Effect of interfacial chemistry on crystallization of polypropylene/multiwall carbon nanotube nanocomposites

Abstract

This study systematically investigates the polymer–carbon nanotube (CNT) interaction when the interphase is tailored. Maleic anhydride‐grafted‐polypropylene (MA‐g‐PP) or polypropylene (PP) was noncovalently coated onto acid functionalized multiwall nanotube (f‐MWNT) through solution mixing. These coated f‐MWNTs were melt microcompounded with neat PP to form PP/f‐MWNT nanocomposites. The effects of functional groups and the thin layer of solution processed polymers, namely, MA‐g‐PP or PP, at the PP/f‐MWNT interface on crystallization and on melting behavior of matrix PP were investigated. The results were compared with a pristine MWNT (p‐MWNT) incorporated system. It was shown that PP coated CNTs can serve as a strong nucleating agent for templated polymer crystal growth. Unlike other PP nanocomposites in the literature, a relatively high shift of 7°C in melting peak maximum (Tp), along with a sharp melt endotherm was achieved with the addition of 0.3 wt% f‐MWNT via PP/f‐MWNT master batch. This indicates refinement of matrix PP crystalline region due to the tailored f‐MWNT surface chemistry. With a designed self‐seeding and templated crystal growth approach, columnar crystalline interphases were found surrounding MWNT which melted at 10.5°C higher temperature than neat PP crystallized without undergoing the same heat treatment protocol. POLYM. ENG. SCI., 59:1570–1584 2019. © 2019 Society of Plastics Engineers

Rheological behavior of polypropylene nanocomposites with tailored polymer/multiwall carbon nanotubes interface

“…Under quiescent crystallization (no applied preshear), the crystallization rate was the fastest in p‐MWNT (5.3 min), followed by PP/f‐MWNT master batch (8 min) and MA‐ g ‐PP/f‐MWNT masterbatch (30 min)‐based nanocomposites (1 wt% MWNT), and then followed by neat PP (69 min). At 1 wt% MWNT, p‐MWNT was found to be a more effective nucleation agent then f‐MWNT due to the presence of the functional group in the latter . However, under the effect of preshear applied at 180°C, both masterbatch‐based samples exhibited a noticeable change of crystallization time while there was nearly no change in the case of neat PP and PP/p‐MWNT (Fig.…”

“…The resulting PP/f‐MWNT, MA‐ g ‐PP/f‐MWNT masterbatches or untreated pristine MWNT (p‐MWNT) were melt microcompounded with PP. In our previous works , it has been demonstrated that the noncovalently modified MWNTs by PP brought about significant improvement not only in f‐MWNT dispersion in PP but also in impact strength (152% increase in impact strength at 1 wt% CNT loading) and crystal perfection (as demonstrated by 7°C increase in peak melting temperature at 0.3 wt% MWNT loading). In this article, we study the role of noncovalently coated polymer on the rheological properties of PP/f‐MWNT nanocomposite melts.…”

“…For example, the polypropylene (PP)/CNT nanocomposites (fibers, foams, bars, etc.) have been studied for mechanical reinforcement , dimensional stability , wear resistance , crystallization , antistatic behavior , electromagnetic shielding , thermal and electrical conductivity , mechanical sensors , and so forth. CNTs have also been reported to reduce die swell and even promote “die shrinkage” due to their larger aspect ratio forming entangled CNT network.…”

Structure, properties, and applications of polyacrylonitrile/carbon nanotube (CNT) fibers at low CNT loading

“…For these MWNTs, an average number of 9 to 10 walls and an average diameter of 12 ± 3 nm were determined by X-ray diffraction and SEM, respectively, in previous study. [35,36] Dimethylformamide (DMF) was obtained from Sigma Aldrich (HPLC grade, >99.9% purity). Methanol (ACS grade) and glycerol were purchased from VWR Chemicals.…”

Carbon nanotubes interaction with amorphous and semi‐crystalline domains of polypropylene in melt‐mixed composites: Influence of multiwall carbon nanotubes agglomerate and their modifications

“…[ 8–10 ] In this context, MWCNTs have shown to increase the bulk crystallization temperature ( T c ) of PP indicating the hetero‐nucleating action of MWCNTs. [ 10–13 ] However, the extent of hetero‐nucleating action of MWCNTs depends on the type of MWCNTs and dispersion state of MWCNTs in PP/MWCNTs composites. Further, dispersion of MWCNTs in PP matrix primarily depends on the extent of “agglomeration” associated with the MWCNTs type, interfacial interaction between PP and MWCNTs and the parameters used in processing.…”