Authors: Sophie Bistac, Ekasit Ananjaroenvong, Irene Campistron, Jean-François Pilard
In this work, polyisoprene was modified to lead oligomers with reactive terminated groups. The objective of these chemical modifications of polyisoprene is to prepare new adhesives using environmentally friendly sources such as natural rubber latex. Polyisoprene oligomers were here chemically modified to obtain polyurethanes with specific physicochemical and mechanical properties. The first step of the adhesives preparation is the synthesis of hydroxytelechelic cis-1,4-polyisoprene of various molecular weight. The second step is then the preparation of epoxidized hydroxytelechelic cis-1,4-polyisoprene with different epoxidation levels. Polyurethane adhesives were finally obtained by reaction of hydroxytelechelic oligomers with toluene diisocyanate. Steel/polyurethane/steel assemblies were obtained after curing of adhesive at 60 °C. A wedge test was used to quantify adherence level of assemblies, for different polyurethanes, prepared from hydroxytelechelic cis-1,4- polyisoprene of various molecular weight and epoxydation degree. Microscopy analysis was used to precisely localize the locus of failure. Surface properties of polyurethane films were also investigated by wettability. Adherence results show that some polyurethanes exhibit high adherence level. Adhesive behaviour is discussed as a function of isoprene molecular weight and epoxidation degree.
Keywords: Cis-1,4-polyisoprene, Polyurethane ,adhesion properties