Pre-gel solution

The sample used to study the relationship between the volume phase transition and the frictional property is poly( /V-isopropylacrylamide) gel which shows a small discontinuous volume phase transition at 33.6 °C. The sample gel is prepared by free radical polymerization 7.8 g of re-crystallized N-iso-propylacrylamide (main constituent, Kodak), 0.133 g lV,iV -methylenebis-acrylamide (cross-linker, Bio-Rad), 240 ml tetramethylenediamine (accelerator, Bio-Rad), and 40 mg ammonium persulfate (initiator, Mallinckrodt) are dissolved in distilled water (100 ml) at 0°C. The gel mold is immersed in the pre-gel solution and then degassed for 40 min at 0°C. The temperature is raised to 20.0 °C after this treatment to initiate the gelation reaction. The sample gel thus obtained is homogeneous and transparent, at least by visual inspection. 

Table lb. Properties of PNIPAAm and po y(NIPAAm-co-sodium acrylate) gels at 25 °C when the polymerization reaction approached completion (24 h). Note the percentage indicated in the gel type notation is the molar substitution of sodium acrylate for NIPAAm in the pre-gel solution. Reprinted from Polymer International (1992) 28 29 by permission of the copyright holder, the Society of Chemical Industry [45] ... 

Equation (88) was used to demonstrate [44] the differences in distributions of molecular sizes in pre-gel stages of an RA3 polymerization with substitution effects as calculated according to a statistical and a kinetics model. The moments of distribution and the gel points were calculated by the numerical solution of a few ordinary differential equations that were derived from Eq. (88) and compared with analogous quantities calculated from a statistical model. 

The preparation of cellulose hydrogels via coagulation depends on the properties of the pre-gel cellulose solutions. In this approach, cellulose solutions are generally stable. The solutions for preparing cellulose hydrogels include cellulose in DM Ac/... 

Micro- and nanoparticles of alginate are effortlessly achieved by gelation with calcium ions. This property enables creation of a pre-gel consisting of miniature aggregates of gel particles, which can be tracked by the addition of an aqueous polycationic solution to make a polyelectrolyte complex coating. Poly-L-lysine (PLL) is a cationic natural polymer that has been used with alginates to formulate nanoparticles. 

T is the viscosity of the solution and given in the pre-gel stage. is the elasticity and given in the post-gel stage. 

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