Reactive compatibilizing agents

Reactive compatibilizing agents of the type A-C can also compatibilize an A/B blend as long as C can chemically react with B. Such studied systems include polyethylene (PE)/nylon-6 blends compatibilized with carboxyl functional PE, polypropylene (PP)/poly(ethylene-terephthalate), with PP-g-acrylic acid, nylon-6,6/EPDM with poly(styrene-co-maleic anhydride), and nylon-6/PP with PP-g-maleic anhydride. 

Reactive interfacial agents formed compatibilizer interlayers around nanosize magnesium hydroxide and CNT. 

In the blends discussed above, the interaction among the components and the compatibilizing agent is purely physical. However, to extend the range of possibilities for optimized blends preparation, reactive processing, where covalent chemical bonds are created between the partners, offers great potential. 

The problems and challenges Inherent to developing useful materials with optimal morphologies and properties from an Immiscible or partially miscible polymer blend are not trivial and have spawned considerable Industrial and academic research. Work on polymer miscibility, compatibilizing agents, reactive systems, and the Influence of flow on the structure and properties of blends Is described in later chapters. 

In the 1950 s, the core-shell, emulsion type methylmethacrylate-butadiene-styrene terpolymer (MBS) was developed to toughen PVC or PC. These blends could also contain other polymers, viz. SAA [Murdock et al., I960] SMM and PS [Murdock et al., 1962] SMM-AN [Schmitt et al., 1967] high heat ABS [Kanegafuchi Chemical Industry, 1967] HIPS [Ward, 1970] MMVAc-AA [Holland et al., 1970] SMMA [Blasius, 1992], etc. Table 1.34 traces evolution of these systems. Later, these multipolymers were modified by incorporation MA, AA, or GMA units to serve as reactive compatibilizers and toughening agents for PA, PEST or PC blends. 

There are hve basic processes for achieving interchain copolymer formation between two polymers during Reactive Compatibilization in an extruder. Table 5.4 shows these hve processes starting with idealized homopolymers A with structure AAAAAAAA and B with structure BBBBBBBB. Each process produces a specihc type of copolymer compatibilizing agent by particular types of chemical reactions. 

The interactions and adhesion involved is basically a surface phenomena, and the nature and characteristics of interfaces and interphases are of prime importance. They can be promoted by use of proper compatibilizing agents (5) or directly, by modifying surface properties (6). Permanent chemical modification of polymer surfaces is a rather difficult task, and for polyolefins, which are poorly reactive this difficulty is even greater. On the other hand, if activated, polyolefins can react with oxygen of the atmosphere easily which is a chain reaction with... 

Various approaches have been undertaken for reactive compatibilization of poly-amide/ABS alloys. Maleic anhydride can be grafted to the ABS. Styrene maleic anhydride (SMA) copolymers have been employed as compatibilizers for polyamide/ABS blends. SMA and SAN copolymers are miscible when the AN and maleic anhydride (MA) contents are equal. The impact strength of these blends has been found to be sensitive to the amount and composition of the SMA copolymer. Addition of SMA to SAN/polyamide blends was found to enhance the tensile and impact properties of these blends. Imidized acrylic polymers have been used as compatibilizers for nylon-6/ABS blends. Glycidyl methacrylate and methyl methacrylate (GMA/MMA) copolymers are used as compatibilizing agents. The epoxide functionality in GMA is capable of reaction with polyamide end groups. GMA/MMA copolymers can be shown to be miscible with SAN over the range of AN content of ABS. Styrene/GMA copolymers have been reported to be used as compatibilizers for polymer pairs such as... 

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