Degree of polymerization, and chain

The actual morphology of a polymer depends primarily on three factors chemical composition, degree of polymerization, and chain configuration. Other variables affecting the final physical state of a polymer sample include its thermomechanical history and processing methods. 

The influence of salt concentration on the reduced viscosity of different polyacrylamide -co -acrylates which have the same degree of polymerization and chain length distribution. 

Figure 29. Influence of degree of polymerization and chain aspect ratio asymmetry on the pairing function,defined here as Ag(r) = 0,5[gAAW + gesW] 3 relatively...

If the amount of termination by radical-radical reaction is neglected the degree of polymerization and the kinetic chain length are given by eq. 29 ... 

Reaction conditions should usually be chosen such that the fraction of initiator-derived chains (should be greater than or equal to the number of chains formed by radical-radical termination) is negligible. The expressions for number average degree of polymerization and molecular weight (eqs. 13 and 14) then simplify to eqs. 15 and 16 ... 

Transfer constants for polystyrene chain radicals at 60° and 100°C, obtained from the slopes of these plots and others like them, are given in the second and third columns of Table XIII. Almost any solvent is susceptible to attack by the propagating free radical. Even cyclohexane and benzene enter into chain transfer, although to a comparatively small extent only. The specific reaction rate at 100°C for transfer with either of these solvents is less than two ten-thousandths of the rate for the addition of the chain radical to styrene monomer. A fifteenfold dilution with benzene was required to halve the molecular weight, i.e., to double l/xn from its value (l/ rjo for pure styrene (see Fig. 16). Other hydrocarbons are more effective in lowering the degree of polymerization through chain transfer. 

Note 1 If the bchains between the branch points of the main chain and the terminal svhchains of the main chain are identical with respect to constitution and degree of polymerization, and the siAQ-chains are identical with respect to constitution and degree of polymerization, the macromolecule is termed a regular comb macromolecule. 

Mean-square dimensions and dipole moments of p-chlorostyrene chains are calculated as a function of their stereochemical structure, degree of polymerization, and temperature. Theoretical arguments and experimental evidence indicate that p-chlorostyrene and styrene chains differ little in conformational energy. Therefore, the present investigation employs conformational energies... 

Cellulose is present in both primary and secondary cell-walls. However, differences in both the degree of polymerization and the control of chain length between the celluloses from these two sources suggest that the two types of cellulose are formed by different mechanisms.289-291 Whereas the mechanisms responsible for formation and orientation of cellulose fibrils are not yet known, some information is available concerning the enzymes capable of catalyzing the formation of celluloselike, 0-(l—>4)-linked D-glucans (see also, Ref. 217). 

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