Natural rubber is one of the most important renewable biopolymers used in many applications due to its special properties that cannot be easily mimicked by synthetic polymers. To sustain the existence of natural rubber in industries, modifications have been made to its chemical structure from time to time in order to obtain new properties and to enable it to be employed in new applications. The chemical structure of natural rubber can be modified by exposure to ultraviolet light to reduce its molecular weight. Under controlled conditions, the natural rubber chains will be broken by photodegradation to yield low-molecular-weight natural rubber. The aim of this work was to obtain what is known as liquid natural rubber via photodegradation, with titanium dioxide nanocrystals as the catalyst. Titanium dioxide, which was firstly synthesized using the sol–gel method, was confirmed to be in the form of an anatase, with a size of about 10 nm. In this work, the photodegradation was carried out in latex state and yielded low-molecular-weight natural rubber latex of less than 10,000 g/mol. The presence of hydroxyl and carbonyl groups on the liquid natural rubber (LNR) chains was observed, resulting from the breaking of the chains. Scanning electron microscopy of the NR latex particles showed that titanium dioxide nanocrystals were embedded on the latex surface, but then detached during the degradation reaction.

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Summary Liquid natural rubber (LNR) is considered as a new material which can be obtained from degradation of natural rubber (NR). In this work, the degradation of NR latex using photochemical degradation under UV light has been studied. In this preliminary result, the degradation degree was found to depend on parameters such as dry rubber content (DRC) of latex and reaction temperature. At the optimized parameters, the molecular weight (Mn) of NR was able to reduce from about 500 kg/mol to as low as 13 kg/mol. The molecular structure of LNR obtained was similar to that the NR, however, the presence carbonyl and hydroxyl groups were observed on the LNR chain as a result of the chain cleavage.

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