Investigating the improving effect of silica nano particles on polyether polyurethane elastomers

Polyurethanes (PU) are one of the most versatile groups of plastic materials. The variety of PUR types reaches from flexible and rigid foams over thermoplastic elastomers to adhesives, paints and varnishes. Polyurethanes are usually obtained from the reaction between an OH containing material with isocyanates forming a linkage of urethane functional groups. Polyurethane elastomers are block copolymers with alternating soft and hard segments that, due to structural differences, separate into phases or domains. Hard segments play the role of physical cross-links and act as high modulus filler, whereas the soft segment provides extensibility [1].Developments in the synthesis of nano particles have developed the research activities in field of nanocomposites. The properties of nanocomposites strongly depend on the organic matrix, nanoparticles and the way in which they were prepared. Many researchers studied organic/inorganic nanocomposite systems, and tried to understand better their mechanism so as to obtain the expected improvement over traditional organic materials. Nanosilica has been reported to enhance tensile strength and elongation of polyurethane based polymers, although the modulus and hardness were lower than neat polymer or micro filler doped composites. Since the surface property, particle size and dispersibility of nanoparticles are so diversified, and tend to aggregate in organic matrix because of their high surface energy, it is very difficult to predict the properties of nanocomposites [2-4]. In this research, in situ forming polymerization technique has been utilized to synthesize the nano silica doped polyether based polyurethane elastomers. Several physical and thermal properties were investigated in the prepared nanocomposites. Interestingly, all of the characteristics would be improved in accordance with nano particle content