Fibrillar structure model

Deficiencies of the cluster-network model become apparent when it is employed to describe the stractural evolution of the PEM from the highly diluted polymer solution Xw 1, to the dry membrane state 0. An earlier conceptual model for this 

Recent models of proton and water transport in PEMs tend to support the notion of cylindrical pore networks. A qualitative distinction between superstructures will be made below, based on the analysis of water sorption data and evaluation of the implications of pore network reorganization upon water uptake. 

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FIGURE 1.13 Fibrillar structure model for Nafion membranes. (Reproduced with permission from Rubatat, L. et af. Macromolecules, 37, 7772, 2004.)... 

Model peptides that could build up quarternary fibrillar structures are not yet known. Though complete explanation of the interdependence between the primary structure and the stability of the quarternary structure has not yet been possible, i.e. the role of the different amino acids in collagen could be understood completely only in correlation with the fibril formation (formation of polar and hydrophobic clusters ). 

In summary, two different Gain-of-Interaction models have been proposed for the fibrillar structure of /12m. The cross-(3 spine model (Ivanova et al., 2004) proposes a core composed of C-terminal /1-hairpins, and the direct-stacking model (Benyamini et al., 2003) proposes a core of native-like /12m molecules with their N- and C-terminal strands displaced. 

C. Gessa C, S. Deiana, and S. Marceddu, Fibrillar structure of Ca-polygalacturonate as a model for soil-root interface. Metal ion absorption and its effect on the free space volume of the system. In Plant Membrane Transport The Current Position. Eds J. Dainty, M I De Michelis, E Marre and F Rasi Caldogno, Elsevier, Amsterdam, 1989. 

C. Gessa and S. Deiana, Ca-polygalacturonate as a model for a soil root interface. II. Fibrillar structure and comparison with natural root mucilage. Plant and Soil. 140 (1992) 1. 

Fig. 10 A Chemical structure of PBLG-PHF-PBLG triblock copolymers B AFM image of a thin film of 1 cast from TFA/CHCI3 (30/70 v/v) C Schematic representation of the spherical nanostructures that can be observed in B D,E AFM images of triblock copolymers 1 (D) and 2 (E) cast from TFA/CHCI3 (3/97 v/v) F Model proposed for the self-assembly of 1 and 2 in the fibrillar structures shown in D and E. (Reprinted with permission from [76]. Copyright 2004. American Chemical Society)...

Kuhfuss and Jackson s polyester containing 60mol% PHB (COP) [8-10] can serve as a PLC model. Pure COP kept under pressure in a mold shows small fibrillar structures at break (Figure 9.1). This diminishes quickly with an increasing amount of PC and is completely lost in that... 

Figure 8.17 The LCP structural model shows the hierarchical, fibrillar texture of LCP materials (from Sawyer and Jaffe [80], reproduced with permission from J. Materials. ScL). 

The precise function of microfibrils in hard elastic polymers is not well understood. Their importance in various models of crystalline polymers has ranged from mere tie points [4,5] to the fundamental element [9]. The recent disclosure of hard elastic behavior in crazed HIPS [11] clearly revealed the connection between microfibrillar superstructure and hard elastic behavior, since no lamellae exists in this material. Polymers with a fibrillar structure are not necessarily hard elastic,however. Gore-Tex has an extensive fibrillar domain as shown in Figure 2c. Its loading cycle (Figure 5), however, clearly reveals an inelastic material. Hence, the necessary criterion of microfibrillar structure for a hard elastic polymer must be established. 

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