Preparation and Characterization of Low-Molecular-Weight Natural Rubber Latex via Photodegradation Catalyzed by Nano TiO2

Abstract

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.

Bio-Based Polymers for Engineered Green Materials

“…Polyesters and NIPU were synthesized using vegetal oils, offering products with enhanced mechanical properties and high thermal stability, respectively [29,30]. Latex was exposed to photodegradation catalyzed by TiO 2 to obtain easy-to-manage low molecular weight rubber [31]. In a study by Yu et al, the possibility to include heavy bio-oils in asphalt rubber to improve the rutting and fatigue resistance of the paving material is shown [32].…”

Recent Developments in Nanocellulose-Reinforced Rubber Matrix Composites: A Review

“…Recently, newly emerging commercial products begin to change from using NR to other synthetic materials. However, as an industrial commodity, NR possesses physical and chemical properties that cannot be fully mimicked by synthetic rubber [ 15 ]. Nevertheless, the uses and economy of synthetic rubber are also blooming due to its variety and adaptability for numerous applications while competing with its natural counterpart.…”

Hydroxyl-Terminated Saponified Natural Rubber Based on the H2O2/P25-TiO2 Powder/UVC-Irradiation System

“…Both hydroxyl and epoxide groups were observed in the degraded NR, and the degradation was influenced by temperature and reaction time. Ibrahim et al functionalized the liquid NR via an oxidative degradation process for 24 h or 48 h [12,13]. Nevertheless, these methods require a toxic chemical and a long reaction time.…”

“…Polymers 2021, 13, x FOR PEER REVIEW 2 of 11 liquid NR via an oxidative degradation process for 24 h or 48 h [12,13]. Nevertheless, these methods require a toxic chemical and a long reaction time.…”

“…In addition, based on the NR particle structure reported by Nawamawat et al [17], the NR particle surface was surrounded by a layer made up of proteins and phospholipids, stabilizing the hydrophobic polyisoprene chains. However, the mixed layer of phospholipids and proteins stabilized the rubber chains and obstructed the NR chains from other molecules once the photocatalytic degradation process occurred [13]. This resulted in a low reaction performance on the NR chains.…”