In this study, we investigated the improvement of the thermal and mechanical properties of Vietnam deproteinized natural rubber (DPNR) via graft copolymerization of methyl methacrylate (MMA). The graft copolymerization was achieved successfully in latex stage using tert-butyl hydroperoxide (TBHPO) and tetra-ethylenepentamine (TEPA) as radical initiators at 30°C. By grafting with various MMA feeds and initiator concentration of 6.6×10−5 mol/g-rubber, the highest grafting efficiency and conversion were achieved at MMA of 15 wt.% per kg of rubber, 68% and 90%, respectively. The structure of grafted copolymers was characterized by 1H NMR, FTIR-ATR, and GPC, and thermal properties were investigated through DSC and TGA measurements. These showed that graft copolymers were more stable and rigid than DPNR. Storage modulus (G′) of graft copolymer was found to double that of DPNR, which contributed to the formation of graft copolymer. After sulfur vulcanization, the mechanical properties of DPNR-graft-PMMA, such as tensile strength, tear strength, and hardness, were improved significantly. Curing behaviors of the graft copolymers were found to be remarkably better than virgin DPNR.
In this study, we investigated the improvement of thermal properties of Vietnam deproteinized natural rubber (DPNR) via graft copolymerization of styrene/acrylonitrile and transfer hydrogenation. The graft copolymerization was achieved successfully in the latex stage using tert‐butyl hydroperoxide and tetraethylenepentamine as radical initiators at 30°C. The obtained graft copolymer was hydrogenated by a diimide reduction system in the presence of different copper (II) homogeneous catalysts. The effects of styrene to acrylonitrile on the total conversion and the grafting efficiency have been studied. The structural characterization of the obtained copolymers was made by 1H NMR and ATR‐FTIR. The graft DPNR was then characterized by gel permeation chromatography (GPC). The effects of different copper (II) catalysts on the system have been evaluated by the hydrogenation degree of each hydrogenated sample. The improvement of the thermal properties of the graft copolymers was confirmed by thermal gravimetric analysis/differential thermal analysis. The core‐shell arrangement was obtained in both DPNR‐graft‐PS/PAN and hydrogenated‐DPNR‐graft‐PS/PAN by transmission electron microscopy.
Homopolymers and copolymers derived from 2,5-furandicarboxylic acid have been extensively studied for their potential in the development of sustainable plastics. This research definitely spotlighted the synthesis of poly(ethylene-co-butylene 2,5-furandicarboxylate) copolymer via the two-step melting polycondensation with various ethylene glycol/1,4-butanediol molar ratios. The structural characterization of the obtained biobased copolymer was carried out by ATR-FTIR and 1H NMR. The average molecular weight of the obtained copolymer was determined by the intrinsic viscosity measurements. It was found that ethylene glycol was preferentially incorporated into the copolymer structures when the molecular weight of the products was not high enough (>18000). The decomposition of two types of monomer units of the obtained copolymer was proven through the degradation two-step process by TGA measurements.
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