Water rinsing physical properties

Physical properties were evaluated using standard DIN or ASTM specifications. The sealants were filled into Teflon molds to form homogeneous test pieces of comparable thickness. The specimens were then moisture cured and conditioned at 25 °C and 50% relative humidity for 14 days before mechanical property testing. The hardness of the cured sealant samples was measured by Shore A. Shelf life at 50 °C was determined for a maximum of 21 days. Tack-free times were determined by finger touch under ambient conditions. For adhesion testing the substrates were first wiped with either methyl ethyl ketone (aluminum, steel, glass, concrete, wood) or methanol (PVC, PMMA, ABS, polystyrene), then washed with detergent, rinsed with distilled water, and allowed to air dry prior to preparation of the test specimens. Specimens were cured for 14 days at ambient conditions. 

There is a linear relationship between the flow and the inverse of the viscosity of the solvent in membranes for NF and UF, indicating that the main mechanism of mass transport in these systems is through convection. In NF membranes, differences in the concentration of organic solvents dissolved in aqueous solutions (water miscible such as ethanol) is most to represent the primary mechanism of mass transport and concentrations of ethanol up to 50%, the viscosity was the main factor while above this threshold, other physical properties such as molar volume of solvent and surface tension, ruled the behavior of permeation. In contrast, in most of the UF membranes, the linear relationship between the flow of solvent and the inverse of viscosity remains independent of the solvent concentrations in aqueous solutions [17]. Membrane manufacturers usually provide them semidry or immersed in water. It is an important condition in most polymeric membranes before use with organic solvents. Conditioning comprises rinsing the membrane and permeation of solvent under appropriate... 

The swelling of insoluble proteins corresponds to the hydration of soluble proteins in that insertion of water between the peptide chains results in an increase in volume and other changes in the physical properties of the protein. For example, the diameter of myofibrils (cf. 12.2.1) increases to 2.5 times the original value during rinsing with l.Omol/L NaCl, which corresponds to a six-fold volume increase (cf. 12.5). The amount of water taken up by swelling can amount to a multiple of the protein dry weight. For example, muscle tissue contains 3.5-3.6 g water per g protein dry matter. 

Following treatment with the alcoholic base and an alcohol rinse, the modified white residues can be removed by immersion in a mixture of an alcohol and an aggressive solvent. SEM and XPS analysis of a polyetherimide sample following treatment in a 50/50 mixture of dimethylformamide/methanol is shown in Figure 10. Little physical change to the plastic surface has occurred. The plastic surface properties, however, have now been altered. The sample is now water wettable. 

S.2.6 Alteration of surfaces. Certain treatments of substrate siufaces change the physical and chemical properties of the surface to produce greater wettabihty and/or a stronger surface. Specific processes are required for each substrate material. The part or area to be bonded is usually immersed in an active solution for a matter of minutes. The parts are then immediately rinsed with deionized water and dried. 

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