Abstract
Copolymers of butyl methacrylate (BMA) and ethyl methacrylate (EMA) having different molecular weights were synthesized by suspension polymerization. These polymer powders and a liquid of butyl phthalyl butyl glycolate were used. The storage modulus G', dynamic viscosity η' and loss tangent tan δ of a mixture of powder and liquid were determined over the frequency range of 0.05 to 70Hz at different temperatures. The master curves of G', η' and tanδ were constructed from the data obtained at different temperatures. Marked effects of the molecular weight of polymer on G' and tanδ were observed at the low frequency range.G' of a material containing PBMA was smaller than that of a conventional material using PEMA, because the long side chain in PBMA acts as an internal plasticizer. The tanδ of PBMA was smaller than that of PEMA in the high frequency range, but was raversed in the low frequency range. These properties are an advantage, because new materials are soft and flexible compared with conventional materials which become hard and stiff with time.More desirable properties for tissue conditioners should be attainable by controlling the composition of BMA and EMA, and molecular weight of the copolymers.
