Copolymer , graft curve

Figure 5.76 Effect of temperature on shear modulus for random, block, and graft copolymers. Bottom curves are the derivative of the log G curves. Reprinted, by permission, from N. G. McCrum, C. P. Buckley, and C. B. Bucknall, Principles of Polymer Engineering, 2nd ed., p. 173. Copyright 1997 by Oxford University Press.

Figure 2. Effect of monomers flow rate on linear copolymer content (curve A) and on grafting efficiency (curve B)...

Fig. 26. Universal calibration curve for SEC. Polystsrrene (linear) O polystyrene ( comb ) + polystyrene ( star ) A polystyrene-poly(methylmethacrylate) copolymer (heterograft) x poly(methylmethacrylate) (linear) poly(vinylchloride) V polystyrene-poly(methylmethacrylate) copolymer (graft-comb) Bpolylphenyl siloxane) A polystyrene-poly(methylmethacrylate) copolymer (statistical-linear) n polybutadiene. From Ref 31.

Figure 9.17 Plot of log [i ]M versus retention volume for various polymers, showing how different systems are represented by a single calibration curve when data are represented in this manner. The polymers used include linear and branched polystyrene, poly(methyl methacrylate), poly(vinyl chloride), poly(phenyl siloxane), polybutadiene, and branched, block, and graft copolymers of styrene and methyl methacrylate. [From Z. Grubisec, P. Rempp, and H. Benoit, Polym. Lett. 5 753 (1967), used with permission of Wiley.]...

Fig. 3. Comparison of SEC traces for poly(MMA-co-HEMA) starting macroinitiator curve a) and poly(MMA-g -CL) final graft copolymer curve b). For synthetic conditions, see Scheme 21...

Fig. 8. Nuclear Overhauser enhancement of PEG-ethylene protons vs irradiation time in P(MAA-j -EG) gels exhibiting complexation. Proton enhancements of graft copolymer with PEG M = 400 in D20 (curve 1), graft copolymer in NaOD solution (curve 2), and polymer mixture with PEG M = 1000 in D20 (curve i). The PEG concentration was 0.01 wt%, PMAA concentration was 0.09 wt%, copolymer concentration was 0.1 wt%, and temperature was 21 °C...

The results are shown in Fig. 9. A small amount of the filler strongly increases the energy contribution which is in full contradiction to the assumed increase in the concentration of active network chains caused by the filler. Curve 2 summarizes the results for filled PDMS rubber and for PDMS block and graft copolymers. It is seen that below 20% of the filler or hard phase, the energy contribution is practically independent of the amount of hard phase, but then a considerable increase of (AU/W)v>t is observed. Although in all these cases the energy contribution is... 

Figure 9 shows the mechanical loss curves of a low-density polyethylene, a PVC, a raw VC/PE (50-50) graft copolymer, and a poly (ethylene-g-vinyl chloride) containing 46 weight % of vinyl chloride. 

The curves of the raw graft copolymer and of the poly(ethylene-g-vinyl chloride) are rather close to that of the low-density polyethylene. The outstanding fact is the absence of the PVC transition peak (between 60° and 100°C) in the mechanical loss curves of these two products. This means that they contain no rigid PVC phase in spite of the presence of about 25 weight % of ungrafted polyvinyl chloride in the raw graft copolymer. This PVC seems thus to be strongly compatibilized with the other constituents by the poly(ethylene-g-vinyl chloride). 

Fractionation Curves of Graft Copolymers and Parent Polymers. 

The shape of the graft copolymer curve is similar to that of the mixture—i.e., there are two precipitation ranges (A and B), but the n values are different. The A fraction precipitates at higher n values than PVC the B fraction precipitates at lower n values than copolymer BD-AN, but no conclusions can be deduced because molecular weights for BD-AN chains are unknown. 

An analogy of the shape of the precipitation curves of these samples and of mixtures of graft copolymers PVC should lead us to put forth the hypothesis of the presence of PVC homopolymer which would be solubilized by the graft copolymer. However, this quantity would be... 

When using high dichloroethane ratios or 1% TDM, precipitation occurs when BD-AN chains collapse—i.e.y at high values of n owing to their more linear macromolecular structure. From the shape of the fractionation curve it is possible to conclude that all PVC chains are grafted in these samples Examination of Figure 13 leads to the conclusion that such copolymer may contain only small quantities of PVC. 

For all curves = f(n), where fi = M — (FPvc + Pg) with M = weight of polymer precipitated at n, PPyC = weight of PVC homopolymer normally precipitated at n, and PG = weight of graft copolymer normally precipitated at n, there is a maximum for n = 6.5/7, which is also the precipitation step of PVC homopolymer. We verified that quantities of... 

Figure 15. Top fractionation of mixtures of PVC-graft copolymers. Bottom fractionation curves for different compositions of PVC-graft copolymer mixtures...

PVC homopolymer as small as 4% of total weight are sufficient to ensure modification of the precipitation curve. Thus, addition of PVC gives an abrupt precipitation about n = 6 and coprecipitation of the graft copolymer with the PVC. 

The inflection point about n = 7 is different from the PVC homopolymer inflection point. A close examination of fractionation curves shows that this point is about that of PVC homopolymer (i.e., around n = 5-6) only for mixtures of PVC homopolymer and graft copolymer and when grafting is performed using 5% TDM. 

Experimental results show that at low grafting temperature (30°C) the solubility of grafted polymers is highly modified by butadiene-acrylonitrile chains. Precipitation curves look like those of polymers prepared using dichloroethane and therefore seem compatible with a less cross-linked BD-AN chain structure. At high grafting temperature (70°C), the precipitation curve resembles that obtained with DVB crosslinked copolymers. 

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