CaltechAUTHORS
  A Caltech Library Service

Effect of Long Chains on the Threshold Stresses for Flow-Induced Crystallization in iPP: Shish Kebabs vs Sausages

Fernandez-Ballester, Lucia and Thurman, Derek W. and Zhou, Weijun and Kornfield, Julia A. (2012) Effect of Long Chains on the Threshold Stresses for Flow-Induced Crystallization in iPP: Shish Kebabs vs Sausages. Macromolecules, 45 (16). pp. 6557-6570. ISSN 0024-9297. https://resolver.caltech.edu/CaltechAUTHORS:20121009-112542596

Full text is not posted in this repository. Consult Related URLs below.

Use this Persistent URL to link to this item: https://resolver.caltech.edu/CaltechAUTHORS:20121009-112542596

Abstract

The addition of small concentrations (2 wt % or less) of ultrahigh molecular weight isotactic polypropylene (M_L ~3500 kg/mol) to a matrix of lower molecular weight chains (MS ~ 186 kg/mol, e.g. M_L/M_S ~ 20) substantially decreases the critical stress for inducing a highly oriented skin under flow-induced crystallization conditions—significantly more than for blends of M_L/M_S ~ 5 (Seki et al.)—and promotes the formation of point precursors and oriented “sausage-like” structures not observed for M_L/M_S ~ 5. These differences correlate with the onset of long chain stretching during shear: the ratio of long chains’ Rouse time to short chains’ disengagement time indicates that 3500 kg/mol chains can easily stretch if tethered onto a point nuclei and even when untethered. Adding 3500 kg/mol chains has strong effects that saturate beyond the overlap concentration, suggesting that an uninterrupted supply of long chains greatly accelerates formation of threads. A conceptual model is proposed that distinguishes between a critical stress for shish initiation and that for propagation.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/ma3000384DOIArticle
ORCID:
AuthorORCID
Kornfield, Julia A.0000-0001-6746-8634
Additional Information:© 2012 American Chemical Society. Received: January 5, 2012. Revised: June 2, 2012. Published: August 1, 2012. We thank Dr. Robert Sammler of Dow Chemical Company for kindly providing the matrix iPP materials used in this study. We are also grateful to Dr. Igors Sics and Dr. Lixia Rong of beamline X27C (NSLS) for assistance in X-ray experiments. The ITP workshop is acknowledged, including discussions with Tom McLeish and Scott Milner. Funding was provided by the National Science Foundation under Grant DMR-0505393. The authors declare no competing financial interest. This article posted ASAP on August 1, 2012. Figures 8 and 12 have been revised. The correct version posted on August 2, 2012.
Funders:
Funding AgencyGrant Number
NSFDMR-0505393
Issue or Number:16
Record Number:CaltechAUTHORS:20121009-112542596
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20121009-112542596
Official Citation: Effect of Long Chains on the Threshold Stresses for Flow-Induced Crystallization in iPP: Shish Kebabs vs Sausages Lucia Fernandez-Ballester, Derek W. Thurman, Weijun Zhou, and Julia A. Kornfield Macromolecules 2012 45 (16), 6557-6570
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:34784
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:09 Oct 2012 18:41
Last Modified:30 Oct 2019 18:45

Repository Staff Only: item control page