Polypropylene Copolymer Blends

This chapter presents a discussion of the multiphase polypropylene copolymers with emphasis on the commercially important blends. The discussion will be more narrowly focused on the composition, structure, and phase morphology of these 

Polyolefin Blends, Edited by Domasius Nwabunma and Thein Kyu Copyright 2008 John Wiley Sons, Inc. 

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Chapter 12 Multiphase Polypropylene Copolymer Blends 359 Table 12.2 Berstorff Twin-Screw Corotating Extruder Conditions. 

In the early stages of development of polypropylene rubbers, particularly butyl rubber, were used to reduce the brittleness of polypropylene. Their use declined for some years with the development of the polypropylene copolymers but interest was greatly renewed in the 1970s. This interest has been centred largely around the ethylene-propylene rubbers which are reasonably compatible in all proportions with polypropylene. At first the main interest was with blends in which the rubber content exceeded 50% of the blend and such materials have been designated as thermoplastic polyolefin elastomers (discussed in Section 11.9.1). There is also increasing interest in compounds with less than 50% rubber, often referred to as elastomer-modified thermoplastics. It is of interest to note... 

Els and McGill [48] reported the action of maleic anhydride on polypropylene-polyisoprene blends. A graft copolymer was found in situ through the modifier, which later enhanced the overall performance of the blend. Scott and Macosko [49] studied the reactive and nonreactive compatibilization of nylon-ethylene-propylene rubber blends. The nonreactive polyamide-ethylene propylene blends showed poor interfacial adhesion between the phases. The reactive polyamide-ethylene propylene-maleic anhydride modified blends showed excellent adhesion and much smaller dispersed phase domain size. 

New Orleans, La., August 1999, p.752-3 POLYSTYRENE/POLYPROPYLENE POLYMER BLEND COMPATIBILISATION WITHOUT ADDITION OF PREMADE BLOCK OR GRAFT COPOLYMERS OR FUNCTIONALISATION Furgiuele N Khait K Torkelson J M (ACS,Div.of Polymer Chemistry)... 

Monasse B, Haudin JM (1995) Molecular structure of polypropylene homo- and copolymers. In Karger-Kocsis J (ed) Polypropylene structure, blends and composites, vol 1. Chapman Hall, London, p 5... 

Meh Spinning. This process is used to produce a broad range of polypropylene fibers ranging from fine, dtex (one denier) staple coarse continuous filaments. Hoiuopolyiners are almost exclusive used to produce fibers, although copolymer blends are used in some special applications. Processing conditions and polymer melt flow vary with the desired fiber type. 

Polymer manufacturers offer paintable grades of polypropylene or copolymer blends with talcum or other mineral fillers with such grades the tolerance of over-treatment seems to be increased—which can be advantageous, especially with flame treatment. 

Lu, B. Chung, T.C. New maleic anhydride modified polypropylene copolymers with block structure synthesis and application in PP/nylon blends. Macromolecules 1999, 32, 2525. 

Fig. 10 Strain at break Vs. UV exposure time for polypropylene copolymer bars made from (a) virgin polymer (V) (b) virgin polymer + undegraded recyclate (U) (c) virgin polymer + photodegraded recyclate (P). Results for blends with recyclate contents of 10% and 25% are shown. (More details in Craig, I.H. White, J.R. Mechanical properties of photo-degraded recycled photo-degraded polyolefins. J. Mater. Sci. 2006, in press.)...

Polypropylene Structure, Blends and Composites. Vol. 2. Copolymers and Blends Karger-Kocsis, J., Ed. Chapman Hall London, 1995. 

In addition to, or instead of, polystyrene and oils, polymers such as polypropylene, polyethylene, or ethylene-vinyl acetate copolymer can be blended with these block copolymers. Blends with S-B-S or (S-B) -X block polymers usually show greatly improved ozone resistance (S-EB-S already has excellent ozone resistance). In addition, these blends have some solvent resistance. In certain cases, some oils that are stable to UV radiation reduce the stability of the blends however, the effects can be minimized by the use of UV stabilizers and absorptive or reflective pigments (e.g., carbon black or titanium dioxide). 

Eor the typical commercial polypropylene copolymer systems the viscosity of the matrix phase is quite high, and the molecular diffusion and solubility of the minor phase component in the matrix phase are relatively high. These factors tend to favor the evaporation/condensation, that is, Ostwald ripening, mechanism and suppress the coalescence mechanism in these systems. Mirabella and coworkers studied a series of multiphase systems, including a hiPP (30), a high density polyethylene (HOPE)/ hydrogenated polybutadiene (HPB) blend, (31) and an unbranched PE molecular... 

The micrographs of polypropylene/epoxy blends shown in Fig. 21.13 contain epoxy particles of diameter 3-4 pm dispersed in polypropylene matrix (70/30). When the blend was compatibilized with MAH-g-PP, fine epoxy particles with an average diameter of 1 pm were dispersed in the PP matrix, that is, the maleic anhydride group of the MAH-g-PP reacted with epoxy group to form a copolymer and acted as a compatibihzer (48). The reaction between the two groups was evident from torque measurements during mixing. 

Styrene-butadiene copolymers are often blended with other polymers. Transparent blends can be made with styrene, styrene-acrylonltrlle copolymers, or styrene-methyl methacrylate copolymers. Blends with styrene have low impact strength even at low styrene levels, while blends with styrene-methyl methacrylate copolymers can have greatly Improved impact strength. Blends with high impact polystyrene, polypropylene, and polycarbonate are opaque. 

Examples of such compatibilized systems that have been studied include EPDM/PMMA blends compatibilized with EPDM- -MMA, polypropylene/polyethylene blends with EPM or EPDM, polystyrene/nylon-6 blends with polystyrene/nylon-6 block copolymer, and poly(styrene-co-acrylonitrile)/poly(styrene-co-butadiene) blends with butadiene rubber/PMMA block copolymer. 

Lee, S.-G., Lee, J. H., Choi, K.-Y., and Rhee, J. M., Glass transition behavior of polypropylene/polystyrene/styrene-ethylene-propylene block copolymer blends, Polym. Bull, 40, 765-771 (1998). 

R. Su, Z. Li, H. Bai, K. Wang, Q. Zhang, Q. Fu, Z. Zhang, Y. Men, Flow-induced epitaxial growth of high density polyethylene in its blends with low crystallizable polypropylene copolymer. Polymer 52, 3655-3660 (2011)... 

C. Kock, N. Aust, C. Grein, M. Gahleitner, Polypropylene/polyethylene blends as models for high-impact propylene-ethylene copolymers. Part 2 Relation between composition and mechanical performance. J. Appl. Polym. Sci. 130, 287-296 (2013)... 

E. Tomasetti, D. Daoust, R. Legras, P. Bertrand, P.G. Rouxhet, Diffusion of adhesion promoter (CPO) into polypropylene/ethylene-propylene (PP/EP) copolymer blends mechanism. J. Adhes. Sci. Technol. V15, 1589-1600 (2001)... 

Varga J. (1995). Crystallization, melting and supermolecular structure of isotactic polypropylene. In Polypropylene Structure, Blends and Composities Structure and Morphology Copolymers and Blends Composites, Karger-Kocsis, J., pp. 56-115, Chapman Hall, ISBN 9780412614309, London. 

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