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Abstract
Objectives
This study investigated the optimal combination of 3-component photoinitiation system, consisting of CQ, p-octyloxy-phenyl-phenyl iodonium hexafluoroantimonate (OPPI), and 2-dimethylaminoethyl methacrylate (DMAEMA) to increase the degree of conversion of resin monomers, and analyze the effect of the ratio of the photoinitiator to the co-initiator.
Materials and Methods
Each photoinitiators (CQ and OPP) and co-initiator (DMAEMA) were mixed in three levels with 0.2 wt.% (low concentration, L), 1.0 wt.% (medium concentration, M), and 2.0 wt.% (high concentration, H). A total of nine groups using the Taguchi method were tested according to the following proportion of components in the photoinitiator system: LLL, LMM, LHH, MLM, MMH, MHL, HLH, HML, HHM. Each monomer was polymerized using a quartz-tungsten-halogen curing unit (Demetron 400, USA) for 5, 20, 40, 60, 300 sec and the degree of conversion (DC) was determined at each exposure time using FTIR.
Results
Significant differences were found for DC values in groups. MMH group and HHM group exhibited greater initial DC than the others. No significant difference was found with the ratio of the photoinitiators (CQ, OPPI) to the co-initiator (DMAEMA). The concentrations of CQ didn't affect the DC values, but those of OPPI did strongly.
Figures and Tables
 | Figure 1Degree of conversion of experimental groups with various combination of photoinitiators according to exposure time.
L, low concentration; M, medium concentration; H, high concentration.
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 | Figure 2Degree of conversion at the first 5 seconds of irradiation.
L, low concentration; M, medium concentration; H, high concentration.
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 | Figure 3Degree of conversion at 20 seconds of irradiation.
L, low concentration; M, medium concentration; H, high concentration.
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 | Figure 4Degree of conversion at 40 seconds of irradiation.
L, low concentration; M, medium concentration; H, high concentration.
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 | Figure 5Degree of conversion at 60 seconds of irradiation.
L, low concentration; M, medium concentration; H, high concentration.
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 | Figure 6Degree of conversion at 300 seconds of irradiation.
L, low concentration; M, medium concentration; H, high concentration.
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 | Figure 7Degree of conversion with various concentration of photoinitiators (CQ + OPPI) to co-initiator (DMAEMA).
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Table 1
Experimental groups of photoinitiator and co-initiator with various concentrations (CQ : OPPI : DMAEMA)
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