Polyacrylate processing data

Typical processing data is given in Table 6.10. Polyacrylate processing is similar to PC but with higher material temperatures (330-370 °C) and higher melt viscosity. 

The temperature position of the secondary fi relaxation (about 290 K 1 Hz), generally attributed to partial rotations of the side chains COOR, is only slightly affected by the polarity and volume of the substituent R but decreases markedly (by 120 K) on removal of the a-methyl group on the main chain. The experimental data obtained contradict the assumption that there is a certain relationship between this temperature and the glass transition temperature. Nevertheless, we can infer that the pertinent molecular mechanism in polymethacrylates differs from that in polyacrylates, probably due to the different participation of the main chains. The values of the individual contributions to the activation energy were estimated by employing a procedure similar to that used in the y relaxation process, and their sum was found to agree approximately with the experimental values. 

As early as 1951, Flory and Osterheld [18] could show that partially ionized polyacrylic acid in aqueous solution of an inert salt shrinks in size if the concentration of the inert salt is increased. This shrinking process can be pushed towards the unperturbed dimensions of the NaPA chains. Known from neutral polymers as 0-state, it is reached for fully ionized NaPA [50] at T=15 °C and 1.5 M KBr. In several papers, the dependence of the intrinsic viscosity was investigated as a function of the molar mass [51]. Data were... 

Kochkodan et al. [76] had found that thin MIP layers could be prepared via a controlled polymer deposition process at low monomer conversion, using the very fast photoinitiation of a cross-linking polymerization by a-scission photo-initiator such as benzoin ethylether which had been previously coated on the surface (see Scheme 4b). This had been investigated with porous membranes as matrix which had been functionalized very evenly (see Fig. 1). With the macroporous MIP composite membranes, the membrane pore size could be used to probe grafted layer thickness, as shown by data from permporometry (see Fig. 2). For the same range of coverage with a cross-linked polyacrylate/acrylamide—estimated... 

Viscosity data for the ethyl-copolymer, A, over the range a=0 to a = 1, reveal the typical electrostatic expansion behavior of a weak polyacid such as polyacrylic acid. Polymer B-II, on the other hand, exists in an abnormally compact state at low a. The curves for polymers B-I and B-III, excluded from Figure 1 for clarity, are identical in shape and differ only in relative magnitude. The five-fold increase in [f/] over the range 0.35[Pg.5]

Figure 5.8 shows the temperature dependence of the relaxation rate in an Arrhenius-plot. The data were obtained in several experiments on polyacrylates and poly(methylacrylates) with pendant cyclohexyl groups. The linearity of the plot is indicative of an activated process, the relaxation time being given by the Arrhenius law... 

Fig. 5.8. Temperature dependence of the relaxation rates of the 7-process in polyacrylates open symbols) and poly (methacrylates) filled symbols) with pendant cyclohexyl groups. Data from Heijboer [50]...

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