Rigid Segments

Diisocyanate Tensile strength (MPa) Elongation at break (%) 300% modulus (MPa) 

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Because of the compact structure of the cycloaliphatic resins the intensity of cross-linking occurring after cure is greater than with the standard diglycidyl ethers. The lack of flexibility of the molecules also leads to more rigid segments between the cross-links. 

More recently, Kunitake and Okahata (1978b) discovered that a stable bilayer structure could be formed from a series of single-chain amphiphiles which possess rigid segments and flexible hydrocarbon tails as in [6]. 

Rigid segments can be, for example, a semicrystalline polybutylene terephthalate, and flexible sequences can be polyesters or polyethers - polyetherglycol, for example. 

In fluid segments, the response to regulation is more likely to come from an earlier stage of development than in rigid segments. 

Polymer Melts. When a rigid, polarizable monomer forms wither a mainchtiin polymer with flexible segments in belween or a side-chain polymer with flexible segments between the rigid segments and the flexible main chain, liquid-crystal phases are usually viable. 

While in case of main chain polymers S relates to the backbone or rigid segments of the backbone, for side chain polymers only the rigid mesogenic moieties of the side chains will be covered neglecting any possible anisotropic orientations of the backbone. 

One can use another way to describe the long macromolecule. One can see that at high temperatures there is no correlation between the orientations of the different parts of the macromolecule, which are not close to each other along the chain. This means that the chain of freely-jointed rigid segments reflects the behaviour of a real macromolecule. This model carries the name of Werner Kuhn who introduced it in his pioneering works (Kuhn 1934). 

However, the syndiotactic segments of extended chains (613 cm"1) are obviously situated in a different local environment. These more rigid segments form into microcrystalline phases which orient as units to much higher degrees than the amorphous isotactic sequences. The C-Cl peak at 613 cm"1 arises mainly from seqeunces of four or more trans conformations in syndiotactic repeat units. With syndiotactic sequences of four or more repeat units, crystallinity can form (17,18). This ease of crystallization has been ascribed to the strong dipole-dipole interaction between the C-Cl bonds. 

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