Blending of polymers is one of the useful methods for developing polymeric materials with improved properties or creating special properties in polymers. The mixture of some polymers is completely or partially miscible, but the mixture of many polymers is immiscible and their microstructure will be multiphase due to high molecular weight and undesirable interactions. Extensive research has been conducted on the development of blend Compatibilization approaches. Surface modification of polymers, addition of block copolymers, reactive Compatibilization, crosslinking, interpenetrating networks, and more recently the addition of fillers in the micro and nano dimensions are some of the methods used to improve the compatibility of mixtures. The reduction of modulus and its related properties, when adding polymeric compatibilizers has caused researchers to pay more attention to nanoparticles and their compatibility effect. Compatibility mechanisms of polymer blends using nanoparticles can be divided into two modes based on their location in the blend. First, nanoparticles in the matrix phase, by forming a three-dimensional network and increasing the viscosity, apply more stress to the dispersed phase, reduce the size of the dispersed regions, and then reduce the coalescence phenomena of dispersed particles. In the second case, the nanoparticles, by locating at the interface between the matrix and dispersed phases reduce the interfacial stress and increase the interfacial adhesion. Also, in this case, they prevent the integration of scattered phase droplets. In this paper, the effect of nanoparticle compatibility on polymer blends, mechanisms, and the affecting structural factors are reviewed.

Due to different polarity and structure between the thermoplastic and elastomeric phases, most thermoplastic elastomers are incompatible. Poor interfacial adhesion and high interfacial tension between rubber and thermoplastic phases are main reasons for incompatibility of these systems. The blends of polypropylene (PP)/ethylene propylene diene monomer (EPDM) containing 20% EPDM may be compatibilized with maleic anhydride grafted PP (PP-g-MAH) and maleic anhydride grafted EPDM (EPDM-g-MAH) ranging from 0 to 6 phr. The dynamic rheological behaviour of the blends in presence of compatibilizer and applying dynamic vulcanization were studied using parallel plate rheometric mechanical spectrometer (RMS) at 190°C. The Cole- Cole and van Gurp-Palmen plots for all samples were plotted to make correlation between rheology and the obtained morphology of the blends. It was found that the complex viscosity (h*) of the dynamic vulcanized blends levelled up with increase of compatibilizer concentration while for un-vulcanized blends it was levelled off for the same ratio of PP/EPDM. Storage modulus of compatibilized samples showed two relaxations shoulder at high concentration of compatibilizer which at low frequencies is attributed to interfacial relaxation and at high frequencies is related to EPDM droplets. There was no considerable difference among intersection frequencies (wc) for un-vulcanized samples which means compatibilizer is more effective in combination with dynamic vulcanization. Morphological study showed that the size of dispersed phase decreased with combination of dynamic vulcanization and Compatibilization.

Polymer blends based on polyacetal (POM) and acrylomtrile butadiene rubber (NBR) were prepared by melt blending technique.The mixing parameters such as temperature, time and speed of mixing were varied to obtain a wide range of properties. The mixing parameters were optimized by evaluating the mechanical properties of the blend over a wide range of mixing conditions. The morphology of the blend indicated a two-phase structure. This study describes an attempt to improve the tensile strength of POM/NBR blends by means of Compatibilization and dynamic vulcanization. A commercial compatibilizer, maleic anhydride (MA), has been used to control the phase morphology of the blend system. Dicumyl peroxide is used to dynamically vulcanize the NBR elastomer in the blend. The tensile strength of the compatibilized systems showed improvement. Dynamic vulcanization raises elastic recovery and tensile modulus of the blends, but the elongation at break decreases.

In order to achieve dramatic improvements in the performance of rubber materials, attempts were made to develop carbon nanotube (CNT) -reinforced rubber composites. The maleic anhydride (MAH) modification of EPDM is an interesting way of compatibilizing the EPDM rubber with CNT. Novel ternary nanocomposites were prepared based on EPDM/EPDM grafted maleic anhydride (EPDM-g -MAH) blend composition with various concentrations (0-7 phr) of multi-wall carbon nanotube (MWCNT) on a two-roll mill. The effect of EPDM-g -MAH as a compatibilizer and MWCNT concentration were investigated on cure characteristics, mechanical, morphological and rheological properties of nanocomposites. The microstructure of nanocomposites has been characterized using scanning electron microscopy (SEM). At the same time the rheological behavior has been evaluated by a rubber processing analyzer (RPA). It was found that the cure time (t90) and scorch time (t5) decreased while maximum torque (MH) and minimum torque (ML) of the compatibilized composites were increased with increasing MWCNT loading which was consistent with the swelling data. It is observed that by increasing MWCNT loading the swelling index in solvent was decreased. This can be related to good interactions between carbon nanotube and EPDM matrix in presence of EPDM-g -MAH compatibilizer. The fracture surface study indicated that compatibilizer facilitated a homogenous dispersion of MWCNTs inside the matrix. On the other hand, carbon nanotubes in matrix caused roughness of the fractured surface compared with uncompatibilized samples. The mechanical properties such as tensile strength and elongation-at-break of compatibilized EPDM/MWCNT were higher than those of uncompatibilized nanocomposites. In addition, due to increasing MWCNT content the rheological properties such as storage modulus (G') increased with respect to angular frequency while the complex viscosity decreased.

In this study, poly carbonate (PC) and poly (ethylene terephthalate) (PET) were reactive melt-blended under two different conditions to produce PC/PET copolymers. For each condition, samples were taken at specified mixing times representative a specific structure of copolymers and each one employed to physically compatibilize a PC/PET blend with a fixed composition. Reactive blending and copolymer structure are described by solubility analysis results. Continues declining and going through a minimum are two trends of solubility versus mixing time depending on reactive blending condition. Decreasing and increasing patterns of solubility curves were attributed to the formation of copolymers with longer and shorter block lengths, respectively, and the level of solubility was related to the amount of produced copolymers. Differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) techniques were employed to investigate blend compatibility. The content and structure of copolymers showed favorable correlation of Tg differences of blend components and PET crystallinity. As expected, Tg of blend components approached to each other by the addition of copolymers, and the copolymers with longer block length caused less Tg differences. The melting point and crystallinity of PET were affected by introducing the copolymers too. In addition to the main melting endotherm, melting endotherm peaks of compatibilized blends had a shoulder that its corresponding melting point and crystallinity are related to the copolymer structure so that the longer length of block copolymer or higher its amount leads to the higher melting points. The SEM micrographs showed that, after the addition of the copolymer, smaller PET particles formed and uniformly dispersed in the PC matrix. A strong correlation between the blend morphology and the level of blend compatibility was demonstrated. The more compatibilized PC/PET blend, the better dispersion of PET particles in the PC matrix was obtained. The results of this study could be a basis for designing and production of compatibilizers suitable to achieve a desired level of compatibility in PC and polyester blends, specially in PC/PET blend.

The Compatibilization effect of a hyperbranched poly(amide-ester) (HBP) on poly(acrylonitrile-butadiene-styrene)/poly(vinylchloride) (ABS/PVC) blends was examined. The effects of the amounts of HBP on mechanical properties of ABS/PVC (80/20, mass ratio) blends were investigated. The results showed that a small quantity of HBP had a significant effect on mechanical properties and can improve the compatibility of the ABS/PVC blends; the tensile strength of the ABS/PVC (80/20) blends reached to a maximum value when HBP content increased to 2 phr and then dropped quickly by adding more HBP, the impact strength of the ABS/PVC (80/20) blend decreased with incorporation of HBP, the higher HBP added, the greater impact strength of ABS/PVC blend decreased. The scanning electron microscopy indicated that the surfaces of ABS/PVC blends were mainly composed of separate tiny droplets and some cavities. When HBP was introduced into ABS/PVC (80/20) blends, the asperity of the surface decreased, and shear band began to form either partially or completely. DSC Analysis also confirmed that HBP could improve the compatibility of the ABS/PVC blends.

Nanocomposites of polyamide 6 (PA6)–, poly(methyl methacrylate) (PMMA)–, functionalized single-wall carbon nanotubes (f-SWCNTs) with hydroxyl (SWCNTOH) and carboxylic acid (SWCNTCOOH) in weight ratios of 79. 5–, 19. 5–, 1, 49. 5–, 49. 5–, 1, and 19. 5–, 79. 5–, 1 were fabricated and investigated in terms of morphology, mechanical and XRD studies. Blends of 80–, 20, 50–, 50, and 20–, 80 weight ratios of PA6–, PMMA have functioned as references. The scanning electron microscopy images of nanocomposites showed a relatively uniform dispersion of PMMA domains as co-continuous phase morphology in the continuous phase of PA6 compared to their respective blends. The f-SWCNTs acted as functional group-dependent compatibilizers for the PA6–, PMMA blend system. Compatibilization of PA6-PMMA blends was higher in the presence of functionalized SWCNTs. XRD analysis indicated that the α, I and α, II phases of the PA6 were dependent on the weight ratio of the PA6 and PMMA and the nature of the f-SWCNTs. The PMMA-rich blends and nanocomposites exhibited the rich α, I phase. The melt strength of the nanocomposites was higher compared to that of the PA6–, PMMA blends. All the nanocomposites exhibited higher tensile strength than their corresponding blends. Tensile modulus increased with increasing weight percent of PMMA in blends (from 810 to 1135 MPa) and in nanocomposites (from 854 to 1298 MPa). PA6–, PMMA–, SWCNTOH19. 5–, 79. 5–, 1 nanocomposites exhibited higher tensile modulus (1298 MPa) compared to all the blends and PA6–, PMMA–, SWCNTCOOH nanocomposites.