Polymer-like behavior

The stream lines of a plain vector field, however, do not in general have a polymer-like behavior. The problem, then, consists of generating a vector field whose stream lines have the mesoscopic properties of real polymers. 

The most austere representation of a polymer backbone considers continuous space curves with a persistence in their tangent direction. The Porod-Kratky model [99,100] for a chain molecule incorporates the concept of constant curvature c0 everywhere on the chain skeleton c0 being dependent on the chemical structure of the polymer. It is frequently referred to as the wormlike chain, and detailed studies of this model have already appeared in the literature [101-103], In his model, Santos accounts for the polymer-like behavior of stream lines by enforcing this property of constant curvature. 

Santos also scrutinized the polymer-like behavior of the constructed stream lines. Two characteristics were analyzed the second moment of the end-to-end distance distribution, (r2)0, which characterizes the spatial configurations of chain molecules, and the radius of gyration, Rg, that indicates how the... 

Within the present model, we have many unsolved problems. Most of the present studies on 3D crystallization from the melt deal with the relatively short Cioo chain. The study of the much longer Ciooo chain is still preliminary we want to clarify more polymer-like behavior such as the reeling-in process of the chains. Since the polymers in the ideal melt are the ideal Gaussian and highly entangled, we need a much larger MD cell to accommodate such large polymers. 

Dimerization of carboxylic acids is also used for the formation of nonmesomorphic molecular assemblies in solid states such as one-dimensional polymeric structures [131, 132], two- or three-dimensional networks [133], and dendritic materials [134]. Dimer formation due to quadruple H-bonding has been designed to obtain highly stable molecular association [135]. The quadruply H-bonded polymer associates from bifunctional compounds show polymer-like behavior in the solution state due to large association constants [135]. 

Fiiedlander, S. K. Polymer-like behavior of inorganic nanoparticle chain aggregates. J. Nanoparticle Res. 1999,1, 9-15. 

The linear systems conforming to the MSOA mechanism exhibit relatively minor changes of DP in response to the above variables. Rheological data offer compelling evidence for the persistence of polymer-like behavior in spite of reversible polymerization.Therefore, applications in areas expanding the uses of conventional polymers were suggested. In particular, the... 

Block (Star) Arrangement. The known star polymers, like their linear counterparts, exhibit microphase separation. In general, they exhibit higher viscosities in the melt than their analogous linear materials. Their rheological behavior is reminiscent of network materials rather than linear block copolymers (58). Although they have been used as compatibiUzers in polymer blends, they are not as effective at property enhancements as linear diblocks... 

In the case of polymer samples, it is expected that, at the temperatures and frequencies at which the rheological measurements were carried out, the polymer chains should be fully relaxed and exhibit characteristic homo-polymer-like terminal flow behavior (i.e., the curves can be expressed by a power-law of G oc co2 and G" oc co). 

Galgali and his colleagues [46] have also shown that the typical rheological response in nanocomposites arises from frictional interactions between the silicate layers and not from the immobilization of confined polymer chains between the silicate layers. They have also shown a dramatic decrease in the creep compliance for the PP-based nanocomposite with 9 wt% MMT. They showed a dramatic three orders of magnitude drop in the zero shear viscosity beyond the apparent yield stress, suggesting that the solid-like behavior in the quiescent state is a result of the percolated structure of the layered silicate. 

Various diverse systems qualify as gels if one assumes that in these systems the common features are the solid-like behavior and the presence of a continuous structure of macroscopic nature (6,7). For the purpose of the discussion in this paper, we describe a gel as a colloidal system comprised of a dispersed component and a dispersion medium both of which the junction points are formed by covalent bonds, secondary valence bonds, or long range attractive forces that cause association between segments of polymer chains or formation of crystalline regions which have essentially infinite life time (8). 

By modifying the functional groups they can be used,for example, as crosslinkers in high solid or powder coatings and in thermosets. Because of their good miscibility and low melt viscosity, they find applications as melt modifiers and as blend components. Modified hyperbranched polymers, like alkyl chain substituted poiy(ether)s and po-ly(ester)s sometimes exhibit amphiphilic behavior.They can, therefore, be used as carriers for smaller molecules,for example, dyestuff into polypropylene. 

Dynamic mechanical experiments yield both the elastic modulus of the material and its mechanical damping, or energy dissipation, characteristics. These properties can be determined as a function of frequency (time) and temperature. Application of the time-temperature equivalence principle [1-3] yields master curves like those in Fig. 23.2. The five regions described in the curve are typical of polymer viscoelastic behavior. 

Samples of polytetrafluoroethylene having very high degrees of crystallinity are characterized by a very low yield strain and exhibit lead-like behavior after deformation. In contrast with other crystalline polymers the yield stress does not increase with increasing crystallinity, but remains almost constant at room temperature. At lower temperatures the yield stress decreases with increasing crystallinity (Riley). 

The control of electron transfer is a critical issue in the fabrication of molecular electronic devices from the viewpoint of electronic circuit formation however, electron transfer processes of redox polymer-coated electrodes fabricated using a conventional polymer-coating method usually shows a diffusion-like behavior because the redox sites are randomly distributed in the polymer film (Fig. la) 17-20 consequently, it is difficult to control the electron transfer direction in three dimensions. 

---