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The degradation of epoxidized natural rubber (ENR-50) and liquid epoxidized natural rubber (LENR) was done via oxidative degradation method for the production of hydroxyl terminated epoxidized natural rubber (HTENR) and hydroxyl terminated liquid epoxidized natural rubber (HTLENR) has been analysed. Cobalt (II) acetylacetonate (CAA) were used as an oxidizing agent for chain scission reaction at temperature 60 C in the presence of ethanol. The reaction temperature was fixed at 60 C meanwhile reaction time and the amount of CAA were varied according to the reaction formulation. The HTENR and HTLENR obtained have been characterized using Gel Permeation Chromatography (GPC), Fourier Transform Infrared (FTIR) and Nuclear Magnetic Resonance (NMR). GPC were used to determine the molecular weight before and after the oxidative degradation of respected HTENR and HTLENR were compared with ENR-50 and LENR. The lowest Mn and Mw of HTLENR that were obtained from the oxidative degradation method were found to be 5,163 g/mol and 58,087 g/mol. The appearances of OH end groups were verified by FTIR and NMR analyses to validate the position of each OH functional groups. FTIR analysis confirmed that HTENR and HTLENR contained OH group with the appearance of a broad peak around 3,400 cm-1 to 3,550 cm-1 after the reaction. The presence of OH end groups was verified by NMR analysis with the appearance at 3.39 ppm and 3.66 ppm, corresponding to methylene proton adjacent to hydroxyl group in HOCH2CH2CH2 and methane proton adjacent to OH group in CH2CH2CH(OH)CH3.

The development and characterization of self-healing polymeric materials are now being considered for engineering applications. This is an emerging and fascinating area of research that could significantly extend the working life and improve the safety of the polymeric components for a broad range of applications. Overviews of various self-healing approaches for polymeric materials are presented in this paper. The approaches used to achieve healing functionality can be divided into three, such as microencapsule, microvascular, and intrinsic based healing system. Microencapsulation is a process of enclosing micron-sized particles of solids, droplets of liquids, or gases in an inert shell, which in turn isolates and protects them from the external environment. Microvascular based healing system can be partitioned in a manner similar to microcapsules base healing system in terms of the design cycle. Microvascular based healing system is known to give a significant improvement and overcome a few limitations present in the microcapsule embedded self-healing membrane design. Intrinsic based healing system is inherently able to restore its integrity which requires an external trigger for the self-healing to take place. This system is less complex than the microcapsule and microvascular based healing system in achieving repair through inherent reversibility of bonding of the matrix polymer. The development of polymers that can repair damage autonomously would be useful to improve the lifetime of polymeric materials. Success in the design of self-healing materials has important consequences on the material safety, product performance and enhanced fatigue lifetime.

Hydroxyl terminated epoxidised natural rubber (HTENR) was synthesised via oxidative degradation method to produce a low molecular weight rubber. Epoxidised natural rubber (ENR) was depolymerised via chemical degradation method using cobalt (II) acetylacetonate (CAA) as the oxidising agent, followed by a treatment with sodium borohydride as a reducing agent to introduce hydroxyl (OH) functional group at both chain ends. The reaction times and the amount of oxidising agent tested were varied from one, three, five and twenty hours and 1to 5 wt% of CAA to obtain the low molecular weight of HTENR. The molecular weight of HTENR was determined using gel permeation chromatography (GPC). The lowest molecular weight of HTENR was achieved at 3 wt% of CAA after 5 h of reaction time at 60 °C where average number (Mn)and average weight (Mw) were 34,000 g/mol and 62,000 g/mol FTIR analysis confirmed that HTENR contained OH groupwith the appearance of a broad peak around 3,200 - 3,600 cm-1 after the reaction. The presence of OH endgroups was verified by NMR analysis with the appearance of two peaks at 3.38 ppm and 3.88 ppm, corresponding to methylene proton adjacent to hydroxyl group in HOCH2CH2CH2 and methane proton adjacent to OH group in CH2CH2CH(OH)CH3.