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Published on: August 20, 2013
Dynamic mechanical analysis of storage modulus development in light-activated polymer matrix composites.
Ronald L Sakaguchi1, Nilam C Shah, Bum Soon Lim
1Department of Biomaterials and Biomechanics, Oregon Health & Science University, 611 SW Campus Dr., SD-503, Portland, OR 97201, USA. sakaguch@ohsu.edu
Summary
This study demonstrates a method using dynamic mechanical analysis in a three-point flexure fixture to monitor storage modulus development in light-activated polymer composites. The technique allows for estimation of polymerization kinetics in dental materials.
Area of Science:
- Materials Science
- Polymer Chemistry
- Biomaterials Engineering
Background:
- Dynamic Mechanical Analysis (DMA) is crucial for characterizing polymer properties.
- Monitoring the development of storage modulus (E') during polymerization is key for understanding composite performance.
- Traditional methods may not capture the dynamic changes in E' during light activation.
Purpose of the Study:
- To evaluate the use of DMA with a three-point flexure fixture in a tubular geometry.
- To monitor the storage modulus (E') development of light-activated polymer matrix composites.
- To establish a method for estimating polymerization kinetics in dental composites.
Main Methods:
- Utilized a dynamic mechanical analyzer (DMA) in a three-point bend fixture with tubular composite samples.
- Measured storage modulus (E') continuously during light activation and post-activation.
- Employed finite element modeling and micro-Fourier Transform Infrared (FTIR) spectroscopy to validate results.
Main Results:
- A linear regression demonstrated a strong correlation (r(2)=0.986) between E' values of the composite within the sheath and core alone.
- The method enabled correction for estimated E' values of the composite core.
- Degree of conversion (DC) was measured for hybrid and microfilled composites.
Conclusions:
- The described DMA method effectively estimates storage modulus growth during light-activated polymerization of highly filled dimethacrylates.
- While phenomenological, the approach provides validated estimates of early polymerization kinetics.
- This technique offers a valuable tool for analyzing the curing process of dental composites.
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