Bis-Ahah Synthesis

3. Experimental Procedure

3.1. Sample preparation
Bis-GMA should be made photo-polymerizable by combining with camphoroquinone (CQ) and dimethylamine ethyl methacrylate (DMAEMA). The chemical characteristics of the materials used for preparing the polymer are presented in table 1.

The procedure for composing the materials is as follows:
1. All materials left in the room temperature for 2 hours before using.
2. Bis-GMA was heated to 50°C to reduce viscosity and mix with the photo-initiators.
3. 0.4 mol% CQ and 0.8 mol% DMAEMA were added to Bis-GMA and blended completely by a spatula.
4. The mixture stored in a dark container prior to prepare the molds.
Some molds of a translucent polymer with 5 mm diameter and 11 mm height were prepared. The internal walls of the molds were lubricated carefully to avoid sticking the polymer after polymerization. Then the photo-polymerized Bis-GMA was injected into the mold and cured with 400 W/m2 LED light for 60 seconds from each side (i.e. top, bottom and surrounding). After that, all samples were ejected from the mold. The top and bottom surfaces of the specimens were grounded by a sand paper to smooth it and to make the

The surface of the disks and the test sample were chosen as the master surface and the slave surface, respectively. The contact direction was then defined from the surface of disks toward the specimen due to the fact that only the master surface can penetrate into the slave one. The finite sliding was selected for the sliding formulation. Moreover, tangential friction was defined between the polymer sample and the compression disks. Since the compression disks are stainless steel, the value of friction coefficient was selected according to the previously defined value for the friction between stainless steel and polymers [24, 25] which is equal to