Balloon swelling

No animals died from these exposures. Examinations of the lung tissues showed mild congestion, some capillary damage in the form of endothelial ballooning, and some endothelial swelling and thickening. These effects were judged reversible. 

Equation 8.4) 1/ — = constant T You probably have some familiarity with this law. Perhaps you have observed a balloon expanding on a hot day or a bag of microwave popcorn swelling as the contents begin to heat up. 

The phenomenon of post-extrusion swelling or "ballooning" has been discussed in Chap. 15. It is related to the so-called Barus effect, according to which the diameter of polymer extrudates is larger than the capillary diameter when the melt is forced through an orifice. All materials with any degree of melt elasticity display this effect. The origin of the effect is related to the elastico-viscous nature of polymer melts, thus to Ni=Tu — T22. 

Caoutchouc so obtained is a colorless, transparent hydrocarbon of the composition CsHg or better (CsHg) . It is an emulsion colloid of a density approximately 0.90. It is a non-conductor of electricity and this is one of its important properties. It takes up liquids and swells. It is moderately resistant to the diffusion of gases and can be used for balloons but is not as good as other materials. Pure caoutchouc is a soft, sticky, gummy mass of low elasticity and in this condition possesses almost no desirable technical properties. In order to give it such properties it is very definitely changed in the process of manufacture. 

Figure 2.14. Ballooning of delignified softwood tracheids after treatment with very strong swelling agents (Wardrop and Dadswell, 1950).

Figure 9.4. Results of melt-spinning a simple bicomponent fiber. Light and dark portions represent different polymer materials. Note the ballooning effect (the die-swell phenomenon) as the blend leaves the common capillary. Since the pressure drop in the common capillary must be the same for each component, careful regulation of the homopolymer capillary diameters is necessary to obtain the desired result.

The clinical symptoms of NRL allergy usually arise from direct contact with a NRL product but may also result from inhalation of airborne allergens bound to e.g. glove powder. The most frequently reported manifestation is contact urticaria, followed by rhino-conjunctivitis (Table 2). Mucosal swelling is a typical symptom after oral, vaginal or rectal exposure to NRL products, such as balloons, gloves and condoms. The systemic reactions consist of generalized urticaria. 

Equivalent weights for PFSI ionomers immediately following precipitation from the reaction medium and for membranes formed as described in section 22.5 were measured by acid-base titration. In brief, the procedure is as follows. A known amount of dried polymer (in a typical measurement, approximately 0.0670 g of polymer) and 0.10 g of NaCl were dissolved in 30 mL of deionized water, and the resulting solution was refluxed in a 150-mL conical-shaped flask at 80°C overnight with constant stirring. The flask was covered with a latex balloon and then filled with nitrogen gas through a septum. The polymer swelled up in water. A few drops of phenolphthalein were added to the solution, which was then titrated with a 0.0100 M... 

Water absorbs into the hydrophilic domains by attractive forces of water solvating the polar sulfonate salt. The hydrophilic domains swell doing work on the surrounding hydrophobic matrix (like blowing up a balloon). Water sorption is limited by the balance between the energy of solvation and the work to swell the matrix. Mechanical properties associated with swelling are very important in determining the water content of Nafion and hence the transport properties. 

---