IADR Abstract Archives
Characterization of Urethane Dimethacrylate Monomers: Degree of Conversion, Hardness, Rheology
Objectives: To characterize some physical and chemical properties of several Urethane dimethacrylate (UDMA) and diacrylate (UDA) monomers and mixtures before and after polymerization.
Methods: Three UDMA monomers (UDMA, PGDMA, UDMA-IPDI) and one UDA were diluted with TEGDMA at 50:50 and 70:30 wt% (UDMA:TEGDMA). A three component photo initiator system was introduced. The viscosity of monomers and eight resin mixtures was measured using a Rheometer (n=3). The resin mixtures were introduced to a Teflon mould (5 mm diameter and 2 mm thick) and photopolymerized using a LED Light Curing unit (20s). The Light transmission (LT) through the surface was measured using a MARC Resin Calibrator (n=5). The Degree of Conversion (DC) immediately and 24 h after cure DC0 and DC24 were measured using FTIR (n=3). The hardness was measured 24 h after cure (VHN24) using a Vickers Indentor (n=5).
Results: The viscosity of the UDMA monomers ranged between 10.3 and 15.30 x103 Pa.s and drastically reduced to 0.07-2.57 Pa.s after dilution with TEGDMA. The LT was highest for 70 UDMA and 50 UDMA-IPDI at 85.7% and 84.9%, and lowest for 50 PGDMA at 56.1%. The mean DCs were significantly higher for UDA mixtures (77.0/73.2%) compared to control UDMA mixtures (66.9/65.9%) and lowest for PGDMA mixtures (45.0%) (ANOVA, p<0.05). UDMA-IPDI mixtures had DC0s of 55.2/52.7%.The DC24 for all monomer mixtures increased compared with DC0, with a maximal increase for PGDMA mixtures (15/6%). The mean VHN24 were significantly higher for 70 PGDMA and 70 UDMA-IPDI (21.8 VHN and 20.8 VHN) compared to control 70 UDMA (17.1 VHN) and 70 UDA (15.7 VHN) (ANOVA p<0.05). The lowest hardness was for 50 PGDMA at 13.4 VHN.
Conclusions: 50 UDMA-IPDI is a promising system with a high % transmission (84.9%) and significantly higher hardness (18.1 VHN) compared to control 50 UDMA (73.7%) with a hardness of 16.5 VHN.
Methods: Three UDMA monomers (UDMA, PGDMA, UDMA-IPDI) and one UDA were diluted with TEGDMA at 50:50 and 70:30 wt% (UDMA:TEGDMA). A three component photo initiator system was introduced. The viscosity of monomers and eight resin mixtures was measured using a Rheometer (n=3). The resin mixtures were introduced to a Teflon mould (5 mm diameter and 2 mm thick) and photopolymerized using a LED Light Curing unit (20s). The Light transmission (LT) through the surface was measured using a MARC Resin Calibrator (n=5). The Degree of Conversion (DC) immediately and 24 h after cure DC0 and DC24 were measured using FTIR (n=3). The hardness was measured 24 h after cure (VHN24) using a Vickers Indentor (n=5).
Results: The viscosity of the UDMA monomers ranged between 10.3 and 15.30 x103 Pa.s and drastically reduced to 0.07-2.57 Pa.s after dilution with TEGDMA. The LT was highest for 70 UDMA and 50 UDMA-IPDI at 85.7% and 84.9%, and lowest for 50 PGDMA at 56.1%. The mean DCs were significantly higher for UDA mixtures (77.0/73.2%) compared to control UDMA mixtures (66.9/65.9%) and lowest for PGDMA mixtures (45.0%) (ANOVA, p<0.05). UDMA-IPDI mixtures had DC0s of 55.2/52.7%.The DC24 for all monomer mixtures increased compared with DC0, with a maximal increase for PGDMA mixtures (15/6%). The mean VHN24 were significantly higher for 70 PGDMA and 70 UDMA-IPDI (21.8 VHN and 20.8 VHN) compared to control 70 UDMA (17.1 VHN) and 70 UDA (15.7 VHN) (ANOVA p<0.05). The lowest hardness was for 50 PGDMA at 13.4 VHN.
Conclusions: 50 UDMA-IPDI is a promising system with a high % transmission (84.9%) and significantly higher hardness (18.1 VHN) compared to control 50 UDMA (73.7%) with a hardness of 16.5 VHN.