The SPE Library contains thousands of papers, presentations, journal briefs and recorded webinars from the best minds in the Plastics Industry. Spanning almost two decades, this collection of published research and development work in polymer science and plastics technology is a wealth of knowledge and information for anyone involved in plastics.
The excess pressure losses due to end effects in the capillary flow of a metallocene linear low-density polyethylene (m-LLDPE) were studied both experimentally and theoretically. They were first determined experimentally as a function of the contraction angle (8° to 150°). It was found that the excess pressure loss function increases with increasing contraction angle from 8° to about 30° and consequently decreases up to contraction angles of 150°. Numerical simulation using a multimode K-BKZ viscoelastic equation and a purely viscous equation (Carreau model) have shown that the excess pressure loss function decreases monotonically with increasing contraction angle, an observation that contradicts the experimental results. The origin of this disagreement is also discussed.
Steve E. Amos, Maria P. Dillon, Susan S. Woods, William Coggio, Joyce Kunde, May 2001
Polymer processing additives are used to reduce melt fracture, increase the processing window and eliminate die lip build-up and gels in polyolefins. There are additives that can interfere with the performance of the PPA by four main mechanisms - adsorption, abrasion, site competition and chemical reaction. Strong bases such as hindered amine light stabilizers (HALS) can cause the PPA to lose effectiveness due to both site competition and chemical reaction. Introduced is a next generation, non-reactive PPA that has improved performance compared to conventional materials.
Plastic hinges are subjected to different types of stresses during service. Some case studies are presented in this paper to show the effect of service history, processing conditions, and part design on hinge failure. Microscopic analysis was used in these investigations to identify the fracture features. Additionally, Finite Element Analysis was used to estimate the stresses on the hinges during service. The first case shows mainly the effect of adverse service history on the hinge performance. The second case illustrates primarily the importance of appropriate processing conditions in preventing hinge failure. The third case describes essentially the combined contribution of end-use and part design on limiting the hinge lifetime.
Manish Seth, Franky Yip, Savvas G. Hatzikiriakos, May 2001
The effect of a new processing additive (boron nitride powder in combination with a fluoroelastomer) on the rheology and processability of molten polymers is studied. The equipment used include an Instron capillary rheometer equipped with a special annular die (Nokia Maillefer wire coating cross-head), a twin screw extruder equipped with a blow moulding unit, and a parallel-plate rheometer. Metallocene polyethylenes with and without boron nitride (BN) and fluoroelastomer are tested in extrusion and conventional high density polyethylenes with and without BN with fluoroelastomer are tested in Blow moulding operations. First, it is demonstrated that BN is a superior processing aid compared to conventional fluoropolymer ones. Secondly, it is found that the combination of BN powders with a small amount of a fluoropolymer improves even further the processability of molten polymers (melt fracture performance).
Adding valve" means to a screw is a concept of screw design optimization in a way of matching four normally concerned processing functions. The four processing functions are conveying melting mixing and pressurizing. This paper discusses the relationships between these four functions and promotes design ideas as to how to change them individually. A design called "valve screw" which contains a screw body groups of shear rings and a tube shaped tip are proposed. The shear rings and tube tip serve as valve means controlling / enhancing mass flow rate melting rate and mixing rate. Pressurizing is also indirectly controlled. A high efficiency overall optimized operation is therefore achieved."
Barrier screw design follows a design philosophy as to keeping melt separate from solid. This leads to ununiform shearing, i.e. all shearing takes within the place of the thin film between the solid bed and the barrel inner surface while the main body of the solid bed has been left no shear at all. The present shear ring screw" breaks the solid bed into small pieces (or individual pellets) at early stage of melting. This would be achieved by using shear rings with series of angled flow through ports which makes the ring self-driven by fed material. "Drag induced melt removal melting mechanism" [12] or "laminar segregated melting mechanism" [3] converts to "pulse dissipative mix-melting mechanism". It is proved theoretically as well as experimentally by Chung and Wang [6] that the heating time required for melting decreases exponentially with decreasing the pellet size and the heat transfer coefficient h (cal/cm2-s-°C) increases substantially due to convections around pellets. These are roots of current design."
The objective of this study is to evaluate the effects of functional polyolefin elastomer (FPOE) on the morphology, and mechanical properties of the blends of polypropylene (PP) and polyamide 6,6 (PA 6,6). PP was blended with different weight concentration of PA 6,6 and functional POE. All blends were carried out in a reactive twin-screw extruder. The mechanical properties of the blends, such as tensile strength at yield (?y), modulus of elasticity (E), and elongation, were examined. Moreover, their morphological behavior was investigated through scanning electron microscopy (SEM). It is clearly indicated that the morphology structure can be controlled through functional POE. It was found that the morphology of the cryogenic fracture surface of the blends was dramatically changed, from micron fibers in the mechanical blending to sub-micron fibers in the reactive blending. The tensile strengths at yield (?y), and modulus of elasticity (E) of the blends with functional POE are increased relative to mechanical blends. However, the elongation of the reactive blends is decreased. These results illustrated that the functional POE can be employed as a effective compatibilizer in the blends of PP and PA 6,6. It stands to reason that functional POE can reduce interfacial tension preventing the blends from agglomerating as well as leading to smaller domain size and better dispersion of PA 6,6 phase in the PP matrix.
This paper presents experimental results on the blends of polypropylene (PP) with functional polyolefin elastomer (FPOE) for recycling of xerographic toners. All experiments were carried out in a co-rotated reactive twin screw extruder. The investigation of the mechanical properties and morphology for different blends consist of PP, xerographic black toners and functional POE (FPOE) through reactive compounding. It is of interest to note that the notched Izod impact resistance of the blends with functional POE (FPOE) is significantly improved relative to physical blends. However, tensile strength at yield (?y) and modulus of elasticity (E) of the reactive blends are reduced. The reason why the impact properties should be so is clearly shown by the stress-strain behavior of the blends. Morphology of the cryogenic fracture surfaces of the blends was studied through scanning electron microscopy (SEM). The results of morphological studies indicated that not only the domain size of the phase of black toners could be reduced but also the interfacial adhesion could be enhanced through proper functional POE (FPOE). The phase morphology of the blends also illustrated that better dispersion of black toners could be obtained through using FPOE whereas serious agglomeration of black toners was found in the physical blends. It is elucidated that the functional POE could be an excellent candidate of compatibilizer for recycling xerographic black toners.
The current lack of qualified operators in the blow molding industry and its effects on blow molding operations is described. The need for the training of blow molding operators is illustrated. Different methods of training are described and evaluated with respect to their effectiveness. The reasons for the lack of trained operators are shown and from there new training methods are developed overcoming some of the shortcomings of other methods. It is shown that only training material closely resembling the actual plant conditions is well accepted by trainees. Engineering concepts need to be translated into understandable training materials. Retention levels are improved by giving short tests challenging the trainees into thinking about the material presented. Given the right methods, one can teach more complex relationships between material properties, machine functions, and settings.
The reciprocating-screw (RS) injection molding machine for microcellular foam has been successfully developed. It creates the necessary conditions for a single-phase solution with a specially designed plasiticizing unit. An overall system is the key for successfully implementing a microcellular foam process. The important components for the microcellular foam molding machine system including a plasticizing unit, injection unit, hydraulic unit, clamp unit, gas unit, are discussed in this paper. The general guidelines to design an injection molding machine for microcellular foam are listed as the conclusions.
Boris L. Serebrennikov, Nick R. Schott, Miftahur Rahman, May 2001
The thermal properties of polymers such as thermal conductivity, k, heat capacity, Cp, and thermal diffusivity, ?, are important properties that affect polymer processing economics due to their critical influence on cooling time and cycle time (1). For cooling calculations one needs the physical properties of k, ?, and Cp to calculate the thermal diffusivity. These vary with each resin and also with the additives, fillers and reinforcements. The task of collecting these data is almost insurmountable since the U.S. has about 8000 resin grades recognized by UL (Underwriter’s Laboratories) and a total of about 30,000 grades are commercially available. By injection molding and experimentally determining the thermal diffusivity under actual molding conditions one can eliminate the individual measurements of k, ? and Cp and instead measure the thermal diffusivity directly. The objective of the study was to show that this is a practical approach to the evaluation of the thermal diffusivity for injection molding cooling calculations.
N. Sanjeeva Murthy, Val A. Kagan, Robert G. Bray, May 2001
Crystalline texture and mechanical (tensile and flexural) properties of injection molded nylon 6 were evaluated to understand the influence of one of the key-processing variable, the melt temperature (Tmlt). We find that mechanical properties are sensitive to Tmlt only below ~ 250°C. Rapid quenching of the surface produces a skin with lower crystallinity than the core, which cools more slowly; this difference in the rate of cooling produces ? crystalline form in the skin and ? crystalline form in the core. Higher tensile strength at yield, lower elongation at break and higher flexural strength were observed in specimens molded at lower Tmlt. These characteristics are associated with thicker and less ordered skin, and a lower crystallinity core. The role of the Tmlt on micro-structure and mechanical properties of injection molded nylon 6, the development of skin and core morphologies, and the role of the residual stresses in the core are discussed.
Nikos G. Pantelelis, Andreas Malikopoulos, Andreas Kanarachos, Nikos Efentakis, May 2001
At this paper the simulation of a gas-assisted injection molded part will be studied. Several gas injection strategies will be developed and simulated using the C-Mold software. As the Gas-Assisted injection molding is a complicated process with many parameters to tune, a detailed analysis of the effects of each processing parameter at the final product will be simulated. Furthermore, a test mould for a commercial product has been constructed and the simulated results will be compared to the real outcome of each strategy. In this way, the accuracy of the simulations according to each production strategy will be evaluated and guidelines will be drawn according to the outcome of these evaluations.
Matthew L. Clingerman, Jeremiah P. Konell, Erik H. Weber, Julia A. King, Kirk H. Schulz, May 2001
The conductive properties of polymers can be improved by adding carbon fillers. The effect of filler content on the mechanical properties must also be considered. High filler concentrations used to maximize thermal and electrical conductivity can degrade mechanical properties. In this study, chopped and milled Polyacrylonitrile PAN-based carbon fibers, nickel coated PAN-based carbon fibers, and a synthetic graphite were added to nylon 6,6 to determine filler amounts needed to obtain acceptable conductivity and mechanical properties.
Poly(aryl ether ketone ketone) was melt-blended with a thermotropic liquid crystalline aromatic copolyester, Vectra 950A. A miscibility of the blend was investigated by dynamic mechanical analysis and differential scanning calorimetry. These polymer blends were found to form partial miscible blends. Glass transition temperature (Tg) and crystallization behavior of each phase in the blends were found to be affected by counterpart component. Tgs of each phase in the blends shifted toward each other compared to those of pure polymers. Slight depression of Tm of both component was observed in the blends. When the crystallization temperature is above the melt temperature (Tm) of LCP, the crystallization rate of PEKK in the blends decreased while it increased at the temperature below Tm of LCP. This result was discussed in terms of phase separated nucleation effect.
Mixing is a key step in almost every polymer processing operation. The traditional methodology for improving machinery performance has relied more on users' experience and trial and error experiments. Recently, the fast development of advanced computing resources has enabled the use of numerical modeling as an alternative and more efficient approach in studying the influence of design and processing conditions on equipment mixing performance. In this work using numerical simulations we record the flow history of a number of tracers in the equipment and use them in conjunction with dispersion kinetics models to evaluate minor component size and concentration distributions.
J.M. Nóbrega, O.S. Carneiro, F.T. Pinho, P.J. Oliveira, May 2001
In this work a methodology to automatically balance the flow in profile extrusion dies is used. For this purpose a computational code, based on the finite-volume method, was developed and used to perform the required three-dimensional numerical simulations of the flow. The methodology is illustrated using two case studies, each one leading to the adoption of a different constructive solution (with and without flow separators). In order to evaluate the quality of the automatically generated die geometries, an objective function, that takes into account the flow balancing and the ratio L/t of the parallel zone, is proposed.
M.J. Oliveira, F.M. Duarte, D. Tchalamov, A.M. Cunha, May 2001
The reinforcement of thermoplastics with short glass fibers is a common way for obtaining composites with high strength and stiffness. These materials are amenable for welding by the hot plate method, although a drop in the mechanical strength is observed. In this paper 20% glass reinforced polypropylene (GRPP) was injection molded in mono-material and bi-material (PP/GRPP) ISO-type tensile testing specimens and welded using the hot-plate technique. Morphological analysis and mechanical testing were used to investigate the effect of the processing parameters and type of molding on the weld behavior. It was found that the welds made with PP/GRPP moldings are stronger than if only GRPP is used in the moldings.
The design of a screw for polymer extrusion based on scientific principles is still a challenging task, which has received relative little attention in the literature. Prior to the definition of the geometric parameters of the screw, the designer has to decide about general features, such as the type and location of mixing zones, which is mainly based on empirical knowledge. Once the main process criteria are identified (e.g., pressure generation capability, mixing efficiency, power consumption), the design is then carried out on a trial-and-error basis. In the present work we consider screw design as an optimisation problem where the aim is to maximise the value of an objective function that describes quantitatively the process performance. A design methodology incorporating this approach is presented. The relevance of the solutions and the sensitivity of the method to changes in the criteria considered are demonstrated with various examples.
Choon K. Chai, Gordon Adams, Jason Frame, May 2001
Die deposit (sometimes known as die drool, die lip build-up, etc) occurs in melt extrusion of polyolefins. It is an undesirable build-up of material, normally on the lip or open faces of extrusion dies. In commercial scale polyethylene extrusion processes (e.g. blown or cast film, fibre spinning, etc), die deposit can have a significant influence on productivity, through the need to shut down processing line periodically to clean the die, and on the end-product quality. There are a wide range of factors or sources that lead to the formation of die deposit as its mechanism is not understood, these include low molecular weight species and volatiles, die swell, die design and polymer structure. This paper investigates, through laboratory-scale extrusion and rheology evaluations, some of the key relationships in the die deposit formation process. A deposition mechanism is thus proposed from these studies, with some suggestions for its reduction.
Kim McLoughlin Senior Research Engineer, Global Materials Science Braskem
A Resin Supplier’s Perspective on Partnerships for the Circular Economy
About the Speaker
Kim drives technology programs at Braskem to develop advanced polyolefins with improved recyclability and sustainability. As Principal Investigator on a REMADE-funded collaboration, Kim leads a diverse industry-academic team that is developing a process to recycle elastomers as secondary feedstock. Kim has a PhD in Chemical Engineering from Cornell. She is an inventor on more than 25 patents and applications for novel polyolefin technologies. Kim is on the Board of Directors of SPE’s Thermoplastic Materials & Foams Division, where she has served as Education Chair and Councilor.
A Resin Supplier’s Perspective on Partnerships for the Circular Economy
About the Speaker
Gamini has a BS and PhD from Purdue University in Materials Engineering and Sustainability. He joined Penn State as a Post Doctorate Scholar in 2020 prior to his professorship appointment. He works closely with PA plastics manufacturers to implement sustainability programs in their plants.
A Resin Supplier’s Perspective on Partnerships for the Circular Economy
About the Speaker
Tom Giovannetti holds a Degree in Mechanical Engineering from The University of Tulsa and for the last 26 years has worked for Chevron Phillips Chemical Company. Tom started his plastics career by designing various injection molded products for the chemical industry including explosion proof plugs and receptacles, panel boards and detonation arrestors for 24 inch pipelines. Tom also holds a patent for design of a polyphenylene sulfide sleeve in a nylon coolant cross-over of an air intake manifold and is a Certified Plastic Technologist through the Society of Plastic Engineers. Tom serves on the Oklahoma Section Board as Councilor, is also the past president of the local Oklahoma SPE Section, and as well serves on the SPE Injection Molding Division board.
Joseph Lawrence, Ph.D. Senior Director and Research Professor University of Toledo
A Resin Supplier’s Perspective on Partnerships for the Circular Economy
About the Speaker
Dr. Joseph Lawrence is a Research Professor and Senior Director of the Polymer Institute and the Center for Materials and Sensor Characterization at the University of Toledo. He is a Chemical Engineer by training and after working in the process industry, he has been engaged in polymers and composites research for 18+ years. In the Polymer Institute he leads research on renewably sourced polymers, plastics recycling, and additive manufacturing. He is also the lead investigator of the Polyesters and Barrier Materials Research Consortium funded by industry. Dr. Lawrence has advised 20 graduate students, mentored 8 staff scientists and several undergraduate students. He is a peer reviewer in several journals, has authored 30+ peer-reviewed publications and serves on the board of the Injection Molding Division of SPE.
Matt Hammernik Northeast Account Manager Hasco America
A Resin Supplier’s Perspective on Partnerships for the Circular Economy
About the Speaker
Matt Hammernik serves as Hasco America’s Northeast Area Account Manager covering the states Michigan, Ohio, Indiana, and Kentucky. He started with Hasco America at the beginning of March 2022. Matt started in the Injection Mold Industry roughly 10 years ago as an estimator quoting injection mold base steel, components and machining. He advanced into outside sales and has been serving molders, mold builders and mold makers for about 7 years.
84 countries and 85.6k+ stakeholders strong, SPE
unites
plastics professionals worldwide – helping them succeed and strengthening their skills
through
networking, events, training, and knowledge sharing.
No matter where you work in the plastics industry
value
chain-whether you're a scientist, engineer, technical personnel or a senior executive-nor
what your
background is, education, gender, culture or age-we are here to serve you.
Our members needs are our passion. We work hard so
that we
can ensure that everyone has the tools necessary to meet her or his personal & professional
goals.
Need help from SPE Headquarters?
SPE HQ provides a range of services to Chapters. If you are a chapter and need HQ services (i.e.,
event registration - full list of HQ services can be found here), please fill out and submit the HQ services request form found
here: www.4spe.org/HQservices.
IMPORTANT! If you are simply looking to post your
event on SPE's calendar, please click the "Submit an Event" button below. All events
submitted for inclusion in the SPE calendar are subject to approval.
Going to a SPE event?
If you are going to a SPE event and need a Visa invitation letter, please submit your request for a Visa Invitation letter.
SPE Members receive discounted rates on all event registrations. Not a member of SPE? Join today!
How to reference articles from the SPE Library:
Any article that is cited in another manuscript or other work is required to use the correct reference style. Below is an example of the reference style for SPE articles:
Brown, H. L. and Jones, D. H. 2016, May.
"Insert title of paper here in quotes,"
ANTEC 2016 - Indianapolis, Indiana, USA May 23-25, 2016. [On-line].
Society of Plastics Engineers, ISBN: 123-0-1234567-8-9, pp. 000-000.
Available: www.4spe.org.
Note: if there are more than three authors you may use the first author's name and et al. EG Brown, H. L. et al.
