Blends of isoprene-styrene/methacrylate monomer systems as denture soft lining material

This work further develops the concept of using an elastomer gelled with methacrylate monomers to produce a methacrylate-based soft lining material without the use of a plasticizer. An isoprene-styrene (SIS) block copolymer was mixed with methyl methacrylate (MMA) and 1,6-hexandiol dimethacrylate (HDMA). The HDMA was used as a cross-linking agent. The elastomer/monomer ratios were maintained at 50/50 whereas the monomers ranged from 0 to 100%) HDMA. Mechanical properties and water absorption/desorption characteristics were used to assess the effect of varying the monomer compositions. The results indicated that phase separation took place, in particular at high HDMA content. This significantly increased the Young's modulus and decreased the elongation to break. Generally, the water uptake tended to decrease with increasing HDMA content, reflecting the effect of modulus. Second absorption cycles gave higher uptake values compared to the first. Formulations with a high amount of HDMA gave materials with modulus values too high for soft lining applications. This suggests that the optimum formulation requires a compromise between modulus and water uptake.