Compatibilizing agents

Blends with good mechanical properties can be made from DMPPO and polymers with which DMPPO is incompatible if an appropriate additive, compatibilizing agent, or treatment is used to increase the dispersion of the two phases. Such blends include mixtures of DMPPO with nylon, polycarbonate, polyester, ABS, and poly(phenylene sulfide). 

It has been found by Baird and others [74-77] that the presence of LCP may accelerate and presumably direct the crystallization of conventional polymers (PET, etc.). Porter [76] has shown that, by blending biphasic polymers such as the PET-poly HBA copolymers, miscibility may be achieved between the conventional phase of the biphasic polymer with another conventional polymer that component is miscible with, i.e., X7-G/PBT. The latter phenomena may offer direction in the search for useful compatibilizing agents for LCP/conven-tional polymer systems. 

In order to overcome the build-up of these stresses, the addition of triblock terpolymers as compatibilizing agents with an elastomeric middle block and end blocks of PS and PMMA, respectively, appears advantageous. One example is the use of polystyrene-Wocfc-poly(l,4-butadiene)-W0cfc-poly(methyl methacrylate)... 

Chain functionalized polymers or graft copolymers are of great technological importance. They are used as compatibilizing agents for immiscible polymer blends (8) and adhesive layers between polymer-polymer co-extruded surfaces (8). Currently, of all polymers sold, about 30% are in the form of compatibilized immiscible blends (9-12). Next we discuss a few examples of chain functionalization. 

It was shown that the clay dispersion was improved with increasing compatibilizing agent, but at the expense of the polymer processability into filaments. Nevertheless, there was no evidence of intercalation or exfoliation, irrespective of the nature of compatibilizer or clay modifier, nor strong improvements of LOI. Despite the absence of formation of true nanocomposites, filaments were sufficiently strong to be knitted into fabrics and presented slower burning behavior than the pure polymer. 

In addition to these polar groups, many types of fluorocarbon and hydrocarbon groups have been attached to the silicone backbone, sometimes in combination with polar groups. Some of these materials are used as compatibilizing agents or for other surface active properties but they lie outside the scope of this chapter. 

The copolymer composition in miniemulsion copolymerization of vinyl acetate and butyl acrylate during the initial 70% conversion was found to be less rich in vinyl acetate monomer units [34]. Miniemulsion polymerization also allowed the synthesis of particles in which butyl acrylate and a PMMA macromonomer [83, 84] or styrene and a PMMA macromonomer [85] were copolymerized. The macromonomer acts as compatibilizing agent for the preparation of core/shell PBA/PMMA particles. The degree of phase separation between the two polymers in the composite particles is affected by the amount of macromonomer used in the seed latex preparation. 

Tmr corresponds to the temperature of maximum rate of weight loss under air atmosphere at a heating rate of 5°C/min, and D to the average bundle diameter obtained by SEM micrographs. Polyetherimide (PEI) is the compatibilizing agent. 

Kaneko [2] prepared compatibilizing agents consisting of methacrylate, (II), and styryl, (III), macromolecules. These materials were polymerized using titanium-based Ziegler-Natta catalysts. 

TEMPO-modified poly(ethylene-co-propylene-g-maleic anhydride), (IV), and poly((ethylene-co-1 -decene)-g-alkylacrylates), (V), were prepared by Matsugi [3] and used as polymer blend compatibilizing agents. 

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