Poly ethylene, surface free energy

Figure 11.63. The effect of treatment time on surface free energy of PVC plasticized with 10 phr of epoxidized soybean oil and 40 phr of di-(2-e1hylhexyl) phthalate and 40 phr of poly(ethylene-co-vinyl ace-tate-eo-carbon monoxide). [Data from Audic J-L Poncin-Epaillard F Reyx D Brosse J-C, J. Appl. Polym. Sci., 79, No.8, 22nd Feb.2001, p.1384-93.]...

Figure 7.30 illustrates the limits from equilibrium to cold crystallization. They are based on a computer calculation for three-dimensional cold crystallization. It is assumed in this case that sequences of less than three A-units do not crystallize, and that at least two out of the four neighboring chains must match the sequence of three repeating units to make the central sequence crystalline. If all four lateral neighbors are crystalline, the repeating unit is in the interior of the crystal, if only three are crystalline, it is on the surface, and if only two are crystalline, it is part of an edge. With this critical sequence length and two surface free energies, experimental data of poly(ethylene terephthalate-co-sebacate) can be discussed, as is shown in Fig. 7.31. The experimental phase diagram of the same copolymer, but after slower cooling, is displayed in Fig. 7.26.

This concept is illustrated in Fig. 8.11 for a poly(ethylene terephthalate) substrate and a mild steel (ferric oxide) substrate with, in both cases, water as the hostile environment. Values of y and yl of the various adhesives may be measured, as described in Chapter 2, or extracted from the literature (see Table 2.3) for example, considering a styrene-butadiene rubbery adhesive the values are 27.8 and 1.3 mJ/m, respectively, and for a typical epoxy adhesive they are 41.2 and 5.0 mJ/m, respectively. Hence, it is evident that these (and most other) adhesives will form an environmentally water-stable interface with the poly(ethylene terephthalate) substrate but an unstable interface with mild steel. Indeed, the data confirm that if only secondary molecular forces are acting across the interface then water will virtually always desorb organic adhesives, which typically have low surface free energies of less than about 60 mJ/m, from a metal oxide surface. Hence, for such interfaces, stronger intrinsic adhesion forces must be forged which are more resistant to rupture by water. 

Figure 33 Fold surface free energy

Because the free radical initiated graft reaction can also lead to the cross-linking of polyethylene, copolymers of ethylene and with acrylic acid (184,185), glycidyl methacrylate (184,186), methacrylic acid and 10-undecenoic acid (187-189) were synthesized to compatibilize polyethylene/polyamide blends. The poly (ethylene-co-methacrylic acid) ionomers neutralized by sodium (184) and zinc (45,118,190-192) has also used as compatibilizers. High energy irradiation, used to modify the surface of fibers or films at beginning, was also used to compatibilize the polyethylene/polyamide blends (193-196). 

Plasma Polymerization n The process of polymerizing a gaseous monomer (e.g., tetrafluorethylene) in a radiofrequency (rf) field in a low vacuum whereby the monomer absorbs electromagnetic energy sufficiently to excite the Jt-bond thereby producting free radicals to initiate polymerization. The polymer adheres to the surfaces within the vacuum chamber (usally falls due to gravity on a surface). Poly(ethylene tetrafluoride) and other films can be deposited on metals, etc., using this... 

We have seen so far that enthalpic interaction parameters are often crucial in controlling the position of NPs in block copolymer assemblies [69-72,74-78]. Nevertheless, it has been shown impressively that the contribution of entropy to the free energy can become important in controlling the position of NPs in vesicular structures [79]. The co-assembly of NPs decorated with polystyrene-b/ocA -poly (ethylene oxide) (PS-b-PEO) copolymers and free (not surface-bound) block copolymers of the same type leads to vesicles with the NPs being incorporated in the (solvophobic) PS domain. Interestingly, depending on the number of monomeric... 

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