PREPARATION, ADHESIVE PERFORMANCE AND STABILITY OF NATURAL RUBBER LATEX GRAFTED WITH N-BUTYL ACRYLATE (BA) AND METHYL METHACRYLATE (MMA)

Pranee  Chumsamrong; Oukrit  Monprasit

Authors

Pranee Chumsamrong School of Polymer Engineering, Suranaree University of Technology, Nakorn Ratchasima, Thailand
Oukrit Monprasit School of Polymer Engineering, Suranaree University of Technology, Nakorn Ratchasima, Thailand

Keywords:

Contact adhesive, graft-modified natural rubber, emulsion polymerization

Abstract

In order to study the potential of increasing the weather stability of natural rubber latex for use as a water-based contact adhesive, the natural rubber latex was modified by graft copolymerization with n-butyl acrylate (BA) and methyl methacrylate (MMA). The grafting reaction was carried out using emulsion polymerization at 60°C. Potassium persulfate was used to initiate polymerization. Four different weight percentage ratios of BA to MMA used in this work were 95:5, 90:10, 85:15 and 80:20. Percentage conversion of the monomer of all latexes prepared was ≥ 79.5%. The grafting efficiency of graft-modified natural rubber with a different monomer ratio tends to decrease with an increase of MMA. 1H-nuclear magnetic resonance spectroscopy (1H-NMR) confirmed that the latexes which were prepared contained graft copolymer. The adhesive performance was characterized by 90° peel strength tests. Only graft-modified natural rubber latex with the monomer ratio of 80:20 possessed an adhesion property enough to conduct peel testing. The peel strength value of graft-modified natural rubber was lower than that of natural rubber latex. However, graft-modified natural rubber latex tends to have a higher weather stability than natural rubber latex.

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