Improvement of thermal properties of Vietnam deproteinized natural rubber via graft copolymerization with styrene/acrylonitrile and diimide transfer hydrogenation

Abstract

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.

Emulsion Polymerization of PMMA onto Natural Rubber

“…Herein, the NR-PMMA copolymer was slightly less subjected to degradation. This result was in line with the previous reports, which modified NR with other monomers. − …”

Ultrafine fully vulcanized natural rubber modified by graft-copolymerization with styrene and acrylonitrile monomers

“…C-H stretching vibration at -CH 2 -is expected around 1448 cm −1 and the absorption band at 1375 cm −1 is assigned to C-H asymmetry vibration of -CH 3 . In addition, the absorption band at 1244 cm −1 is attributed to vibration of C-C stretching next to C=C, which is (R 2 C=CH-R) or at cis1,4 addition position, while the peak of 836 cm −1 indicated C=C bending vibration in NR main chain (Dinsmore and Smith 1948; Kishore and (Nguyen Duy et al 2020). Furthermore, the new absorption band appeared at wavenumber 2247 cm −1 ascribed to vibration of C≡N stretching in PAN.…”

“…The results revealed that the proper monomer content was 5 phr and proper radiation dose was 300 kGy for producing UFPNR-g-PS and UFPNR-g-PAN with maintaining rather high thermal stability. Therefore, the combination of St and AN monomer to form St/AN copolymer grafting on NR backbone is expected to improve the thermal stability and solvent resistance of NR and probably the compatibility with various polymer matrices having different polarity (Angnanon et al 2011 ; Dung et al 2017 ; Fukushima et al 1988 ; Indah Sari et al 2020 ; Nguyen Duy et al 2020 ; Nguyen et al 2019 ; Prasassarakich et al 2001 ).…”

Ultrafine fully vulcanized natural rubber modified by graft-copolymerization with syrene and acrylonitrile monomers

“…exhibited TGA thermograms of virgin NR and UFPNR-g-(PS-co-PAN) at various radiation doses. Td5 of grafted NR was found to be higher than virgin NR due to the presence of PS-co-PAN, besides the stable aromatic rings in PS may prevent the formation of macroradicals in NR structure when exposed to heat [7,8].…”

“…The maximum value for the highest Conv and GE were achieved at weight ratio of 80/20 percentage by weight of ST/AN. Since, ST has similar polarity to polyisoprene in NR, which has higher reactivity to firstly react with polyisoprenyl macroradicals capable of further copolymerizing with AN monomer [4,7]. As the grafting on natural rubber can permanently retain the modified surface of NR particles by reducing the tackiness between particles.…”