Effect of the loading of organomodified clays on the thermal and mechanical properties of a model dental resin

Abstract

Experimental dental resins composed of triethyleneglycol dimethacrylate, urethane dimethacrylate, ethoxylated bisphenol-A-dimethacrylate and bisphenol A glycidyl methacrylate containing an organoclay as filler were prepared by photopolymerization. The addition of organoclay fillers results in slower polymerization rates (0.59 and 0.24 mol L -1 min -1 , for the formulations without and with 15% of organoclay, respectively) and lower degrees of conversion (0.50 and 0.35 for the formulations without and with 15% of organoclay), as determined by photocalorimetry. The influence of the organoclay on the thermal and mechanical properties of the resins was evaluated using thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA) techniques. The (tan δ) and E´ curves indicate the formation of more rigid materials and the damping curve data indicates more homogeneous materials. An increase of storage modulus, E', was observed for composites with the higher organoclay filler contents. These effects are due to the higher viscosity of the systems with organoclay, resulting in a lower mobility of the radicals during the propagation step of polymerization, as well as to the scattering of the incident photopolymerizing radiation, which lowers the amount of initiation centres.

Characterization of glycidyl methacrylate based magnetic nanocomposites

“…Initially, only the mPGMTdeta sample has shown a loss of about 10 wt.% below 100 o C, which might be assigned to the loss of physically retained or occluded solvents [31]. Next, all three samples exhibited a certain weight loss of nearly 1 wt.% between 100 and 250 o C probably due to the loss of water or unpolymerized monomers [32].…”

New fluorescein dye derivatives and their use as an efficient photoiniator using blue light LED

“…It is known that the C=C bond requires 60 kJ mol -1 to cleave the ligation, which is considered the standard enthalpy of polymerization (∆ ) [18][19][20][21], and the energy obtained in polymerization peak DSC curves of polymers refers to residual monomer in photopolymerization ( ). Then, the DC (%) can be obtained from DSC curves using Equation 1.…”

Use of DSC in degree of conversion of dimethacrylate polymers: easier and faster than MIR technique

“…The thermal events observed in the DSC curves were used to calculate the degree of conversion (DC). The C=C bond requires 60 kJ mol -1 to cleave the p ligation, which is considered the standard enthalpy of polymerization (DH pol ) [23][24][25][26]. The energy obtained in polymerization peak in DSC curves of polymers refers to residual monomer in polymers previously photopolymerized (E p ).…”