Preliminary study on the preparation of latex foam rubber from graft copolymer of deproteinised natural rubber and methyl methacrylate
2001
Nakason, C. | Kaesaman, A. | Yimwan, N. | Ketsarin, K.
Deproteinised natural rubber (DPNR) latex was prepared by incubation of fresh field natural rubber latex with a proteolytic enzyme in the presence of an emulsifier. The nitrogen content was decreased from 0.9% (in the fresh field natural rubber latex) to 0.07% (in the DPNR). A graft copolymer of the deproteinised natural rubber latex and poly(methyl methacrylate) (PMMA) was then synthesized using tert. butylhydroperoxide and tetraethylene pentamine as a redox initiator. The presence of grafted PMMA in the natural rubber molecules wax confirmed using FTIR. Intense absorption peaks at 1732 cm-1 (-C=0 stretch) and 1140 cm-1 (-C=0 stretch) were observed. Il was also found that the quantity of grafted PMMA increased with the increase in the level of MMA used in the grafting reaction. The graft copolymer latex was later compounded and processed into a latex foam rubber. Results showed that the latex of graft copolymer blended with high ammonia concentrated latices provided high quality latex foam rubber. This included surface appearance and physical properties, such as hardness, compression set and density. It was also found that hardness, compression set and density of the latex foam rubber increased with the increase in the level of graft copolymer in compounding formulation. Furthermore, at the same blend ratio, the properties increased with the increase in the level of methyl methacrylate used in the grafting reaction.
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