Influence of Trace Amount of Well-Dispersed Carbon Nanotubes on Structural Development and Tensile Properties of Polypropylene

Abstract

Functionalized multiwalled carbon nanotubes (F-MWCNTs) were individually dispersed in a commercial polypropylene (PP) matrix using our well-established α-zirconium phosphate (ZrP) nanoplatelet-assisted dispersion approach. The F-MWCNTs remained uniformly dispersed in PP after melt mixing and injection-molding and were found to remarkably enhance modulus and strength at only 0.1 wt % loading. The individual F-MWCNTs were mostly oriented and extended in the flow direction and were shown to be integrated within the crystalline structure of the matrix. The change in mechanical properties is attributed to both the modification in crystal structure due to MWCNT-induced nucleation and the direct reinforcement of crystalline lamellae and amorphous regions by the MWCNTs. We propose that the compatibilized F-MWCNTs exhibit sufficient interfacial interaction with the PP matrix to anchor lamellae stacks and resist interlamellar slip. The F-MWCNTs also reinforce amorphous domains between crystallites and behave as “super”-tie chains, thereby achieving improvement in tensile properties at low MWCNT loading. This approach for nanocomposite preparation is scalable and easily adapted for other thermoplastics by proper MWCNT surface functionalization.

Structure evolution in poly(ethylene terephthalate) (PET) – Multi-walled carbon nanotube (MWCNT) composite films during in-situ uniaxial deformation

“…From the published literature it has been argued [25][26][27][28] that CNTs act as the shish so that the PET crystallites (kebabs) then grow expitaxially from these shish, thus the CNTs act as nucleating points in this process. Therefore, the nanohybrid shish-kebab structure (NHSK) [25][26][27][28][29][30] proposed for PE and iPP CNT composites is valid here with respect to our PET-MWCNT composites.…”

“…However, a NHSK structure was formed in the composites under low shear conditions where they concluded that the CNTs have a clear role in polymer chain orientation and hence an oriented shish-kebab structure. Also, Liu [29] and Chen [30] described the morphology development in isotactic polypropylene (iPP)-MWCNT composites when injection molded or under melt-shear flow respectively. In each case, using small-angle X-ray scattering M A N U S C R I P T…”

Crystallization and orientation of isotactic poly(propylene) in cylindrical nanopores

“…All other growing crystals are physically impinged by the nanopore walls (middle and bottom row). It has been reported that the lamellar thickness of polypropylene is 11.7 nm or even as low as 5.3 nm . As such, the 15 nm nanopores are possibly just wide enough to accommodate the growing lamellae and force it to orient along the pore axis.…”

Tensile Deformation of Oriented Poly(ε-caprolactone) and Its Miscible Blends with Poly(vinyl methyl ether)

“…In fact, the effect of the crystalline structure and orientation on the mechanical behavior of polymers has been reported by numerous investigations. 3,[15][16][17][18] Being composed of the interpenetrating networks built up by both crystalline lamellae and the entangled amorphous polymeric chains in between, semicrystalline polymers always exhibit a complex deformation behavior under tensile deformation. 1,[19][20][21][22][23] The behavior of the polymers during stretching is generally influenced by both the crystalline and the amorphous phases.…”