Measurement and control of extensional viscosity in barrier coating dispersions, TAPPI Journal November 2023

 


Application: Extensional viscosity can be used to improve the operating window of a curtain coater and reduce reliance on surfactants. This study compares different viscoelastic additives and discusses two methods of measur-ing extensional viscosity.

TAPPI conference proceedings and presentations, technical papers, and publication articles provide technical and management data and solutions on topics covering the Pulp, Paper, Tissue, Corrugated Packaging, Flexible Packaging, Nanotechnology and Converting Industries.

Simply select the quantity, add to your cart and your conference paper, presentation or article will be available for immediate download.
Author: Watti Lehtimäki, Andreas Schröder, Vesa Kukkamo, and Martti Toivakka
Measurement and control of extensional viscosity in barrier
ABSTRACT: This study aimed to understand the effect of various rheological additives on the extensional viscosity of barrier coating dispersions, as well as to understand the role extensional viscosity plays in stabilizing a liquid curtain. The apparent extensional viscosity was measured using two devices that create accelerating flows: a capillary viscometer and an orifice rheometer. Additives tested include several polyvinyl alcohols, a high molecular weight polyethylene oxide, and carboxymethylcellulose. Extensional viscosity plays a significant role in stabilizing a liquid curtain, as it slows down hole expansion and prevents impurities and disturbances from causing holes in the first place. Some of the additives could substantially increase the extensional viscosity of the dispersions without increasing the shear viscosity outside the typical range of processability for a curtain coater. Some of the additives exhibited coil-stretch transition, meaning they start increasing extensional viscosity above a certain extension rate. Polymers with low chain lengths exhibited finite extensibility, which indicates the polymer chain has fully extended and cannot provide further extensional viscosity, even though the extending force is increased. Polymeric additives with stiff or branched chains significantly raised shear viscosity without increasing extensional viscosity. Both methods could reliably measure extensional viscosity in curtain coating barrier dispersions.
0.00

New Releases

TAPPI PRESS Catalog eBook 2024


Experience the Power of Publications in the 2024 TAPPI Press Catalog


Open
 

Kraft Recovery Boilers, Third Edition  


Sponsored by the Recovery Boiler Program R&D Subcommittee of the American Forest & Paper Association (AF&PA) and published by TAPPI Press.


Purchase
 

Handbook For Pulp and Paper Technologists (The SMOOK Book), Fourth Edition

The best-selling text to introduce the entire technology of pulp and paper manufacture.

Purchase
 

Guidelines for Safe Assessment and Operation of Yankee Dryers  


A project of the Yankee Dryer Safety & Reliability Committee.

Purchase
 

Check our newest additions.


TAPPI Press offers some of the most in-depth resources and references for the forest products and related industries. 

See More
   
 

Available for Purchase – Conference Proceedings


TAPPI maintains a record of key conference papers, presentations, and other conference publications, available for purchase in a variety of formats.

See More