Moisture transport testing

Similar studies of moisture transport across a barrier also have been done using in vitro methods that determine the movement of water vapor across a film coated with a measured amount of the material to be tested. These are rapid methods for rough determinations of occlusivity and work very well for screening several ingredients at a reasonable cost. Once again, petrolatum s occlusivity has been shown in tests of this nature.28,29... 

Moisture resistance. The adhesive should be formulated to minimise moisture transport through the adhesive itself. The equilibrium water content (A/ ) should not exceed 3% by weight after immersion in distilled water at 20 °C. The permeability, obtained from the product of the coefficient of diffusion (D) and My, should not exceed 5 x 10 " m-/s at 20 °C (see Fig. A.l). A film of adhesive, approximately 1 mm thick cast in polytetrafluoroethylene-lined moulds and weighing at least 3 g, is suggested for this test(3). This requirement is to enhance the potential for a durable adhesive/adherend interface, even if moisture uptake is not deleterious to the adhesive itself. 

The wetting and drying behaviors of PLA and PET fabrics have been tested under simulated conditions. Figure 29.9 shows the appearances of PLA and PET fabrics at 1 and 15 min after a drop of water was put on the fabrics. It can be seen that water diffuses faster and dries quicker in the PLA fabric. This excellent moisture transport of PLA fabric leads to a more comfortable feel [5]. 

Diverse appHcations for the fabric sometimes demand specialized tests such as for moisture vapor, Hquid transport barrier to fluids, coefficient of friction, seam strength, resistance to sunlight, oxidation and burning, and/or comparative aesthetic properties. Most properties can be deterrnined using standardized test procedures which have been pubHshed as nonwoven standards by INDA (9). A comparison of typical physical properties for selected spunbonded products is shown in Table 2. 

Primary container-closure system-related data will need to cover storage, transportation, and use. The choice of materials of construction, their description, and the ability of the container-closure system to protect from moisture and/or light will need to be considered. The compatibility of the container-closure and its contents will need to consider sorption, leaching, and safety. The performance of the container-closure system will also need to be considered in terms of dose delivery from any associated device that is to be supplied as part of the product. Container-closure components will require adequate specifications covering description, identification, critical dimensional tolerances, and test methodology (including pharma-copeial and noncompendial methods). More data are likely to be required for liquid or semi-liquid products than for solid dosage forms. In the latter, product stability data and container-closure system specifications may suffice. 

Kernel Drying. The moisture content of fresh kernels is about 20%. If bagged or stored in this condition fresh kernels would soon become moldy. In addition there would be a rapid increase in the FFA of palm kernel oil (the oil content of dried kernels can be over 50%). Tests have shown that if the moisture content is reduced to about 7%, kernels can be safely stored and transported without deterioration due to mold growth. 

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