Rheological Evaluation of Carbon Nanotube Redistribution in Polymer Melt

Abstract

We investigated changes to the linear viscoelastic properties of a mixture comprising polycarbonate (PC) containing 3 wt.% of a multiwalled carbon nanotube (MWCNT) and high-density polyethylene (HDPE), also containing 3 wt.% MWCNT, during post-processing annealing. The oscillatory shear moduli-i.e., the storage modulus G′ and the loss modulus G′′-gradually increased with residence time in a rheometer (i.e., annealing). The samples were prepared by compression-molding at low temperature, during which the MWCNTs became oriented by the applied squeeze flow. The marked increase in the oscillatory moduli may be attributed to the formation of a conductive MWCNT network owing to Brownian motion. Furthermore, the moduli increased more rapidly during high-temperature annealing. These increases can be expressed by a simple equation using only one characteristic time, i.e., the time required for MWCNT redistribution by Brownian motion. This characteristic time is considered one of the factors that control the structure of composites containing MWCNTs.

Modulus enhancement of polypropylene by sorbitol nucleating agent in flow field

“…One example is the addition of carbon nanotubes (CNT) to polyethylene (PE) 17,21 . CNTs show strong nucleating activity for PE 23 and orient to the flow direction, 24 so a crystalline structure similar to that of the shish‐kebab is easily formed. This is referred to as a ‘nanohybrid shish‐kebab’ 17 .…”

Carbon nanotube localization at interface in cocontinuous blends of polyethylene and polycarbonate

“…The density of the composite was approximately 2300 kg m –3 . Further details were described in the literature …”

Effect of carbon nanotube addition on structure and properties for extrudates of high‐density polyethylene

“…Moreover, the details in the crystalline structure of PE grown on the MWCNT surface are still unknown . Because the relaxation time of the MWCNT orientation is long compared with the characteristic time under the flow, that is, the inverse of the shear rate, MWCNTs can behave like shish at conventional processing operations. We found that MWCNTs enhance the chain orientation of HDPE to a surprising extent.…”