<![CDATA[Natural rubber (NR), an unsaturated cis-1,4-polyisoprene polymer, exhibits limited resistance to oils, ozone, and thermal degradation, necessitating chemical modification to enhance its performance. This study evaluates two synthetic routes for producing liquid epoxidized natural rubber: epoxidation followed by oxidative degradation (NR → ENR → LENR) and degradation followed by epoxidation (NR → LNR → ELNR). Epoxidation was carried out using in situ peroxyacetic acid generated from acetic acid and hydrogen peroxide, while periodic acid in tetrahydrofuran was employed for oxidative chain scission. Structural evolution was characterized using Fourier Transform Infrared Spectroscopy (FTIR). Key transformations include attenuation of the C=C stretching band near 1660 cm⁻¹, the appearance of oxirane absorptions at 1240–1250 and 870–890 cm⁻¹, and the development of carbonyl (1717–1735 cm⁻¹) and hydroxyl (3275–3435 cm⁻¹) groups. The ENR → LENR pathway showed substantial epoxide loss and stronger oxygenated signatures, indicating extensive oxirane ring-opening during degradation. Conversely, the LNR → ELNR pathway yielded clearer and more intense oxirane bands with moderate oxidation, demonstrating that epoxide formation is more effective on low-molecular-weight chains generated prior to epoxidation. These findings confirm that reaction order critically governs epoxide retention, oxidative product distribution, and final polymer polarity. ELNR is thus suitable for applications requiring high epoxide content and reactivity, whereas LENR is more advantageous for systems requiring higher polarity and a broader range of oxygenated functional groups.]]>
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