Improvement of thermal properties of Vietnam deproteinized natural rubber via graft copolymerization with styrene/acrylonitrile and diimide transfer hydrogenation
Hieu Nguyen Duy, Niratchaporn Rimdusit, Tung Tran Quang, Quyet Phan Minh, Nam Vu Trung, Thị Nhạn Nguyễn, Thu Hà Nguyễn, Sarawut Rimdusit, Toshiaki Ougizawa, Tran Thi Thuy
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 1 H 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.