Percent research is concerned with polymerization of various monomers on the surface of different clays and with the properties of thus prepared clays as polymer fillers. The monomers used were methyl methacrylate, styrene and butadiene and Japanese acid clay.
The clay surfaces were activated by acid treatment (50% $H_2SO_4$),followed by drying at 120 ℃ under vacuum. The samples were subjected to the following polymerization processes :
1) Redox solution polymerization in which N, N-dimethyl aniline was adsorbed on the clay prior to the polymerization of monomer with a peroxide. Methyl methacrylate was polymerized this manner.
2) Gas phase polymerization. The monomers polymerized were styrene and butadiene.
The polymer-coated samples were analyzed by I.R., TGA, and furnace combustion, and then as fillers for low density polyethylene. The filled applied as fillers for low density polyethylene. The filled samples were subjected to mechanical testings and the following observation were made.
i) Generally the following to break was reduced by filling, while the tensile strength and initial modulus increased, regardless of the type of fillers employed.
ii) Acid-treated clays exhibited higher tensile strength and initial modulus, and lower elongation to break than that of untreated clays, presumably due to stonger physical adhesion generated by the surface porosity.
iii) Polymer-encapsulated halloysite showed lower elongation to break, and higher tensile strength and initial modulus than those of acid-treated halloysite. Strength of chemical adhesion between polymer-encapsulated halloysite and the polymer matrix was not as strong as physical adhesion between acid-treated halloysite and the matrix indicating high effectiveness of surface porosity.
iv) Untreated halloysite showed a reduced effect of the concentration of filler on the tensile strength and initial modulus because of lower strength of adhesion.
