Microstructure and Properties of Polypropylene/Carbon Nanotube Nanocomposites

Abstract

In the last few years, great attention has been paid to the preparation of polypropylene (PP) nanocomposites using carbon nanotubes (CNTs) due to the tremendous enhancement of the mechanical, thermal, electrical, optical and structural properties of the pristine material. This is due to the unique combination of structural, mechanical, electrical, and thermal transport properties of CNTs. However, it is well-known that the properties of polymer-based nanocomposites strongly depend on the dispersion of nanofillers and almost all the discussed properties of PP/CNTs nanocomposites are strongly related to their microstructure. PP/CNTs nanocomposites were, mainly, prepared by melt mixing and in situ polymerization. Young’s modulus, tensile strength and storage modulus of the PP/CNTs nanocomposites can be increased with increasing CNTs content due to the reinforcement effect of CNTs inside the polymer matrix. However, above a certain CNTs content the mechanical properties are reduced due to the CNTs agglomeration. The microstructure of nanocomposites has been studied mainly by SEM and TEM techniques. Furthermore, it was found that CNTs can act as nucleating agents promoting the crystallization rates of PP and the addition of CNTs enhances all other physical properties of PP. The aim of this paper is to provide a comprehensive review of the existing literature related to PP/CNTs nanocomposite preparation methods and properties studies.

Multi-walled Carbon Nanotube Filled Polypropylene Nanocomposites: Electrical, Mechanical, Rheological, Thermal and Morphological Investigations

“…When the MWCNT content reached 6wt%, the dielectric constant increased significantly by 15 and 16 times for the nanocomposites processed at speed 200 and 270rpm respectively. However, the dielectric constant values were found to be lower than those reported by Tjong et al [17] and Bikiaris [16]. This was probably the consequence of the agglomerations of MWCNT formed in the nanocomposite, as illustrated in the FE-SEM micrograph in Fig.…”

“…At low MWCNT content, partial tensile stress could be transferred to the MWCNT embedded in the PP matrix, leading to an increase of the tensile strength. With further addition of the MWCNT, it was difficult to disperse the MWCNT during melt mixing [16][17]. Hence, more agglomerates of MWCNT were formed in PP matrix; they acted like many defects in the PP matrix.…”

“…The resistivity decrement was believed to have caused by the formation of conductive chains in the composites [15]. The percolating network of the MWCNT at all the concentrations tested seemed to have assumed random positions but MWCNTs were observed to have overlapped with other MWCNTs [16] and formed interconnected conductive pathway as enclosed in Fig. 1.…”

Experimental and computational micro-mechanical investigations of compressive properties of polypropylene/multi-walled carbon nanotubes nanocomposite foams

“…Each spherulite consists of many crystalline lamellae separately alternated by amorphous inter-layers as shown by Bao and Tjong (2008); Bédoui et al (2006). In case of PP/CNTs nanocomposites, the optical micrographs show trans-crystalline inter-phases around the carbon fibers and the polypropylene spherulites away from the carbon fibers Bikiaris (2010). The trans-crystalline inter-phase is characterized by oriented crystalline lamellae surrounding the carbon fibers.…”

Thermal stability and flammability of butadiene–styrene rubber nanocomposites

“…During the initial degradation stage of nanocomposites the degradation products of vulcanizates diene rubbers may considerably be entrapped into the lumens of HNTs, resulting higher randomness of lumen ends. The lumen could therefore entrap the degradation products more effectively [27].…”