1:30 pm – 6:00 pm:
W12-Applied Rheology

(Moderators: Kurt Koppi and Qian Qin)-Room S320A

1:30 pm – 2:00 pm:
KEYNOTE: Rheology of Polymer Nanocomposites

Avraam I. Isayev, The University of Akron
The rheological behavior of polymer nanocomposites is a field of vital importance to scientists and engineers in the plastic and rubber industry. The rheological behavior of nanocomposites is affected by type of fillers (nanoparticles, graphene, nanofibers and nanotubes) their concentration, filler-filler and polymer-filler interactions. After decades of extensive research, the theoretical description of the linear and nonlinear behavior of nanocomposites is still lacking. This presentation will discuss the rheological behavior of the polymer nanocomposites in small and large amplitude oscillatory flow (SAOS and LAOS), start-up shear flow and step-strain relaxation. Our current understanding of theoretical description of various rheological properties obtained in these flow regimes will be presented. The model parameters will be obtained from SAOS experiments. Then these parameters will be used to describe the nonlinear behavior in various flow regimes.

2:00 pm – 2:30 pm:
Modification of Rheological and Crystallization Properties of High Performance Polymers for Thermoplastic Composite Applications

Sarah Morgan, U. Southern Mississippi
Continuous fiber reinforced thermoplastic composites offer many advantages over thermoset composites, including longer shelf lives of raw materials, faster processing times, design freedom, and the ability to recycle. High performance resins offer high use temperature and excellent mechanical properties in composites, however they present the challenges of high processing temperatures and melt viscosities. Polyhedral oligomeric silisesquioxane (POSS) nanostructured chemicals offer the opportunity to enhance melt flow and increase crystallization rates in polymer systems when they can be dispersed at the nano-level. We describe the rheological and crystallization performance of POSS blends with PPS and PEEK resins.

2:30 pm – 3:00 pm:
Investigation on the Viscosity Characterization of the Glass Mat Thermoplastics (GMT) in Compression Molding System

Chien Tse-Yu, Department of Chemical and Material Engineering in Tamkang University
Due to its great features of lower tooling cost, better retaining fiber length and concentration, glass fiber mat thermoplastics (GMT) material has been attracting a lot of attention in modern lightweight technology development. However, some defects and unstable quality control problems are still bothering us. To overcome these troubles, people are usually applying CAE technology to assist. However, in this field, CAE is not mature enough yet due to the rheological properties of the GMT material are not measured properly. In this study, we have proposed a method to measure the rheological properties of GMT material through a compression system. Specifically, we have focused on the viscosity of the squeeze flow under the operation of compression processing. The analyzed data is further used for estimation of the rheological parameters and calculation of viscosity at various temperature settings. Moreover, the estimated rheological parameter of the GMT material is integrated into Moldex3D to evaluate the squeeze flow behavior under the compression operation through numerical simulation and experimental study. Results showed that under the higher compression speed, the loading force is increased exponentially as melt flow time is increasing. The numerical simulation prediction is consistent with that of experimental result. However, at slower compression speed, the deviation becomes more serious for simulation approach and experiment. The reason needs to be investigated later. Also, there are various conditions need to consider in the coming future.

3:00 pm – 3:30 pm:
Visualization of the Flow Paths in a Tangential Internal Mixer to Optimize the Mixing Behavior

Annika Lipski, Institute of Plastics Processing in Industry and the Crafts at the Aachen University of Technology
The visualization of the flow paths in a tangential internal mixer gives the opportunity to understand which kind of mixing is pronounced in dependency of process parameters. With this knowledge the mixing processes can be optimized, so that shorter mixing times and more homogenous mixing is possible. The flowing behavior between the rotor and the mixing chamber was already investigated extensively but the complex flow paths between the rotors is not well known yet. With different colored compounds, it is possible to visualize the flow paths in the mixing chamber. Hereby, the mixing process is stopped after different mixing times and the mixing chamber is completely opened to take the compounds out of it. Those compounds are sliced and photographed. The complex flow paths can be analyzed with different methods that are evaluated in this contribution. One possibility is the analysis of objects in the area between the rotors to draw conclusion on the distributive and dispersive mixing.

3:30 pm – 4:00 pm:
The Effects of Metal Stearates on the Rheological Properties of Powder Injection Molding Feedstocks and Resulting Molded Green Parts

Michael Shone, UMass Lowell
The effects of adding metal stearates to a powder injection molding (PIM) feedstock prepared with a wax based binder system and silicon powder was investigated. The rheological properties and molding properties of the feedstocks were characterized. Predictive viscosity models were developed for each feedstock. The zero-shear viscosity was constant with the introduction of metal stearates while, the yield stress was seen to decrease. The molded green parts were produced with a traditional injection molding process. The surface quality of the molded green parts did not seem to change. The quality through the thickness changed as vacuum voids started to form with the introduction of the metal stearates.

4:00 pm – 4:30 pm:
Root Cause Analysis of Polyolefin-Based Wire and Cable Formulation Die Build-Up

Kurt Koppi, Dow
Die build-up negatively impacted the capacity of a compounding line for the production of a polyolefin-based wire and cable formulation. This paper discusses a root cause analysis performed on the die build-up defect, the identified solution, and the resulting economic impact.

4:30 pm – 5:00 pm:
Rheological Method Development: Polymer Designs for Blow-molded, Automotive Seatbacks

Mary Ann Jones, The Dow Chemical Company
Extrusion blow-molding of very large parts such as those used in the automotive industry can exceed the melt strength limits of the polymer or polymer blend of choice. This study was undertaken to define new rheological tests capable of defining the maximum parison weight a material can maintain in the blow-molding process at a given die dimension and temperature. In addition, this is balanced with 1) measurements of the extent of shear thinning as it relates to shear heating that reduces melt strength and 2) measurements of strain recovery that add to the parison weight required to achieve a given length. These rheological measurements are combined with the mechanical properties required to meet specific automotive material specifications as responses in a design of experiments approach to polymer development. Compositional factors associated with PC/ABS blends were defined to successfully produce a model predicting both the ability to fabricate a part from a 30 lb. parison as well as have the mechanical properties necessary to meet the requirements of the European Luggage Retention impact standard for a seatback.

5:00 pm – 5:30 pm:
The Importance of How Online Rheometers Accurately Indicate Melt Flow Rate in an Extruder

Catherine Lindquist, Dynisco
Online rheometers have been growingly used in the plastics processing industry to improve the process productivity and sustainably as it continuously certifies the resins or regrinds to be within the required specification. A newly developed online rheometer (Dynisco® ViscoIndicator) was designed to duplicate the test conditions of a standard melt flow rate tester and monitor the rheological properties particularly melt flow rate (MFR) and intrinsic viscosity (IV) of the plastics materials while processing in an extrusion line. Also, the temperature dependency of the flow parameters was correlated by calculating the activation energy of the samples. By considering the value of activation energy, ViscoIndicator is able to calculate the MFR value of the extruded materials at the standard temperature regardless of the temperature that extrusion is running at. The recorded data from the online ViscoIndicator was validated through comparison with that from actual laboratory testing. A good agreement was found between online and offline measurements which makes the ViscoIndicator useful for quality and process control purposes in variety of manufacturing and recycling industries.

5:30 pm – 6:00 pm:
A Mechanistic Model for Nanocavity Filling

Donggang Yao, Georgia Institute of Technology
In this paper, we present an analytical study on the influences of different competing factors on the nanocavity filling process. Particularly, various dimensionless groups are defined to gauge into the size effects in nanocavity filling. A mechanistic model for nanochannel flow is formulated on the basis of disentanglement between molecular layers. The focus was placed on determining the major enabling factors for achieving cavity fill in an extremely short imprinting period on the order of 1 second. It is found that a high-energy mold surface is necessary in roll-to-roll imprinting where the contact time is extremely short and a high imprint pressure is difficult to apply. Additionally, in-mold solidification must be incorporated in precision replication, suppressing shape distortion caused by elastic recovery.