8:30 am – 9:00 am:
Effect of Die Exit Stress State, Deborah Number and Extensional Rheology on Neck-in Phenomenon
Martin Zatloukal, Tomas Bata University in Zlin
In this work, effect of the second to first normal stress difference ratio at the die exit, uniaxial extensional strain hardening, planar-to-uniaxial extensional viscosity ratio and Deborah number has been investigated via viscoelastic isothermal modeling utilizing 1D membrane model and a single-mode modified Leonov model as the constitutive equation. Numerical solutions of the utilized model were successfully approximated by a dimensionless analytical equation relating the normalized maximum attainable neck-in with all above mentioned variables. Suggested equation was tested by using literature experimental data. It was found that approximate model predictions are in a very good agreement with the corresponding experimental data for low as well as very high Deborah numbers. It is believed that the obtained knowledge together with the suggested simple analytical model can be used for optimization of the extrusion die design, molecular architecture of polymer melts and processing conditions to suppress neck-in phenomenon in production of very thin polymeric flat films.
9:00 am – 9:30 am:
Micro-layered Tubing and Pips Via Multi-layer Co-extrusion
Tyler Schneider, Case Western Reserve University
A die was designed and validated for a layer multiplication co-extrusion line, capable of producing layer structures of tens to thousands of layers, and achieving layer thicknesses from millimeters to tens of nanometers. Validation extrusion runs utilizing the die shows the ability to successfully produce high layer number, micrometer layer thickness, samples with annular structure for an LDPE layered system. Weld lines and the formation of a concentric layer structure were achieved by the implication of an annular land having angular rotation capabilities.
9:30 am – 10:00 am:
Role of Interfacial Crystallization in Designing Polyolefin Blends From Mixed Stream Recycle Feeds
Alex Jordan, University of Minnesota
Polyolefin production requires ~8% of global oil and natural gas production for monomer supply and the energy required for polymerization; often these polyolefins are used in short term applications such as packaging. While researchers work toward long term solutions involving sustainable polymers, the short term focus on how to better recycle polyolefins currently in the production/consumption cycle must be addressed. Given their chemical similarity and similar density, recycled polyolefins are difficult to separate from recycle streams often resulting in mixed stream recycle feeds. Previously we presented the role of residual oligomer after Ziegler-Natta polymerization of polyethylene (PE) and isotactic polypropylene (iPP) in preventing cross interfacial crystallization of immiscible PE-iPP bilayers which resulted in weak interfacial adhesion. We also presented strategies for promoting cross interfacial crystallization via processing (rapid interfacial quenching) and materials selection (thickened interfaces) in PE-iPP bilayers. Here we investigate the role of interfacial adhesive strength between three PE-iPP blends in the absence of applied shear during processing. With poor interfacial adhesion between PE/iPP, brittle failure of each blend was observed, as expected with immiscible polymer pairs. When interfacial adhesion strength exceeded that of the strength of component homopolymer, exciting synergism was observed between PE/iPP blends. Processing in the presence of applied shear flows (injection molding and film extrusion) will also be discussed. This finding highlights the importance of considering interfacial strength when designing mixed polyolefin recycle streams.
10:00 am – 10:30 am:
Evaluation of Thermoplastic Polyurethane (TPU) Resins as Possible Substitutes of Current Resins for Escalator Hadrails
Qingping Guo, EHC Canada
Two new thermoplastic polyurethanes (TPU) were evaluated in their possibility to substitute two TPUs currently used in the production of escalator handrail. The assessment is carried out through comparison of their thermal, rheological and mechanical properties. It was found that although the new TPUs show promise, changes should be carried out to make them more compatible with the current process set up and conditions.
10:30 am – 11:00 am:
Preliminary Study of Birefringence Distribution in Blown Film
Jin Wang, The Dow Chemical Company
A birefringence scanner was used in this study to measure the distribution of birefringence in blown films. The objective of this study was to evaluate the birefringence scanner as a new tool for blown film research. Seven films were made on a small-scale research line at various process conditions (i.e., thickness, blow up ratio (BUR), rate and frost line height (FLH)). Clear in-plane birefringence variations were found in all films. More significant birefringence variation was found in the cross machine direction (CD) of the film and less variation in the machine direction (MD). The birefringence variation on the CD direction could be caused by uneven flow and cooling in the die and air ring. There were no clear relationships found among mechanical properties of films, process conditions and average in-plane birefringence in the films studied. This demonstrates that birefringence scan of film is a very useful tool for studying the fundamentals of blown film process.
11:00 am – 11:30 am:
Energy Gap Method (EGM) Applied to Improve Extrusion Energy Performance: Successful Case Studies
Juan Carlos Ortiz Pimienta, ICIPC-Instituto de Capacitación e Investigación del Plástico y del Caucho
A novel and upgraded strategic decision methodology to increase energy efficiency in industrial processes, the Energy Gap Method (EGM), is presented. For this methodology, six different specific energy consumption levels are proposed. Five gaps or differences between specific energy consumptions can be calculated: production, quality, process, technological, and R&D gaps. Three industrial successful case studies enhancing the energy efficiency, two in extrusion blow molding and one in sheet extrusion are presented, obtaining specific energy consumption (SEC) reductions between 14 and 65%.