Rigidity of polymer chain

The rigidity of polymer chains is especially high when there are cyclic structures in the main polymer chains. Polymers such as cellulose have high Ts and Tm values. On the other hand, the highly flexible polysiloxane chain (a consequence of the large size of Si) results in very low values of Tg and Tm. 

When the salt of PMAA is formed the rigidity of polymer chain is increased a little that leads to little increase of values of mean-square length of monomer unit and distance between polymer chain ends. The result obtained under addition to polymer salt solvent in methanol (40 vol. % of water, at large content of water the solution is not vitrificated, but is crystallized) represents special interest at that the macromolecule in solid state keeps conformation of Gauss ball (Figure 2), however, as we should expect, rigidity (parameter a) and sizes of ball are increased (Table 1). 

In fact, the flexibility (or rigidity) of polymer chains affects the elastic constants. The molecular bend elasticity is a measure of the flexibility of liquid crystalline polymers and the persistence length is associated with the chain flexibility by... 

The moduli of as-spun fibers of Me-HQ/Cl-PEC or Cl-HQ/Cl-PEC were 72 and 68 GPa,respectively which were higher than those of Me-HQ/PEC or Cl-HQ/PEC.The reason of higher modulus appeared to be the increased rigidity of polymer chain caused by the restricted rotation of the ether-linkage of Cl-PEC due to the steric hindrance as shown in Fig. 2(1,5).Ph-HQ/... 

In order to obtain high modulus as-spun fibers,the stability of liquid crystalline state and the rigidity of polymer chain are influential factors.Therefore,we expected that the polyarylates derived from BB would show higher modulus than those from PEC or Cl-PEC.As-spun fiber of the polyarylate derived from Cl-HQ and BB modified with TA(Cl-HQ/BB/TA) showed the modulus of 95 GPa(m/n= 7/3) which was higher modulus compared with that of Me-HQ/Cl-PEC. However,as-spun fiber of Cl-HQ/BB/TA showed the modulus of only 11 GPa(m/n=8/2) in spite of the rigid chemical structure,and this is referred to the decreased elongational flow orientation as shown in Fig. 4(3). 

Thus,the relationship between the modulus of as-spun fibers and the modulus of injection molded test pieces is not clear,but the flexural modulus is depending upon the BB mol% of polyarylates and the BB mol% might be used as the parameter of the rigidity of polymer chains.We observed many plate-like fibrils and a few needle like fibrils on the cross section of the flexural fractured test pieces of Me-HQ/BB/Cl-PEC(m/n=9/l).Then we prepared TLCPs with more rigid chemical structure,Me-HQ/BB/Cl-PEC(m/n=9.5/0.5),which showed a similar flexural modulus of 39 GPa as Me-HQ/BB/Cl-PEC(m/n 9/l),but X-ray diffraction pattens and SEM of these 2 polymers were quite different.The injection molded test pieces of Me-HQ/BB/Cl-PEC(m/n-9.5/0.5) showed lower degree of orientation and fewer fibrils than those of m/n=9/l as shown in Fig.7 and8(8). 

Thus,in order to obtain high modulus injection molded parts, the rigidity of polymer chain is the most important factor... 

The solvent in which the polymer network swelled is able to change the number of intermolecular bonds, to decrease observable flexibility of chain parts between points, and to stretch the system, i.e., to perform labor over it. Its influence on the Qon parameter, according to accepted approximations, is similar to the influence on the process in which only low-molecular compounds participate. Some deviation can be observed as a consequence of suppressing the solvent molecules in the network. One can find that the change of observable local rigidity of the chain as a consequence of network swelling is similar by its first approximation to its change for... 

The 7 g of elastomers synthesized at AWE was generally found to be within the range 30° to 40°C (see Table 2), which is significantly higher than that for standard poly(dimethylsiloxane). The introduction of the bulky m-carborane unit into the siloxane backbone has clearly elevated the Tg. However, although the carborane unit introduces conformational rigidity, the polymer chains retain sufficient flexibility and mobility to have a T% < -30°C. 

The interaction between the water and the polymer occurs in the vicinity of the polymer chains, and only the water molecules situated in this interface are affected by the interaction. The space fractal dimension da is now the dimension of the macromolecule chain. If a polymer chain is stretched as a line, then its dimension is 1. In any other conformation, the wrinkled polymer chain has a larger space fractal dimension, which falls into the interval 1 < d( < 2. Thus, it is possible to argue that the value of the fractal dimension is a measure of polymer chain meandering. Straighter (probably more rigid) polymer chains have da values close to 1. More wrinkled polymer (probably more flexible) chains have da values close to 2 (see Table III). 

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