Network microstructure

In Figure 6, these data are plotted versus the branching density z of crosslinking molecules. Gy./G is fairly independent of network microstructure. It covers a range of 0.24 to 0.32 as a result of statistical scattering, averaging to 0.28 as in case of the networks with tetrafunctional crosslinks. 

Comparison with Statistical Theory at Moderate Strains. So far we have shown, that a transition between the two limiting classical theories, i.e. affine theory and phantom theory, is possible by a suitable choice of the network microstructure. This argument goes beyond the revised theory by Ronca and Allegra and by Flory, which predicts such a transition as a result of increasing strain, thus explaining the experimentally observed strain dependence of the reduced stress. 

Epoxy thermosets are typical densely cross-linked polymer materials. They are used in a wide variety of practical applications and thus have been studied extensively. However, the quantitative dependence of physical properties, such as strength, stiffness, and fracture toughness, on network microstructure are largely undetermined. This can be attributed, in part, to the lack of adequate techniques for characterizing densely cross-linked network structure. Several microstructiu e variables that have been studied with some success are (1) cross-link density,... 

Adam-Berret M, Boulard M, Riaublanc A, Mariette F. Evolution of fat crystal network microstructure followed by NMR. J Agric Food Chem. 59(5) (2011) 1767-1773. 

Figure 22.9(a) shows unfilled NR, (b) is for Na -MMT/NR and (c) is for NR/O-MMT. The dramatic variation in SIC with increasing strain is seen in the case of NR/O-MMT nanocomposites. Addition of nanoclay platelets in NR provides a regular polymer network microstructure. The O-MMT and NR are hydrophobic in nature. Hence NR chains are interfacially adsorbed at the outer surface of O-MMT. But in Na-MMT, no such interaction is present due to the changes in dipole distribution. So in the SIC analysis, the NR/O-MMT nanocomposites show sharper crystalline peaks than the other clay nanocomposites. 

Mayer, B. P. Lewicki, J. P. Weisgraber, T. H. Small, W. Chinn, S. C. Maxwell, R. S., Linking Network Microstructure to Macroscopic Properties of Siloxane Elastomers Using Combined Nuclear Magnetic Resonance and Mesoscale Computational Modeling. Macromolecules 2011,44,8106-8115. 

Figure 21.8. Schematic illustrations showing (a) grafted and (c) untreated nanoparticles/polymer composites before and after stretching. Magnified TEM photo in (b) shows that fibril-like agglomerates indeed contain networked microstructure...

Figure 3-21 SEM image after etching (2.5% HF, 10 sec) showing high content of iithium disilicate crystals of 70 vol% crystallinity in a network microstructure.

Furthermore, BC/SiO NPs aerogels (4-9 wt%) prepared by freeze drying and showing a polymer interpenetrating network microstructure of BC and silica, (Figure 2.24), presented density, specific surface area and low thermal conductivity values (2 x 10 g.cm 734 m. g 3.1 x 10 W.mfK S respectively) comparable to those of pure silica aerogels, and are simultaneously more flexible due to the presence of micro-cracks left by freeze drying [246]. 

Static Crystallization Behavior of Cocoa Butter and Its Relationship to Network Microstructure... 

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