PP/EVA blend

The cross-linking of a polymer could be enhanced by the incorporation of a second polymer easily cross-linkable. In PP/EVA blends containing 70% of PP and 30% of EVA, EVA was described to cross-link under low doses of irradiation, whereas PP underwent chain scissions. Minkova et al. found that higher amounts of EVA in PP matrix favored cross-linking and increased the cross-linking density. EVA in PP slows the oxidation of alkyl radicals of PP. °... 

Mihailova, M., Kresteva, M., Aivazova, N., Krestev, V, Nedkov, E., X-ray investigation of polypropylene and poly(ethylene-co-vinyl acetate) blends irradiated with fast electrons WAXS investigation of irradiated i-PP/EVA blends. Radiation Physics and Chemistry 1999, 56(5-6), 581-589. 

Aghjeh R. Masoud, Khonakdar A. Hossein, and Seyed H. Jafari. Application of mean-field theory in PP/EVA blends by focnsing on dynamic mechanical properties in correlation with miscibility analysis. Compos. B. Eng. 79 (2015) 74—82. 

The water sorption isotherms of all PP/EVA blends are shown in Figure 14.4. With regards to the EVA content, differences in water uptake are apparent... 

Figure 23.21 Growth of peroxyl radicals during copolymers of vinyl acetate content 18% and storage of PP and PP/EVA blends e-beam- 28%, respectively. Reprinted with permission irradiated with a dose of 25 kCy. PPE1(13) and from Ref [92] 2007, Elsevier.

In the PP/EVA blend system, the effect of mixing time (converted as residence time) on phase coarsening has revealed a substantial linear particle size increase as a function of the mean residence time. As illustrated in Figure 22.4, the phase morphology is set up very fast (within a minute) and starts evolving by a more dominant coalescence process as the residence time is increased. The particle size is doubled after 2 min 30 s of residence time in the extruder. The pronounced coarsening effect is ascribed to a decrease in the viscosity of the dispersed phase a low viscosity favors flow of particles, their subsequent collision, and merging. 

Canto LB. On the coarsening of phase morphology of PP/EVA blends during compounding in a twin screw extruder. Polym Test 2014 34 175-182. 

Id. Thus, it is expected that in the modified PRP-EVA blend, probably due to interface modification by reactive processing, a transesterification between the pendant MAH group in MAH-PP, and acetate groups in the EVA elastomer, as predicted in reaction Scheme 1, the dispersed rubber particles become more efficient in craze initiation. 

It was proposed [85] that PLA could improve the properties of PP/HDPE/EVA blends. The mechanical properties showed that the polymer blend had optimum tensile and burst strengths at 4 wt% PLA incorporated into the PP/HDPE/EVA blend. The tear strength decreased with increasing PLA content in both the machine and the transverse directions. The friction coefficient was found to be the lowest at 4 wt% PLA... 

Dalai, S., Wenxiu, G., Radiation effects on poly(propylene) (PP)/ethylene-vinyl acetate copolymer (EVA) blends. Journal of Applied Polymer Science 2002, 86, 3420-3424. 

The double reptation model was used to evaluate viscoelastic behavior of metallocene-catalyzed polyethylene and low-density polyethylene blends by Peon et al. (2003). They compared their results with those obtained for HDPE/BPE blends prepared under similar conditions. Since this model assumes miscibility between the mixed species, the experimental viscosity of HDPE/BPE blends showed only small deviation compared to that expected according to the reputation miscible model. However, the model underestimated the compositional dependence of the zero-shear viscosity for mPE/LDPE blends, especially at intermediate levels. The enhanced zero-shear viscosity in immiscible blends such as PETG/EVA, PP/EVA, or EVA/PE blends was found to be more abrupt than it is for mPE/LDPE blends (Lacroix et al. 1996, 1997 Peon et al. 2003). 

Aliphatic dicarboxylic acid dichlorides were applied to the surface-saponified blend of 50 wt% poly(ethylene-co-propene) and 50 wt% poly(ethylene-co-vinyl acetate) (PP/EVA). After coupling without cyclization, the second carboxylic acid group is available for the covalent binding of the protein via the W-terminal amino group [ 140]. The use of anhydrides, e.g. glutaric acid anhydride, is another possibility to introduce free carboxyl groups into the polymer surface. 

Lasagabaster, A., Jose Abad, M., Barral, L., Ares, A., and Bouza, R. (2009) Application of FTIR spectroscopy to determine transport properties and water-polymer interactions in polypropylene (PP)/poly (ethylene-co-vinyl alcohol) (EVA) blend films effect of poly(ethylene-co-vinyl alcohol) content and water activity. 

Abolhasani, M., Arefazar, A., and Mozdianfard, M. (2010) Effect of dispersed phase composition on morphological and mechanical properties of PET/EVA/PP ternary blends. J. Polym. Sci. Part B Polym. Phys., 48 (3), 251-259. 

Figure 224 Number-average (dn) and volume-average (dv) diameters of EVA droplets in the PP/EVA 80/20 blends compounded in a Co-TSE as a function of the mean residence time (f), showing the coarsening kinetics during compounding in the Co-TSE. Canto [27]. Reproduced with permission of Elsevier.

EM micrographs of PP/EVA/silica blends. All the components were added simultaneously in the extruder, (a) PP/EVA2803 (/W =53,500g/mol)/hydrophilic silica, (b) PP/EVA28420 (W = 12,000g/mol)/hydrophilic silica, (c) PP/EVA2803/hydrophobic silica, (d) PP/EVA28420/hydrophobic silica [73]. 

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