Reactively compatibilized blends

PPS with PPE/PSF and/or PC, GF the first, reactively compatibilized blends Bailey, 1977... 

In immiscible blend systems, the accent was put on the fractionated crystallization features. A new and interesting work has been done since the first edition. This is extensively highlighted in the present chapter. The phenomenon is significant when the ciystallizable phase is dispersed in the amorphous phase of the second blend component. Reactively compatibilized blends were compared to uncompatibilized... 

BLENDING METHOD Mechanical blending COMPATIBILIZATION Chemical and reactive compatibilizer BLEND MANUFACTURE Injection molding or extrusion BLEND MORPHOLOGY... 

In the early 1980s, a quite different, reactively compatibilized blend was introduced by DuPont, which not only controlled the dispersed phase size, but also enabled the dispersed phase domains to take on a preferred shape in later processing [25-27]. The addition of a PE-g-MA compatibilizer to a 80/20 PE/PA6 blend sufficiently strengthened the interfacial layer that melt drawing of the blend in film or bottle forming processes results in overlapping lamellae of the PA. The lamellar structure provides an excellent barrier to the diffusion of molecules soluble in the polyolefin but insoluble in PA6. This concept was commercialized by DuPont in 1982 as Selar . Other Selar grades were introduced later, in which the PA6 was replaced by amorphous PA and PET. 

Determination of the Interfacial Tension in Reactively Compatibilized Blends. .. 72... 

An important part of the present chapter discusses the interrelation between reactive compatibilization and the blend phase morphology generation, as well as the crystallization behavior of reactively compatibilized blends containing crystallizable components. The phase morphology development in reactive blending is discussed in conjunction with the non-reactive blending approach. 

The screening of the patent literature reveals a very large number of references in the area of reactively compatibilized blends. The PPO/PA6.6/S(E)BS blend is commercialized under Noryl GTX trade name by GE Plastics in this blend combination, maleic anhydride end-capped PPO is used as the reactive intermediate. Another blend which consists of ABS/PA6/(S-AN-MA) was commercialized under the Triax trade name by Monsanto it is most likely that the terpolymer S-AN-MA is used as reactive polymer for the compatibilization. PP/PA/PP-g-MA (Akuloy of DSM) and the supertough PA containing EPDM-g-MA, commercialized under the trade name Zytel ST by DuPont, are also typical examples of commercial reactive blends, where the reaction between maleic anhydride groups and amine end-groups of polyamides is used for compatibilization. 

Reactive blending is an important technique which is very frequently used for control of the phase morphology, phase stabilization and interfacial adhesion in multiphase immiscible polymer blends. Recently a lot of attention has been focused on the reactive blending process in order to understand how phase morphology develops in reactively compatibilized blends. The stability of the in situ formed copol3aner at the interface and its influence on phase morphology generation, phase co-continuity and on the crystallization behavior of the ciystallizable component(s) are crucial aspects with respect to the blend material properties. 

Steric stabilization is believed to be the primary mechanism by which coalescence is reduced due to the presence of a copolymer at the interface [42, 43]. Simdararaj and Macosko [33] have provided a schematic illustration of steric supression of coalescence due to the presence of a copolymer at the interface, Fig. 5.12. The surface coverage of copolymer required to inhibit coalescence of submicron droplets has been estimated [1, 42]. Most commercial reactively compatibilized blends have quite sufficient chemical... 

This study shows that some of the same factors, which are intuitively believed to increase the efficiency of mixing in polymer blends, could have an opposite effect on reactively compatibilized blends where the dispersed phase is more finely dispersed. More intensive mixing, after die minimum particle size has been attained, can lead to coalescence of the dispersed phase particles to form significandy larger domains. This is particularly so, if the compatibilizer has a tendency to leave the interfaces under intensive shear. 

Harrats C, Omonov T, Groeninckx G, Moldenaers P. Phase morphology development and stabilization inpolycyclohexyl-methacrylate/polypropylene blends Uncompatibilized and reactively compatibilized blends using two reactive precursors. Polymer 2004 45 8115-8126. 

---