Modification of Vietnam Natural Rubber via Graft Copolymerization with Styrene

Abstract

Graft copolymerization of styrene onto deproteinized natural rubber (DPNR) using tert-butyl hydroperoxide (TBHPO) and tetraethylene pentamine (TEPA) as redox initiator have been investigated. The effects of initiator and monomer concentration on conversion and grafting efficiency were studied. The dynamic mechanical and thermal properties of the graft copolymer were investigated over the wide range of temperatures. It is shown that a high value of storage modulus for the graft copolymer, which was about 25 times as high as that of DPNR, was achieved. The graft copolymer (DPNR-graft-PS) showed the outstanding tensile strength and stable thermal properties. These enhancements were attributed to the interaction between NR and polystyrene as a result of the graft copolymerization. Morphology observation by transmission electron micrograph (TEM) revealed that the core-shell arrangement of the DPNR-graft-PS with about 30 nm in thickness of polystyrene nano-layer was achieved.

Dynamic Mechanical Properties of Vietnam Modified Natural Rubber via Grafting with Styrene

“…Afterwards TBHPO/TEPA were added as an initiator followed by styrene as a monomer. The reaction was carried out by stirring the latex at above 400 rpm for 2.5 hours at room temperature [24,29,30].…”

“…The styrene conversion and grafting efficiency of graft copolymerization were determined by gravimetric method [24].…”

“…By studying the dependence of storage and loss moduli on temperature or frequency, it is possible to show the dynamic mechanical properties of the materials and their applications [20][21][22][23]. Graft copolymerization of styrene onto deproteinized natural rubber resulted in a formation of 2 International Journal of Polymer Science core-shell structure, in which natural rubber particle as a core was surrounded by polystyrene nanolayer as a shell [24]. This structure and polystyrene chain play an important role in outstanding mechanical properties of graft copolymer; for instance, the tensile strength of graft copolymer increases about 4 times that of natural rubber.…”

“…This structure and polystyrene chain play an important role in outstanding mechanical properties of graft copolymer; for instance, the tensile strength of graft copolymer increases about 4 times that of natural rubber. The dynamic mechanical properties of graft copolymer had also been measured and the results showed that the storage modulus of graft copolymer increases about 25 times compared with that of natural rubber [24]. However, DMA measurement had been carried out in narrow range of frequencies from 0.1 to 100 Hz due to the limitation of the equipment.…”

Design and synthesis study of the thermo‐sensitive copolymer carrier of penicillin G acylase

“…[28][29][30] Recently, researchers have developed their study to design and copolymerize thermo-sensitive with other functional monomers to prepare a special material for special use. The study about copolymerization could be separated to random copolymerization, 31,32 graft copolymerization, 33,34 block copolymerization, 35,36 and their combinations. 37,38 Because block copolymers covalently bonded more than 2 homopolymer segments in its backbone, it can combine the excellent properties of different homopolymers to obtain multifunction polymer materials, and such study has been attracted many researchers.…”