Resistance to Cleavage of Core⁻Shell Rubber/Epoxy Composite Foam Adhesive under Impact Wedge⁻Peel Condition for Automobile Structural Adhesive.

Epoxy foam adhesives are widely used for weight reduction, watertight property, and mechanical reinforcement effects. However, epoxy foam adhesives have poor impact resistance at higher expansion ratios. Hence, we prepared an epoxy composite foam adhesive with core⁻shell rubber (CSR) particles to improve the impact resistance and applied it to automotive structural adhesives. The curing behavior and pore structure were characterized by differential scanning calorimetry (DSC) and X-ray computed tomography (CT), respectively, and impact wedge⁻peel tests were conducted to quantitatively evaluate the resistance to cleavage of the CSR/epoxy composite foam adhesives under impact. At 5 and 10 phr CSR contents, the pore size and expansion ratio increased sufficiently due to the decrease in curing rate. However, at 20 phr CSR content, the pore size decreased, which might be due to the steric hindrance effect of the CSR particles. Notably, at 0 and 0.1 phr foaming agent contents, the resistance to cleavage of the adhesives under the impact wedge⁻peel condition significantly improved with increasing CSR content. Thus, the CSR/epoxy composite foam adhesive containing 0.1 phr foaming agent and 20 phr CSR particles showed high impact resistance (EC = 34,000 mJ/cm²) and sufficient expansion ratio (~148%).

New approach to the reduction of recombination in dye-sensitised solar cells via complexation of oxidised species.

Although dye-sensitised solar cells (DSSCs) have received great attention as low-cost and clean energy conversion devices, their conversion efficiency still lags behind that of inorganic solar cells. One of the reasons is due to the recombination of injected electrons with the oxidised species of the redox couple that are present in the electrolyte near the surface of the bare TiO2 particles. While most research has focused on blocking the bare surface of the TiO2 nanoparticles, we have introduced a new approach that can directly reduce the concentration of the oxidised species of the redox couple present in the electrolytes through complex formation. Recombination was reduced by the addition of cyclodextrins (CDs) to a polyethyleneglycol dimethyl ether (PEGDME) electrolyte containing iodide/triiodide redox couples that can form a complex with the triiodide. Experimental and theoretical investigation of the complex formation between triiodide and the CD in PEGDME matrix was performed. Increase in total power conversion efficiency was achieved using the alpha-CD as an additive in a low volatile PEGDME based electrolyte. Electrochemical impedance spectra and intensity modulated photovoltage spectroscopy measurements showed that the increase in the short-circuit current density is due to the suppression of surface recombination by the complex formation between the CDs and the triiodide ions.