Preservation Services

Low levels of formaldehyde were determined by preconcentration with poly(allylamine) beads and analysis by flow-injection system with immobilized formaldehyde dehydrogenase. Formaldehyde dehydrogenase was immobilized on tresylate-poly(vinyl alcohol) beads and packed into a stainless-steel column (5cm×4mm). The column was incorporated in a flow-injection system with fluorimetic detection. The calibration graph was linear from 0.5 to 10μM (15–300μgl−1). The poly(allylamine) beads (0.5g)

Formaldehyde and acetaldehyde in water were determined by preconcentration with poly(allylamine) beads, derivatization with 2,4-dinitrophenylhydrazine (DPH) and analysis by HPLC. Poly(allylamine) beads (0.5 g) were used to adsorb formaldehyde and acetaldehyde at 1.2-150 microg l(-1) and 3.5-220 microg l(-1) from water (1 l). The concentration factor is 50 fold. The aldehydes were eluted and derivatized with 2 mM DPH in 0.5 M H2SO4 (10 ml). The time of analysis was 1 h. The detection limits (S/N=3) for formaldehyde and acetaldehyde were 0.6 and 2 microg l(-1), respectively.

Low levels of formaldehyde were determined by preconcentration with poly(allylamine) beads and analysis by flow-injection system with immobilized formaldehyde dehydrogenase. Formaldehyde dehydrogenase was immobilized on tresylate-poly(vinyl alcohol) beads and packed into a stainless-steel column (5cm×4mm). The column was incorporated in a flow-injection system with fluorimetic detection. The calibration graph was linear from 0.5 to 10μM (15–300μgl−1). The poly(allylamine) beads (0.5g)

Formaldehyde and acetaldehyde in water were determined by preconcentration with poly(allylamine) beads, derivatization with 2,4-dinitrophenylhydrazine (DPH) and analysis by HPLC. Poly(allylamine) beads (0.5 g) were used to adsorb formaldehyde and acetaldehyde at 1.2-150 microg l(-1) and 3.5-220 microg l(-1) from water (1 l). The concentration factor is 50 fold. The aldehydes were eluted and derivatized with 2 mM DPH in 0.5 M H2SO4 (10 ml). The time of analysis was 1 h. The detection limits (S/N=3) for formaldehyde and acetaldehyde were 0.6 and 2 microg l(-1), respectively.

The mechanical properties of latex paint films containing different volume fractions of TiO2, CaCO3 and kaolin were measured in uniaxial tension over a broad range of temperatures and crosshead speeds. Young’s modulus results in the glassy region are first compared with several micromechanics theories for particle-filled composites containing elastic phases. It was found that the Mori-Tanaka theory [1, 2] slightly under-predicted the modulus enhancement, while the Lielens approach [3, 4] provided very accurate results. A nonlinear viscoelastic material model involving a Prony series and the neo-Hookean hyperelastic function was used to represent the tensile data up to relatively small strains (3-4%). Using the experimental data, the material model was calibrated and the parameters of the model were determined. The derived parameters were then used to re-construct time dependent shear modulus plots which were compared with the approximations given by Clements and Mas [5, 6] for the viscoelastic Mori-Tanaka theory in the time-domain. It was found that the experimentally observed modulus enhancement was much stronger than the predicted values in the rubbery region. This is attributed to the small particle size, the high level of constraint posed on the latex matrix at the particle interface or possibly the formation of a particle network.

The tensile properties of latex paint films containing TiO2 pigment were studied with respect to temperature, strain-rate and moisture content. The purpose of performing these experiments was to assist museums in defining safe conditions for modern paintings held in collections. The glass transition temperature of latex paint binders is in close proximity to ambient temperature, resulting in high strain-rate dependence in typical exposure environments. Time dependence of modulus and failure strain is discussed in the context of time–temperature superposition, which was used to extend the experimental time scale. Nonlinear viscoelastic material models are also presented, which incorporate a Prony series with the Ogden or Neo-Hookean hyperelastic function for different TiO2 concentrations.