pps proceeding - Abstract Preview
pps proceeding
Symposium: S06 - (General Session 6) Morphology and Structural Development
Poster Presentation
 
 

Understanding the effect on the morphology of Halloysite as a second filler in PP/Graphene nanocomposites

Simon Douglas Alexandre (1)*, Bischoff Eveline (2), Daitx Tales (2), Benetti Luana (2), Mauler Raquel Santos (2)

(1) IFRS - Campus Farroupilha - Farroupilha - Brazil, (2) UFRGS - Porto Alegre - Brazil

Polymer using graphene as filler have much interest in the field of nanocomposites as results point out to great improvement in mechanical properties with content as low as 0,07%. Recently, Coleman introduced an improved method to produce few layers graphene with exciting yield using shear exfoliation in liquids and a surfactant. Furthermore, the use of particles decorated with a second filler is usually applied to produce hybrid composites to challenge compatibility problems, but also increases the complexity of the system. In this work, we evaluate the morphology of Polypropylene nanocomposites with Graphene and Halloysite fillers, prepared by shear exfoliation process. TEM images show that PP/graphene nanocomposites with no surfactant tend to agglomerate into graphitic like structures during processing. The same effect is seen in halloysite due to interaction of hydrophilic clay with the hydrophobic polymers. When we perform liquid shear exfoliation of halloysite and graphite in a 1:1 ratio in water with a surfactant, a fine black powder was obtained after centrifugation. TEM images show that both fillers are exfoliated and interact to create a combined larger particle. Other researches showed that the use of surfactant produces hemi-cylindrical surface micelles that repel other particles, and seems that graphene-graphene interaction are as likely as graphene-halloysite to happen in our structure. When this complex hybrid particle is mixed with PP in a twin-screw extruder it is completed separated, resulting in few layers graphene and single halloysite rods well dispersed in the matrix. These results shows that shear exfoliation in liquid is efficient to exfoliate two particles together due to the use of surfactant. Additionally, larger particles consisting of two fillers with surfactant are fully dispersed during extrusion, resulting in separated single particles in the polymer. Keywords: Second Filler, Shear Exfoliation in Liquid, Graphene, Halloysite