Compatibilization polymer blend

Block copolymers in selective solvents exhibit a remarkable capacity to self-assemble into a great variety of micellar structures. The final morphology depends on the molecular architecture, tlie block composition, and the affinity of the solvent for the different blocks. The solvophobic blocks constitute the core of the micelles, while the soluble blocks form a soft and deformable corona (Fig. Id). Because of this architecture, micelles are partially Impenetrable, just like colloids, but at the same time inherently soft and deformable like polymers. Most of their properties result from this subtle interplay between colloid-like and polymer-like features. In applications, micelles are used to solubilize in solvents otherwise insoluble compounds, to compatibilize polymer blends, to stabilize colloidal particles, and to control tire rheology of complex fluids in various formulations. A rich literature describes the phase behavior, the structure, the dynamics, and the applications of block-copolymer micelles both in aqueous and organic solvents [65-67],... 

Riemann RE, Cantow HJ, Friedrich Chr. Interpretation of a new interface-governed relaxation process in compatibilized polymer blends. Macromolecules 1997 30 5476-5484. 

Immiscible, compatibilized polymer blend with modified interface and morphology. 

It is also not the purpose of this chapter to summarize examples of compatible polymer blends formed in a solution step involving dissolution of the polymer components. In some cases such blends are only pseudo-stable , since they may not have been processed above the Tg of one or both of the components. Also, mixing in solution followed by devolatilization is rarely economical for practice in industry, particularly since many commercially important compatibilized polymer blends comprise at least one semicrystalline component e.g., PA) which is poorly soluble in common solvents. There are included in the Tables a small number of examples of solution blended polymer blends when these complement similar examples prepared by melt processing. 

It is also not the purpose of this chapter to describe examples of compatibilized polymer blends formed by polymerization of a monomer in the presence of a second polymer. In these cases the growing polymer chain reacts with functionality on the second polymer to form a... 

The problem of controlling the redistribution process does not stop at the manufacturing stage. After a compatibilized polymer blend leaves the manufacturer, it undergoes further thermal histories such as molding or paint-oven drying at the processing facilities of the final user. Continued redistribution reaction in the hands of a final user may cause deterioration and nonreproducibility in blend properties. 

Brief reviews covering redistribution reactions in polyester and in polycarbonate binary blends have been prepared by Porter et al. [1989] and Porter and Wang [1992]. Selected references for redistribution processes in PEST/PEST blends are listed in Table 5.7. Early studies of these processes focused on measuring the extent of redistribution under specific processing conditions rather than on producing compatibilized polymer blends with an attractive balance of properties. A number of more recent studies have reported the limits of miscibility for certain melt-mixed polyester pairs in the absence of transesterification — see for example the NMR study of PC/PET blends [Abis et al., 1994]. 

Compatibilized Polymer Blends. Immiscible blends in which the microstructure and physical properties can be stabilized by adding surface-active species called compatibilizers. These compatibiliz-ers will influence various morphological processes, such as deformation, breakup, and coalescence of droplets. 

Thus, from this data, it appears that both the alternating and diblock copolymers are the most efficient at compatibilizing polymer blends. Unfortunately, these two copolymers are also the most difficult to realize and therefore, this is of little use from a commercial standpoint. It is interesting that the alternating copolymer may rival the diblock copolymer as a compatibilizer and this possibility is currently under investigation in our laboratory. Within the random copolymers (Px = 0.5, 1.0, and 1.5), these results suggest that the blocky structure is much better at interacting with the homopolymers than the alt-ran structure, and thus should be a more effective interfacial modifier. 

Dextrol OC-45N Dextrol OC-50 Dextrol OC-65K Dextrol OC-78N Dextrol OC-180 Dextrol OC-1025 Dextrol OC-1525 Dextrol OC-2225 Dextrol OC-4025 Dextrol OC-6025 Dextrol OC-7525 Strodex MRK-98 Strodex PK-OVOC Strodex PK-80A Strodex PK-90 Strodex PK-95G Strodex PK-95H Strodex PSK-28 Strodex SFK-50D compatibilizer, pigment dispersions Methylpropanedbl, MPDiol Glycol compatibilizer, polymer blends paper coatings... 

PEG-4 diheptanoate compatibilizer, personal care Methylpropanediol compatibilizer, pigment dispersions Methylpropanediol compatibilizer, polymer alloys Propylene/MA copolymer compatibilizer, polymer blends Propylene/MA copolymer compatibilizer, rubber C20-40 pareth-10 compatibilizer, silicone/organic Cetearyl methicone compatibilizer, silicones Phenyl trimethicone compatibilizer, UV coatings Cetoleth-5... 

The components are then melt blended. Thereby a compatibilized polymer blend is prepared, wherein the pol5nners (A) and (B) have an essentially continuous morphology. At cooling the blend to room temperature, retaining its morphology should be retained. 

Polymer alloy immiscible but compatibilized polymer blend implies a modified interphase and,... 

Table 5.2 Change of dispersed phase dimensions in compatibilized polymer blends upon annealing (Adapted fiom White and Min 1989)...

Seves, A., and Testa, G. (1998) Melt rheology of miscible or compatibilized polymer blends obtained from polyamidic and polyolefinic polymers. Adv. Polym. Technol., 17 (4), 317-327. 

Creating compatibilized polymer blends allows polymer compounders to supply potential product fabricators with a very broad spectrum of required properties. Over the last 50 or so years, progress in successful blends formation has rested on experimental studies. This has been achieved, primarily, by the international... 

Asthana Himanshu, and Jayaraman Krishnamurthy. Rheology of reactively compatibilized polymer blends with varying extent of interfacial reaction. Macromolecules. 32 no. 10 (1999) 3412-3419. 

Fortelny Ivan. An analysis of the origin of coalescence suppression in compatibilized polymer blends. Eur. Polym. J. 40 no. 9 (2004) 2161-2166. 

Van Hemelrijck Ellen, Van Puyvelde Peter, Macosko Christopher, and Moldenaers Paula. The effect of block copolymer architecture on the coalescence and interfacial elasticity in compatibilized polymer blends. J. Rheol. 49 no. 3 (2005) 783-798. 

An alternate method for achieving similar results was recently proposed by Pack et al. [10], who showed that RDP-coated clays can also compatibilize polymer blends, and are even more effective than Cloisite 20A clays when the blends contain styrenic components. In this case, the FR did not compete with the polymers for the clay surfaces, because both polymers also adsorbed onto the RDP-coated surfaces. As a result, addition of these clays improved the mechanical properties of the blends and resulted in a material that was able to pass the UL-94 VI flame test. 

Phase Separation Kinetics during Shear in Compatibilized Polymer Blends... 

Figure 3.16 Schematic representation of two possible mechanisms of the coalescence suppression in compatibilized polymer blends, (a) Due to Marangoni stress (b) Due to steric repulsion. Adapted from Ref [128] 2001, Elsevier.

A variety of reactive polymers have been utilized for compatibilizing polymer blends. They can be classified into eight major categories, with each category having one type of... 

Table 3.2 Examples of Reactively Compatibilized Polymer Blends Making Use of Ring Opening In Situ Reactions...

The rheologies of un-compatibilized polymer blends have been the topic of numerous in depth studies [68-73]. The reader is directed to these references for background information, as this chapter will focus only on reactive blends. 

---