Compatibilizers, also referred to as coupling agents, are additives, that when added to a blend of immiscible materials during extrusion, modifies their interfacial properties and stabilizes the melt blend.
The role of compatibilizer will be playing physical role for the promotion of polymer composites. But coupling agents will act as chemical role between two or more compounds which are existing in polymer composites.
Compatibilizers are used to promote interfacial adhesion between pair of polymer which are otherwise immiscible. They are usually block copolymers, both blocks being compatible with one of the phases. these molecules tend to concentrate at the interfaces and stabilize them thus allowing finer dispersion of mutually incompatible pairs. Coupling agents are chemicals which improve the interfacial properties of mineral fillers and polymers (they reduce the interfacial tension which is diadvnatageous rather than advantageous, but simultaneously they reduce the agglomeration tendency of filler particles, thus improving their accessibility to polymer molecules). Coupling agents usually react with the filler surface but exhibit at least one side group which react with the polymer matrix or is at least compatible with it.
Though the function of a compatibilizer and a coupling agent is the similar of bringing the components closer to one another, the usage of this terminology is not common in the case of composites. Compatibilizer is a general term used for bringing two polymers together in a physical mixture (blend) especially in the case of immiscible blends. In this way, one can form polymer alloys. But coupling agent term is used to bring dissimilar materials close to each other as in the case of composites.
compatibilizer - based on physical interaction
coupling - chemical bond
I totally agree with Gyorgy Banhegyi. These agents have a similar function: promote a good dispersion and interactions between the polymeric matrix and the dispersed phase. However, the term compatibilizer it refers to blends formed by two polymers which are otherwise immiscible. Tipically , these agents are a block or graft copolymer with segments structurally similars to each polymers present in the polyblend.
The coupling agents are used to promote a good adhesion between a filler and the polymeric matrix
Compatibilizer: Polymer or copolymer that, when added to an immiscible polymer blend, modifies its interfacial character and stabilizes its morphology.
Coupling agent: Interfacial agent comprised of molecules possessing two or more functional groups, each of which exhibits preferential interactions with the various types of phase domains in a composite.
Compatibilizer and coupling agent have the same function to promote interfacial adhesion between two components. Compatibilizer term commonly used in blending of the immiscible polymers. Compatibilizer acts as a bridge between two immiscible polymers.
Coupling agent term commonly used in composites. Coupling agent acts as a bridge between the polymer and the filler/fiber.
Definitely, both Compatibilizer and coupling agent have similar kind of roll of binding blend /composite components to get blend /composite with better properties but the nature of intermolecular interactions are different and some time complicated in both the cases.
Compatibilizer : generally used in blends, where intermolecular interactions between blend components are chemical in nature. the Compatibilizer helps to enhance better dispersion (better mixing) of blend components results in better chemical interactions between the blend components.
coupling agent: generally used in composites, where the nature of intermolecular interactions are physical in nature. In addition to that coupling agent also help to enhance dispersion/ reduce agglomeration of components in the composites.
Compatilizer and coupling agents are both one kind of binding agents to inhance the composites property, comptilizer is weak binding agent while coupling is strong.
Bambang Afrinaldi I agree with the answer by Dr Bambang. However, I would like to add that maleated PP has also been used as a compatibilizer to improve adhesion between PP and natural fillers.
Anyone disagree with my answer? There are many such journal papers re[ported in established polymer journals
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