An earlier study identified a formulation comprising a butadiene/styrene co
polymer (PBS) gelled with ethyl hexyl methacrylate (5 + formulation) as a p
otential denture soft lining material. It had good mechanical properties bu
t water uptake was high as a result of the presence of a separating agent.
This study has compared the tensile and water absorption properties of four
elastomers free from separating agent (three butadiene/styrene, HBS, EBS,
SBS, and one isoprene/styrene, SIS) with those of PBS all using the 5 + for
mulation. HBS is emulsion polymerized; the others are solution polymerized.
SIS5 + had the better tensile properties whereas HBS5 + had the lowest wat
er uptake. All the other 5 + formulations had higher uptakes than PBS5 +, w
hich is thought to be due to the presence of hydrophilic groups from the so
lution polymerization process. All materials showed some sign of oxidation.
Emulsion polymerized elastomers are regarded as less suitable for medical
uses than the solution polymerized alternatives. Of these, SIS5 + seems to
be less prone to oxidation and has the better mechanical properties so was
considered to be the most suitable material for further development. (C) 20
01 Kluwer Academic Publishers.