Compatibilization techniques

Strong elongational deformation and use of matrix polymers whose viscosity is higher than that of TLCP phase are better to ensure uniform and fine fibril formation. But application of compatibilizing techniques to in situ composite preparation can be useful to get the most desirable products. These can reduce the high costs of the liquid crystalline polymers and expensive special engineering plastics used for the in situ composite preparation and reduce the processing cost, whereas they can increase the performance of produced in situ composites, hence, their applications, too. 

In addition to dynamic vulcanization, the technological compatibilization technique was also adopted by Coran and Patel [34] to obtain thermoplastic vulcanizate having good mechanical integrity and elastic recovery. 

Compatibility of immiscible PP-NBR blends was improved by the reactive compatibilization technique using various modified polypropylenes. In this study. 

Greco et al. [50] studied the effect of the reactive compatibilization technique in ethylene propylene rubber-polyamide-6 blends. Binary blends of polyamide-6-ethylene propylene rubber (EPR) and a ternary blend of polyamide-6-EPR-EPR-g-succinic anhydride were prepared by the melt mixing technique, and the influence of the degree of grafting of (EPR-g-SA) on morphology and mechanical properties of the blends was studied. 

The applicability of Noolandi and Hong s theory of compatibilization of immiscible blends using block copolymers has been extended to the reactive compatibilization technique by Thomas and coworkers [75,76]. According to Noolandi and Hong [77], the interfacial tension is expected to decrease linearly with the addition... 

In comparing the different blends, the specific advantages of each type, as well as any potential overlap in performance with other type of blends have also been discussed. The fundamental advantage of polymer blends viz. their ability to combine cost-effectively the unique features of individual resins, is particularly illustrated in the discussion of crystalline/amorphous polymer blends, such as the polyamide and the polyester blends. Key to the success of many commercial blends, however, is in the selection of intrinsically complementing systems or in the development of effective compatibilization method. The use of reactive compatibilization techniques in commercial polymer blends has also been illustrated under the appropriate sections such as the polyamide blends. 

Melt blending of PA-6 (or 66) with such an anhydride functionalized polypropylene causes a fast graft copolymer reaction between the polyamide and PP at the interface, which subsequently compatibilizes the blend. Some commercial polyamide/polypropylene blends may utilize such types of reactive compatibilization techniques. Properties of commercial PA/PP blends, both unfilled and glass filled grades, are shown in Tables 15.18 and 15.19. Typically, these blends... 

While tremendous strides have been achieved during the past two decades, there are still a number of unsolved problems and emerging opportunities as noted in Table 17.7. Improved predictability will continue to be desired, and molecular modeling offers the longer range solution to this need. Improved compatibilization techniques to combine immiscible polymer pairs will allow for new and commercially important polymer blends, some of which have been highlighted in this section. 

Reactive compatibilization techniques using MDI, MA, etc., are emerging as successful methods for modification of interfadal interaction within the biodegradable blends and nanocomposites. 

The technological definition of compatibilization, such as in the modification of NR blends, is the process that produces a desirable set of properties. These approaches can be defined and may assist the development of materials. Table 7.2 shows the various types of compatibilization techniques for several NR/polymer blended applications. 

Table 7.2 Compatibilization techniques for natural rubber blends.

Smbar WV, Pilla S, Wright ZC, Ryan CA, Greene JP, Frank CW, Billington SL (2012) Mechanisms and impact of fiber-matrix compatibilization techniques on the material characterization of PHBV/oak wood flour engineered biobased composites. Compos Sci Technol 72 708-715... 

The two most common compatibilization techniques of additive and reactive compatibilization differ in the origin of the compatibilizer. In the former case, the preprepared compatibilizer is added to the blend and has to diffuse to the interface during mixing. In reactive compatibilization, the compatibilizer is generated in situ directly at the interface by a chemical reaction of one or both blend... 

Most of these compatibilization techniques have been applied to polyolefins and olefin copolymers, and will be illustrated throughout this review. 

A compatibilization technique specifically suitable for emulsion polymerization involves the in-situ polymerization of a polymer in the presence of a previously polymerized polymer. As applied to emulsion polymerization, this is typically referred to as core-shell polymerization. The procedure involves the initial polymerization of seed particles. The addition of other monomers can result in two distinct results. One result involves swelling of the monomer in the particles followed by phase separation once a critical molecular weight is achieved (if the two polymers are thermodynamically immiscible). The other result would involve the... 

Liao and Wu [125] prepared and characterized ternary blends of PLA and PCL, using a reactive compatibilization technique. From their results, it can be seen that the thermal and mechanical properties of the blend improved owing to better compatibilization. 

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