Mauro Alfredo Soto Oviedo

The effects of ultrasound on organoclay dispersion in the PP matrix.

PP/MMT nanocomposites were prepared by solution intercalation using sonication and quiescent conditions, and the effects on the morphological, thermal and mechanical properties were evaluated by WAXD, TEM, DMA, TGA and DSC analyses. The present study aims to clarify the effects of ultrasound use on the organoclay surface with different amounts of organic modifiers and on the exfoliation processes. The sonication process decreased around of 200 nm the aspect ratio of C15A organoclay. Besides, the effectiveness of the ultrasound process was only achieved with the C15A system because there is a small energetic barrier between their layers (clay with larger d 001). The sonication process increased the exfoliation and distribution of the C15A platelets in the PP matrix, increasing by 5% its reinforcement capacity. However, for I44P system, the use of ultrasound did not show any significant effect on the morphology and consequently on the final properties of the PP matrix. The T(c) temperature and the thermal stability of the PP nanocomposites were increased, independent of the clay type or of the ultrasound use.

Evaluation of surfactants addition as compatibilizers for halloysite nanotubes filled polypropylene nanocomposites

PP nanocomposites were obtained with halloysite nanotubes (HNT) by melting blending using a twin screw extrusion. Some additives were used for obtaining good mechanical and thermal properties, such as PP-g-MA and nonionic surfactants to increase the force of adhesion between the clay and the thermoplastic matrix. Three dimensional, edge-to-edge and face-to-edge interactions between HNT occurred, which are the main reasons for the simultaneous increases in Young modulus and impact Izod of PP/HNT nanocomposites. The use of PP-g-MA increases the formation of aggregates of the HNT in the matrix. On the other hand, the use of nonionic surfactants increase the dispersion of HNT in PP matrix and showed some individual HNT in the matrix. Tm and Xc were not affected by its presence, PP-g-MA or nonionic surfactants. The use of HNT showed a slight nucleation effect in the crystallization of PP. The use of PP-g-MA reduces the mechanical and thermal properties due to the larger-sized aggregates of HNT formed in the ma...

HIGH-IMPACT PP NANOCOMPOSITES: INFLUENCE OF CLAY CONTENT ON MECHANICAL AND THERMAL PROPERTIES

The preparation of high-impact polypropylene nanocomposites with different organo-montmorillonite (O-MMT) contents by means of meltprocessing was investigated. The nanocomposite properties were evaluated by transmission electron microscopy (TEM), flexural modulus, izod impact strength, dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). It was noticed that the PP/O-MMT nanocomposites properties were affected by clay content. Exceptional improvements in impact strength were obtained (maximum of 185%) by the use of low O-MMT content. The results showed that higher enhancement on mechanical/thermal properties was obtained by 3 wt.% of O-MMT instead of higher quantities.