In recent years, the authors have been developing novel fluoride-releasing dental composites containing ternary zirconium fluoride chelates. The aim of this study was to improve the physical and mechanical properties of these composites by improving the formulation of the monomers and photoinitiators. The hypothesis was that reduction of hydrophilic monomers and improvement of the photoinitiators could reduce water sorption and significantly increase the mechanical properties of the composite. The degree of conversion of the composites containing different compositions of photoinitiators was studied by Fourier transform near-infrared spectroscopy (FT-NIR). Ten experimental composites containing different compositions of ethoxylated bisphenol-A dimethacrylate (EBPADMA), 1,6-hexanediol dimethacrylate (HDDMA), triethylene glycol dimethacrylate (TEGDMA), and 2,2-bis[4-(2-hydroxy-3-methacryloyloxypropoxy)phenyl]-propane (BisGMA) were tested for flexural strength, viscosity, and water sorption. The experimental composite containing 20% synthesized fluoride-releasing monomer, 30% BisGMA, 30% EBPADMA, and 20% HDDMA showed significantly higher fluoride release and recharge, but physical and mechanical properties similar to those of the control composite containing 40% BisGMA, 40% EBPADMA, and 20% HDDMA.
The mechanical properties of four ply-lam cross-laminated timbers (CLTs) containing a plywood layer were compared with those of glued laminated timber (GLT) and CLT. The bending, out-of-plane shear, compression strengths were highest in the GLT, which was followed by the ply-lam CLTs and CLT. The modulus of elasticity values for three studied ply-lam CLT samples were 1–2.5 GPa higher than GLT; however, the bending strength of all ply-lam CLTs was 7.3–18.8 MPa lower than GLT. The length of the plywood product is 2,440 mm, and longitudinal bonding is required to manufacture ply-lam CLTs of length > 3m. The prediction of bending capabilities by shear analogy was compared with the bending properties when joints were included. The performances of all the pilot-scale ply-lam CLT samples exceeded the predicted bending performance standards for MOE (10 GPa) and modulus of rupture (30 MPa) All samples exceeded 10 GPa and 30 MPa, based on projected and experimental data.
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