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In this study, the epoxidized palm oil was synthesized with hydrogen peroxide (H2O2) as an oxygen donor and formic acid as an oxygen carrier. The effect of H2O2 concentration on the chemical structure and thermal properties of epoxidized palm oil was investigated. The FT-IR results showed the disappearance of unsaturated double bonds together with the formation of oxirane groups. The excess concentration of H2O2 caused an undesirable reaction that the oxirane ring was diminished. DSC results showed that the Tm and Tc of epoxidized palm oil were shifted toward higher values. The epoxidation of palm oil can be utilized as a reactant for bio-based epoxy resins, which improve local resource value-added palm oil in Thailand.

This article investigated the electromagnetic wave absorbing properties of natural rubber latex (NRL) foam filled with carbon black. The influence of different grades (N330, N660 and conductive grade) of carbon black and content on the foam morphology and electromagnetic wave absorption were of interest. The experimental results revealed that the addition of carbon black can improve the ability of electromagnetic wave absorption NRL over a wide frequency range. The NRL foam filled with the conductive carbon black exhibited more electromagnetic wave susceptibility in comparison to the those filled with classical carbon black. The addition of carbon black results in a decrease in cell size and increase in the number of foam cells. The proposed NRL foams are expected to be used as electromagnetic absorber in lightweight and flexible electromagnetic shielding materials.

In contemporary civilization, the electromagnetic radiation from electronic devices and communication systems has become a substantial pollutant. High-performance electromagnetic absorbers have become a solution for absorbing unwanted electromagnetic waves. This research proposed a lightweight and flexible electromagnetic absorber produced from natural rubber filled with conductive carbon black (CCB) and Fe3O4. The effect of CCB, Fe3O4, and a combination of CCB and Fe3O4 as a hybrid filler on foam morpholog, electromagnetic reflectivity, tensile strength, and compression set properties were investigated. In addition, the effect of the alternating layered structure of CCB and Fe3O4 on electromagnetic absorption was investigated. The results indicated that the composite foam exhibited an interconnected network structure that enhanced the electromagnetic attenuation in the absorber. CCB increased the electromagnetic absorption of the foam, whereas Fe3O4 had less of an effect. The foam filled with the hybrid filler at the CCB/Fe3O4 ratio of 8/2 exhibited excellent electromagnetic absorption. The composite foam had a higher tensile modulus and higher strength compared to neat foam. The addition of CCB decreased the compression set; however, the compression set was improved by the incorporation of Fe3O4. Composite foams filled with hybrid filler can serve as highly efficient electromagnetic absorbing materials.