Structure-property relationships of irradiation grafted nano-inorganic particle filled polypropylene composites

An irradiation grafting method was applied for the modification of nanopart icles so that the latter can be added to polymeric materials for improving their mechanical performance, using existing compounding techniques. The fo llowing items are discussed in particular, in this paper: (a) chemical inte raction between the grafting monomers and the nanoparticles during irradiat ion; (b) properties including modulus, yield strength, impact strength and fracture toughness of the resultant nanocomposites; and (c) possible morpho logical changes induced by the addition of nanoparticles. Through irradiati on grafting polymerization, nanoparticle agglomerates turn into a nano-comp osite microstructure (comprising the nanoparticles and the grafted, homopol ymerized secondary polymer), which in turn builds up a strong interfacial i nteraction with the surrounding, primary polymeric matrix during the subseq uent mixing procedure. Due to the fact that different grafting polymers bro ught about different nanoparticle/matrix interfacial features, microstructu res and properties of the ultimate nanocomposites could thus be tailored. I t was found that the reinforcing and toughening effects of the nanoparticle s on the polymer matrix could be fully brought into play at a rather low fi ller loading in comparison to conventional particulate filled composites. U nlike the approaches for manufacturing of the other types of nanocomposites , including intercalation polymerization, the current technique is characte rized by many advantages, such as simple, low cost, easy to be controlled a nd broader applicability. (C) 2000 Elsevier Science Ltd. All rights reserve d.