No abstract

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) is a low-molecular-weight polymer resulting from degradation of natural rubber (NR) with a similar monomer along the backbone chain. Hydrogenated LNR (HLNR) was synthesized from LNR, in which diimide generated through the thermolysis of p-toluenesulfonyl hydrazide (TSH) served as the source of hydrogen. The products' structure was confirmed on the basis of changes in main peaks featuring carbon–carbon unsaturated bonds in Fourier-transform infrared and nuclear magnetic resonance spectra after hydrogenation. Gel-permeation chromatography showed that HLNR had a lower molecular weight (Mw &lt; 104) than LNR (Mw &lt; 105) and NR (Mw &gt; 106) because of chain degradation during hydrogenation. The targeted conversion percentage (&gt;90%) was attained by manipulating the reaction parameters. A ratio of 3:1 TSH/LNR was optimum for achieving a high percentage of hydrogenation at 130 °C in a 6 h reaction period. Thermogravimetric analysis indicated that the hydrogenation process increased the degradation temperature of LNR. HLNR also can act as a compatibilizer to improve the miscibility of natural rubber/polystyrene blends based from an optical microscope.

In this study, we investigated the effect of the addition of cellulose nanofiber (CNF) fillers on the performance of poly(lactic acid) (PLA). Modification of the hydroxyl group of cellulose to the acyl group by acid anhydrides changed the compatibility of the CNF with PLA. CNF was modified by acetic anhydride, propionic anhydride, and butyric anhydride to form surface-modified acetylated CNF (CNFa), propionylated CNF (CNFp), and butyrylated CNF (CNFb), respectively, to improve the compatibility with the PLA matrix. The effects of the different acid anhydrides were compared based on their rates of reaction in the acylation process. PLA with modified cellulose nanofiber fillers formed smoother surfaces with better transparency, mechanical, and wettability properties compared with the PLA/CNF composite film. The effects of CNFa, CNFp, and CNFb on the PLA matrix were compared, and it was found that CNFp was the best filler for PLA.

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.