Membranes Lab Report

Membranes were prepared by solvent casting for which 600 mg of the dispersions (table 1) were deposited on PVDF cylindrical plates and dryed at 60ºC from 12 hours under vacuum. The membranes formed are carefully retired from the PVDF plates, analysed for fractures and deformations and their thickness were measures using a digital micrometer (Mitutoyo). Al samples shows a mean thickness between 100-200 µm.
Membranes are stored on plastic bags at ambient temperature.
Membrane characterization:
Water vapour permeability determination:
Circular portions of the membranes of 1.1 cm of radius were punched out by means of a metal die of 2 cm of diameter. Glass vials are filled with 10 ml of water and membranes were placed in the exit hole of the

24 is a factor to convert the time in the 24h scale.
Mechanical Analysis
The mechanical resistance of the membranes was determined by sextuplicate by tensile test experiment using a universal testing machine Lloyd LR5K. Membranes were cut in probes of 25 mm of length and 5 mm of with and secured by two clamps maintain a distance between clamps of 5 mm. The tension test speed was 5 mm/min recording the force-displacement curve. The young modulus, breaking strength and stress were calculated from the curve.
Triamcinolone acetonide diffusivity across membranes:
Diffusion experiments were developed using side-by-side diffusion cells (Crown Glass Co., Inc, USA) with a volume of compartments of 3.4 mL. Membranes were placed between the cells compartments, leaving an effective area of diffusion of 0.79 cm2. Receptor medium was HCL 0.1N or phosphate buffer pH 6 and donor medium a saturated solution o acetonide of triamcinolone in water. Compartments are maintaining under continuous stirring and at 37ºC during the experiment.
Samples were withdrawing at specific times and replaced by fresh medium an TA concentration were determined by UV-vis spectroscopy using a wavelength of 242 nm.

Elaboration of

The inlet air temperature was 68-72ºC. The solution containing the component of the coating was sprayed using a spray nozzle of 1 mm and a flux of 0.5g/min and an air pressure of 1.8 bar. Coating dispersion was maintained in continuous stirring at 60ºC to avoid sedimentation. Once finalized the coating process the pellets was maintaining 15 min at the same temperature to complete dry and curing the coating.
Pellet characterisation.
Shape and size:
Morphological and size characterization of pellets was made using Image analysis tecniques.
Particle images were acquired with an Olympus SZCTN stereomicroscope equipped with a JVC TK-S350 video camera and an Olympus Europe Highlight 2000 cold light illuminating the sample perpendicularly from above against a black background employing the optimal values
Stablished by Almeida and colleagues (2, 3). The images were digitalized with a Matrox Comet video card, using PCA Image VGA 24 software. SigmaScan Pro Image Analysis 5.0.0 (SPSS Inc.) were used and binary images were obtained from digitalized images using a relative grey-level threshold of 60% [4]. The pixel size selected was 4.26 µm, so we are under maximum pixel size as we defined in our previous papers (2, 3). The parameters circularity, aspect ratio, Vr and Vp calculated as describes Almeida et al (4) was used.
Microstructure:
SEM