SPE Library
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.
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Conference Proceedings
Reduced Order Kinetic Model for Corrosion of High-Density Polyethylene in Bleach Solutions
Susan Mantell, May 2020
A reduced order kinetics model is proposed for the corrosion of polyethylene in bleach solution. Hypochlorous acid (ClOH) is considered as the oxidizing agent which is formed from the hydrolysis of bleach. The model simulates the diffusion of ClOH into the non-polar polymer matrix followed by its dissociation into radicals. The reaction between the radicals and the polymer is phenomenologically modeled using an ordinary differential equation. The model is suitable for coupling with mechanical models for life-time analyses of polymers members under mechanical loading and exposure to corrosion. The model captures the effect of the chain oxidation process which causes the accelerated aging of the polymer.
Reduction of Demoulding Force Through Innovative Surface Modification
Ruben Schlutter, May 2020
Plastic parts are becoming more and more complex. Thus, the demolding of such parts is becoming more and more challenging. Meanwhile it is difficult to reproduce the conditions, appearing during the demolding of a part from a molding tool. To overcome this gap a simple and robust test setup has been developed to measure the necessary torque to demold a plastic test specimen from a defined surface of a test blank. During the test, two variables are measured and evaluated, the adhesion torque, which describes the loss of adhesion between the plastic test specimen and the metal surface of the test blank, and the sliding integral, which describes the torque needed to overcome the sliding friction between friction partner. As a result of the tests the influence of the used plastic, the influence of the process and the influence of the functionalizing of the metal surface via structuring and coating on the demolding behavior is shown.
Reinforced Thermoplastic Containing Recycled Cardboard Fibers for Recreational Vehicles Applications
Liqing Wei, May 2020
Lightweight reinforced thermoplastic (LWRT) composites are ideal for the recreational vehicle (RV) industry where traditional building materials are unable to provide the performance required. The LWRT composite is more durable and can be assembled for RV exterior and interior sidewall, ceilings, and roofs of both towables and motorhomes. Due to lighter weight, LWRT-based RVs may provide opportunity for towing with smaller vehicles, can be more fuel efficient, or can carry more cargo than traditional, wood-based RVs. This paper presents the initial investigations into the properties of LWRT composite panel produced from recycled (or old) corrugated cardboard (OCC) fiber, glass fiber and thermoplastic materials using a wet-laid process. New composite systems have been obtained varying the loading levels of OCC fibers (0, 10, and 20 %) and density of the resultant composite panels. The flexural test results showed panels made from OCC fibers were 30 to 50 % stronger and stiffer in machine direction (MD) and 30 to 40 % stronger and stiffer in cross-machine direction (CD) than the control composite material without OCC fibers. The sound absorption properties of the composite panels containing OCC fibers depend on the loadings of OCC fibers and the density of the panel, and 20 % OCC fiber-based composite showed best sound absorption results. The addition of OCC fiber resulted in a smoother surface and better aqueous glue compatibility than the control composite material. In addition, the flame retardancy results showed the addition of OCC fibers decreased the flame spreadability (FSI = 30) according to ASTM E84 standard. The results suggested that sustainable fibers could be used to produce strong and stiff composite panels with significantly lighter weight.
Reliability Evaluation of Conductive Tracks Integrated Into Additively Manufactured Components
Kaja Schmidt, May 2020
The use of 3D printing technologies enhanced with component placement and electrical interconnect deposition can provide structural electronic systems with higher fabrication freedom. Thermosetting resins that are used as adhesives in electronic packaging processes have the potential to fulfill new requirements coming from this application. Their use as building and conductive materials in additive manufacturing can lead to advantages, especially when selecting the same chemical basis. In this work, an extrusion-based additive manufacturing process was used to process the adhesives. A basic concept is introduced how the integration of electrical components and conductive tracks can be realized with this process-material combination and experimental work on two-dimensional tracks is presented. The developed process and the material selection for 2D-tracks was evaluated electrically as well as mechanically and was supported by highly accelerated life tests to ensure reliable performance. Different aspects of the integration were covered with three experiments that provide an understanding of properties of conductive adhesives printed as a tracks as well as their contacting behavior on SMD components. First design rules are derived from these experiments that can serve as a first step for developing processes for three-dimensional tracks and the procedure of contacting a component within the printing process.
Ship Less Air –Flexible Chip Bag Filling Simulation for Sustainability
Jay Yuan, May 2020
The snack flexible packages on the market today, such as potato chips, pita chips, taco chips, tortilla chips, etc., are typically sold by weight, that is, the packages need to fulfill the label claims by weight. However, the size of the packages is determined by the overall volume of the products. The determination of the overall volume of a given product weight is not trivial. The volume is a function of chip broken rate, chip size distribution profile, bag width, bag film gage and material, production line speed (bag/minute), VFFS machine type, etc. Traditionally, the size of the bag is determined by trial & error process through iterative lab testing and production trials. This approach typically results in unnecessary large bags due to the concerns of sealing contamination induced leakage issues in the case of the bag being too small. This leads to significant sustainability issues in shipping and distribution since the shipping trucks are often cubed out by volume (not by weight) for chip/snack packages. The energy is wasted by shipping more air (thus, less chip/snack packages) during distribution. In this work, authors propose a novel approach of bag size determination by using a virtual simulation of the VFFS chip filling process, where the potential influential attributes, such as chip broken rate, chip size distribution profile, bag width, bag film gage and material, production line speed (bag/minute), and VFFS machine type, can be modeled and their impact on the bag size can be quantified. A progressive 3-case simulation is performed and presented in this paper. The results are directionally correct based on the authors’ observation and past experience. Currently, authors are looking for industry partners (brand owners, co-packers and machine manufacturers) to collect production data and validate the analysis model. The intent of this paper is to bring the awareness of applicability of the simulation technology regarding to the bag size determination and chip/snack filling process, and ultimately help the industry in adopting the technology to make the chip bag filling process more sustainable, i.e., to ship less air.
Simulation of a Saxton-Mixer in High-Performance Extruders Using the Immersed Boundary Method
Jochen Kettermann, May 2020
The Immersed Boundary Surface Method(IBS)is a novel and very promising implementation of the Immersed Boundary Method (IBM) for modeling complex, moving processes. In order to validate IBS for the first time in plastics processing, this paper deals with the numerical simulation of a Saxton-mixer in foam-extend (release of OpenFOAM)as a complex application geometry.The Saxton-mixer [1] is well suited for validation because it canstillbe solved using traditional simulationmethods, but is alreadycomplex enough to test andvalidate IBS within a real-worldprocessing environment. For this purpose, body-fitted andIBS simulations are performedin the same wayand their results compared. In addition, the mixing zone is also investigated experimentally in order to evaluate the model qualityof the simulations.The results of both simulation methods are consistent and differ only slightly. Thus, the implementation of IBS is valid. Furthermore, a comparison of the simulation model with experimentsreveals asignificant influence of the rheological flow model. The results of thenon-Newtonian IBS modelare already approaching the experiments well and are therefore promising results for further applicationsof IBSin plastics processing.
Simulation of Structure Development During Isothermal Crystallization of Semi-Crystalline Polymers
Tobias Daniel Horn, May 2020
Structures evolve at different scales when semi-crystalline polymers crystallize from the melt. During crystallization from a viscous melt or solution with moderate undercooling, the polymer forms lamellae by chain folding at the nanometer scale. These lamellae grow predominantly in radial direction and branch irregularly by non-crystallographic branching. By this, spherulites are formed at the micrometer scale. In this contribution, a simulation model for isothermal crystallization of semi-crystalline polymers is presented. For the simulation the polymer chains are divided into four different categories according to their mobility. In order to use a cellular automaton, different rules for diffusion and conversion are defined for the four categories. These rules cover the physical processes the chains experience during crystallization. With this simulation model, the crystallization of the polymer to a spherulite is simulated and compared to experimental results.
Stabilization of Polymers for a More Circular Economy
Ian Query, May 2020
Polyethylene and polypropylene are two of the most easily recycled polymers. Recycling polyolefins can result in downcycling to simple functional polymers, true recycling for reuse in the intended application, or upcycling of the polymer into higher quality products. To take advantage of the available feedstock and improve its utilization, stabilizers are can be added to allow the polymer to retain its original physical properties. A variety of customer-based case studies on recycling and upcycling will be covered showing how additives allow for improvements in the recycle stream.
Studies of Material Properties of Htpb- Based Composite Under Aging Conditions
Jaehee Jeong, May 2020
Hydroxyl-terminated polybutadiene (HTPB)-based rubber composite is usually used for solid propellant binder. In order to investigate the long-term material properties in the storage environment, it is recommended to set up the conditions refer to MIL-STD-810G. After aged for 100, 200, 300 hours with different temperature and humidity conditions, the key properties, i.e. tensile test, Fourier transform infrared spectroscopy (FTIR), and surface morphologies were examined. Also, by using these experimental data, diffusion model using finite element method suggested. This study will be useful for the life evaluation of HTPB-based composites considering diffusion.
Study On The Properties Of Microcellular Injection Molded Polyolefin/Polycaprolactone Composites
Chi-Chuan Hsu, May 2020
This study investigated the effects of polycaprolactone(PCL) loading on the morphology, tensile strength, and thermal properties of foamed injection molded PP and PPgMA composites. PCL is one of the biodegradable materials and can be used in heavy metal removal study. Results showed that PCL could increase tensile strength on PP but only small amount of it could enhance the tensile strength on PPgMA. PCL could affect the crystallization temperature and glass transition temperature both on PP and PPgMA. Storage modulus was enhanced by addition of PCL into PP and PPgMA.
Submicron Texturing of Injection Molds Using Femtosecond Laser
Leonardo Piccolo, May 2020
In injection molding, part thickness reduction is the main leverage to decrease process cost and material consumption. However, low thickness cavities require high pressure to be replicated. Controlling the surface properties of the mold/polymer interface can be a solution for drag reduction. Conventional micro- and nano-texturing technologies requires clean room environment, high-cost equipment, and are based on time-consuming multi-step processes. In this work, we presented a novel approach to sub-micron texturing of steel injection molds using femtosecond laser. A high-frequency and high-energy laser source is used to create regular and homogeneous ripples. The effect of these structures on the injection molding process are here discussed, showing how texturing can be used to reduce the injection pressure and promote wall slip.
Superhydrophobic Coatings for Encapsulation of Flexible Hybrid Electronics
K. Jaju | A. Bar | K. Puleo | J. Krantz | E. Keaney | J. Mead | D. Kazmer | B. Budhlall, May 2020
Recent advances in encapsulation process of Flexible Hybrid Electronics (FHE) provide routes to enormous application in advanced healthcare, smart layer based integrated sensor network, and digital microcontroller circuits. Stretchable/flexible encapsulation for advanced FHE devices requires new material sets and processes to ensure physical protection of any microchips in the FHE devices. Innovation in this research is creating a superhydrophobic coating that is spray coated and slot die coated on the FHE as an encapsulation process. The superhydrophobic coating is based on a cellulose acetate resin with hydrophobic silica nanoparticles and plasticizers incorporated. Here, two critical aspects are under examination; the content of plasticizer which is determined by glass transition temperature, migration and durability, and the hydrophobic silica nanoparticles which is determined by surface energy and durability. Both aspects are optimized and evaluated. Optimization of Spraying technique and its requirements is also under examination.
Surface Modifications of Cellulose Nanocrystals by Grafting Polylactic Acid via Polymerization—From Technique
Hormoz Eslami, May 2020
Cellulose nanocrystals (CNCs) have drawn significant attention in recent years owing to their specific strength, renewability, widespread availability and relatively low cost. As a result, they have gained scientific and commercial interest and are currently produced at a pilot scale in many jurisdictions for several polymer composite applications. However, their poor dispersion in typically non-polar polymer resins limits the translation of their exceptional nanoscale properties to the macroscale. In this paper,we presenteda method for the surface modification of CNC by grafting polylactic acid(PLA) onto CNCs. The dispersibility of the native and surface modified CNCs(SMCNC)in rubber latex is compared and reported here. SMCNC showed a very good dispersibility in both water and chloroprene rubber(CR)which make it a good candidate for latex composite applications.
The Advanced Study of Hybrid Molding by CAE Simulation
Yann-Jiun Chen, May 2020
Hybrid Molding is an emerging molding technology that is used in composite products. It has integrated molding characteristics, which can integrate multi-step process, save cost, reduce cycle time and make the product multifunctional. However, it is very hard to know what happened between composite sheet and melt during the process. In this study, we try to use CAE software to simulate the hybrid molding process. From the analysis results, it is possible to know the temperature change of composite sheet at any time and any place during the hybrid molding process, thereby helping to optimize the process and avoid possible problems.
The Challenge of Simulation For Ear-Flow Phenomenon In Injection-Mold Filling
Venny Yang, May 2020
Plastics applications are found in almost all areas of everyday living due to their versatility with an economically attractive choice in the manufacturing industry. Injection molding is the most common manufacturing process for producing plastic parts. However, there is a long-running problem requiring an urgent solution for the industry: to date, prior state-of-the-art predictive engineering tools have always provided unsatisfactory results regarding “so-called Ear-flow”, in which the advance of the flow front in the centre of the cavity is obviously slower than at the edges. Thus, the primary objective of this work is to simulate a reliable Ear-flow for neat polycarbonate (PC) material in injection molded disk via a new Moldex3D Flow solver coupled with the viscoelastic constitutive equation [U.S. Patent Pending in USPTO with Application No. 62/886,539 (2019)].
The Complexity of Service Life Prediction For Polyolefins In Chlorinated Disinfectants
Karin Jacobson, May 2020
Despite much effort, it is still very difficult to predict the service life of polyolefins when used in contact with the chlorinated disinfectants; chlorine, chlorine dioxide and chloramines. The actual degradation mechanism, both for the degradation of the additives and the subsequent, or in some cases parallel, degradation of the polymer, is still under debate. Also, it is not really that well known if chemical or physical properties are the most decisive in improved resistance to disinfectants. How much effect will the morphology, number and lengths of side chains, creep resistance, density, crystallinity, type and amount of stabilizer, number of tertiary hydrogens, double bonds, processing quality, solubility and diffusion rate of stabilizers, disinfectant and oxygen etc play? Since it is very difficult to change just one parameter at the time, this is quite difficult to investigate. For hot water pipes the aim is to have at least 50 years’ service life. Today the ASTM F2023 is used to test if a material will achieve this service life or not. Even if this testing is quite time consuming, with exposure times at the lowest temperature up to two years, or even longer, its validity to really predict the service life is quite questionable. The ASTM F2023 method is a pipe and materials test not a systems test and discards failures at fittings, while in fact this is often where the failure in service appears. In recent years a number of papers and presentations have been made presenting alternative accelerated testing methods and possible degradation mechanisms but very little can be found in the literature on investigations of pipes taken out of service and the correlation between the accelerated ageing with actual failures. This paper aims at describing the complexity in accelerated ageing and service life predictions of polyolefins in chlorinated disinfectants.
The Effect of Argon Plasma Irradiation On 3D Scaffolds For Bone Tissue Engineering
Katherine Wood, May 2020
Tissue engineering using 3D scaffolds is an alternative to bone repair techniques that are currently used, such as autografts or allografts for bone non-union. Plasma irradiation is used as a sterilization method and can alter the surface topography of the scaffolds. We have prepared 3D scaffolds composed of poly(lactic-co-glycolic)acid (PLGA) and nanohydroxyapatite (nHA) using thermally– induced phase separation (TIPS) and 3D-plotting (3DP) techniques. We have also performed experiments to study murine stem cell adhesion to scaffolds that have been plasma irradiated. The scaffolds that were plasma irradiated with argon gas had ~140% more cell adhesion compared to untreated scaffolds.
The Effect of Clamping Force on Product Quality: A Study on Platen Deformation
Wei-Jie Su, May 2020
The clamping force is a critical parameter to the stability of mold during injection molding process. An improper setting of the mold clamping force can adversely affect the service life of movable and stationary platens, tie bars, and molds. Thus, the clamping force is a key factor in product-quality consistency. This study bonded strain gauges to both sides of the movable platen to measure, in real time, strain changes in the platen under different clamping-force settings. The results were assessed using the corresponding cavity pressure and mold separation values to determine the molding clamping force’s effect on product quality (with respect to thickness, weight, and appearance). The findings indicated the following. (1) The mold clamping force is significantly correlated with cavity pressure, mold separation, and platen deformation. A low clamping force can cause mold separation to increase, which in turn results in greater platen deformation. (2) For the prediction of mold separation, strain gauges that are mounted on the movable platen can sufficiently replace displacement transducers that are placed within the molds. In other words, the condition inside the molds can be predicted using sensing devices outside the molds. (3) The analytic results for platen deformation and product quality indicate that an insufficient mold clamping force potentially results in excessive mold separation and platen deformation, causing flashing and an increase in product weight and thickness.
The Influence of Laser Power Variation on SLS-printed PA6 Parts and their Long-term Properties
Tobias Heckner, May 2020
In the field of Additive Manufacturing (AM), Selective Laser Sintering (SLS) is well-known as anAM technique to produce partswith comparatively high load capacity. The usage of Polyamide 6 (PA6) materials allowshigher continuous operating temperatures than Polyamide 12 (PA12) materials, which aretypicallyused forSLS. For this work,PA6 SLS specimens were printed with a high temperature SLS industry printer. The samples were aged thermo-oxidatively at different temperatures, tested mechanically and investigated with different analytical methods. The SLS processing of PA6 materials has not beenstudied sufficiently yet. The aim of this study was to deliver first contributions:the laser power energy wasvaried to identify the influence on the mechanical properties of the printed specimens andtheirlong-term properties. In addition, the material structure of the specimens wasinvestigated and the viscosity number (VN) was determined.
The Influence of Recycling On Thermotropic Liquid Crystalline Polymer and Glass Fiber Composites
Tianran Chen, May 2020
In this paper, high-performance thermotropic liquid crystalline polymer (TLCP)/polypropylene (PP) and glass fiber (GF)/PP composites were prepared by the injection molding process. Mechanical recycling of TLCP/PP and GF/PP composites consisted of grinding of the injection molded specimens and further injection molding of the granules. The influence of mechanical recycling on mechanical and thermal properties was investigated. In situ TLCP/PP maintains tensile modulus and strength during the recycling process, indicating the regeneration of polymeric fibrils at each reprocessing stage. GF/PP composite exhibits deterioration of mechanical properties after recycling because of fiber breakage during processing, which is a very common issue on reusing glass or carbon fiber reinforced composites. The experimental results reveal that the TLCP/PP composite has better recyclability than GF/PP and significantly enhances the mechanical properties of the blend.
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