9:00 am – 9:30 am:
PET Advancements in Extrusion Blow Molding
Scott Steele, SWS Consluting, LLC
I would propose creating a summary of efforts to utilize PET in extrusion blow molding. The main processes for making PET bottles involve creating an expensive injection mold in combination with expensive blow mold tooling. This approach works for large volume production of 100million containers or more, but many potential packages for lower volume users are not well served. Resin suppliers have created grades of PET with increased melt strength that have begun to address this market need. These materials are imposing problems for recycling of PET which needs to be addressed. I think a summary paper of the activity that has taken place will be of interest to ANTEC attendees. I have not written the paper but will if the organizers wish a presentation.
9:30 am – 10:00 am:
A Simulation Framework for Blow-molding: A Preliminary Case Study on Injection Stretch Blow Molding for Bulb Covers
Raghavendra Janiwarad, SABIC
In this report, we present preliminary results on the use of blow-molding simulation as a tool for optimizing processing conditions and preform / parison geometry to achieve a blow molded part with the desired thickness distribution. Simulations were carried out using the software B-SIM† in the context of stretch-blow-molding of PC injection-molded preforms for LED bulb cover applications. This application requires optical quality parts and imposes stringent requirements on tolerances for the thickness uniformity of the blow-molded cover. Baseline simulations — with preform geometry matching that used in initial experimental trials, and employing processing conditions similar to those employed in the blow-molding trials – estimated thickness variations exceeding the tolerances imposed by the application. Virtual iterations with B-SIM† simulation trials were then employed to optimize the geometry of and initial temperature distribution within the preform, as well as the processing conditions to result in predictions of significant improvement in thickness uniformity of the blown part.
10:00 am – 10:30 am:
Numerical Simulation of Shrinkage and Warpage Derformation of an Intermittent-Extrusion Blow Molded Part:
Validation Case Study
Zohir Benrabah, National Research Council Canada
Intermittent extrusion blow molding is increasingly being used in polymer forming processes for the production of complex thermoplastic industrial parts with short cycle times. During this process residual stresses caused by inhomogeneous cooling and relaxation of polymer chains, often result in shrinkage and warpage of the final part. One challenging quality requirement of industrial blow molded parts is geometric tolerances. Therefore part deformation, due to cooling and solidification, needs to be controlled and optimized according to specific design criteria. In particular, the complex design shapes of plastic fuel tank (PFT) shells exacerbate these challenges which need to be resolved upfront, in the early stages of product development and tool design. Consequently, the development of an accurate simulation tool, well suited for industrial applications, to predict thermoplastic part deformations due to cooling and solidification, has become essential for part designers to help achieve an efficient production with minimum manufacturing cost. The aim of this work is to present the latest advancements in predicting the shrinkage and warpage deformation of a curved PFT, designed for agricultural machinery, using NRC’s BlowView software. This case study validation considers the entire blow molding stages (i.e., polymer flow in the die, parison formation, inflation, and finally in and out of mold cooling during part solidification). The simulation results, in terms of thickness distribution and displacements, are compared to an actual scanned part using the best fit technique in order to exemplify the accuracy and reliability of the modelling approach.
8:00 am – 11:30 am:
W5-Engineering Properties and Structure: Polymer Physical Properties II
(Moderators: Gerry Billovits and Paul Hans)-Room S320B
8:00 am – 8:30 am:
Foam Structure and Thermal Comfort in Polyurethane Mattress Foams
Douglas Brune, The Dow Chemical Company
The cell structure of a mattress foam influences a number of foam physical properties which are important to the thermal comfort of a sleeping person. An interconnected model was developed to quantify these relationships with the following model components: 1) semi-empirical sub-models to relate foam structure to foam properties, 2) finite element analysis to simulate transport of heat and moisture within a foam mattress, and 3) lumped-parameter model to quantify human thermal response to external environment. This paper presents the results of numerical simulations using the combined model, in which important structural parameters are traced to their ultimate effects on thermal comfort.
8:30 am – 9:00 am:
Prediction of Fiber Reinforced Plastics Considering Local Fiber Length and Orientation
Fabian Willems, Institut für Kunststofftechnik
The gaining importance of sustainability in recent years has also led to a closer look on lightweight materials such as fiber reinforced plastics. However, these materials usually pose a challenge in application. Purposeful virtual engineering and prediction is part of it. A new approach allows the reliable prediction of discontinuous fiber reinforced plastics based on integrative simulations while taking local fiber orientation and local fiber length into account. The results obtained with this method already show an improvement in prediction of simple part geometries. Further gain in quality is expected by complex parts where fiber orientation distribution and fiber length distribution spread more widely.
Anthony Sullivan, Tufts University
Liquid crystal polymers (LCP’s) make up a class of performance materials that derive favorable mechanical, chemical, and electrical characteristics from their long-range molecular ordering. This unique microstructure gives rise to anisotropic bulk behavior that can be problematic for industrial applications, and thus the ability to model this directionality is essential to the design of manufacturing processes for isotropic material production. Previous efforts to model LCP orientation have typically been restricted to structured grids and simple geometries that demonstrate the underlying theory, but fall short of simulating realistic LCP manufacturing methods. In this investigation, a methodology is proposed to simulate the director field in practical LCP process geometries for the prediction of the bulk material orientation state. The polymer flow is first simulated using a commercial CFD software and the rheological results are input into post-processing calculations of the polymer directionality. It is shown that the model predicts the expected change in anisotropy as the mold cavity thickness is changed for an LCP injection molding process.
9:30 am – 10:00 am:
Crystallization Mechanism of Polyvinylidene Fluoride via Non-isothermal Crystallization and Supercritical CO2 Processing
Ji Eun Lee, York University
Polyvinylidene fluoride (PVDF) is a non-toxic, conformable, and low-cost alternative to traditional piezoelectric ceramic in sensors and actuators. While fabrication methods such as mechanical stretching are commonly used, a combination of non-isothermal processing and supercritical carbon dioxide (ScCO2) processing has been used to successfully promote the electroactive phase (i.e., α, β, and γ phases) of PVDF. In this paper, this processing method was further analyzed by decoupling the manufacturing process into individual steps to elucidate the processing-to-structure properties and mechanisms that affect the crystallization behaviors of the electroactive phases. Differential scanning calorimetry, scanning electronic microscopy, and infrared spectroscopy were utilized to study the crystallization of the polymorph phases. Experimental results further supported our findings on the formation of γ crystal phase and its inverse relationship to β crystal phase. The results were revealed to be comparable to the mechanical stretching method with a maximum electroactive crystal phase of 72.2%.