Synthesis and evaluation of methyl 3,4,5-trihydroxybenzoate and methyl 3,4,5-trihydroxybenzohydrazide as additives for natural rubber composites

Methyl 3,4,5-trihydroxybenzoate (methyl gallate) was synthesized from 3,4,5-trihydroxybenzoic acid (gallic acid) by reaction with methanol in presence of sulphuric acid.Methyl gallate was then reacted with hydrazine monohydrate to give 3,4,5trihydroxybenzohydrazide (galloyl hydrazide).The structure of methyl gallate and galloyl hydrazide was characterized with Fourier transforms infrared (FTIR) spectroscopy, mass spectrometry (MS), and field emission scanning electron microscope (FESEM).Gallic acid, methyl gallate, and galloyl hydrazide were mixed with natural rubber by concentrations 1-3phr (part per hundred parts of rubber), using the rubber two roll mill machine.Rheological characteristics and physico-mechanical properties of the prepared natural rubber composites were measured.Swelling in toluene and crosslink density were calculated.Also, the surface morphology was studied using FESEM.The results showed that galloyl hydrazide almost has superior properties over both methyl gallate and gallic acid.Consequently, galloyl hydrazide can be recommended as a good rubber additive as it shows the behavior of secondary accelerator in natural rubber composites.Also, it can be used as an antioxidant.