Preparation And Mechanical Properties Of PMMA/HNTs Nanocomposites

Halloysite nanotubes (HNTs) is one of the important filler materials of rubberand plastic because of its excellent performances. However, the surfaces of HNTsare usually hydrophilic and unstable. This could result in the agglomeration of HNTsin the polymer, and further lead to a poor performance of the composite, whichhinders the applications of HNTs to some extent. Surface treatment of HNTs isrecommended to improve the dispersion of HNTs in polymer matrix, which howevermakes the preparation process more complicate.In this paper, methyl methacrylate (MMA) was selected as the matrix, andcopolymerized with a small amount of cationic comonomer2-(methacryloyloxy)ethyltrimethyl ammonium chloride (DMC) and anionic comonomer2-acrylamido-2-methyl propane sulfonic acid (AMPS) respectively. Simultaneously the positively/negatively charged copolymer could electrostatically adsorb untreated HNTs whichare negatively charged outside and positively charged inside to prepare thenanocomposites microspheres by in situ suspension copolymerization, and further tofabricate the nanocomposites. Prepared nanocomposites microspheres werecharacterized by1H-NMR, the electrostatic interaction between copolymer matrix andHNTs was verified by Zeta potential and FT-IR, the effects of ionic comonomer andHNTs on the microsphere morphology and molecular weight of PMMA wereinvestigated by SEM and GPC, and the mechanical property of nanocomposites wasstudied in detail.The results indicated that，PMMA based charged copolymers were successfullysynthesized despite of the presence of HNTs, the presence of ionic comonomer hadscarcely effect and the presence of HNTs had slightly effect on both the microspheremorphology and molecular weight of PMMA, it was confirmed that a strongelectrostatic interaction existed between the P(MMA-co-DMC) copolymer and HNTs,and a weak electrostatic interaction existed between the P(MMA-co-AMPS)copolymer and HNTs. When the content of DMC and nanosilica was10vol%and1.5wt%respectively, the tensile and flexural strength of P(MMA-co-DMC)/HNTsimproved by47.5%and164.9%respectively. When the content of AMPS and HNTswas5vol%and1.0wt%respectively, the tensile and flexural strength ofP(MMA-co-AMPS)/HNTs improved by13.6%and89.5%respectively.