National Week of Plastics Processing
National Week of Plastics Processing

2021 Plastics Processing Conference Presentations

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Day 1- April 6th  
9:00 – 9:10 am Welcome and Introductions (LV BoD)

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Sustainability  
9:15-10:00 am KEYNOTE: "One Man's Trash"
Conor Carlin, SPE Vice President of Sustainability & (Managing Director) Illig LP
Though many in the plastics industry are familiar with the overwhelming benefits that polymeric materials provide, the public has become highly skeptical. And rightly so – when you see clogged rivers and dead fish, what are people supposed to think? Let's rethink plastics among ourselves for a moment, at least in terms of how the public views it. By acknowledging the paradoxical nature of plastics' efficiency, we can perhaps take a more holistic approach to design that utilizes the full value of a material's properties while considering end-of-life implications. The nuances and complexities of modern plastics ensure that there are no easy answers. And though we have to make difficult choices, we cannot let the perfect be the enemy of the good.

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10:00-10:30 am Sustainable Polymer Additives from Recycled Feedstocks: Novel Tools to Drive Performance, Enhance Value, and Boost PCR Content
Domenic DiMondo, VP of Technology & Business Development, GreenMantra

GreenMantra Technologies utilizes its advanced recycling technology to produce novel polymer additives and specialty chemicals from recycled plastics. This technology takes advantage of the integrity of the plastic molecule while modifying the chemical structure to produce new value-creating materials that are used as processing aids and performance enhancers in various industrial applications. GreenMantra additives can be utilized in roofing, extruded plastic, and other construction infrastructure applications that have useful lifespans of 20-50+ years, opening new pathways for utilizing recycled plastics and extending the life of single-use-plastics.

Specific to the plastic processing industry, GreenMantra's polyethylene and polypropylene additives help overcome processing challenges experienced when incorporating recycled plastic content. To compensate for the variable properties of recycled plastic streams, formulators must often make a sacrifice in performance, efficiency, and/or profitability in order to incorporate recycled content into their products. GreenMantra's polymer additives allow formulators to defy that paradigm, enabling compounders and plastic processors to improve performance and lower formulation / operational costs, while simultaneously increasing the recycled content of their finished product.

GreenMantra's business model bridges new circles together to expand the lifespan and applicable end markets for discarded plastics. By "thinking outside the circle", GreenMantra has successfully scaled its chemical recycling business and is diverting millions of pounds annually of waste plastic from landfills and our oceans into new applications each year.

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10:30–10:55 am

Break — Gold Sponsor

10:55–11:00 am

Kenrich® Petrochemicals, Inc. — Gold Sponsor
Advanced Processing of Polymer Blends Using 1.5-Nanometer Titanates and Zirconates
Salvatore Monte, Kenrich Petrochemicals Inc.

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Twin Screw Compounding  
11:00 – 11:30 am Compounding via Twin Screw Extrusion for 3D Filaments
Charlie Martin, President, Leistritz Extrusion
Twin screw extruders (TSEs) are commonly used to compound plastics formulations to impart desired properties into a 3D filament. Polymers, additives, particulates and active ingredients are metered into the TSE process section, where rotating screws impart shear and energy to facilitate mixing, devolatilization and reactive extrusion. Pellets are often produced that then are fed into a single screw extruder mated to a downstream system that makes a 3D filament. The same downstream system can be mated to the twin screw extruder to make a 3D filament in one-step, which results in the final product having one less heat and shear history. TSE compounding fundamentals and a comparison of direct extrusion versus pelletization and a 2nd stage single screw extrusion operation, with the benefits of each, will presented and explained.

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11:30 – 12:00 pm Tool Box for Quality Color Pigment Dispersions on Twin Screw Extruders
Justyn S. Pyz, Process Engineer, Coperion Corporation
Colors have a way of captivating the senses and triggering emotions, while evoking any number of other sensations. For example, the color green may be evocative of the smell of grass, yellow may evoke the sour taste of a lemon and red echoes the sound of a 1967 Rally Red Chevrolet Corvette along with its 427 cu. in. Turbo-Jet V8 engine racing down the street. In the plastics industry, color encapsulates the same senses, emotions and sensations that bring simple everyday life to plastic products that are encountered on a daily basis. Co-rotating intermeshing twin screw extruders are exceptionally suitable for the processing of color pigment masterbatches, providing excellent mixing properties to make a homogenously consistent product. Of course, processing of color pigment masterbatches comes with its own set of challenges, such as handling of raw ingredients, dispersion of pigments and cleanliness between color changes. However, twin screw extruders offer benefits, such as excellent dispersion at high throughput rates, high pigment loading levels, long lifetime of screw and barrel parts and simple machine operation. This paper will explore the tools that are available for producing quality color pigment masterbatches, as well as techniques to overcome processing challenges while maximizing throughput and product quality.

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12:00 PM Adjourn  
Day 2 – April 7th  
Rheology & Polymer Modification  
9:30-10:00 am Tailoring Melt Strength of PP using an additive
Brett Robb, Application Chemist, Total Petrochemicals & Refining USA
Polypropylene is a semi-crystalline polymer with low melt strength. HMS-PP is often used to overcome this deficiency. Adding Dymalink 9200 into PP creates a unique dynamic network leading to unusually high melt strength behavior even at very low loadings. This allows for a tailored approach to high melt strength in PP-based homopolymers, copolymers, and elastomers that are used in extrusion and foaming applications. Additionally, the boost in melt strength allows for increased incorporation of regrind. Finally, the increase in melt strength can expand the applications for post-industrial and post-consumer recycled PP, allowing it to be thermoformed or foamed.

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10:00-10:10 am

Break — Gold Sponsor

Injection Molding  
10:15-10:45 am Polypropylene Compounds with Enhanced Melt Flow for Injection Molding Application to Meet Stringent Flame Retardancy Requirements
An Du,Product Development Manager, PMC
Non-halogenated flame retardant polypropylene (PP) compounds have become a new trend for different markets and applications to comply with strict environmental regulations. PMC Polymer Products has developed a new PP compound that is non-halogenated by using a proprietary intumescing and flow enhancing technology for injection molding applications. The flow enhancer helps with dispersing additives, colorants and fillers as well as improves the practical melt flow. With the shear thinning effect, flowability during injection molding process is improved significantly compared to standard flame retardant PP compounds at the same injection pressure and temperature. The proprietary intumescing technology also allows the PP compound to meet different flame retardancy requirements, such as UL-94 V-0 rating, low peak heat release rate and low smoke production using the cone calorimetry testing method (ASTM E-1354). This environmentally friendly PP compounding technology has helped PMC Polymer Products to widen our product portfolio and strengthen our visibility in the flame retardant market.

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10:45-11:15 am Hot Runner Variability and Options for Improved Control
Matt Carnovale, Engineering Group Leader, Teleflex

While our industry has made significant advances in terms of machining methods and process development approaches such as what is commonly referred to as Scientific Injection Molding, there is seemingly a lack of understanding of the sources of variation that keep us from being even more successful and in the worst of cases cause us to regress.

Hot runner systems like any other thermal process are going to be a source of variation. Ideally it is “normal” variation and once the system reaches equilibrium, it proves to yield consistently molded components from cycle to cycle, i.e. the process is under control. Unfortunately for a number of reasons described below that is not always the case when hot runners are in play.

Important is that the hot runner system will permit a manageable level of fill balance across multiple cavities. The challenge is getting a hot runner supplier to commit to a given fill balance. Their response is often that they cannot given not all elements of the process are under their control, i.e. there can be tooling differences from cavity to cavity inclusive of gate size and the process may not have been optimized. Sometimes the response is it “depends” but they’re not clear as to depend upon what.

The majority of our work here at Teleflex has been with valve gated hot runner systems. The use of such systems however is still relatively new to the company. Our place in that learning curve is likely contributing to the challenges we face – perhaps as simple as not knowing the right questions to ask.

Like many others, Teleflex is using valve gated hot halves to provide one with a means to gate into otherwise difficult locations while still meeting cosmetic expectations for the gate region of the part. We’re also doing our part to be green and not creating unnecessary waste.

What follows is a list of issues we’ve encountered during my relatively short time here at Teleflex:

  • Supplier of hot half completes CAE work but it is often once and done and does not necessarily address issues that will limit the consistent use of the system
    • For example, we typically concern ourselves with three items:
      1. Pressure drop through the system
      2. Shear influence on the melt as the plastic is made to flow and
      3. Residence time (number of cycles) held within the manifold and drops
    • Too often we’ve receive this work after the fact, i.e. the system is designed and built
    • A common oversight seems to be that the system as designed and built has too great of a residence time for the material being molded.
    • That compromise may have been acceptable had it not been a case where the predicted pressure drop was relatively low and the estimated shear influence was well within the limits for the material
  • There is seemingly a “it worked that way before” or a “one size fits all” approach to hot half designs and therefore why should we even consider doing it some other way
    • We’ve had tools where the gate and therefore the valve pin is sized too small for the particular material in question.
    • We’ve had situations where a valve gated hot half uses pneumatically actuated piston to open and close the valve pin only to find out that the pistons in use are plumbed in series and therefore are not all opening at the same time nor closing at the same time.
    • We’ve learned only after struggling through fill imbalance challenges and shot repeatability struggles that the amount of air flow to the pistons was not to the hot runner supplier’s specifications
      • One may say that is upon the user to confirm the applied pneumatics are appropriate
      • My position is that the hot runner supplier should have a standard approach to insure not only their elements of the system are correct but that all inputs inclusive of pneumatics and controls are appropriate.
  • There are also shear imbalance issues with hot runner systems that hot half suppliers are seemingly unwilling to take ownership of
    • The exception is likely INCOE given their partnership with Beaumont to provide “melt flipping features” within the manifold to counteract those shear imbalances
      • We have investigated but do not to date have hands-on experience
    • Even when a patented solution such as that provided by INCOE and Beaumont is not utilized, there are design features for the manifold that can be incorporated to counteract a potential shear imbalance
      • The most common counter-action is an elevation step or two
  • Including those steps makes the hot half of therefore the mold “thicker”
  • It becomes however a challenge if and when that overall stack height for the mold does not fit into the intended press
    • The choices are leave it out of the hot half design or buy a new press
    • What do you think happens?
  • We’ve seen that the cooling water pattern used around the drops is such that the cooling influence when the water first comes in to the mold is not the same as that delivered to the drops at the tail end of the cooling water channel
    • This can manifest itself into fill balance issue. A classic example was when we were able to change the fill such that the half of the mold that was filling first filled last simply by reversing the IN and OUT cooling lines to the manifold
    • We’ve also seen evidence that the amount of cooling water delivered to the hot half of the tool is not enough
      • This result is often a chimney effect in which unmanaged heat from the lower half of the mold rises into the top half of the mold causing cavities in that region to fill faster
      • It also can manifest itself into component issues such as sticking & cracking
  • Under the category of not understanding the functionality of the hot half system is the “spring effect” that exists in every hot runner system.
    • The influence of that “spring effect” will vary by material type, to some extent melt temperature, by gate size, flow path channel sizes, the effectiveness of the control of the tip temperature and ultimately how much melt is being held in the manifold at any one time (see above CAE opportunity)
    • For very small parts in which individual cavities are less than 1 gram each it can and does create havoc
    • The delivery of the melt starts and if it does not immediately release through the gate, the controls of the injection molding machine are going to counteract what is happening by applying more force (pressure)
    • When it does release it is instantaneous and if the screw has already moved a significant portion of the shot size, the rest of the delivery is more or less out of control
      • It can dramatically influence the percent full of the part prior to transfer from velocity control to pressure control
    • As a result, our use of hot runners with smaller parts has compromised our Scientific Injection Molding approach to the process
      • Our work around has been to reduce the plastic flow rate
      • Then when variations in viscosity occur, and it always does, we’re more likely to see differences in the parts
      • We also see that the process window is significantly reduced

When we are fortunate enough to witness consistency of fill from cycle to cycle, we are able to adjust drop temperatures to improve fill balance. To that end it is our intent to incorporate the PRIAMUS Control H solution in which we will monitor when the melt reaches a very small temperature sensor in each cavity and based upon the calculated first to last time difference, close loop control with the hot runner temperature controller. We’re optimistic it will permit us to open our processing windows considerably.

With regards to controllers, we also find that they’re not all equal. Many controller suppliers do a good job of controlling the rise of temperature during startups. Once the actual temperature reaches setpoint, that is where we tend to see differences between controllers. Some for example control to first decimal place temperature while others control to only whole numbers. As to what is actually needed naturally depends upon the application.

Additionally but not likely last is the maintenance that is required for these systems. The nature of a valve gated hot runner is that fits and clearances need to be precisely controlled. Otherwise we get plastic where is was never intended to be and our efforts are further compromised. As the plastic is melted it needs to outgas and the hot runner systems typically have design features to permit venting of those gasses out of the system. That venting process however often leaves residue as the gas condenses and in turn those vent features, just as we see in the mold, get clogged. If it was as easy to clean these vent features as it is for cleaning the vents in the mold then no problem but the hot runner vents often require disassembly. The risk is that our technicians are not as skilled as they need to be to accomplish such tasks without inadvertently impacting the hot half design intent. We recognize it is a training issue but also implore the hot runner suppliers to consider user friendliness.

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11:15 – 11:25 am

Break — Silver Sponsor

Graduate Student Presentations  
11:30 – 12:00 pm Vibration Assisted Injection Molding: A Dynamic Melt Modulation Technique for Faster Production and Enhanced Properties
Peng Gao, Graduate Student, Lehigh University
Vibration assisted molding (VAIM) is a process which an oscillatory motion is introduced to injection screw during injection stage. In this process, the travel of the injecting screw is moved back and forth to introduce a compression-decompression cycle in the polymer melt in the die cavity, the frequency, duration and the initiation point of which can be individually controlled. It has been demonstrated that polystyrene (PS) and Polylactic Acid (PLA) parts fabricated via VAIM had enhanced mechanical properties. This research is focused on understanding the effect of the various processing parameters on physical characteristics of PLA parts. A detailed investigation of the crystallinity development in the PLA parts has been carried out utilizing x-ray diffraction and differential scanning calorimetry (DSC) techniques. It has been observed that the degree of crystallinity increased significantly with the introduction of the oscillatory motion. The frequency of the oscillation critically affects the overall crystallinity, crystal structure and the sizes of crystalline domains in the PLA parts. In addition, the processing cycle time can be reduced by as much as 40% with the VAIM technique. The faster cycle time was achieved by reducing the cooling time drastically without sacrificing the dimensional stability of the molded parts.

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12:00– 12:30 pm Experimental Analysis of Inducing Crystallization on Polymer Melt by Altering Flow Area in Additive Manufacturing
Hussam Noor, Graduate Student, Lehigh University
Although additive manufacturing has been around for decades, it has not lived up to its potential. Thus, a new manufacturing method that enables additive manufacturing to control the properties of each single rod is proposed. A novel patent pending additive manufacturing technique has been developed in the Manufacturing Science Laboratory at Lehigh University.The technique utilizes an extrusion based 3D printer, which has the ability to regulate the gab of the polymer flow inside the extrusion head, thus, allowing precise control over shear rate applied to polymer melt. The controlled shear alters the melt rheology, which in turn controls the evolution of crystallinity in the printed parts. The temporal control of shear translates to spatial control of melt rheology. Thus, the localized evolution of molecular orientation and nucleation/ crystallization kinetics as well as the mechanical and optical properties can be precisely controlled during the additive manufacturing process. This research is focused on semi crystalline poly-lactic acid (PLA), a plant based biodegradable polymer. The effect of application of shear on PLA is investigated analytically and validated experimentally. The primary focus is on the role of confinement of polymer melt at the tip of extrusion. The confinement will induce shear on the polymer the degree of which can be controlled by the gap between the conical cavity and the conical extruder tip. The analytical modeling results indicate that this strategy can increase the induced shear rate by a factor of four. Preliminary experimental analysis validated an increase on cystallinity percentage for up to 6%. Resulting in the ability to precisly control the local properties of the printed rod.

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12:30pm Adjourn  



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