Compatibilization of blends

Reactive compatibilization of blends and filled systems is common, and Table 6.1 highlights typical systems and their compatibilizers. 

The third trend is the growing interest in functionalization of polyolefin blends in their melt by means of reactive extrusion. Particular attention has been paid to blended systems PP/PE, PP/EPR, PE/ethylene-octene copolymer (EOC), PP/EOC, PE/PS, and PP/PS functionalized in melt by reactive extrusion. The major field for application of functionalized polyolefin blends is compatibilization of blends of condensation polymers, where they can be used in place of homopolyolefins. 

The major field of application of functionalized PO blends and functionalized homo-polyolefins is compatibilization of blends of condensation polymers. The use of functionalized PO blends, in place of homopolyolefins, has a number of advantages. First, by ratio variation of PO in the blend, it is possible to change the degree of microheterogeneity of the final product this fact is of importance for impact strength (67). Second, the selective nature of grafting can be useful in controlling the functionalization power of one or another component in PO blends. 

Blends of functionalized PO have mostly been used for compatibilization of blended systems based on engineering plastics. They have found applications in the development of thermoplastic dynamic vulcanizates. 

According to Paul and Newman (1), even 2 wt% of an A-B-type copolymer is sufficient for compatibilization of blends of A and B polymers if its molecular weight is wlO". The block copolymers reduce the surface tension and raise the adhesion between phases. The latter may rise up to 100 times against the adhesion between the components (7). 

PVC/PU blends were compoimded from rigid and plasticized PVC (plasticized PVC contained 36 phr DOP). Figure 12.7 shows that elongation behavior of two blends is dramatically different. It is suspected that the plasticizer helps in the compatibilization of blend components. The blend with plasticized PVC appears to be uniform on the macroscopic scale. Addition of DOP to ABS/PVC blend improved impact strength and elongation but hardness, tensile strength, and Young modulus were reduced."... 

Compatibilization of blend polymers by hydrogen bonds formation. 

According to these TEM images of polymer-clay nanocomposites, the presence of FR particles can affect the compatibilization of blends. The degree to which the clays compati-bilize the blends depends on the ability to the polymer to adsorb onto the clay surfaces, and hence is correlated with the extent of exfoliation or intercalation. To observe whether the clays are exfoliated or intercalated, we conducted SAXS on PMMA/DB/AO/Cloisite20A, PS/PMMA/Cloisite 20A, PS/PMMA/DB/AO/Cloisite 20A, PC/SAN24/Cloisite 20A, and PC/SAN24/DB/AO/Cloisite20A nanocomposites and compared the results with SAXS data... 

Heino, M. T. and Seppala, J. V., Studies on compatibilization of blends of polypropylene and a thermotropic liquid crystalline polymer, J. Appl. Poiym. Sci. 48 1611 (1993). 

Li et al. [100] studied the blends of HOPE and PA6 prepared by ultrasonic extrusion. The extruder set-up, equipped with a capillary die and an ultrasonic device, is shown in Figure 8.27. Ultrasonic irradiation led to the degradation of polymers and in-situ compatibilization of blends, as confirmed by variations in complex viscosity, storage modulus and loss modulus. The relationship between storage modulus and loss modulus indicated the effect of ultrasonic irradiation on the compatibility of HDPE/PA6 blends. Theoretically, in the linear viscoelastic region (co O), the G and G" of compatible polymer blends have the following relationship ... 

M, Pracella and D. Chionna, Reactive compatibilization of blends of PET and PP modified by GMA grafting, Macromol. Symp., 198 161-171, August 2003. 

Triacca VJ, Ziaee S, Barlow J-W, Keskkula H, Paul DR. Reactive compatibilization of blends of nylon 6 and ABS materials. Polymer 1991 32 1401-1413. 

Fig. 6. Illustration of (a) compatibiLization of immiscible blends of polymers and B by block or graft copolymers and (b) the subsequent modification of...

The treatment of blends as a two phase system opened up an interesting field of modifying the composite properties by the use of a (third component within the interface boundaries, which is termed as compatibilizers [1]. Such modifications are still being extended to the formation of microgel out of the interaction between the two blend partners having a reactive for functionalities. This type of interchain crosslinking does not require any compatibilizer to enhance the blend properties and also allows the blends to be reprocessed by further addition of a curative to achieve still further improved properties [3,4]. Such interchain crosslinking is believed to reduce the viscoelastic mismatch between the blend partners and, thus, facilitates smooth extrusion [5,6]. 

Els and McGill [48] reported the action of maleic anhydride on polypropylene-polyisoprene blends. A graft copolymer was found in situ through the modifier, which later enhanced the overall performance of the blend. Scott and Macosko [49] studied the reactive and nonreactive compatibilization of nylon-ethylene-propylene rubber blends. The nonreactive polyamide-ethylene propylene blends showed poor interfacial adhesion between the phases. The reactive polyamide-ethylene propylene-maleic anhydride modified blends showed excellent adhesion and much smaller dispersed phase domain size. 

Commercial thermoplastics are the engineering materials containing two or more compatibilized polymers that are chemically bounded in a way that creates a controlled and stable morphology with a unified thermodynamic profile. In view of multiplicity and contradictory requirements of various properties for most of the applications, almost all the commercial PBAs are made of two or more thermoplastics, elastomeric modifiers along with a series of compatibilizers with modifiers compounded together. A considerable number of blends have been appearing in the market regularly, some of which are listed in Table 9. 

The kinetics of the reactive compatibilization of nylon-6-PP by acrylic acid modified PP was investigated by Dagli et al. [47]. The compatibilization reaction in this system involved the reaction between the acid group of acrylic acid modified PP and the amine group of nylon-6. A typical intensive batch mixer torque (t) vs time (t) trace for a ternary blend showing an increase in mixing torque upon the addition of PP-g-AA to a binary PP-NBR (85 7.5) blend is shown in Fig. 3. The kinetic... 

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