0.26)GPa, and the heat deflection temperature about 143% up to (143.3±1.14)°C compared to pristine PP. Based on Scanning Electron Microscopy observation on the fracture surfaces, it was shown that the mode of failure on the composites failure surfaces was "fiber pull-out" , which due to the poor interface bond between the fiber and the matrix.

The compatibility of oil-palm-trunk fibers and cement was investigated. Cold-water and hydrothermal carbonization treatments were applied on the fibers, and then the hydration temperature was measured to observe the compatibility. Calcium chloride (CaCl₂), as an accelerator, was added at 1.5, 3.0, 4.5 and 6.0% of cement weight. The results showed that cold-water treatment and hydrothermal carbonization of the fibers reduced the hemicelluloses and ash content, thereby increasing the compatibility. Fourier transform infra-red analysis showed that functional groups of untreated and treated fibers were almost identical, indicating that the addition of treated fibers did not interfere the hardening process of cement. The treatment of fibers resulted in reduced thermal stability of the cement-fibers mixture, and the addition of CaCl₂ decreased the hydration temperature of the mixtures, indicating that the chemical accelerated the hardening of the cement-fibers mixture. The addition of 1.5% CaCl₂ to the cement mixture with treated fibers was adequate to obtain a low inhibitory index. Field emission scanning electron microscopy showed that higher formation of calcium silicate hydrate and calcium carbonate was observed in the treated fibers compared to the untreated fibers. The board modulus of elasticity increased by 215% and 281% after the fibers underwent with cold-water treatment and hydrothermal carbonization, respectively.

The use of synthetic fibers as reinforcement in composites has disadvantage which are unsustainable and an adverse impact on the environment. An alternative reinforcement for composites is natural fiber. Polypropylene and Sumberejo kenaf fibers were used respectively as the matrix and reinforcement. The aim of this research was to obtain the optimum tensile properties and deflection temperature with the variation of kenaf fiber fractions. Polypropylene/kenaf fiber composites were fabricated by hot press method. The kenaf fiber was soaked in NaOH solution before being used as the reinforcement and polypropylene was extruded before being used as the matrix. The weight fractions were varied to produce composites and pristine polypropylene samples were also prepared for comparison. The optimum tensile strength, modulus and deflection temperature were found in the composites with the 40 wt% kenaf fiber fraction with an increase up to 80% and 170% compared to the pristine polypropylene with the values of (60.3 ± 4,3) MPa and (159.1 ± 1,8) °C respectively. The Scanning Electron Microscope observation results in the fracture surface of the composites with the 40 wt% fiber fraction showed a relatively good bonding interface between fibers and the matrix and the failure modes were fiber breakage and matrix failures.

Clay minerals have received considerable attention in the last years because of their environmental compatibility, low cost, high selectivity, and operational simplicity. Although clays are very useful for many application in the field of catalysis, they have main disadvantage: their lack of pore volume and spesific surface area. Porosity and stability of these materials are improved by pillaring the clay layers with SnCl₄, which leads to materials known as pillared clays (PILC). This research aims were to characterize the Bentonite and Sn-Bentonite as catalysts for cracking and oligomerization. The Sn-Bentonite was prepared by pillarization method with a variation in metal ratio of 5 mmol dan 10 mmol.gr⁻¹ of bentonit. The catalyst characterized by X-ray Diffraction, X-ray Fluorescence, Fourier Transform Infra Red, Brunauer Emmett Teller, Thermogravimetric Analysis. The results showed that the Sn-Bentonite catalyst had large basal spacing and good porous structure, and the specific surface areas increased. XRF detected the Sn in the Bentonite and TGA results showed the ability Sn-Bentonite in receiving heat. FTIR test showed two type of acidity, broansted and lewis acid. The characterized results indicated that Sn-Bentonite with metal ratio 5 mmol.gr⁻¹ better than Sn-Bentonite with metal ratio 10 mmol.gr⁻¹, in which there was a significant increase the basal spacings, specific surface area, and pore volume. The TGA results for Sn-Bentonite appeared to be more thermally stable than Bentonite.