Friction Terms Links

In Eq. (141), it is assumed that the diffusing particle and the surrounding medium have been put in contact in an infinitely remote past, as pictured by the lower integration bound —oo in the retarded friction term. Both F(t) and v(t) can be viewed as stationary random processes. Their spectral densities are linked by... 

Term IV is the friction force applied by the fluid on the particle in a steady-state regime. As the Reynolds number is small, we recover here the classical result associated with Stokes law (Chapter 15, Table 15.1). A complementary friction term (IVcorr term) appears on the right-hand side, and is linked to the shear of the velocity field of the fluid flow. 

Fibers. The principal type of phenoHc fiber is the novoloid fiber (98). The term novoloid designates a content of at least 85 wt % of a cross-linked novolak. Novoloid fibers are sold under the trademark Kynol, and Nippon Kynol and American Kynol are exclusive Hcensees. Novoloid fibers are made by acid-cataly2ed cross-linking of melt-spun novolak resin to form a fuUy cross-linked amorphous network. The fibers are infusible and insoluble, and possess physical and chemical properties that distinguish them from other fibers. AppHcations include a variety of flame- and chemical-resistant textiles and papers as weU as composites, gaskets, and friction materials. In addition, they are precursors for carbon fibers. 

Each submolecule will experience a frictional drag with the solvent represented by the frictional coefficient /0. This drag is related to the frictional coefficient of the monomer unit (0- If there are x monomer units per link then the frictional coefficient of a link is x(0- If we aPply a step strain to the polymer chain it will deform and its entropy will fall. In order to attain its equilibrium conformation and maximum entropy the chain will rearrange itself by diffusion. The instantaneous elastic response can be thought of as being due to an entropic spring . The drag on each submolecule can be treated in terms of the motion of the N+ 1 ends of the submolecules. We can think of these as beads linked... 

The second term on the right-hand side of Eq. 1 represents the reversible work done by the fluid against the external pressure field this term is linked to the compressibility of the fluid and is known in the literature as flow work. The third term on the right-hand side of Eq. 1 is linked to the work done by the fluid on adjacent layers due to the action of the shear forces this work is transformed into heat by means of an irreversible process called viscous dissipation in the English language literature and as internal friction in the Russian literature. 

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