Influence of the Polymeric Matrix and Thermal Treatment on the Properties of Polyolefin‐Graphite Nanosheets Nanocomposites

Abstract

Homo and copolymers of metallocenic poly(propylene) with 1‐hexene and 1‐octadecene are used to prepare nanocomposites via melt mixing by using graphite nanosheets (GNSs) as filler. Different amounts of GNSs are used in order to study the influence of the filler on the thermal, mechanical, and electrical properties of nanocomposites. Significant changes have been observed in the crystallization temperature (Tc) of the nanocomposites. Thermogravimetric analysis shows improvement in thermal stability. Young's modulus and elongation at break of the nanocomposites are depended on the type of the matrix and the amount of GNSs. Materials with high flexibility are obtained in the cases of matrices based on copolymers even at high filler loading. Nanocomposites have become a semiconductor material reaching conductivity of 10−4 S cm−1. Two different thermal treatments have been applied in the preparation of the films by compression molding. X‐ray diffraction analysis shows the existence of polymorphism according to the thermal treatment applied.

Effect of Graphene Nanofibers on the Morphological, Structural, Thermal, Phase Transitions and Mechanical Characteristics in Metallocene iPP Based Nanocomposites

“…Moreover, the presence of graphene favors the obtainment of this γ form, increasing its fraction as the graphene content rises in the nanocomposite, independently of the type of nanofiber used. This favorable formation of the γ modification was analogously observed when graphene nanosheets were employed [24] instead of the graphene nanofibers used in the present materials.…”

“…This shift up of T c is beneficial from an industrial point of view since it implies shorter cycle times during processing. This nucleation effect has been also observed in other iPPs composites incorporating different types of graphene or derivatives [24,[38][39][40][41]56,57]. The subsequent second melting curves are rather similar in both shape and T m location for all the different samples, independently of the type of nanofiber incorporated, GHS or GLS.…”

“…Crystallization temperature (T c ) of iPP was found to be shifted up to 10 • C in nanocomposites achieved by in situ polymerization of propylene in presence of graphene nanosheet (GNS) compared with that observed in the neat iPP [21,22]. Changes in properties (thermal stability, mechanical properties, and electrical characteristics) were even more noticeable if nanocomposites were prepared by in situ polymerization from copolymers of propylene with α-olefins and GNS [23,24].…”

“…The stress-strain curve in the neat HMP is characteristic of a cold drawing behavior. This is a common feature in metallocene iPP [11,23,24]. The S samples become more rigid and brittle than the Q specimens and, accordingly Young's modulus (E) and yield stress (σ Y ) values increase while deformation at break, ε B , is reduced in nanocomposites where a slow crystallization has been imposed due to its higher f c and size of α crystallites (Q samples do not develop γ crystals).…”

Efficient interfacial interaction for improving mechanical properties of polydimethylsiloxane nanocomposites filled with low content of graphene oxide nanoribbons

“…Carbon nanollers including carbon nanotubes (CNTs), graphite, graphene sheets and their derivatives have recently received considerable interest for improving the mechanical and functional properties of various polymers due to their unique structure and intriguing physical performance. [12][13][14][15][16][17][18][19][20][21][22][23] Among these carbon nanollers, graphene nanoribbons (GNRs) integrate the structures and properties of 1D CNTs and 2D graphene sheets, 24,25 and exhibit excellent chemical/physical properties. [26][27][28] Especially, graphene oxide nanoribbons (GONRs) are narrow strips of graphene oxide (GO) sheets with high length-towidth ratio (usually more than 10, similar to CNT) and high specic surface area ($511 m 2 g À1 ), 29 which can be fabricated by longitudinal unzipping CNTs or chemical vapor deposition method.…”