Controlled degradation of natural rubber and modification of the obtained telechelic oligoisoprenes: Preliminary study of their potentiality as polyurethane foam precursors

Abstract

Telechelic oligoisoprenes were successfully prepared by the selective controlled degradation of natural rubber, a renewable source, via epoxidation and cleavage reactions. The molar mass of the oligoisoprene product obtained depends on the degree of epoxidation of the starting materials. The chemically modified structures obtained via epoxidation, hydrogenation, and ring opening of epoxide groups were also studied, and the chemical structures and thermal properties of the oligoisoprene products were determined. Moreover, the preliminary study of preparation of hydroxytelechelic natural rubber (HTNR)-based polyurethane foam was performed. A novel HTNR-based polyurethane foam was successfully prepared and its thermal properties were investigated and the results indicated that the HTNR-based polyurethane foam has a good low temperature flexibility.

Functionalization of Liquid Natural Rubber via Oxidative Degradation of Natural Rubber

“…However, for LNR prepared in an alkaline medium, there is an additional peak at 2.17 ppm and small peaks between 9.0 and 10.0 ppm. These peaks may indicate the presence of carbonyl groups as the peak at 2.1 ppm can be assigned to protons on the carbon adjacent to the C=O, whilst peaks at 9.0 to 10.0 ppm to the aldehyde protons which had shifted far downfield due to anisotropy of C=O groups [32,35,36]. 1 H NMR spectrum of LNR prepared in neutral medium.…”

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

“…The determination of reactive groups such as hydroxyl and carbonyl groups on the LNR chain is quite challenging as the quantity of these groups is extremely low compared to the whole mass of LNR. In this present work, 1 H and 13 C NMR showed a reliable signal-to-noise ratio and good resolution to determine and identify the presence of end groups which resulted from chain-breaking during the photodegradation reaction [16].…”

“…LNR commonly has a molecular weight of less than 20,000 g/mol and is considered as a new material derived from NR. Furthermore, the degradation process also opens up the opportunity to use LNR in various applications such as in binders [8], adhesives [9], coatings [10], processing aids [11,12], compatibilizers [13], and encapsulation of paraffin wax [14], as well as precursors for new materials [15,16] and further modifications [17]. Consequently, reducing the molecular weight has extended the potential and possible applications of NR.…”

Preparation of natural rubber-based polyol by oxidative degradation under supercritical carbon dioxide for flexible bio-based polyurethane foams

“…Besides other renewable feedstock, such as soybean oil, cotton seed oil, palm oil, and rape seed oil, 1–3 natural rubber (NR) attracts many researchers to be an alternative, sustainable bio-based raw material for preparation of the polyol. 4–7…”

“…Besides other renewable feedstock, such as soybean oil, cotton seed oil, palm oil, and rape seed oil, [1][2][3] natural rubber (NR) attracts many researchers to be an alternative, sustainable bio-based raw material for preparation of the polyol. [4][5][6][7] As the repeating unit of NR-cis-1, 4-isoprene-consists of double bonds which can be modified towards specific functional groups, this advantage leads to high-functionality derivatives of NR such as epoxidized natural rubber (ENR), carbonyl telechelic natural rubber (CTNR), and hydroxyl telechelic liquid natural rubber (HTNR). 8 However, there are some drawbacks of NR that lead to difficulties in preparing bio-based PU foams: high molecular weight of about 10 6 g/mol and a wide range of molecular weight distribution.…”