Blends of poly

Blends of poly(vinyl chloride) (PVC) and a-methylstyrene—acrylonitrile copolymers (a-MSAN) exhibit a miscibiUty window that stems from an LCST-type phase diagram. Figure 3 shows how the phase-separation temperature of 50% PVC blends varies with the AN content of the copolymer (96). This behavior can be described by an appropriate equation-of-state theory and interaction energy of the form given by equation 9. 

Copolymers of S-caprolactone and L-lactide are elastomeric when prepared from 25% S-caprolactone and 75% L-lactide, and rigid when prepared from 10% S-caprolactone and 90% L-lactide (47). Blends of poly-DL-lactide and polycaprolactone polymers are another way to achieve unique elastomeric properties. Copolymers of S-caprolactone and glycoHde have been evaluated in fiber form as potential absorbable sutures. Strong, flexible monofilaments have been produced which maintain 11—37% of initial tensile strength after two weeks in vivo (48). 

Poly(ethyl methacrylate) (PEMA) yields truly compatible blends with poly(vinyl acetate) up to 20% PEMA concentration (133). Synergistic improvement in material properties was observed. Poly(ethylene oxide) forms compatible homogeneous blends with poly(vinyl acetate) (134). The T of the blends and the crystaUizabiUty of the PEO depend on the composition. The miscibility window of poly(vinyl acetate) and its copolymers with alkyl acrylates can be broadened through the incorporation of acryUc acid as a third component (135). A description of compatible and incompatible blends of poly(vinyl acetate) and other copolymers has been compiled (136). Blends of poly(vinyl acetate) copolymers with urethanes can provide improved heat resistance to the product providing reduced creep rates in adhesives used for vinyl laminating (137). 

As with other rigid amorphous thermoplastic polymers such as PVC and polystyrene (see the next chapter) poly(methyl methacrylate) is somewhat brittle and, as with PVC and polystrene, efforts have been made to improve the toughness by molecular modification. Two main approaches have been used, both of which have achieved a measure of success. They are copolymerisation of methyl methacrylate with a second monomer and the blending of poly(methyl methacrylate) with a rubber. The latter approach may also involve some graft copolymerisation. 

Compatibilization along with dynamic vulcanization techniques have been used in thermoplastic elastomer blends of poly(butylene terephthalate) and ethylene propylene diene rubber by Moffett and Dekkers [28]. In situ formation of graft copolymer can be obtained by the use of suitably functionalized rubbers. By the usage of conventional vulcanizing agents for EPDM, the dynamic vulcanization of the blend can be achieved. The optimum effect of compatibilization along with dynamic vulcanization can be obtained only when the compatibilization is done before the rubber phase is dispersed. 

Jha A. and Bhowmick A.K., Thermoplastic elastomeric blends of poly(ethyleneterephthalate) and carylate rubber 1. Influence of interaction on thermal, dynamic mechanical and tensile properties. Polymer, 38, 4337, 1997. 

Malinconico M, Immirzi B, Massenti S, La Mantia FP, Mormile P, Petti L (2002) Blends of poly-vinylalcohol and functionalized polycaprolactone. A study on the melt extrusion and post-cure of films suitable for protected cultivation. J Mat Sci 37 4973 1978 Mallek SB, Prather TS, Stapleton JJ (2007) Interaction effects of Allium spp. residues, concentrations and soil temperature on seed germination of four weedy plant species. Appl Soil Ecol 37 233-239. doi 10.1016/j.apsoil.2007.07.003... 

C Zhang, H von Seggern, K Pakbaz, B Kraabel, H-W Schmidt, and AJ Heeger, Blue electroluminescent diodes utilizing blends of poly(p-phenylphenylene vinylene) in poly(9-vinylcarbazole), Synth. Met., 62 35—40, 1994. 

A.P. Kulkarni and S.A. Jenekhe, Blue light-emitting diodes with good spectral stability based on blends of poly(9,9-dioctyfluorene) interplay between morphology, photophysics, and device performance, Macromolecules, 36 5285-5296, 2003. 

H Jagt, Y Dirix, R Hikmet, and C Bastiaansen, Linear polarizers based on polymer blends oriented blends of poly(ethylene-2,6-naphthalenedicarboxylate) and a poly(styrene/methylmethacrylate) copolymer, Jpn. J. Appl. Phys., 37 4389-4392, 1998. 

Bicakci, E., Zhou, X. and Cakmak, M., Phase and uniaxial deformation behavior of ternary blends of poly(ethylene naphthalate), poly(ether imide) and poly(ether ether ketone), in Proceedings of the 55th SPE ANTEC 97 Conference, May 5-8, 1997, Toronto, ON, Canada, Society of Plastics Engineers, Brookfield, CT, 1997, Vol. 2, pp. 1593-1599. 

Manea, C. and Mulder, M. 2002. Characterization of polymer blends of poly-ethersulfone/sulfonated polysulfone and polyethersulfone/sulfonated poly-etheretherketone for direct methanol fuel cell applications. Journal of Membrane Science 206 443-453. 

Blends of poly (ethylene terephthalate) (PETP) and polypropylene (PP) with different rheological properties were dry blended or compounded, and extrusion foamed using both physical blowing and chemical agents, and the foam properties compared with those of foam produced from the individual components in the absence of compatibilisers and rheology modifiers. The foams were characterised by measurement of density, cell size and thermal properties. Low density foam with a fine cell size was obtained by addition of a compatibiliser and a co-agent, and foamed using carbon dioxide. The presence of PP or a polyolefin-based compatibiliser did not effect... 

Robeson LM, Kuphal JA (1989) Blends of poly(vinylacetate) and poly(propylene carbonate). US Patent 4,912,149... 

Figure 4.2 An Archimedean tile morphology for blends of poly(2-vinylpyridine-/)-isoprene-/)-vinylpyridine) with poly(styrene-/)-4-hydroxystyrene) in a 2 1 vinylpyridine/hydroxystyrene blend. The vinylpyridine/hydroxystyrene domains are the cylinders at the vertices of polystyrene hexagons within a polyisoprene continuous phase. Reprinted from Asari et al. (2006). Copyright 2006 American Chemical Society.

Ghosh S, Rasmusson J, Inganaes O. Supramolecularself-assembly for enhanced conductivity in conjugated polymer blends. Ionic crosslinking in blends of poly(3,4-ethylenedioxythiophene)-poly(styiene sulfonate) and poly(vinylpyrrolidone). Adv Mater 1998 10 1097-1099. 

Blend of poly chloroprene and NBR Carbon black and multifunctional acrylate 50 15,000 20 (2,900)... 

Originality Intimate blends of poly(4-phenylene sulfide) and nylons have not... 

This group (1) previously prepared stents consisting of blends of poly(L-lactide) and po I (g I yco I ide-co- -caprolactone) containing phase-separated poly[(gly-colide-co-7-caprolactone)-c0-L-lactide], (I), as the compatibilizer. This group... 

The blend of poly(bisphenol A carbonate)-(poly(caprolactone) PC-PCL is particularly unusual in that both polymers are capable of crystallization and FT-IR has been used to study the state of order in these blends as a function of the method of preparation 254,255). In this case, PCL is a macromolecular plasticizer for PC. The PCL becomes progressively less crystalline as the concentration of PC increases. PC is amorphous if the blend is cast from methylene chloride but semicrystalline if cast from tetrahydrofuran. When PC in the pure form is exposed to acetone, it will not crystallize, but in the blend, exposure of acetone causes the PC to crystallize which emphasizes the additional mobility of the PC in the blend. 

Vamell, D. F., Runt, J. P., Coleman, M. M. FT-IR and Thermal Analysis Studies of Blends of Poly(Caprolactone) and Homo- and Copolymers of Poly(vinylidene chloride). Preprint submitted to CARBON... 

J.A. Kuphal, L.M. Robeson, and D. Sagl, Miscible blends of poly(vinyl acetate) and polymers of acrylic acid, US Patent 5 171 777, assigned to Air Products and Chemicals, Inc. (Allentown, PA), December 15,1992. 

In addition, ASA may be blended with other polymers that themselves exhibit high heat distortion temperatures. For example, blends of poly(ether imide) and ASA exhibit an improved heat distortion temperature, improved flexural properties and tensile properties in comparison to the ASA component alone and have lower impact strengths as well (35). The statement above has been exemplified using Ultem 1000 as a poly(ether imide) resin and Geloy 1020 as ASA component. 

The anisotropy of polarizability can be positive (eg, polycarbonate) as well as negative (eg, polystyrene). This offers the possibility of minimizing birefringence by copolymerization or blending of suitable polymers with the right mixture ratio, eg, blends of poly(phenylene ether) (PPE) and polystyrene (PS). The magnitude of birefringence of axial-symmetrically oriented polymers vs their molecule orientation has been described (182). 

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