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 < 104) than LNR (Mw < 105) and NR (Mw > 106) because of chain degradation during hydrogenation. The targeted conversion percentage (>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, linear low-density polyethylene/graphene nanoplatelets (LLDPE/GNPs) nanocomposites were prepared from conventional melt-mixing method and our new approach; two-step premix mixing technique. Indirect mixing technique (IDT) was employed to fabricate a premix of LLDPE/ GNPs in the ratio of 80:20 wt%. The effects of GNPs loadings and the processing method of nanocomposites on the mechanical strength, decomposition temperature, crystallinity, electrical impedance and morphology were investigated. Irrespective of processing methods, the prepared nanocomposites exhibited crystalline structure due to the presence of GNPs whilst the degradation temperature was recorded to be increased with GNPs loadings that signified improved thermal stability. The inclusion of GNPs provided electrical impedance ability on LLDPE matrix as a result from the formation of conductive networks of GNPs. LLDPE/GNPs nanocomposites prepared from two-step premix mixing technique showed better mechanical properties than those of melt-mixing method. Apparently, two-step premix mixing of LLDPE/GNPs nanocomposites promoted better dispersion of GNPs in matrix based on SEM images. Our findings have proved that our new, profound technique of preparing premix before mixing could result in enhanced quality of nanocomposites that are potentially useful in packaging or electronic applications.
Kaedah rangsangan permukaan (RSM) dengan reka bentuk komposit putaran tengah (CCRD) telah digunakan untuk mengoptimumkan parameter bagi penghidrogenan getah asli cecair (LNR) dalam sistem hidrazin hidrat (HH) dan hidrogen peroksida (H 2 O 2) dengan kehadiran selenium sebagai mangkin. Parameter yang dikaji bagi tindak balas ini adalah nisbah mol HH:LNR (1.25-2.25), nisbah mol H 2 O 2 :LNR (1.25-2.25), suhu (40-80°C) dan masa tindak balas (4-8 jam). Berdasarkan data yang diperoleh, penghasilan getah asli cecair terhidrogen (HLNR) sesuai dijelaskan dengan model kuadratik. Model kuadratik ini mempunyai nilai pekali penentuan (R 2) sebanyak 0.9596 yang menunjukkan korelasi yang tinggi antara peratus penghidrogenan sebenar dengan peratus yang telah diramalkan. Berdasarkan plot permukaan tindak balas 3D, suhu tindak balas memainkan peranan penting dalam penghidrogenan LNR. Keadaan optimum yang diperoleh melalui RSM bagi kajian ini adalah nisbah mol HH:LNR pada 1.50, nisbah mol H 2 O 2 :LNR pada 2.00, suhu tindak balas pada 53.34°C dengan masa tindak balas selama 5.21 jam yang memberikan peratusan penghidrogenan HLNR sebanyak 68.98%. Persamaan polinomial kuadratik yang diperoleh daripada RSM ini berguna untuk menghasilkan HLNR dengan peratusan penghidrogenan yang dikehendaki. Kata kunci: Getah asli cecair (LNR); kaedah rangsangan permukaan (RSM); penghidrogenan; reka bentuk komposit putaran tengah (CCRD); selenium
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