Demand for the use of polymers in different industries with different properties is increasing. However, pure polymer does not have the ability to create a wide range of desired features. To solve this problem, various additives are used, many of which are minerals. The polar nature of these additives has made them impossible to use in non-polar polymers, such as polyolefins, due to the incompatibility and poor interface adhesion. Various methods are used to increase compatibility, one of which is the use of COMPATIBILIZERs. Functionalized waxes are among the materials that researchers have studied over the years. The backbone of functional waxes is miscible with a polymer, and the functional groups on the wax surface can interact with the groups present on the additive surface. Therefore, their use improves the dispersion and distribution of additive particles in the polymer. Also, due to their low molecular weight, these waxes can penetrate the pores and capillaries on the additive surface and act as a successful co-COMPATIBILIZER. In this study, first, the methods of increasing compatibility and the cases used for this purpose are briefly reviewed. Then, the performance of functionalized waxes as a COMPATIBILIZER and co-COMPATIBILIZER and their effect on the physical, mechanical, and thermal properties of the polymer composites are investigated in details.

Effect of Kraft lignin as a COMPATIBILIZER on the short-term water absorption (2 and 24 hours) and mechanical properties of wood flour-polypropylene composites was studied. The black liquor of Chooka pulp and paper mill was acidified and Kraft lignin was extracted by precipitation. The extracted lignin at three levels of 2, 5 and 10 percent was mixed with wood flour by physical mixing method. All materials used were oven-dried. Wood flour, lignin and PP with or without MAPP were used to produce composites by flat hot press method. The results of this study indicated that generally lignin improved physical (short term water absorption) and mechanical properties (flexural modulus, flexural strength and impact strength). The bending test result showed that without MAPP, the composites with 2 and 10 percent lignin exhibited higher flexural modulus and strength, respectively. But at the presence of COMPATIBILIZER, the composites with 5 percent lignin exhibited the highest flexural modulus and strength. The composite with 2 percent of lignin exhibited higher flexural modulus and shortterm water absorption rather than the composites with 2% MAPP. This result indicated positive effect of lignin in the composites. Also the composites with 10 percent lignin exhibited the highest impact strength and short-term water absorption. But there were no significant difference between the impact strength of composites with 5 and 10 percent lignin.

Blend of PP/PET is an immiscible composition because of the difference between solubility coefficient and lack of attraction between polar/non-polar polymers. For inducing required miscibility in the blend, various COMPATIBILIZERs are used. In this research, PP-g-MA is being employed. This copolymer is produced from the chemical reaction and grafting between maleic anhydride (MA), dicumyl peroxide (DCP) and polypropylene (PP) The effect of adding DCP concentration (at constant MA) increases the grafting efficiency on PP and on the other hand, enhancing MA concentration (at constant DCP) decreases grafting efficiency. The results indicate that PP-g-MA makes PET fibrillar to become smaller and it also makes the phases to become closer. It is found however that using this COMPATIBILIZER, specially in large amount, decreases the mechanical properties of the blend.

PP/PEP blends, because of different solubility factors, are incompatible. The aim of this research was to use PP-g-MA COMPATIBILIZER in a two-component blend. After preparing this COMPATIBILIZER in internal mixer and investigating different parameters on producing process, optimum compatibilization was obtained. PP/PET (60/40) Blend fibers with different percentages of this COMPATIBILIZER in two groups, including recycled and. virgin PET were prepared. The results show that PP-g-MA causes smaller PET phase in fibers including vir- gin PET but in fibers with recycled PET, up to 5 wt% of COMPATIBILIZER, the cross-section uniformity is reduced. In addition, by increasing COMPATIBILIZER, the mechanical properties of two groups including recycled and virgin PET, at first increase and then decrease. Cold drawing causes increase in crystallinity and therefore enhancement of tensile strength. It is obvious that fibers with recycled PET and compatibilized fibers demonstrate better mechanical properties by cold drawing.

The objective of this work was to study the COMPATIBILIZER effect on polypropylene (PP) and acrylonitrile butadiene styrene (ABS) blends. The blends were coextruded and injection molded in various ratios of ABS with and without COMPATIBILIZERs. Universal testing machine was employed to analyze the tensile properties of basic PP/ABS binary blends. From the mechanical testing, the impact and tensile properties of PP/ABS blend were optimized at 80/20 weight ratio. Various COMPATIBILIZERs such as PP-g-MAH, SEBS-g-MAH and ethylene a-olefin copolymer were used and their comparative performance on binary blend was enumerated. Hybrid compatibilization effect was also studied and reported. However, the addition of COMPATIBILIZERs showed the maximum increase in impact strength attributed to rubber toughening effect of ABS. The effect of COMPATIBILIZERs on morphological properties was examined using scanning electron microscopy (SEM). SEM micrographs depicted the more efficient dispersion of ABS particles in PP matrix with the addition of COMPATIBILIZERs. Further, interparticle distance analysis was carried out to evaluate the rubber toughening effect. The ABS droplet size in compatibilized PP/ABS blend was brought to minimum of 3.2 mm from 9.9 mm with the addition of COMPATIBILIZERs. The melt rheology of PP/ABS blend systems was investigated through parallel plate arrangement in frequency sweep. Linear viscoelastic properties like storage (G') and loss (G") modulus and complex viscosity (h*) have been reported with reference to the virgin materials. It is understood that the combination of COMPATIBILIZERs (hybrid COMPATIBILIZER) had a considerable effect on the overall blend properties.

The effects of differently functionalized polypropylene (PP) and styrene-ethylene-butene-styrene copolymer (SEBS) on different properties of stretched-extruded films of PP/EVOH blend were examined. The effect of melt stretching after die was also studied. The stretched films of the original and polymer g diethyl maleate (DEM) modified blends showed laminar morphology whereas, their maleic anhydride (MA) functionalized counterparts showed fibrillar morphology. Rheology of the neat polymers along with their straight and compatibilized blends was studied to assess the quality of mixing under the actual conditions of blending in a counter-rotating twin-screw extruder to control and retain laminar morphology. Differential scanning calorimetry (DSC) tests showed a higher rate of interactions in the case polymer g MA modified blends. The SEBS-modified blends showed a lower elasticity at low temperatures. Mechanical properties were improved for almost all modified blends. SEM Micrographs revealed that as a result of melt-stretching a finely dispersed EVOH phase in PP matrix was obtained in the case of polymer-g-MA COMPATIBILIZER, whereas a laminar one was obtained in the case of polymer-g-DEM COMPATIBILIZER. The lowest permeability to oxygen gas observed for DEM-grafted polymers. The SEBS g DEM modified blends showed a barrier performance 90% better than that of pure matrix (PP) and 60% better than that of the original stretched blend.

The joint adhesion strength of low density poly ethylene to thermoplastic plasticized starch (TPS) and their compatibilized versions with poly (ethylene-co-vinyl acetate) (EVA), maleated polyethylene (PE-g-MAH) and maleated styrene-ethylene-butadiene-styrene block copolymer (SEBS-g-MAH) were investigated with peel-test. For localization of the COMPATIBILIZERs at PE/TPS interface, they were blended with TPS. In addition, thermodynamic work of adhesion between joint components was evaluated by contact angle measurements by applying the existing theories.The results obtained showed the thermodynamic work of adhesion increment from 64 mJ/m2 for PE/TPS to 70, 79, 86 mJ/m2 for compatibilized interface by EVA, PE-g-MAH, and SEBS-g-MAH, respectively. The adhesion improvement was attributed to comatibilizer migration to the interface during high temperature joint formation and resultant enhanced stress transfer capability at the interface. Furthermore, joint loss function was to depend not only on joints main components tan d ratio at room temperature but also on tan d of the thin layer of COMPATIBILIZERs. Therefore, a new parameter was introduced namely tan d of the peel arms to the adhesive tan 8 multiplied by the COMPATIBILIZERs tan d to rationalize the observed data.