Resist layer, swelling

Blowing agents swell a thick carbon foam which envelopes the object in a heat-resistant layer... 

Where q = The Ratio of the Volumes In the Swollen and Dry States V = The Specific Volume of the Polymer Vf = The Molar Volume of the Solvent Mg = The Molecular Weight Between Crosslinks M = The Molecular Weight of the Polymer X = Polymer-Solvent Interaction Parameter Figure 12. Swelling of the resist layer... 

Figure 3.3 Photoresist profiles. (A) Positive resist (a) desired resist profile for lift-off i.e. exposure-controlled profile, also called overcut (b) perfect image transfer by applying a normal exposure dose and relying moderately on the developer (c) receding photoresist structure with thinning of the resist layer i.e. developer control, also called undercut. (B) Negative resist the profile is mainly determined by the exposure. Development swells the resist a little but has otherwise no influence on the wall profile.

Finishing coats are also fine barrier layers, but applied as the last layer rather than the first one. Because they have to cure in air, UP resins remain tacky due to the influence of atmospheric oxygen, have an unpleasant odor, are not weather resistant, and swell up with a whitish color in rain. 

With respect to pH sensitivity and an adequate speed of response (time constant r = RC where R is the resistance of the measuring circuit and C the capacitance of the electrode), a certain degree of superficial swelling is needed however, the gel layer thus formed should remain thin in order to minimize the solubility of the glass and to guarantee sufficient durability of the electrode. In this respect lithium barium silicates offer an attractive compromise32. 

In spite of the unsaturation of rubber it is said to be resistant to chemical attack since a few chemical derivatives like chlorinated rubbers, cyclised rubbers and chlorides are formed as protective layers retarding further attack by the chemicals. Properly compounded vulcanizates satisfactorily resist the action of most inorganic acids other than oxidizing acids such as nitric, hydrochloric and sulphuric acids. Rubber linings which are to resist swelling to a lower degree should be "tightly" vulcanized. 

---