Swelling definition

When a bead of a gel-type CFP material is in the dry state, for practical purposes it can be considered as a solid material (thus possessing a mass, a volume and a shape). When in the swollen state, a CFP material can be still considered as a solid from the practical point of view, but this circumstance is now an authentic approximation. In fact, physico-chemical analysis reveals that under some circumstances this alleged solid material is rather a very viscous liquid. More precisely, it is a suspension of interconnected polymer chains in the swelling agent. Each swollen CFP bead can be considered as a drop, which can retain a definite shape owing to the existence of the polymer framework. 

Tea leaf growth occurs in a definite and distinctive cycle.17 A typical cycle begins with the formation of a small (5 mm) leaf bud that swells but... 

Thus, for the purposes of this chapter, a hydrogel is considered to be a polymeric material that can absorb more than 20% of its weight in water while maintaining a distinct three-dimensional structure. This definition includes dry polymers that will swell in aqueous environments in addition to the water-swollen materials which inspired the original definitions [3], A hydrogel that dries without significant collapse of the macroscopic structure and which absorbs water into... 

Both Qv(x) and Q°(x) decrease as the polymerization proceeds and, after a definite conversion Qv(x) may reach the value of Qx(x). Since the dilution of a gel cannot be greater than its equilibrium degree of swelling, the excess of solvent should separate from the gel phase resulting in the syneresis, i.e. in phase separation. The condition for incipient phase separation during copolymerization of divinyl/vinyl monomers is given by [107]... 

It is probable that varying degrees of ordering of chains exist in a cellulosic material and that a sharp differentiation of crystalline and non-crystalline celluloses may not be feasible or even possible. Theoretically, the lateral surfaces of crystallites are amorphous but may have far less importance in determining such properties as strength, flexibility and extensibility than the non-crystalline cellulose which supplies continuity of structure in the direction of crystallite orientation. Yet properties like moisture absorption and swelling may be more dependent upon the amount of cellulose which exceeds a certain degree of disorder (permeability) than upon location. The definition of crystallinity may, therefore, be made ultimately in terms of practical objectives. 

By definition, mucoadhesive hydrogels are a elass of polymeric biomaterials that exhibit the basic characteristic of an hydrogel to swell by absorbing water and interacting by means of adhesion with the mucus that covers epithelia. 

Butyl acrylate/0.3 moles/kg crosslinker copolymers In toluene. See Experimental for a definition of swell Index. 

Acute gouty arthritis-50 mg 3 times/day until pain is tolerable, then rapidly reduce the dose to complete cessation of the drug. Definite relief of pain usually occurs within 2 to 4 hours. Tenderness and heat usually subside in 24 to 36 hours, and swelling gradually disappears in 3 to 5 days. Do not use sustained-release form. 

The already mentioned definition of seeded polymerization is in the broad sense of the word. Seeded polymerization in the narrow sense is polymerization after swelling the seed particle with monomer. Figure 12.2.4 shows what the seeded polymerization can form. Making larger particles is one of popular uses of seeded polymerization, but it does not belong to surface modification. Therefore, making larger particles is not discussed here. 

WORKBOOK FOR CHEMICAL REACTOR RELIEF SYSTEM SIZING Figure A3.2 DEFINITION OF TERMS IN LEVEL SWELL CALCULATIONS... 

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