Cure performance of multifunctional monomers to photo-initiators: a thermoanalytical study onbis-GMA-based resins

Optimum pressure for the high-pressure polymerization of urethane dimethacrylate

“…Due to concerns related to the toxicity of bis-phenol A (BPA) [17,18] and other advantages of UDMA over Bis-GMA, such as its smaller molecular weight (and consequently a higher concentration of double bonds per weight) and lower viscosity (due to the presence of the flexible urethane linkage and absence of aromatic groups, which may improve toughness of the polymer/composite [19,20]), we decided to use the UDMA monomer in this study. For the determination of DC, several analytical methods have been used: differential scanning calorimetry (DSC), which provides a measure of methacrylate conversion based on the enthalpy of the exothermic polymerization process [21][22][23]; hardness test [24]; optical microscopy [25]; vibrational methods, such as Fourier-transform infrared spectroscopy [26][27][28], near infrared spectroscopy [15,29] and Raman spectroscopy [30]. However, the majority of analyses have been based on the use of Fourier-transform infrared and near infrared spectroscopy, which provides a direct measure of unreacted methacrylate groups.…”

Dental application of crystalline monomer with urethane linkages: a thermoanalytical study on bis-GMA-based resins

“…Bis-GMAbased A1,B1 and C1 resins had almost the same activation curing energies (10.9, 10.5, 12.4kcal/mol) and the 10wt% addition of crystalline DME-TDC (A2, B2, C3) to each base resin exhibited a minimum value. It was known that the polymerization reaction was enhanced by DMAEMA as a reducing agent [9]. The effect of DME-TDC present within unfilled bis-GMA-based resins was determined using the thermal reaction of curing, showing that the activation energy for curing was reduced, associated with the smaller peak temperature in the DSC curve.…”

“…Transmission Fourier transform-infrared analysis (FT-IR) [4] and thermoanalytical methods [5][6][7][8][9][10] have shown that resin polymerization appears to be due to the monomer composition of dental resin and the concentration of camphorquinone (CQ) and reducing agents as the photo-initiator in relation to base monomers. Photopolymerization of dental composite resins was initiated by visible light in a spectrum range of 400 to 650 nm [11 13].…”

“…They were heated to 800°C with a heating rate of 10 °C min-1 during the DTA measurement and also cured with radiation from a visible light source (Quick Light, J. Morita Co, Kyoto) for 120 s at 37 °C during the DSC measurement (ambient temperature, N2 gas flow). The same conditions as previously reported were used for DTA and DSC analyses [8,9,13]. …”

Effect of filler content on mechanical strength in bis-GMA-based resins with urethane linkages

“…Because of incomplete polymerization of resin composites cured by visible light, maximum mechanical strength is not attained [1][2][3][4]. The monomer compositions and the concentration of catalyst in the resins need to be optimized in visible light polymerization [5,6].…”