Flexible segments

MOLECULAR WEIGHT INFLUENCES ON THE PHYSICAL PROPERTIES OF POLYETHYLENE ADIPATE-BASED ELASTOMERS (WITH NDI) 

EFFECT OF POLYESTER BLENDS ON URETHANE ELASTOMER PROPERTIES (1,5-NAPHTHALENE DIISOCYANATE-BASED ELASTOMERS)  

Polyester Tensile strength (MPa) Elongation at break (%) Hardness (IRHD) Cold- hardening 

Poly(ethylene propylene adipate) 70 30 28 725 65 Only when stretched 

Poly(ethylene propylene adipate) 50 50 26 750 69 Does not harden 

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These materials also have high thermal and oxidative stabiHty. Flexible segments such as amide siloxane can be incorporated into the imide-based stmcture for hot melt or injection appHcations. General Electric (GE) and Hoechst-Celanese are suppHers of these high performance plastics. 

A helix bundle is a protein composed of a series of rodlike helical domains linked by flexible segments and inserted into a membrane to form a cluster of helices roughly parallel to one another and perpendicular to the plane of the membrane. 

This is a copolymer of the (AB)n type, where the UGU sequences represent the urethane hard segment , and the wavy line represents the soft flexible segment. Microphase separation of the hard segment occurs as illustrated below ... 

Flexible segment used to link successive mesogenic units in the molecules of MCPLCs or to attach mesogenic units as side-groups onto the polymer backbone of SGPLCs. 

Rubber elasticity, which is a unique characteristic of polymers, is due to the presence of long chains existing in a temperature range between the Tg and the Tm. The requirements for rubbery elasticity are (1) a network polymer with low cross-link density, (2) flexible segments which can rotate freely in the polymer chain, and (3) no volume or internal energy change during reversible deformation. 

In addition to the lauryl groups and the polyamine framework, attached imidazole residues are also represented in the model. These may be recognized as the five-membered rings. One of them is particularly noticeable at the upper right of the white arrow. Since in practice they are linked primarily to primary amines, the imidazole groups in this model are attached at the termini of flexible segments of the polymer, as is apparent in Fig. 11. It is readily possible for the imidazole residue to approach a bound substrate molecule, as would be required for its observed catalytic effect. 

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. 

The treatment of internal motion of a flexible segment (such as a methyl or phenyl group) superposed on overall motion requires an appropriate TCF describing that motion. Assuming that these motions are independent, the total TCF, G, (t), may be written as a product of the individual TCFs28 ... 

For the preparation of these segmented polyimides or block copolyimides, diamines rather than dianhydrides are preferred as the monomer bearing the flexible segment. Some of these monomers have been listed in Table 1. 

Flexible Segments of Domain II and the Topology of Proteinase Surface 49... 

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