8:00 am – 10:00 am:
W9-Flexible Packaging: Film Sealing and Barrier
(Moderator: Lora Liang)-Room S322
8:00 am – 8:30 am:
KEYNOTE: Rethinking Machine Direction Sealing
Michael Pilolli, D.R. Joseph, Inc.
Flexible packaging design is often limited by the perception that machine direction seals represent a weakness in the integrity of the product. Material returns due to failed seals can cause both operators and customers to lose confidence in traditional slit seal systems. Fortunately, new technology provides an innovative approach to machine direction sealing that can reestablish confidence in seal integrity while simultaneously improving seal appearance. This approach works with polymer properties, rather than against them by avoiding thermal degradation to create a strong bond. This presentation will look at the new tools, methods and opportunities related to expanding possibilties beyond typical hot knife system limitations. Rethinking MD sealing opens up a myriad of opportunities to produce smarter, quicker and with greater flexibility.
Dan Ward, NOVA Chemicals
Heat transfer through multilayer or coextruded films is an important but often overlooked consideration that affects package converting operations and end-use package integrity. Predicting or modelling heat transfer in coextruded films is difficult because thermodynamic properties of polymers such as specific heat (Cp) and thermal conductivity (k) are not constant with changing temperature. NOVA Chemicals recently developed test methods for estimating Cp and k over a broad range of temperatures which enabled us to develop a predictive heat transfer model for multilayer films containing up to 9 polymer layers. The model provides useful guidance on polymer selection, coex layer ratios and layer placement when specific temperature or thermal performance targets are required. Two case studies will be presented that demonstrate how heat transfer modelling can be used to optimize multilayer structure design for improved performance. The first study demonstrates how interior polymer layers affect sealant cooling rates after the seal jaws are opened. By accelerating sealant cooling rates, the apparent hot tack strength and hot tack temperature window can be increased. The second study demonstrates how multilayer film thickness, the types or polyethylene or Nylon and layer distributions affect heat retention during vacuum thermoforming. When more heat is retained during the forming process, the finished package typically has better gauge uniformity and part definition.
9:00 am – 9:30 am:
Thermo-Rheological Modeling and Simulation of Heat Sealing Process for Multi-Layer Flexible Packaging Applications
Vinod Kumar Konaganti, NOVA Chemicals Coroporation
Heat sealing processes are the most widely used sealing technique in form-fill-seal packaging applications. This process involves the optimization of sealing temperature, dwell time and sealing pressure to achieve a hermetic seal between two monolayer/multilayer polymer films. During this process, the heat transfers through the film structure, melts the resin at the interface and allows the polymer molecular chains to diffuse across the interface to develop the required seal strength. In order to develop strong seals at the interface, it is important to understand the interactions between thermal and rheological behavior of each layer in the multilayer structure as well as the dynamics of melting and crystallization at the seal interface. A novel phenomenological model based on thermo-rheological properties of polymers in the sealing regime has been developed to describe the heat sealing behavior of multilayer polymer films as a function of processing/operating conditions and resin architectural characteristics. In this modeling framework, a dynamic model combining heat transfer and deformation during the squeeze flow has been implemented to understand the coupled effects of phase change (melting/crystallization) and polymer rheology on the heat sealing behavior. The present model is capable of predicting the temporal variations of the interfacial temperature and seal behavior by considering the effects of: (a) non-isothermal squeeze flow of polymer films; (b) processing conditions (seal pressure, seal bar temperature, and dwell time); (c) resin molecular characteristics; and (d) phase transitions (melting/crystallization). The predicted seal characteristics are compared with the experimental data to validate simulation results. This model may serve as a robust tool for efficient multilayer film structure development and optimization of various processing/operating conditions.
9:30 am – 10:00 am:
Barrier Materials Having Layer-Like Morphology for Packaging Use:Extruded Film and Oriented Film
Guojun Zhang, A. Schulman Inc.
It is well known that gas permeability of packaging is a key element for improving food shelf life . In order to achieve desired gas barrier for specific gas species as well as maintain other physical properties and being cost efficient, multilayer structures are widely used in packaging industry to meet different requirements. It is a trend that the industry is transforming from monolayer structure and 3-layer structure to 5-layer structure, 9-layer structure and even 11-layer structure . Multilayer structures not only provide flexibility for manufacturers to apply various functionalities, but also potentially reduces the cost of complex packaging systems. However, multilayer co-extrusion process itself is sometimes a challenge for many producers. In this study, an alternative technique, which produces materials with layer-like morphology is reported. These materials are innovatively formulated and engineered so that multilayer-like morphology arises after they are simply extruded through a single extruder. These materials can be used as monolayer films or co-extruded with other polymers. Good gas barrier (both OTR and WVTR) properties are discovered for these materials. Nevertheless, these materials depending on the specific grade can be used for cast film, blown film and biaxially-orientation film.
10:00 am – 11:30 am
(Moderator: Mukul Kaushik)-Room S322
10:00 am – 10:30 am:
KEYNOTE: Shifting Marketplace Synamics and Positioning TPEs for Future Profitability, Diversification and Growth
Robert Eller, Robert Eller Associates LLC
This paper will examine: -Key inter-TPE competitions and how they are changing -The impacts of commoditization and globalization of the TPE marketplace -Supply chain shifts affecting TPEs -Important new TPE/fabrication couples, their impact on the marketplace and strategies for competing in new TPE sectors including sensing, smart applications, vehicle electrification.
10:30 am – 11:00 am:
Elastic Recovery and Actuation in Polyolefin Thermoplastic Elastomers
Barbara DeButts, Virginia Tech
Polyolefin elastomers (POEs) are a class of thermoplastic elastomer (TPE) that can be easily processed. POEs have broad applications from the automobile industry to the footwear industry, but for highly customizable materials the POEs must be altered on the microstructural scale. In this work, a systematic study of how thermal processing affected the ability of ethylene-octene random copolymers to store and dissipate applied strain energy was undertaken. Ethylene-octene copolymers with different degrees of crystallinity were compression molded and slow cooled, quench cooled, or annealed. Copolymer blends were mixed, varying the ratio of high crystallinity copolymer to low crystallinity copolymer. Tensile testing of the cooled samples showed that the crystallinity correlated to the elastic modulus and hysteresis behavior. The higher crystallinity samples exhibited higher hysteresis and higher modulus than the lower crystallinity samples. The blends were immiscible but exhibited physical behavior between the two components. Actuators were built by molding POE bilayers where one layer had higher elastic recovery than the other layer. Stretching and releasing the bilayer resulted in different extents of bending and twisting depending on the applied strain. Microstructural control will allow for the optimal design of elastomeric materials and actuators with anticipated properties.
11:00 am – 11:30 am:
From Recycled Tires to Plastic Parts: Micronized Recycled Rubbers in Thermoplasitc Polyolefins
Haikun Xu, Entech, Inc.
Micronized rubber powders (MRPs) have shown superior compatibility in TPOs and excellent elastomeric properties. However, it requires efforts to explore the use of MRPs in useful products and a few challenges need to be addressed. In this study, MRP-filled TPEs were compounded at various loading ratios and the effect of sizes of MRPs was investigated. In addition, the surface details of injection molded parts were studied and induction-heated molding were implemented to improve the surface finish for various applications. Finally, multiple conventional plastic processes were explored and injection-molded parts made out of MRP-filled compounds were demonstrated to discover more potential applications.