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The development and performance of high-strength, environmentally friendly, and renewable nunang fiber (Cordia dichotoma)-reinforced polyester composites continue to be refined to achieve optimal performance. This study characterizes the key properties of nunang fiber-reinforced polyester composites with carbon powder fillers. The polyester composites were fabricated using a hot-press method with a nunang fiber volume fraction of 20% (by weight) and varying carbon powder content from 0–10% (by weight). The results of the investigation show that the tensile and bending strengths of the composites increase with increasing carbon powder content up to 2.5%. However, adding carbon powder filler up to 10% to the polyester–nunang fiber composites reduces their tensile and bending strengths. A different trend is observed for the impact toughness of the composites, which increases up to a carbon powder content of 5% and decreases when the carbon powder content reaches 10%. This phenomenon is attributed to the ability to form an optimal fiber-matrix interface between the nunang fibers and the polyester–carbon powder matrix. SEM morphological observations confirmed fiber pull-out failure and matrix failure due to the high stiffness caused by the presence of the carbon powder filler.

Background: Class II restoration according to the classification of Greene Vardiman Black is one of the procedures in dental conservation that often presents a challenge for operators or dentists during treatment. Class II restorations have their own level of difficulty, particularly during the placement of restorative materials into the cavity. One of the possible failures in Class II restorative treatment is marginal leakage, which can lead to microleakage at the restoration margins. Purpose: To report the success of class II restoration with composite resin using tofflmire matrix. Case report: A 23-year-old female patient came with a complaint of cavities, the complaint was felt since 1 year ago in the lower left back tooth, there was no pain and had never been treated. In the case, preparation and restoration were carried out using composite resin with isolation using tofflmire matrix, applied using an Incremental technique. Discussion: Class II posterior tooth restorations have challenges such as leakage due to the techniques and materials used. Composite resin is chosen because of its good adaptation, esthetics, and wear resistance. Incremental techniques are preferred because they reduce polymerization stress and provide optimal curing results. Tofflemire matrix is ​​used for stability and soft tissue protection.Conclusion: The selection of composite resin with an Incremental technique and the use of a Tofflemire matrix provides more optimal, aesthetic, and minimal risk of failure results for class II posterior tooth restorations.

Natural fiber based composite materials are increasingly being developed as an environmentally friendly alternative to synthetic fiber-based composites. This study aims to characterize the thermal and mechanical properties of natural fiber composite materials and evaluate their potential use as sustainable materials. Composites are made using natural fibers as reinforcement and a polymer matrix through a specific molding method. Mechanical property characterization includes tensile tests, flexural tests, and impact tests, while thermal property characterization is carried out using thermal analysis to determine the thermal stability of the material. The test results show that the addition of natural fibers has a significant effect on improving the mechanical properties of the composite, especially tensile strength and elastic modulus, compared to the unreinforced matrix. In addition, natural fiber composites show quite good thermal stability over a certain temperature range, making them suitable for non-structural applications. Based on these results, natural fiber composite materials have the potential to be developed as environmentally friendly materials that have competitive mechanical and thermal performance.

The increasing need for insulation in electric power systems encourages the discovery of high-performance and sustainable dielectric materials. This study presents a Literature Review of biomass-based composite insulator research from 2018-2025 to synthesize the effect of filler type and treatment on the electrical, thermal, and mechanical properties of polymer composites. Literature was analyzed from reputable databases with inclusion criteria, and thematic analysis data extraction. Processing methods generally include washing, acid/alkali treatment, calcination, and advanced production techniques such as sol-gel and ultrasonication, integration of biomass fillers especially at low fractions (3-7%). The results show 1) the dominance of the use of rice husk as a source of biosilica for the main matrix filler of the insulator. 2) the performance of biomass composite insulators is highly dependent on the quality of purification, particle size, and surface modification of the filler. 3) there is a significant increase in the insulator's breakdown strength, resistivity, and thermal stability with the addition of biomass fillers to the main matrix. 4) the long-term stability of biomass materials against humidity and thermal aging has not been evaluated in depth.  

Composite materials have the potential to be used as an alternative material for e-scooter frames due to their low weight and good mechanical strength. The mechanical properties of composite materials are strongly influenced by their constituent materials, particularly the fiber fraction. This study aims to analyze the effect of fiberglass composition variations on the tensile strength of composite materials as an alternative for e-scooter frames. The results show that increasing the fiberglass content leads to an improvement in the tensile strength of the composite material. The tensile strength increased by 51.52% when the fiberglass content was increased from 40% to 50%, while an increase of 19.5% was observed from 50% to 60%, indicating a decreasing rate of improvement. At higher fiberglass compositions, voids were observed due to imperfections in the manufacturing process, which affected the bonding between the fiber and the resin. In addition, increasing the fiberglass content resulted in a reduction in tensile strain from 1.1% at 40% fiberglass to 0.55% at 60% fiberglass, indicating that the material became stiffer and more brittle. These results indicate a trade-off between increased tensile strength and reduced ductility of the composite material.

Leaf springs serve as vehicle weight supports and vibration dampers from uneven roads. Reducing vehicle weight can support fuel consumption reduction. The use of composite materials allows for a reduction in leaf spring weight without reducing load capacity and stiffness. The purpose of this study was to find the composition of composite leaf springs with a polyurethane matrix that were resistant to tensile and flexural tests using e-glass, epoxy, and polyurethane materials. This study used an experimental method, in which specimens were tested using a tensile and flexural testing machine. The variations included polyurethane matrices of 10%, 20%, and 30%. The data was statistically analyzed using Excel to determine the significant effect of the variables. The results showed the effect of polyurethane variation on the composite. The tensile test showed that the greatest tensile stress was on the 30% polyurethane specimen at 1.574 N/mm² and the smallest was on the 10% specimen at 7.007 N/mm². In the flexural test, the greatest effect on flexural strength was observed in the 30% specimen at 14.36 MPa and the smallest in the 10% specimen at 25.82 MPa. Without the addition of polyurethane, the tensile stress was 39.678 N/mm² and the flexural strength was 157.09 MPa. Conclusion: The addition of polyurethane reduces the mechanical strength of composite leaf spring material without polyurethane addition.

Leaf springs serve as vehicle weight supports and vibration dampers from uneven roads. Reducing vehicle weight can support fuel consumption reduction. The use of composite materials allows for a reduction in leaf spring weight without reducing load capacity and stiffness. The purpose of this study was to find the composition of composite leaf springs with a polyurethane matrix that were resistant to tensile and flexural tests using e-glass, epoxy, and polyurethane materials. This study used an experimental method, in which specimens were tested using a tensile and flexural testing machine. The variations included polyurethane matrices of 10%, 20%, and 30%. The data was statistically analyzed using Excel to determine the significant effect of the variables. The results showed the effect of polyurethane variation on the composite. The tensile test showed that the greatest tensile stress was on the 30% polyurethane specimen at 1.574 N/mm² and the smallest was on the 10% specimen at 7.007 N/mm². In the flexural test, the greatest effect on flexural strength was observed in the 30% specimen at 14.36 MPa and the smallest in the 10% specimen at 25.82 MPa. Without the addition of polyurethane, the tensile stress was 39.678 N/mm² and the flexural strength was 157.09 MPa. Conclusion: The addition of polyurethane reduces the mechanical strength of composite leaf spring material without polyurethane addition.

Composite materials have the potential to be used as an alternative material for e-scooter frames due to their low weight and good mechanical strength. The mechanical properties of composite materials are strongly influenced by their constituent materials, particularly the fiber fraction. This study aims to analyze the effect of fiberglass composition variations on the tensile strength of composite materials as an alternative for e-scooter frames. The results show that increasing the fiberglass content leads to an improvement in the tensile strength of the composite material. The tensile strength increased by 51.52% when the fiberglass content was increased from 40% to 50%, while an increase of 19.5% was observed from 50% to 60%, indicating a decreasing rate of improvement. At higher fiberglass compositions, voids were observed due to imperfections in the manufacturing process, which affected the bonding between the fiber and the resin. In addition, increasing the fiberglass content resulted in a reduction in tensile strain from 1.1% at 40% fiberglass to 0.55% at 60% fiberglass, indicating that the material became stiffer and more brittle. These results indicate a trade-off between increased tensile strength and reduced ductility of the composite material.

This paper was made to explain the results of research on how to obtain the most appropriate citric acid adhesive composition in the manufacture of randu wood fiber composites in order to obtain a strong and suitable composite material. The research was carried out by experimental methods in the laboratory through a series of mechanical tests, namely the bending strength test and the screw grip strength test. The sample specimen is 5 cm × 20 cm × 1 cm for flexural strength testing and 5 cm × 10 cm × 1 cm for screw grip strength test. Composite specimens were made with variations in the composition of citric acid adhesives of 2.5%, 5%, 7.5%, 10%, 12.5%, 15%, 17.5%, and 20% by weight of randu wood. The results showed that the composite of randu wood particles with a citric acid matrix had optimal strength at a certain ratio, which was 7.5%. At the same ratio, the test results of the screw grip strength test also provide the highest value. These findings confirm that the exact composition of the adhesive has a significant impact on the final performance of the resulting composite.

This study aims to analyze the comparison of the durability of natural fiber and synthetic fiber composites in a high-temperature production environment. Testing was conducted on carbon fiber, aramid (synthetic), ramie, and jute (natural) fiber-based composites with exposure to temperatures of 80-150°C for 500 hours. The parameters measured include tensile strength, elastic modulus, dimensional stability, morphological changes, and moisture absorption. The research results show that synthetic fiber composites have superior durability compared to natural fibers. Carbon fiber composites retain 87% of their initial tensile strength with only a 4.2% reduction in modulus, while flax fibers only retain 62% strength with a 26% reduction in modulus. Microscopic analysis revealed significant delamination in natural fiber composites with interface gaps of 15-25 μm, compared to 3-5 μm in synthetic fibers. Natural fibers undergo thermal degradation due to the decomposition of lignin and hemicellulose, resulting in significant color changes and a dimensional shrinkage of 3.2%. The moisture absorption of natural fibers increases to 8.5% after exposure, indicating damage to the cellular structure. This research concludes that synthetic fiber composites are more suitable for long-term high-temperature production applications, but natural fibers can still be considered for low-temperature applications with appropriate chemical modification.