Development of butyl elastomer/methacrylate monomer systems as denture soft lining materials

Area of Science:

• Polymer Science
• Materials Science

Background:

• Elastomer/methacrylate monomer formulations exhibit good strength but suffer from high water uptake and oxidation.
• Butyl elastomers are known for their superior oxidation resistance.

Purpose of the Study:

• To evaluate the tensile and water uptake properties of three butyl elastomers: butyl (PB), chlorobutyl (PCB), and bromobutyl (PBB).
• To assess the suitability of these elastomers in methacrylate-based formulations for potential applications.

Main Methods:

• Three butyl elastomers (PB, PCB, PBB) were gelled with ethyl hexyl methacrylate, ethylene glycol dimethacrylate, and lauryl peroxide (5+ formulation).
• Tensile properties (strength, elongation to break) and water uptake were measured for the formulated elastomers and pure elastomers.
• Materials were analyzed for signs of oxidation over a 203-day period.

Main Results:

• Formulated elastomers exhibited low tensile strength (PCB5+ = 3.09 MPa, PBB5+ = 3.90 MPa) but high elongation to break (PCB5+ = 797%, PBB5+ = 599%).
• All formulations showed high and protracted water uptake, with none reaching equilibrium within 203 days.
• Chlorobutyl elastomer (PCB5+) displayed the highest water uptake (approx. 6%), while PBB5+ and PB5+ showed similar uptake (approx. 4%).
• No signs of oxidation were observed in any of the tested materials.

Conclusions:

• Bromobutyl (PBB) demonstrated the best overall properties, including excellent oxidation resistance and high elongation, making it suitable for further development.
• While water uptake remains a challenge, the inherent oxidation resistance of butyl elastomers is advantageous.
• Further research is warranted to optimize formulations for reduced water absorption while maintaining desirable mechanical properties.