Liquid natural rubber (LNR) is a depolymerized natural rubber (NR) which consists of shorter polymeric chains and lower molecular weight (Mw<105). Hydrogenated LNR (HLNR) was synthesized via the thermal decomposition ofp-toluenesulfonyl hydrazide (TSH) or 2,4,6-trimethylbenzenesulfonyl hydrazide (MSH). The LNR and HLNR structures were characterized by Fourier-transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopies. The percentage of hydrogenation was calculated from NMR spectrum. The optimum percentage of hydrogenation (>90%) was achieved by manipulating the reaction parameters such as sources of diimide, TSH concentration, solvent, and reaction time. The optimum condition was 3 : 1 weight ratio of TSH/LNR ino-xylene at 130°C in 4-hour reaction period.
Liquid natural rubber (LNR) was functionalized into liquid epoxidized natural rubber (LENR) and hydroxylated LNR (LNR-OH) via oxidation using a Na 2 WO 4 /CH 3 COOH/H 2 O 2 catalytic system. Microstructures of LNR and functionalized LNRs were characterized using Fourier Transform Infrared (FTIR) and Nuclear Magnetic Resonance (NMR) spectroscopies. The effect of CH 3 COOH, H 2 O 2 , Na 2 WO 4 , reaction time and temperature. reaction time and temperature on epoxy content were investigated. LNR-OH was obtained when oxidation reaction was conducted at a longer reaction time, higher temperature or excess amount of catalyst. Thermogravimetric analysis (TGA) reported the thermal behavior of functionalized LNRs. Molecular weight and polydispersity index (PDI) were determined using gel permeation chromatography (GPC).
This article reports an efficient, mild-temperature method for the hydrogenation of liquid natural rubber (LNR). The hydrogenation of LNR was studied using diimide generated in situ from the thermolysis of 2,4,6-trimethylbenzenesulfonyl hydrazide (MSH) in o-xylene at 100 C. The effects of reaction temperature, reaction time, solvent, and MSH/LNR weight ratio on the percentage of hydrogenation were evaluated. 1 H NMR analysis revealed that~80% hydrogenation was achieved with a weight ratio of MSH: LNR = 1:1 at 100 C in o-xylene within 60 min.
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