Viscoelastic properties of nanosilica‐filled polypropylene in the molten state: Effect of particle size

Abstract

ABSTRACT:Composites of polypropylene (PP) with nontreated nanosilica at different particle sizes are prepared, and their viscoelastic properties are studied by dynamic strain-and frequency-sweep experiments. It is clear that incorporation of nanoparticles in a polymer matrix due to the huge specific surface area enhances both moduli so that the storage modulus is intensified more than loss modulus. The specific surface area of a particles increases as a particle size decreases, leading to a stronger tendency to form reinforcing structures. In nanocomposites of smaller particles due to existence of a larger contact area between particles, more and stronger filler clusters are formed. Thus, a stronger filler-filler network is formed by decreasing the particle size so that both storage and loss moduli present higher values. The slope of dynamic moduli as a function of frequency decreases with filler loading augmentation in a low-frequency region, and this solid-like behavior becomes more significant with particle size reduction. The PP composites in high filler loadings exhibit a yield stress, and weight fraction corresponds to the onset of this well-defined yield stress and is lower in the case of smaller filler particles. In addition, the polymer chains adsorption on the particles and/or clusters surface and formation of filler-polymer network increases with filler loading augmentation. The influence of these two reinforcing mechanisms leads to a gradual enhancement of the Payne

Study of viscoelastic properties of nanocomposites of SiO2–acrylonitrile–butadiene–styrene

“…As observed by other authors,9, 10, 14, 21 the behavior of loss modulus is similar to that of storage modulus, but with a maximum near a critical strain in the G ″‐curve. Aranguren et al21 observed a maximum in loss modulus for nanocomposites of PDMS and untreated silica and they assumed this overshoot to be related to energy dissipation produced by the breakdown of silica aggregates.…”

“…The effects of nanoparticles on the different viscoelastic properties of nanocomposites have been investigated so that the various changes in mechanical behavior of polymer composite could be observed. Several authors investigated that particle size is an effective parameter in viscoelastic properties of composite polymer melts 4–9. For example, Jianga et al7 studied the composites of acrylonitrile–butadiene–styrene (ABS) reinforced with micron and nano‐sized precipitated calcium carbonate particles.…”

“…They concluded that the larger contact area of nanoparticles relative to that of microparticles leads to propagation of more and stronger filler clusters in the composites. Haghtalab and Marzban9 investigated the effect of nanosilica particles on the rheological properties of polypropylene with respect to the influence of particle loading and size. The surface‐treated nanoparticles showed better dispersion in the polymer so that a reduction of dynamic moduli was observed by changing the particle's surface energy 4, 8, 10.…”

“…He believes that the filler network breakdown is adequate for describing the strain dependence of dynamic mechanical properties of composites 14. The solid‐like behavior nonlinearity has been found in many nanocomposites at high filler loading in the low‐frequency region7–9, 15, 16 and in most of them, a network formation by the particles is considered the cause for such behavior.…”

Improvement of Mechanical and Physical Property of Polypropylene Nano Composites by the Addition of Multi-walled Carbon Nano Tube

“…Rahim [3], the viscoelastic properties of nanocomposites ABS / SiO 2 polymer blends with ABS / PA6 / SiO 2 were examined. They have reported that increasing the percentage of polymer chains and reduce the size of nanoparticles increases the absorption of nanoparticles, increasing entanglement chains and create a three-dimensional network nanopaticles.…”