| Attapulgite is the magnesium silicate clay mineral with rod-like fibrous structure. It contains a large number of reactive groups such as Si-OH, Mg-OH, Al-OH on the surface, making it easy to form bundle-like aggregates. As a result, it has poor dispersibility in an aqueous solution. Attapulgite clay has a large specific surface area and strong adsorption, and it is widely used in refrigerator deodorant, wastewater treatment agent. In addition, attapulgite has good mechanical stability and thermal stability, and can be used as the reinforcer or filler applied for coatings and polymers. Surface modification of attapulgite is needed in order to improve the dispersivity of attapulgite in aqueous or organic solution, the hydrophobility of the composite, and the compatibility of attapulgit with the polymer matrix. Typical modified methods are physical adsorption and chemical grafting, acidification, coupling agent treatment, surfactant treatment and hydrothermal modification.In this study, the dispersivity and hydrophobility of attapulgite were improved through the surface modification with double-bond acid MTT and the free radical polymerization. ATP/acrylate hybrid emulsion(PAE) was prepared via emulsion blending and situ polymerization, whose film has better adhesion and mechanical strength with large trasmittance(More than 80%) firstly. More stable ATP/PAE was prepared by the same time. Details were as follows:(1)ATP was modified by graft polymerization with MTT to improve dispersivity of ATP both in water and polymer. The surface morphology, size and distribution, and hydrophobic property of the modified attapulgite were characterized by transmission electron microscopy (TEM), particle size analyzer, and the contact angle tester. It was found that the attapulgite was covered with polydouble-bond acid MTT after the modification. The dispersivity of the attapulgite in water was improved with the increase of the content of MTT. The film could come from poly-MTT/ATP after being modified and its hydrophobic was stronger as the increase of ATP.(2)Attapulgite/acrylate hybrid emulsion was prepared by emulsion blending, The influence of the amount of attapulgite and MTT to the properties of composites emulsion such as hardness, water absorption and impact resistance was studied. It was found that with the increase of the content of attapulgite, the pendulum hardness was increased, the water resistance was improved, and the pencil hardness was increased, but when the amount of attapulgite was more than 15%, the mechanical properties were improved barely with the increase of the amount of attapulgite.(3)Attapulgite/acrylic composite emulsion was prepared via in situ polymerization. The affect of the amount of attapulgite was studied, and the properties of the attapulgite/acrylic composite emulsion was characterized. It was found that, The degree of crosslinking of the composite was increased with with increase of the content of attapulgite because that MTT link ATP with polymer after copolymer and graft polymerization. When the content of attapulgite was 10%, the transmittance of composites film was more than 80% because graft polymerization could improve the dispersivity of ATP in the polymer. When the mass rate of MTT to attapulgite was 1/5, the composite emulsion showed the best mechanic properties and transparency, lowest water absorption, best adhension and pencil Hardness. |
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