Undiluted high molecular weight

For a diluted network v = [v] and d = [d]/x where [ ] denotes the value for the undiluted high molecular weight species (Note that the relation for v was previously given incorrectly by Kramer to be v = [v] x)- All the quantities in Eq. (33) are known with the exception of which must be measured using LAED. 

Here c is the polymer concentration by weight. < the density of the polymer, a an effective bond length or measure of the coil dimensions, and to the monomeric friction factor. The subscript zero indicates the pure polymer. Since 2 (H), the mean-square end-to-end chain separation, the viscosity will be directly proportional to the polymer concentration unless the plasticizer modifies the coil swelling. At high molecular weight the monomeric friction factor is increased by the factor (MIMf)" and M, is increased relative to the undiluted polymer [equation (55)]. Thus... 

The culmination of this trend is illustrated in Fig. 5.2 by dynamic data on undiluted polystyrene of low molecular weight (124). Agreement with the Rouse model here is by no means as good as that seen in Fig. 5.1 with the Zimm model for a high molecular weight polystyrene at infinite dilution. Indeed, the value of Je° deduced from G (to) for the sample in Fig. 5.2 exceeds the value from... 

Figure 5.6 shows the same data plotted as a function of cM0 6S to test the low concentration reduction scheme based on c rf] with a typical value of the Mark-Houwink exponent for good solvents. The data have been shifted vertically to achieve superposition at high molecular weights. It is clear that the cM variable produces a better superposition of data at all molecular weights and concentrations. The apparent variation in the values of cM at the intersections in Fig. 5.4 (Table 5.1) is largely due to a lack of data to define the limiting behavior at low molecular weights at some concentrations. The intersection on the superposed plot in the composite Fig. 5.5 is cM = 30000, giving Mc = 30600 for undiluted polystyrene (q = 0.98 at T = 217° C, in good agreement with the value 31200 reported by Berry and Fox (16).

In this type of polymerization, an undiluted monomer or mixture of monomers is converted to a high molecular weight homopolymer or copolymer. The progress of the reaction is characterized by a large increase in the viscosity of the reacting mixture (from less than 50 Pa-s to greater than 1,000 Pa-s). Two reaction mechanisms of bulk polymerization have been implemented in REX free-radical addition and condensation reaction chemistries. 

Plasma normally contains about 10-30 mg of combined high molecular weight kininogen and factor XII per 100 mL, and about 300 mg of fibrinogen in the same volume. For undiluted plasma, H should then be about 200/20 xm, and for plasma diluted 1 10, H should be 200/2 xm. Actual values were about 10 and 120 xm, respectively (see Table II). 

Polymerization, bulk Also called mass polymerization or step-growth polymerization. It is from undiluted low molecular weight starting materials. It is the simplest and oldest method for the synthesis of macromolecules. This method has a reaction, which is relatively simple, and rapid, plastics of high purity are formed, and the plastics obtained are immediately processable. Basically, the polymerization process involves only monomer and polymerization initiator or catalyst. It is carried out in the absence of a solvent or other dispersion media. This technique is applicable to both addition and condensation polymerization. Fundamentally differences exist. 

FIG. 13-13. Steady-state compliance J i, plotted against weight fraction of high molecular weight component vv2 for binary blends of undiluted polystyrenes open circles, results of Akovali et al. with Ml = 1.25 X 10 and M2 = 2.67 X 10 black circles results of Mills etal. with Mi = 8.68 X 10 and M2 = 5-00 X 10 solid curves theoretical results from cubic blending law dotted curves theoretical from quadratic blending law. (Kurata and collaborators. ) Reproduced, by permission, from the Journal of Polymer Science. 

Other viscoelastic properties also acquire new characteristics at high concentration. In undiluted systems the long time end of the relaxation time distribution remains approximately Rouse-like for chains with molecular weight below Mc, as suggested by the agreement with reduced Rouse moduli in Fig. 5.2. 

Many molecules with a high nitrogen content are potentially explosive. Low molecular weight aryl azides are generally stable but as undiluted solids or liquids they should be handled with respect, especially if they are prepared in gram amounts. For example, distillations should be done under... 

---