Natural rubber (NR) is a high molecular weight natural polymer and can be degraded to liquid natural rubber (LNR) leaving certain functional groups at the end of chains. In this study, LNR samples prepared via oxidative degradation using H₂O₂ and NaNO₂ as reagents were found to have different end groups depending on the pH of the reaction medium. In an acidic medium, LNR with hydroxyl terminal groups was formed as the degradation reaction was initiated by hydroxyl radicals produced from decomposition of peroxynitrite acid. In contrast, a redox reaction took place in an alkaline medium to yield LNR with carbonyl terminal groups. The mechanisms of reaction are discussed and proposed to explain the formation of different end groups when reaction carried out in acidic and alkaline media. Chain degradation in an acidic medium seems to be more effective than in an alkaline medium, and thus yields LNR with lower M_n.

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.

Maintaining the properties of deproteinised natural rubber (DPNR) after the production is critical and essential since it tends to deteriorate after the removal of proteins. During the preparation, transportation and storage, rubber may be exposed to contamination and an unfavourable environment that may affect the properties over time. Therefore, this work was conducted to determine the factors that affect the properties of DPNR during storage. In this work, DPNR samples were prepared with and without the presence of zinc oxide (ZnO) and hydrogen peroxide (H2O2) as contaminants. These samples were then stored under different environments such as opened room temperature (RT), closed RT, chilled and heated. Their physical properties were examined during 76 weeks of storage. NR control sample showed the most stable properties along the storage period studied. Removal of proteins in DPNR samples in overall has reduced its whole properties especially when it was contaminated with H2O2. These properties became worsen when the sample was stored in a hot environment (40 °C). Its properties such as Mooney viscosity and plasticity retention index (PRI) decreased significantly with time and reached below 70 MU and 40 units, respectively. This result was supported by the reduction of their molecular weight, which indicates the degradation of these samples during storage. The results showed that the quality of DPNR could be compromised by the presence of contaminants such as H2O2 during production and would be worsen by improper storage conditions.