This study aims to optimize the formulation of natural rubber (Hevea brasiliensis) into a compound for applications in military vehicles when passing through various field conditions. Natural rubber types SIR 20 and RSS 1 were used with Carbon Black types N220 and N550 as fillers. In this study, samples that were both normal and samples that had aged for 72 hours at 70°C were created. The results showed that the mixture of RSS 1 - CB N220 (i.e., 100 phr–75 phr) influenced strength and stiffness. The physical and mechanical properties of the specimens, including curing time, tensile strength, tear strength, elongation at break, and compression set had been defined. By utilizing the resulting mechanical characteristics, rubber compounds are optimized to meet the specific requirements of airless tires, including durability, comfort, and performance. It is anticipated to create an airless tire that provides essential performance while reducing the risk of punctures and flats.

Density and compressive strength are two important properties in the manufacture of syntactic foam materials. Syntactic foams are composites that are filled with hollow particles (microballoon). In this research, epoxy resin and glass microballoon were used as the main component. Two ways are usually done to get the syntactic foam properties as desired. The first way is by adjusting the composition of the microballoon and the second way is by choosing the type of microballoon. The effect of two types of microballoons with different crushing strengths (K15 and iM16K) on density, porosity, and compressive strength was carried out in this study. Instead of microballoons type, the composition of vol.% microoballoons varied as 40, 50, 60, 70, and 80% to investigate the influence of formulation. The results showed that at the same composition, microballoon with high crushing strength obtained higher compressive strength, but the density for microballoon with lower crush strength is lower. The increase in volume fraction for both types of microballoons resulted decreasing in density. With the use of low crushing strength microballoons, the compressive strength properties were decreasing with the higher volume fraction. But for microballoons with high crushing strength, there was no significant change in volume fraction variation.

This study evaluates the performance of ethylene propylene diene monomer (EPDM) composites for rubber sealing applications in a cable-based tsunami system. Rubber composites were prepared using EPDM rubber with varying monomer and filler content to determine the most suitable composite. Mechanical characterization reveals that the composition of EPDM and the amount of filler loading influence the mechanical properties. Dynamic mechanical analysis shows that ethylene and 5-ethylene-2-norbornene (ENB) content influence the glass transition and viscoelastic behavior of the composite. Thermal analysis of rubber composites using EPDM containing 70% ethylene and 5% ENB indicates no change in thermal stability due to prolonged immersion in seawater. Visual inspection using a microscope reveals no cracks on the surface of the rubber seal after the pressure chamber test for rubber composites utilizing EPDM with 70% ethylene and 5% ENB. It was shown that EPDM containing 70% ethylene and 5% ENB, with optimal reinforcement with 80 phr carbon black, exhibits the best performance for rubber sealing applications in subsea environments.

This aims to examine the engineering and environmental properties of C-type fly ash (FA-C)-ferronickel slag 4 (FNS 4)-based geopolymer mortar under heat curing is examined. The series of C-type fly ash-based geopolymer mortar was generated with 0%, 10% and 20% ferronickel slag 4. The heat curing...