The effect of ethanol on surface of semi-interpenetrating polymer network (IPN) polymer matrix of glass-fibre reinforced composite.

Aim of the Study: The aim of this laboratory study was to evaluate the effect of ethanol treatment on the surface roughness (S _a ), nano-mechanical properties (NMP) and surface characterization of dental fiber reinforced composite (FRC) with semi-interpenetrating polymer network (IPN).
Materials and Methods: A total of 240 FRC specimens with bisphenol A-glycidyl methacrylate - triethyleneglycol dimethacrylate - Poly (methylmetahcrylate) (bis-GMA-TEGDMA-PMMA) IPN matrix system were light cured for 40 s and divided into 2 groups (L and LH). The group LH was further post-cured by heat at 95 °C for 25 min. The specimens were exposed to 99.9%, 70% and 40% for 15, 30, 60 and 120 s respectively. The treated specimens were evaluated for S _a using non-contact profilometer. NMP were determined using nanoindentation technique and chemical characterization was assessed by Fourier Transform-Infrared (FTIR) spectroscopic analyses. Scanning electron microscopic (SEM) images were made to evaluate the surface topographical changes.
Results: Both the L and LH group showed changes in the S _a and NMP after being treated by different concentrations of ethanol and at different time interval. The highest S _a was observed with L-group (0.733 μm) treated with 99.9% ethanol for 120 s. Specimens in LH-group treated with 99.9% ethanol for 120 s (1.91 GPa) demonstrated increased nano-hardness, and group treated with 40% ethanol for 120 s demonstrated increased Young's modulus of elasticity (22.90 GPa). FTIR analyses revealed changes in the intensity and bandwidth in both the L and LH groups.
Conclusion: The present study demonstrated that both light-cured and heat post-cured FRC were prone for ethanol induced alteration in the surface roughness (S _a ), nano-mechanical properties (NMP) and chemical characterization. The interphase between the glass fibers and the organic matrix was affected by ethanol. The changes were considerably less in magnitude in the heat post-cured FRC specimens.
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