Relationship between swelling ratio solvents

Another important parameter is the swelling ratio. A sample is placed in a solvent and the variation of its height is monitored as a function of time through a contact probe. A relationship between sample and solvent allows for the evaluation of the cross-link density and the chain length between cross-links. The technique is named swell ratio testing (SRT) in the American ASTM F2214-02, or hot set test (OST) in the German DIN 57472 Standard. " ... 

FIG. 77 Relationship between relative haze Hz) and processing index (PI) of LDPE. PI = B /B (where B < B ) where B is the equilibrium die swell of the extrudate after the shearing and B is the swell ratio of the material in the stable state after solvent or heat treatment. When the PI is unity, the viscoelastic properties of the materials are independent of the shear processing but as the PI becomes smaller than unity, the materials become sensitive to the shearing. (From Ref. 136.)... 

Figure 2. Relationship between the swelling ratio (mU of the poly(ferrocenyldimethylsilane) gel 5b, and the solubility parameter of the various solvents. Maximum swelling occurs at 5 -18.7 (7) MPa . ...

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